Seaweed Bioactive Compounds against Pathogens and Microalgae: Potential Uses on Pharmacology and Harmful Algae Bloom Control.

PubMed

Zerrifi, Soukaina El Amrani; El Khalloufi, Fatima; Oudra, Brahim; Vasconcelos, Vitor

2018-02-09

Cyanobacteria are found globally due to their adaptation to various environments. The occurrence of cyanobacterial blooms is not a new phenomenon. The bloom-forming and toxin-producing species have been a persistent nuisance all over the world over the last decades. Evidence suggests that this trend might be attributed to a complex interplay of direct and indirect anthropogenic influences. To control cyanobacterial blooms, various strategies, including physical, chemical, and biological methods have been proposed. Nevertheless, the use of those strategies is usually not effective. The isolation of natural compounds from many aquatic and terrestrial plants and seaweeds has become an alternative approach for controlling harmful algae in aquatic systems. Seaweeds have received attention from scientists because of their bioactive compounds with antibacterial, antifungal, anti-microalgae, and antioxidant properties. The undesirable effects of cyanobacteria proliferations and potential control methods are here reviewed, focusing on the use of potent bioactive compounds, isolated from seaweeds, against microalgae and cyanobacteria growth.

Toxicity assessment of pesticide triclosan by aquatic organisms and degradation studies.

PubMed

Taştan, Burcu Ertit; Tekinay, Turgay; Çelik, Hatice Sena; Özdemir, Caner; Cakir, Dilara Nur

2017-12-01

Triclosan is considered as an important contaminant and is widely used in personal care products as an antimicrobial agent. This study demonstrates the biodegradation of triclosan by two freshwater microalgae and the acute toxicity of triclosan and 2,4-dichlorophenol. The effects of culture media and light on biodegradation of triclosan and the changing morphology of microalgae were systematically studied. Geitlerinema sp. and Chlorella sp. degraded 82.10% and 92.83% of 3.99 mg/L of triclosan at 10 days, respectively. The microalgal growth inhibition assay confirmed absence of toxic effects of triclosan on Chlorella sp., even at higher concentration (50 mg/L) after 72 h exposure. HPLC analysis showed that 2,4-dichlorophenol was produced as degradation product of triclosan by Geitlerinema sp. and Chlorella sp. This study proved to be beneficial to understand biodegradation and acute toxicity of triclosan by microalgae in order to provide aquatic environmental protection. Copyright © 2017 Elsevier Inc. All rights reserved.

Seaweed Bioactive Compounds against Pathogens and Microalgae: Potential Uses on Pharmacology and Harmful Algae Bloom Control

PubMed Central

Zerrifi, Soukaina El Amrani; El Khalloufi, Fatima; Oudra, Brahim; Vasconcelos, Vitor

2018-01-01

Cyanobacteria are found globally due to their adaptation to various environments. The occurrence of cyanobacterial blooms is not a new phenomenon. The bloom-forming and toxin-producing species have been a persistent nuisance all over the world over the last decades. Evidence suggests that this trend might be attributed to a complex interplay of direct and indirect anthropogenic influences. To control cyanobacterial blooms, various strategies, including physical, chemical, and biological methods have been proposed. Nevertheless, the use of those strategies is usually not effective. The isolation of natural compounds from many aquatic and terrestrial plants and seaweeds has become an alternative approach for controlling harmful algae in aquatic systems. Seaweeds have received attention from scientists because of their bioactive compounds with antibacterial, antifungal, anti-microalgae, and antioxidant properties. The undesirable effects of cyanobacteria proliferations and potential control methods are here reviewed, focusing on the use of potent bioactive compounds, isolated from seaweeds, against microalgae and cyanobacteria growth. PMID:29425153

Red light and carbon dioxide differentially affect growth, lipid production, and quality in the microalga, Ettlia oleoabundans.

PubMed

Yang, Ying; Weathers, Pamela

2015-01-01

Ettlia oleoabundans, a freshwater unicellular green microalga, was grown under different light qualities ± carbon dioxide-enriched air to determine the combined effects on growth and lipid production of this oleaginous species. Keeping total light intensity constant, when a portion of the cool white was replaced by red, volumetric lipid yield increased 2.8-fold mainly due to the greater yield of oleic acid, a desirable biodiesel precursor. Only 30 min of red light treatment was sufficient to increase lipid yield and quality to the same level as cultures provided red light for >14 days, indicating the potential role of red light in stimulating lipid production of this species. Carbon dioxide enrichment via air sparging enhanced exponential growth, carbon conversion efficiency, and nutrient consumption. Together, these results showed that light quality plays an important role in microalgal lipid production. Adjustment in light quality and gas delivery efficiency with carbon dioxide enrichment improved lipid yield and quality in this and possibly other oleaginous algal species.

Carbon biofixation and lipid composition of an acidophilic microalga cultivated on treated wastewater supplied with different CO2 levels.

PubMed

Neves, Fábio de Farias; Hoinaski, Leonardo; Rörig, Leonardo Rubi; Derner, Roberto Bianchini; de Melo Lisboa, Henrique

2018-05-15

This study evaluated productivity, CO 2 biofixation, and lipid content in biomass of the acidophilic microalga Chlamydomonas acidophila LAFIC-004 cultivated with five different carbon dioxide concentrations. The influence of carbon dioxide concentration on nutrient removal and pH was also investigated. Treated wastewater (secondary effluent) was used as culture medium. Five experimental setups were tested: T-0% - injection of atmospheric air (0.038% CO 2 ), T-5% (5% CO 2 ), T-10% (10% CO 2 ), T-15% (15% CO 2 ) and T-20% (20% CO 2 ). The T-5% and T-10% experiments showed the highest values of productivity and CO 2 biofixation, and maximum biomass dry weight was 0.48 ± 0.02 and 0.51 ± 0.03 g L -1 , respectively. This acidophilic microalga proved to be suitable for carbon biofixation and removal of nutrients from secondary effluent of wastewater treatment plants with high CO 2 concentration. All assays were performed without pH control. This microalga species presented high lipid content. However, fatty acid methyl esters (FAME) are not suitable for biodiesel use.

Visual Simulation of Microalgae Growth in Bioregenerative Life Support System

NASA Astrophysics Data System (ADS)

Zhao, Ming

Bioregenerative life support system is one of the key technologies for future human deep space exploration and long-term space missions. BLSS use biological system as its core unit in combination with other physical and chemical equipments, under the proper control and manipulation by crew to complete a specific task to support life. Food production, waste treatment, oxygen and water regeneration are all conducted by higher plants or microalgae in BLSS, which is the most import characteristic different from other kinds of life support systems. Microalgae is light autotrophic micro-organisms, light undoubtedly is the most import factor which limits its growth and reproduction. Increasing or decreasing the light intensity changes the growth rate of microalgae, and then regulates the concentration of oxygen and carbon dioxide in the system. In this paper, based on the mathematical model of microalgae which grew under the different light intensity, three-dimensional visualization model was built and realized through using 3ds max, Virtools and some other three dimensional software, in order to display its change and impacting on oxygen and carbon dioxide intuitively. We changed its model structure and parameters, such as establishing closed-loop control system, light intensity, temperature and Nutrient fluid’s velocity and so on, carried out computer virtual simulation, and observed dynamic change of system with the aim of providing visualization support for system research.

Carbon dioxide dynamics in an artificial ecosystem

NASA Astrophysics Data System (ADS)

Hu, Enzhu; Hu, Dawei; Tong, Ling; Li, Ming; Fu, Yuming; He, Wenting; Liu, Hong

An experimental artificial ecosystem was established as a tool to understand the behavior of closed ecosystem and to develop the technology for a future bioregenerative life support system for lunar or planetary exploration. Total effective volume of the system is 0.7 m3 . It consists of a higher plant chamber, an animal chamber and a photo-bioreactor which cultivated lettuce (Lactuca sativa L.), silkworm (Bombyx Mori L.) and microalgae (Chlorella), respectively. For uniform and sustained observations, lettuce and silkworms was cultivated using sequential cultivation method, and microalgae using continuous culture. Four researchers took turns breathing the system air through a tube for brief periods every few hours. A mathematic model, simulating the carbon dioxide dynamics was developed. The main biological parameters concerning photosynthesis of lettuce and microalgae, respiration of silkworms and human were validated by the experimental data. The model described the respiratory relationship between autotrophic and heterotrophic compartments. A control strategy was proposed as a tool for the atmosphere management of the artificial ecosystem.

Oxidative stress induced by inorganic nanoparticles in bacteria and aquatic microalgae--state of the art and knowledge gaps.

PubMed

von Moos, Nadia; Slaveykova, Vera I

2014-09-01

Nanotechnology has revolutionised many areas of modern life, technology and research, which is reflected in the steadily increasing global demand for and consumption of engineered nanomaterials and the inevitable increase of their release into the environment by human activity. The overall long-term impact of engineered nanomaterials on ecosystems is still unknown. Various inorganic nanoparticles have been found to exhibit bactericidal properties and cause growth inhibition in model aquatic microalgae, but the mechanisms of toxicity are not yet fully understood. The causal link between particle properties and biological effects or reactive oxygen species generation is not well established and represents the most eminent quest of nanoecotoxicological investigation. In this review, the current mechanistic understanding of the toxicity of inorganic metal and metal oxide engineered nanomaterials towards bacterial and aquatic microalgal model organisms based on the paradigm of oxidative stress is presented along with a detailed compilation of available literature on the major toxicity factors and research methods.

Ecotoxicological effects of enrofloxacin and its removal by monoculture of microalgal species and their consortium.

PubMed

Xiong, Jiu-Qiang; Kurade, Mayur B; Jeon, Byong-Hun

2017-07-01

Enrofloxacin (ENR), a fluoroquinolone antibiotic, has gained big scientific concern due to its ecotoxicity on aquatic microbiota. The ecotoxicity and removal of ENR by five individual microalgae species and their consortium were studied to correlate the behavior and interaction of ENR in natural systems. The individual microalgal species (Scenedesmus obliquus, Chlamydomonas mexicana, Chlorella vulgaris, Ourococcus multisporus, Micractinium resseri) and their consortium could withstand high doses of ENR (≤1 mg L -1 ). Growth inhibition (68-81%) of the individual microalgae species and their consortium was observed in ENR (100 mg L -1 ) compared to control after 11 days of cultivation. The calculated 96 h EC 50 of ENR for individual microalgae species and microalgae consortium was 9.6-15.0 mg ENR L -1 . All the microalgae could recover from the toxicity of high concentrations of ENR during cultivation. The biochemical characteristics (total chlorophyll, carotenoid, and malondialdehyde) were significantly influenced by ENR (1-100 mg L -1 ) stress. The individual microalgae species and microalgae consortium removed 18-26% ENR at day 11. Although the microalgae consortium showed a higher sensitivity (with lower EC 50 ) toward ENR than the individual microalgae species, the removal efficiency of ENR by the constructed microalgae consortium was comparable to that of the most effective microalgal species. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microalgae as source of biofuel: technology and prospective

NASA Astrophysics Data System (ADS)

Ferraro, Angelo

2017-12-01

Microalgae are autotrophic organisms found in solitary cells or in groups of single cells connected together. Their natural environment are typically freshwater and marine systems. Microalgae produce, via photosynthesis, approximately one-half of oxygen generated on earth while simultaneously consume carbon dioxide (CO2). Among the technologies being examined to produce green fuels (e.g. biodiesel, bioethanol and syngas), microalgae are viewed by many in the scientific community as having the greatest potential to become economically viable fuels. Nevertheless, to reach economic parity with fossil fuels there are still several challenges to be tackle. These include improving harvesting and oil extraction processes as well as increasing biomass productivity and oil content. All of these challenges can be impacted by genetic, molecular, and ultimately synthetic biology techniques.

Investigation of biomass concentration, lipid production, and cellulose content in Chlorella vulgaris cultures using response surface methodology.

PubMed

Aguirre, Ana-Maria; Bassi, Amarjeet

2013-08-01

The microalgae Chlorella vulgaris produce lipids that after extraction from cells can be converted into biodiesel. However, these lipids cannot be efficiently extracted from cells due to the presence of the microalgae cell wall, which acts as a barrier for lipid removal when traditional extraction methods are employed. Therefore, a microalgae system with high lipid productivity and thinner cell walls could be more suitable for lipid production from microalgae. This study addresses the effect of culture conditions, specifically carbon dioxide and sodium nitrate concentrations, on biomass concentration and the ratio of lipid productivity/cellulose content. Optimization of culture conditions was done by response surface methodology. The empirical model for biomass concentration (R(2)  = 96.0%) led to a predicted maximum of 1123.2 mg dw L(-1) when carbon dioxide and sodium nitrate concentrations were 2.33% (v/v) and 5.77 mM, respectively. For lipid productivity/cellulose content ratio (R(2)  = 95.2%) the maximum predicted value was 0.46 (mg lipid L(-1)  day(-1) )(mg cellulose mg biomass(-1) )(-1) when carbon dioxide concentration was 4.02% (v/v) and sodium nitrate concentration was 3.21 mM. A common optimum point for both variables (biomass concentration and lipid productivity/cellulose content ratio) was also found, predicting a biomass concentration of 1119.7 mg dw L(-1) and lipid productivity/cellulose content ratio of 0.44 (mg lipid L(-1)  day(-1) )(mg cellulose mg biomass(-1) )(-1) for culture conditions of 3.77% (v/v) carbon dioxide and 4.01 mM sodium nitrate. The models were experimentally validated and results supported their accuracy. This study shows that it is possible to improve lipid productivity/cellulose content by manipulation of culture conditions, which may be applicable to any scale of bioreactors. Copyright © 2013 Wiley Periodicals, Inc.

PHYTOTOXICITY

EPA Science Inventory

Handbook of Ecotoxicology. Second Edition.. Lewis Publishers, Boca Raton, FL. 32 p.

Phytoplankton, benthic and epiphytic microalgae, and macroalgae are energy sources critical to most aquatic ecosystems. Changes in their density and composition can effect the chemical and...

Production of EPA and DHA in aquatic ecosystems and their transfer to the land.

PubMed

Gladyshev, Michail I; Sushchik, Nadezhda N; Makhutova, Olesia N

2013-12-01

Most omnivorous animals, including humans, have to some degree relied on physiologically important polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from food. Only some taxa of microalgae, rather than higher plants can synthesize de novo high amounts of EPA and DHA. Once synthesized by microalgae, PUFA are transferred through trophic chain to organisms of higher levels. Thus, aquatic ecosystems play the unique role in the Biosphere as the principal source of EPA and DHA for most omnivorous animals, including inhabitants of terrestrial ecosystems. PUFA are transferred from aquatic to terrestrial ecosystems through riparian predators, drift of carrion and seaweeds, emergence of amphibiotic insects, and water birds. The essential PUFA are transferred through trophic chains with about twice higher efficiency than bulk carbon. Thereby, PUFA are accumulated, rather than diluted in biomass of organisms of higher trophic levels, e.g., in fish. Mankind is faced with a severe deficiency of EPA and DHA in diet. Although additional sources of PUFA supply for humans, such as aquaculture, biotechnology of microorganisms and transgenic terrestrial oil-seed producing plants are developed, natural fish production of aquatic ecosystems will remain one of the main sources of EPA and DHA for humans. Aquatic ecosystems have to be protected from anthropogenic impacts, such as eutrophication, pollution and warming, which reduce PUFA production. Copyright © 2013 Elsevier Inc. All rights reserved.

Structure/Function of the Novel Proteins LCIB and LCIC in the Chlamydomonas CCM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, Spalding H.

2017-05-09

The goal of this project was to investigate the function of two novel proteins, LCIB and LCIC, which together form an essential protein complex that is required for function of a carbon-dioxide-concentrating mechanism (CCM) required by microalgae to grow in environments where carbon dioxide levels are at or below air equilibration levels.

Extraction of carotenoids and chlorophyll from microalgae with supercritical carbon dioxide and ethanol as cosolvent.

PubMed

Macías-Sánchez, Maria Dolores; Mantell Serrano, Casimiro; Rodríguez Rodríguez, Miguel; Martínez de la Ossa, Enrique; Lubián, Luís M; Montero, Olimpio

2008-05-01

The extraction of carotenoids and chlorophylls using carbon dioxide modified with ethanol as a cosolvent is an alternative to solvent extraction because it provides a high-speed extraction process. In the study described here, carotenoid and chlorophyll extraction with supercritical CO(2 )+ ethanol was explored using freeze-dried powders of three microalgae (Nannochloropsis gaditana, Synechococcus sp. and Dunaliella salina) as the raw materials. The operation conditions were as follows: pressures of 200, 300, 400 and 500 bar, temperatures of 40, 50 and 60 degrees C. Analysis of the extracts was performed by measuring the absorbance and by using empirical correlations. The results demonstrate that it is necessary to work at a temperature of 50-60 degrees C and a pressure range of 300-500 bar, depending on the type of microalgae, in order to obtain the highest yield of pigments. The best carotenoid/chlorophyll ratios were obtained by using supercritical fluid extraction + cosolvent instead of using conventional extraction. The higher selectivity of the former process should facilitate the separation and purification of the two extracted pigments.

Applications of microfluidics in microalgae biotechnology: A review.

PubMed

Juang, Yi-Je; Chang, Jo-Shu

2016-03-01

Microalgae have been one of the important sources for biofuel production owing to their competitive advantages such as no need to tap into the global food supply chain, higher energy density, and absorbing carbon dioxide to mitigate global warming. One of the key factors to ensure successful biofuel production is that it requires not only bioprospecting of the microalgae with high lipid content, high growth rate and tolerance to environmental parameters but also on-site monitoring of the cultivation process and optimization of the culturing conditions. However, as the conventional techniques usually involve in complicated procedures, or are time-consuming or labor intensive, microfluidics technology offers an attractive alternative to resolve these issues. In this review, applications of microfluidics to bioprospecting in microalgae biotechnology were discussed such as cell identification, cell sorting/screening, cell culturing and cell disruption. In addition, utilization of microalgae in micro-sized fuel cells and microfluidic platforms for biosensing was addressed. This review reports the recent studies and offers a look into how microfluidics is exploited to tackle the issues encountered in the microalgae biotechnology. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biodiesel production with microalgae as feedstock: from strains to biodiesel.

PubMed

Gong, Yangmin; Jiang, Mulan

2011-07-01

Due to negative environmental influence and limited availability, petroleum-derived fuels need to be replaced by renewable biofuels. Biodiesel has attracted intensive attention as an important biofuel. Microalgae have numerous advantages for biodiesel production over many terrestrial plants. There are a series of consecutive processes for biodiesel production with microalgae as feedstock, including selection of adequate microalgal strains, mass culture, cell harvesting, oil extraction and transesterification. To reduce the overall production cost, technology development and process optimization are necessary. Genetic engineering also plays an important role in manipulating lipid biosynthesis in microalgae. Many approaches, such as sequestering carbon dioxide from industrial plants for the carbon source, using wastewater for the nutrient supply, and maximizing the values of by-products, have shown a potential for cost reduction. This review provides a brief overview of the process of biodiesel production with microalgae as feedstock. The methods associated with this process (e.g. lipid determination, mass culture, oil extraction) are also compared and discussed.

Ecological value of macrophyte cover in creating habitat for microalgae (diatoms) and zooplankton (rotifers and crustaceans) in small field and forest water bodies.

PubMed

Celewicz-Gołdyn, Sofia; Kuczyńska-Kippen, Natalia

2017-01-01

Due to their small area and shallow depth ponds are usually treated as a single sampling unit, while various microhabitats offer different environmental conditions. Thus, we tested the effect of different habitat types typically found within small ponds on the microalgae and zooplankton communities. We found that submerged macrophytes have the strongest impact on microalgae and zooplankton communities out of all the analysed habitats. Some epontic diatoms (e.g. Fragilaria dilatata, Cymbella affinis) and littoral-associated zooplankton species (e.g. Simocephalus vetulus, Lecane bulla) were significantly related to elodeids. However, pelagic species (e.g. bosminids) preferred less complex helophytes, which suggests that the most heterogeneous elodeid habitats were not an anti-predator shelter for cladocerans. Selection of different macrophyte types by taxonomically various organisms suggests that it is not only macrophyte cover that is desired for healthy aquatic environment but that a level of habitat mosaic is required to ensure the well-being of aquatic food webs. Species-specific preferences for different types of macrophytes indicate the high ecological value of macrophyte cover in ponds and a potential direction for the management of small water bodies towards maintaining a great variation of aquatic plants. Moreover, the type of surrounding landscape, reflecting human-induced disturbance (28 field ponds) and natural catchment (26 forest ponds), significantly influenced only zooplankton, while diatoms were affected indirectly through the level of conductivity. Nutrient overload (higher content of TRP) and increased conductivity in the field landscape contributed to a rise in microalgae (e.g. Amphora pediculus, Gomphonema parvulum) and zooplankton (e.g. Thermocyclops oithonoides, Eubosmina coregoni) abundance. An awareness of the responses of both components of plankton communities to environmental factors is necessary for maintaining the good state of small water bodies in various types of landscape.

Toxicological effects of chlorpyrifos on growth, enzyme activity and chlorophyll a synthesis of freshwater microalgae.

PubMed

Chen, Shangchao; Chen, Mindong; Wang, Zhuang; Qiu, Weijian; Wang, Junfeng; Shen, Yafei; Wang, Yajun; Ge, Shun

2016-07-01

This paper aims to acquire the experimental data on the eco-toxicological effects of agricultural pollutants on the aquatic plants and the data can support the assessment of toxicity on the phytoplankton. The pesticide of Chlorpyrifos used as a good model to investigate its eco-toxicological effect on the different microalgae in freshwater. In order to address the pollutants derived from forestry and agricultural applications, freshwater microalgae were considered as a good sample to investigate the impact of pesticides such as Chlorpyrifos on aquatic life species. Two microalgae of Chlorella pyrenoidosa and Merismopedia sp. were employed to evaluate toxicity of Chlorpyrifos in short time and long time by means of measuring the growth inhibition rate, the redox system and the content of chlorophyll a, respectively. In this study, the results showed that EC50 values ranging from 7.63 to 19.64mg/L, indicating the Chlorpyrifos had a relatively limited to the growth of algae during the period of the acute toxicity experiment. Moreover, when two kinds of algae were exposed to a medium level of Chlorpyrifos, SOD and CAT activities were importantly advanced. Therefore, the growth rate and SOD and CAT activities can be highly recommended for the eco-toxicological assessment. In addition, chlorophyll a also could be used as a targeted parameter for assessing the eco-toxicity of Chlorpyrifos on both Chlorella pyrenoidosa and Merismopedia sp. Copyright © 2016 Elsevier B.V. All rights reserved.

Ecological Relationships Between Components in Closed Aquatic Ecosystems

NASA Astrophysics Data System (ADS)

Pisman, Tamara; Somova, Lydia

The work considers the problems of relationships between algae and other microorganisms in aquatic ecosystems. Using small-scale laboratory "autotroph-heterotroph" ecosystems with different types of closure, we showed the results of the investigation into the ecological relation-ships of algae in biocenoses. The autotrophic component was represented by green microalgae, and the heterotrophic component -by yeast and bacteria. An important role in functioning of algobacterial communities is played by 2 -2 (oxygen -carbon dioxide) exchange. The gas exchange between algae and yeast was studied in the "autotroph-heterotroph" gas-closed ecosystem with space-divided components. It was shown that the gas exchange closure of the components into a system prolongs its existence. Hav-ing increased the degree of the system closure by introducing two yeast species with positive metabolic interaction to the heterotrophic component, we observed a significant increase in the gas exchange between the components and thus in the biomass of algae and yeast. The most ancient and ecologically relevant symbioses known in nature are symbiotic associa-tions of algae and heterotrophic organisms. The main symbionts of algae in aquatic ecosystems are bacteria. The cenosis-forming role of algae is based on two characteristics: firstly, their mucous covers and membranes are able to absorb and retain large amounts of water; secondly, many algae evolve various organic substances during their lifetime. An example of algobacterial associations are microalgae Chlorella vulgaris and accompanying microbial flora. Experiments with non-sterile batch culture of algae showed that the increase in the algae biomass was accompanied by the increase in the bacterial biomass. As a result of theoretical and experi-mental investigation into their relationships, it was shown that the largest biomass of bacteria is achieved when using organic substances evolved by algae and having bacteria grow on dead algae; i.e. bacteria can also act as decomposers. It was demonstrated that the cenosis-forming role of algae and bacteria in an algobacterial cenosis is determined by accumulation of both organic matter and nitrogen which is included into the cycle of matter. Thus, the process of C-compound evolution by algae in an algobacterial cenosis is strongly connected with the process of consumption of these compounds by corresponding bacteria, which, in their turn, ensure photosynthesis and algae development by evolving 2 and nitrogen.

Toxic effect of silver and platinum nanoparticles toward the freshwater microalga Pseudokirchneriella subcapitata.

PubMed

Książyk, Małgorzata; Asztemborska, Monika; Stęborowski, Romuald; Bystrzejewska-Piotrowska, Grażyna

2015-05-01

The growing use of nanoparticles in a wide range of products has resulted in their release into the aquatic environment; therefore, an understanding of the toxic effects of nanoparticles on aquatic organisms is of permanent importance. The aim of this study was to evaluate the toxicity of silver and platinum nanoparticles toward the freshwater microalga, Pseudokirchneriella subcapitata. Algal growth and photosynthetic pigments were determined to quantitate the effects of varying concentrations of Ag and Pt nanoparticles. The silver nanoparticles were much more toxic than the platinum ones. The concentrations causing total inhibition of algal growth were 5.0 and 22.2 mg L(-1), respectively. Similar results were obtained by analyzing the concentration of photosynthetic pigments in P. subcapitata exposed to nanoparticles. Thus, simple spectrophotometric determination of chlorophyll is a convenient tool for the analysis of nanoparticle toxicity to algae.

Extraction fatty acid as a source to produce biofuel in microalgae Chlorella sp. and Spirulina sp. using supercritical carbon dioxide

NASA Astrophysics Data System (ADS)

Tai, Do Chiem; Hai, Dam Thi Thanh; Vinh, Nguyen Hanh; Phung, Le Thi Kim

2016-06-01

In this research, the fatty acids of isolated microalgae were extracted by some technologies such as maceration, Soxhlet, ultrasonic-assisted extraction and supercritical fluid extraction; and analyzed for biodiesel production using GC-MS. This work deals with the extraction of microalgae oil from dry biomass by using supercritical fluid extraction method. A complete study at laboratory of the influence of some parameters on the extraction kinetics and yields and on the composition of the oil in terms of lipid classes and profiles is proposed. Two types of microalgae were studied: Chlorella sp. and Spirulina sp. For the extraction of oil from microalgae, supercritical CO2 (SC-CO2) is regarded with interest, being safer than n-hexane and offering a negligible environmental impact, a short extraction time and a high-quality final product. Whilst some experimental papers are available on the supercritical fluid extraction (SFE) of oil from microalgae, only limited information exists on the kinetics of the process. These results demonstrate that supercritical CO2 extraction is an efficient method for the complete recovery of the neutral lipid phase.

Nickel has biochemical, physiological, and structural effects on the green microalga Ankistrodesmus falcatus: An integrative study.

PubMed

Martínez-Ruiz, Erika Berenice; Martínez-Jerónimo, Fernando

2015-12-01

In recent years, the release of chemical pollutants to water bodies has increased due to anthropogenic activities. Ni(2+) is an essential metal that causes damage to aquatic biota at high concentrations. Phytoplankton are photosynthesizing microscopic organisms that constitute a fundamental community in aquatic environments because they are primary producers that sustain the aquatic food web. Nickel toxicity has not been characterized in all of the affected levels of biological organization. For this reason, the present study evaluated the toxic effects of nickel on the growth of a primary producer, the green microalga Ankistrodesmus falcatus, and on its biochemical, enzymatic, and structural levels. The IC50 (96h) was determined for Ni(2+). Based on this result, five concentrations were determined for additional tests, in which cell density was evaluated daily. At the end of the assay, pigments and six biomarkers, including antioxidant enzymes (catalase [CAT], glutathione peroxidase [GPx], superoxide dismutase [SOD]), and macromolecules (proteins, carbohydrates and lipids), were quantified; the integrated biomarker response (IBR) was determined also. The microalgae were observed by SEM and TEM. Population growth was affected starting at 7.5 μg L(-1) (0.028 μM), and at 120 μg L(-1) (0.450 μM), growth was inhibited completely; the determined IC50 was 17 μg L(-1). Exposure to nickel reduced the concentration of pigments, decreased the content of all of the macromolecules, inhibited of SOD activity, and increased CAT and GPx activities. The IBR revealed that Ni(2+) increased the antioxidant response and diminished the macromolecules concentration. A. falcatus was affected by nickel at very low concentrations; negative effects were observed at the macromolecular, enzymatic, cytoplasmic, and morphological levels, as well as in population growth. Ni(2+) toxicity could result in environmental impacts with consequences on the entire aquatic community. Current regulations should be revised to protect primary producers. Copyright © 2015 Elsevier B.V. All rights reserved.

Kinetic parameter estimation model for anaerobic co-digestion of waste activated sludge and microalgae.

PubMed

Lee, Eunyoung; Cumberbatch, Jewel; Wang, Meng; Zhang, Qiong

2017-03-01

Anaerobic co-digestion has a potential to improve biogas production, but limited kinetic information is available for co-digestion. This study introduced regression-based models to estimate the kinetic parameters for the co-digestion of microalgae and Waste Activated Sludge (WAS). The models were developed using the ratios of co-substrates and the kinetic parameters for the single substrate as indicators. The models were applied to the modified first-order kinetics and Monod model to determine the rate of hydrolysis and methanogenesis for the co-digestion. The results showed that the model using a hyperbola function was better for the estimation of the first-order kinetic coefficients, while the model using inverse tangent function closely estimated the Monod kinetic parameters. The models can be used for estimating kinetic parameters for not only microalgae-WAS co-digestion but also other substrates' co-digestion such as microalgae-swine manure and WAS-aquatic plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

HARMFUL ALGAL BLOOMS AS INDICATORS OF ECOSYSTEM CONDITION

EPA Science Inventory

There are approximately 40 species of microalgae inhabiting coastal waters in the Gulf of Mexico that produce or potentially can produce biotoxins that negatively impact aquatic ecosystems, human health, and local economics. While nutrient enrichment and reduced water quality may...

Optimal control of nutrition restricted dynamics model of Microalgae biomass growth model

NASA Astrophysics Data System (ADS)

Ratianingsih, R.; Azim; Nacong, N.; Resnawati; Mardlijah; Widodo, B.

2017-12-01

The biomass of the microalgae is very potential to be proposed as an alternative renewable energy resources because it could be extracted into lipid. Afterward, the lipid could be processed to get the biodiesel or bioethanol. The extraction of the biomass on lipid synthesis process is very important to be studied because the process just gives some amount of lipid. A mathematical model of restricted microalgae biomass growth just gives 1/3 proportion of lipid with respect to the biomass in the synthesis process. An optimal control is designed to raise the ratio between the number of lipid formation and the microalgae biomass to be used in synthesis process. The minimum/ Pontryagin maximum principle is used to get the optimal lipid production. The simulation shows that the optimal lipid formation could be reach by simultaneously controlling the carbon dioxide, in the respiration and photosynthesis the process, and intake nutrition rates of liquid waste and urea substrate. The production of controlled microalgae lipid could be increase 6.5 times comparing to the uncontrolled one.

Cyanobacteria and microalgae: a renewable source of bioactive compounds and other chemicals.

PubMed

Encarnação, Telma; Pais, Alberto A C C; Campos, Maria G; Burrows, Hugh D

2015-01-01

Microalgae and cyanobacteria are rich sources of many valuable compounds, including important bioactive and biotechnologically relevant chemicals. Their enormous biodiversity, and the consequent variability in the respective biochemical composition, make microalgae cultivations a promising resource for many novel chemically and biologically active molecules and compounds of high commercial value such as lipids and dyes. The nature of the chemicals produced can be manipulated by changing the cultivation media and conditions. Algae are extremely versatile because they can be adapted to a variety of cell culture conditions. They do not require arable land, can be cultivated on saline water and wastewaters, and require much less water than plants. They possess an extremely high growth rate making these microorganisms very attractive for use in biofuel production--some species of algae can achieve around 100 times more oil than oil seeds. In addition, microalgae and cyanobacteria can accumulate various biotoxins and can contribute to mitigate greenhouse gases since they produce biomass through carbon dioxide fixation. In this review, we provide an overview of the application of microalgae in the production of bioactive and other chemicals.

Palm oil mill effluent treatment and CO2 sequestration by using microalgae-sustainable strategies for environmental protection.

PubMed

Hariz, Harizah Bajunaid; Takriff, Mohd Sobri

2017-09-01

In this era of globalization, various products and technologies are being developed by the industries. While resources and energy are utilized from processes, wastes are being excreted through water streams, air, and ground. Without realizing it, environmental pollutions increase as the country develops. Effective technology is desired to create green factories that are able to overcome these issues. Wastewater is classified as the water coming from domestic or industrial sources. Wastewater treatment includes physical, chemical, and biological treatment processes. Aerobic and anaerobic processes are utilized in biological treatment approach. However, the current biological approaches emit greenhouse gases (GHGs), methane, and carbon dioxide that contribute to global warming. Microalgae can be the alternative to treating wastewater as it is able to consume nutrients from wastewater loading and fix CO 2 as it undergoes photosynthesis. The utilization of microalgae in the system will directly reduce GHG emissions with low operating cost within a short period of time. The aim of this review is to discuss the uses of native microalgae species in palm oil mill effluent (POME) and flue gas remediation. In addition, the discussion on the optimal microalgae cultivation parameter selection is included as this is significant for effective microalgae-based treatment operations.

Bioethanol production from the nutrient stress-induced microalga Chlorella vulgaris by enzymatic hydrolysis and immobilized yeast fermentation.

PubMed

Kim, Kyoung Hyoun; Choi, In Seong; Kim, Ho Myeong; Wi, Seung Gon; Bae, Hyeun-Jong

2014-02-01

The microalga Chlorella vulgaris is a potential feedstock for bioenergy due to its rapid growth, carbon dioxide fixation efficiency, and high accumulation of lipids and carbohydrates. In particular, the carbohydrates in microalgae make them a candidate for bioethanol feedstock. In this study, nutrient stress cultivation was employed to enhance the carbohydrate content of C. vulgaris. Nitrogen limitation increased the carbohydrate content to 22.4% from the normal content of 16.0% on dry weight basis. In addition, several pretreatment methods and enzymes were investigated to increase saccharification yields. Bead-beating pretreatment increased hydrolysis by 25% compared with the processes lacking pretreatment. In the enzymatic hydrolysis process, the pectinase enzyme group was superior for releasing fermentable sugars from carbohydrates in microalgae. In particular, pectinase from Aspergillus aculeatus displayed a 79% saccharification yield after 72h at 50°C. Using continuous immobilized yeast fermentation, microalgal hydrolysate was converted into ethanol at a yield of 89%. Copyright © 2013 Elsevier Ltd. All rights reserved.

Extraction of microalgae derived lipids with supercritical carbon dioxide in an industrial relevant pilot plant.

PubMed

Lorenzen, Jan; Igl, Nadine; Tippelt, Marlene; Stege, Andrea; Qoura, Farah; Sohling, Ulrich; Brück, Thomas

2017-06-01

Microalgae are capable of producing up to 70% w/w triglycerides with respect to their dry cell weight. Since microalgae utilize the greenhouse gas CO 2 , they can be cultivated on marginal lands and grow up to ten times faster than terrestrial plants, the generation of algae oils is a promising option for the development of sustainable bioprocesses, that are of interest for the chemical lubricant, cosmetic and food industry. For the first time we have carried out the optimization of supercritical carbon dioxide (SCCO 2 ) mediated lipid extraction from biomass of the microalgae Scenedesmus obliquus and Scenedesmus obtusiusculus under industrrially relevant conditions. All experiments were carried out in an industrial pilot plant setting, according to current ATEX directives, with batch sizes up to 1.3 kg. Different combinations of pressure (7-80 MPa), temperature (20-200 °C) and CO 2 to biomass ratio (20-200) have been tested on the dried biomass. The most efficient conditions were found to be 12 MPa pressure, a temperature of 20 °C and a CO 2 to biomass ratio of 100, resulting in a high extraction efficiency of up to 92%. Since the optimized CO 2 extraction still yields a crude triglyceride product that contains various algae derived contaminants, such as chlorophyll and carotenoids, a very effective and scalable purification procedure, based on cost efficient bentonite based adsorbers, was devised. In addition to the sequential extraction and purification procedure, we present a consolidated online-bleaching procedure for algae derived oils that is realized within the supercritical CO 2 extraction plant.

Strategies for Lipid Production Improvement in Microalgae as a Biodiesel Feedstock

PubMed Central

Li, Z. H.; Hiltunen, E.

2016-01-01

In response to the energy crisis, global warming, and climate changes, microalgae have received a great deal of attention as a biofuel feedstock. Due to a high lipid content in microalgal cells, microalgae present as a promising alternative source for the production of biodiesel. Environmental and culturing condition variations can alter lipid production as well as chemical compositions of microalgae. Therefore, application of the strategies to activate lipid accumulation opens the door for lipid overproduction in microalgae. Until now, many original studies regarding the approaches for enhanced microalgal lipid production have been reported in an effort to push forward the production of microalgal biodiesel. However, the current literature demonstrates fragmented information available regarding the strategies for lipid production improvement. From the systematic point of view, the review highlights the main approaches for microalgal lipid accumulation induction to expedite the application of microalgal biodiesel as an alternative to fossil diesel for sustainable environment. Of the several strategies discussed, the one that is most commonly applied is the design of nutrient (e.g., nitrogen, phosphorus, and sulfur) starvation or limitation. Other viable approaches such as light intensity, temperature, carbon dioxide, salinity stress, and metal influence can also achieve enhanced microalgal lipid production. PMID:27725942

Strategies for Lipid Production Improvement in Microalgae as a Biodiesel Feedstock.

PubMed

Zhu, L D; Li, Z H; Hiltunen, E

2016-01-01

In response to the energy crisis, global warming, and climate changes, microalgae have received a great deal of attention as a biofuel feedstock. Due to a high lipid content in microalgal cells, microalgae present as a promising alternative source for the production of biodiesel. Environmental and culturing condition variations can alter lipid production as well as chemical compositions of microalgae. Therefore, application of the strategies to activate lipid accumulation opens the door for lipid overproduction in microalgae. Until now, many original studies regarding the approaches for enhanced microalgal lipid production have been reported in an effort to push forward the production of microalgal biodiesel. However, the current literature demonstrates fragmented information available regarding the strategies for lipid production improvement. From the systematic point of view, the review highlights the main approaches for microalgal lipid accumulation induction to expedite the application of microalgal biodiesel as an alternative to fossil diesel for sustainable environment. Of the several strategies discussed, the one that is most commonly applied is the design of nutrient (e.g., nitrogen, phosphorus, and sulfur) starvation or limitation. Other viable approaches such as light intensity, temperature, carbon dioxide, salinity stress, and metal influence can also achieve enhanced microalgal lipid production.

Co-generation of biohydrogen and biomethane through two-stage batch co-fermentation of macro- and micro-algal biomass.

PubMed

Ding, Lingkan; Cheng, Jun; Xia, Ao; Jacob, Amita; Voelklein, Markus; Murphy, Jerry D

2016-10-01

Aquatic micro-algae can be used as feedstocks for gaseous biofuel production via biological fermentation. However, micro-algae usually have low C/N ratios, which are not advantageous for fermentation. In this study, carbon-rich macro-algae (Laminaria digitata) mixed with nitrogen-rich micro-algae (Chlorella pyrenoidosa and Nannochloropsis oceanica) were used to maintain a suitable C/N ratio of 20 for a two-stage process combining hydrogen and methane fermentation. Co-fermentation of L. digitata and micro-algae facilitated hydrolysis and acidogenesis, resulting in hydrogen yields of 94.5-97.0mL/gVS; these values were 15.5-18.5% higher than mono-fermentation using L. digitata. Through the second stage of methane co-fermentation, a large portion of energy remaining in the hydrogenogenic effluents was recovered in the form of biomethane. The two-stage batch co-fermentation markedly increased the energy conversion efficiencies (ECEs) from 4.6-6.6% during the hydrogen fermentation to 57.0-70.9% in the combined hydrogen and methane production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Feasibility study of algae-based Carbon Dioxide capture

EPA Science Inventory

SUMMARY: The biomass of microalgae contains approximately 50% carbon, which is commonly obtained from the atmosphere, but can also be taken from commercial sources that produce CO2, such as coal-fired power plants. A study of operational demonstration projects is being undertak...

Experimental and mathematical modeling of the consumer’s influence on productivity of algae in a model aquatic ecosystem

NASA Astrophysics Data System (ADS)

Pisman, T. I.; Galayda, Ya. V.; Shirobokova, I. M.

A "producer-consumer" ( Chlorella vulgaris- Paramecium caudatum) closed aquatic system has been investigated experimentally and theoretically. It has been found that there is a direct relationship between the growth of the paramecia population and their release of ammonia nitrogen, which is the best form of nitrogen for Chlorella growth. The theoretical study of a model of a "producer-consumer" aquatic biotic cycle with spatially separated compartments has confirmed the contribution of paramecia to nitrogen cycling. It has been shown that an increase in the concentration of nitrogen released as metabolites of paramecia is accompanied by an increase in the productivity of microalgae.

Carbon dioxide utilization in a microalga-based biorefinery: Efficiency of carbon removal and economic performance under carbon taxation.

PubMed

Wiesberg, Igor Lapenda; Brigagão, George Victor; de Medeiros, José Luiz; de Queiroz Fernandes Araújo, Ofélia

2017-12-01

Coal-fired power plants are major stationary sources of carbon dioxide and environmental constraints demand technologies for abatement. Although Carbon Capture and Storage is the most mature route, it poses severe economic penalty to power generation. Alternatively, this penalty is potentially reduced by Carbon Capture and Utilization, which converts carbon dioxide to valuable products, monetizing it. This work evaluates a route consisting of carbon dioxide bio-capture by Chlorella pyrenoidosa and use of the resulting biomass as feedstock to a microalgae-based biorefinery; Carbon Capture and Storage route is evaluated as a reference technology. The integrated arrangement comprises: (a) carbon dioxide biocapture in a photobioreactor, (b) oil extraction from part of the produced biomass, (b) gasification of remaining biomass to obtain bio-syngas, and (c) conversion of bio-syngas to methanol. Calculation of capital and operational expenditures are estimated based on mass and energy balances obtained by process simulation for both routes (Carbon Capture and Storage and the biorefinery). Capital expenditure for the biorefinery is higher by a factor of 6.7, while operational expenditure is lower by a factor of 0.45 and revenues occur only for this route, with a ratio revenue/operational expenditure of 1.6. The photobioreactor is responsible for one fifth of the biorefinery capital expenditure, with footprint of about 1000 ha, posing the most significant barrier for technical and economic feasibility of the proposed biorefinery. The Biorefinery and Carbon Capture and Storage routes show carbon dioxide capture efficiency of 73% and 48%, respectively, with capture cost of 139$/t and 304$/t. Additionally, the biorefinery has superior performance in all evaluated metrics of environmental impacts. Copyright © 2017 Elsevier Ltd. All rights reserved.

An assessment of the economic aspects of CO2 sequestration in a route for biodiesel production from microalgae.

PubMed

Soares, Fabio Rubens; Martins, Gilberto; Seo, Emília Satoshi Miyamaru

2013-01-01

Photosynthetic microalgae are unicellular organisms that, during their cultivation, can fix carbon dioxide efficiently from various sources, including the air and exhaust gases from industrial processes. This feature can lead to economic benefits in the production process of biodiesel by way of the clean development mechanism, for which carbon credits for environmental benefits may be granted and which will contribute towards reducing costs in the production process. This study seeks to quantify the contribution of carbon credits in the operating costs of a route for biodiesel production from microalgae, as proposed by Davis et al. [Techno-economic analysis ofautotrophic microalgae for fuel production. Appl Energy. 2011; 88:3524-3531]. The results showed a reduction in annual operating costs by around 5%. This figure may be conservative, since the production process considered can be further improved to reduce operating costs and thus increase the contribution margin of carbon credits, which will reduce costs. On the other hand, the price of carbon may also rise in the future, thereby increasing its contribution towards a reduction in operating costs.

Continuous production of biodiesel from microalgae by extraction coupling with transesterification under supercritical conditions.

PubMed

Zhou, Dan; Qiao, Baoquan; Li, Gen; Xue, Song; Yin, Jianzhong

2017-08-01

Raw material for biodiesel has been expanded from edible oil to non-edible oil. In this study, biodiesel continuous production for two kinds of microalgae Chrysophyta and Chlorella sp. was conducted. Coupling with the supercritical carbon dioxide extraction, the oil of microalgae was extracted firstly, and then sent to the downstream production of biodiesel. The residue after decompression can be reused as the material for pharmaceuticals and nutraceuticals. Results showed that the particle size of microalgae, temperature, pressure, molar ration of methanol to oil, flow of CO 2 and n-hexane all have effects on the yield of biodiesel. With the optimal operation conditions: 40mesh algae, extraction temperature 60°C, flow of n-hexane 0.4ml/min, reaction temperature: 340°C, pressure: 18-20MPa, CO 2 flow of 0.5L/min, molar ration of methanol to oil 84:1, a yield of 56.31% was obtained for Chrysophyta, and 63.78% for Chlorella sp. due to the higher lipid content. Copyright © 2017. Published by Elsevier Ltd.

DCERP Defense Coastal/Estuarine Research Program Workshop Proceedings

DTIC Science & Technology

2005-02-01

indicators, both in terms of ecological health and human impacts. • Phytoplankton and benthic microalgae species, especially bloom-forming ones that...composition) Chlorophyll a and other diagnostic photopigments Phytoplankton /zooplankton community composition Primary production (Photosynthesis...Satellite imagery for phytoplankton and higher plant communities Aerial sensors for submerged aquatic vegetation, salt marshes, ocean color 22 IR

FY 1987 Aquatic Species Program: Annual report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, D.A.; Sprague, S.

The goal of the Department of Energy/Solar Energy Research Institute Aquatic Species Program is to develop the technology base to produce liquid fuels from microalagae at prices competitive with conventional alternatives. Microalgae are unusual plants that can accumulate large quantities of oil and can thrive in high-salinity water, which currently has no competing uses. The algal oils, in turn, are readily converted into gasoline and diesel fuels. The best site for successful microalgae production was determined to be the US desert Southwest, with potential applications to other warm areas. Aggressive research is needed, but the improvements required are attainable. Themore » four prime research areas in the development of this technology are growth and production, engineering design, harvesting, and conversion. Algae are selected for three criteria: tolerance to environmental fluctuations, high growth rates, and high lipid production. From 1982 to 1986, the program collected more than 3000 strains of microalgae that are more than twice as tolerant to temperature and salinity fluctuation than the initial strains. Productivity has been increased by a factor of two in outdoor culture systems since 1982, and lipid content has also been increased from 20% of body weight in 1982 to greater than 66% of body weight in 1987. Research programs are ongoing in lipid biochemistry and genetic engineering so that ultimately strains can be modified and improved to combine their best characteristics. An outdoor test facility is being built in Roswell, New Mexico.« less

Pilot project at Hazira, India, for capture of carbon dioxide and its biofixation using microalgae.

PubMed

Yadav, Anant; Choudhary, Piyush; Atri, Neelam; Teir, Sebastian; Mutnuri, Srikanth

2016-11-01

The objective of the present study was to set up a small-scale pilot reactor at ONGC Hazira, Surat, for capturing CO 2 from vent gas. The studies were carried out for CO 2 capture by either using microalgae Chlorella sp. or a consortium of microalgae (Scenedesmus quadricauda, Chlorella vulgaris and Chlorococcum humicola). The biomass harvested was used for anaerobic digestion to produce biogas. The carbonation column was able to decrease the average 34 vol.% of CO 2 in vent gas to 15 vol.% of CO 2 in the outlet gas of the carbonation column. The yield of Chlorella sp. was found to be 18 g/m 2 /day. The methane yield was 386 l CH 4 /kg VS fed of Chlorella sp. whereas 228 l CH 4 /kg VS fed of the consortium of algae.

Genetic Engineering: A Promising Tool to Engender Physiological, Biochemical, and Molecular Stress Resilience in Green Microalgae

PubMed Central

Guihéneuf, Freddy; Khan, Asif; Tran, Lam-Son P.

2016-01-01

As we march into the 21st century, the prevailing scenario of depleting energy resources, global warming and ever increasing issues of human health and food security will quadruple. In this context, genetic and metabolic engineering of green microalgae complete the quest toward a continuum of environmentally clean fuel and food production. Evolutionarily related, but unlike land plants, microalgae need nominal land or water, and are best described as unicellular autotrophs using light energy to fix atmospheric carbon dioxide (CO2) into algal biomass, mitigating fossil CO2 pollution in the process. Remarkably, a feature innate to most microalgae is synthesis and accumulation of lipids (60–65% of dry weight), carbohydrates and secondary metabolites like pigments and vitamins, especially when grown under abiotic stress conditions. Particularly fruitful, such an application of abiotic stress factors such as nitrogen starvation, salinity, heat shock, etc., can be used in a biorefinery concept for production of multiple valuable products. The focus of this mini-review underlies metabolic reorientation practices and tolerance mechanisms as applied to green microalgae under specific stress stimuli for a sustainable pollution-free future. Moreover, we entail current progress on genetic engineering as a promising tool to grasp adaptive processes for improving strains with potential biotechnological interests. PMID:27066043

Effects of TiO2 nanoparticles and sunscreens on coastal marine microalgae: Ultraviolet radiation is key variable for toxicity assessment.

PubMed

Sendra, M; Sánchez-Quiles, D; Blasco, J; Moreno-Garrido, I; Lubián, L M; Pérez-García, S; Tovar-Sánchez, A

2017-01-01

Given the large numbers of sunbathers on beaches, sunscreen compounds are being released into the coastal aquatic environment in significant amounts. Until now the effect of these potential pollutants on microbiota has been not well-known. Phytoplankton is a key component of the microbiota community. It forms the basis of the aquatic trophic networks, and any change in the natural population of phytoplankton can affect the structure of aquatic biota. This paper describes an experiment performed outdoors (in natural sunlight conditions including ultraviolet radiation (UVR) and with UVR blocked) on mixed microalgae populations (four species from different key marine taxonomic groups, Nannochloropsis gaditana, Chaetoceros gracilis, Pleurochrysis roscoffensis and Amphidinium carterae), for three days, exposed to a range of concentrations of three commercial sunscreens (with variable TiO 2 concentrations: highest concentration for sunscreen C, followed by sunscreen A; and sunscreen B did not contain TiO 2 in its composition). With regard to UVR effect, in the absence of sunscreens, the most sensitive species is the centric diatom, Chaetoceros gracilis, and the least is Nannochloropsis gaditana; this last species presented the same behavior in the absence of UVR and with high sunscreen concentrations. The toxicity gradient obtained for sunscreens and nanoparticles under UVR is: TiO 2 NPs>Sunscreen C>Sunscreen A>Sunscreen B. The differential sensitivity of microalgae to sunscreens and TiO 2 NPs can produce a change in the dynamics of phytoplankton populations and provoke undesirable ecological effects (such as giving dinoflagellates more prominence). The effects of UVR, commonly neglected in bioassays, could alter the results in important ways and should be considered when performing environmentally-relevant bioassays. The toxicity mediated by hydrogen peroxide production associated with the concentration of TiO 2 NPs cannot be considered the only factor responsible for the toxicity: the organic compounds in the sunscreens must also be taken into account. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lipid Production from Nannochloropsis

PubMed Central

Ma, Xiao-Nian; Chen, Tian-Peng; Yang, Bo; Liu, Jin; Chen, Feng

2016-01-01

Microalgae are sunlight-driven green cell factories for the production of potential bioactive products and biofuels. Nannochloropsis represents a genus of marine microalgae with high photosynthetic efficiency and can convert carbon dioxide to storage lipids mainly in the form of triacylglycerols and to the ω-3 long-chain polyunsaturated fatty acid eicosapentaenoic acid (EPA). Recently, Nannochloropsis has received ever-increasing interests of both research and public communities. This review aims to provide an overview of biology and biotechnological potential of Nannochloropsis, with the emphasis on lipid production. The path forward for the further exploration of Nannochloropsis for lipid production with respect to both challenges and opportunities is also discussed. PMID:27023568

Conversion of microalgae to jet fuel: process design and simulation.

PubMed

Wang, Hui-Yuan; Bluck, David; Van Wie, Bernard J

2014-09-01

Microalgae's aquatic, non-edible, highly genetically modifiable nature and fast growth rate are considered ideal for biomass conversion to liquid fuels providing promise for future shortages in fossil fuels and for reducing greenhouse gas and pollutant emissions from combustion. We demonstrate adaptability of PRO/II software by simulating a microalgae photo-bio-reactor and thermolysis with fixed conversion isothermal reactors adding a heat exchanger for thermolysis. We model a cooling tower and gas floatation with zero-duty flash drums adding solids removal for floatation. Properties data are from PRO/II's thermodynamic data manager. Hydrotreating is analyzed within PRO/II's case study option, made subject to Jet B fuel constraints, and we determine an optimal 6.8% bioleum bypass ratio, 230°C hydrotreater temperature, and 20:1 bottoms to overhead distillation ratio. Process economic feasibility occurs if cheap CO2, H2O and nutrient resources are available, along with solar energy and energy from byproduct combustion, and hydrotreater H2 from product reforming. Copyright © 2014 Elsevier Ltd. All rights reserved.

Production of biodiesel from microalgae through biological carbon capture: a review.

PubMed

Mondal, Madhumanti; Goswami, Shrayanti; Ghosh, Ashmita; Oinam, Gunapati; Tiwari, O N; Das, Papita; Gayen, K; Mandal, M K; Halder, G N

2017-06-01

Gradual increase in concentration of carbon dioxide (CO 2 ) in the atmosphere due to the various anthropogenic interventions leading to significant alteration in the global carbon cycle has been a subject of worldwide attention and matter of potential research over the last few decades. In these alarming scenario microalgae seems to be an attractive medium for capturing the excess CO 2 present in the atmosphere generated from different sources such as power plants, automobiles, volcanic eruption, decomposition of organic matters and forest fires. This captured CO 2 through microalgae could be used as potential carbon source to produce lipids for the generation of biofuel for replacing petroleum-derived transport fuel without affecting the supply of food and crops. This comprehensive review strives to provide a systematic account of recent developments in the field of biological carbon capture through microalgae for its utilization towards the generation of biodiesel highlighting the significance of certain key parameters such as selection of efficient strain, microalgal metabolism, cultivation systems (open and closed) and biomass production along with the national and international biodiesel specifications and properties. The potential use of photobioreactors for biodiesel production under the influence of various factors viz., light intensity, pH, time, temperature, CO 2 concentration and flow rate has been discussed. The review also provides an economic overview and future outlook on biodiesel production from microalgae.

An outlook on microalgal biofuels.

PubMed

Wijffels, René H; Barbosa, Maria J

2010-08-13

Microalgae are considered one of the most promising feedstocks for biofuels. The productivity of these photosynthetic microorganisms in converting carbon dioxide into carbon-rich lipids, only a step or two away from biodiesel, greatly exceeds that of agricultural oleaginous crops, without competing for arable land. Worldwide, research and demonstration programs are being carried out to develop the technology needed to expand algal lipid production from a craft to a major industrial process. Although microalgae are not yet produced at large scale for bulk applications, recent advances-particularly in the methods of systems biology, genetic engineering, and biorefining-present opportunities to develop this process in a sustainable and economical way within the next 10 to 15 years.

Impacts of potassium ferrate(VI) on the growth and organic matter accumulation, production, and structural changes in the cyanobacterium Microcystis aeruginosa.

PubMed

Liu, Shu-Yu; Xu, Jingling; Chen, Wen-Li; David, Berthold E; Wu, Minghong; Ma, Fang

2017-04-01

Cyanobacterial blooms generated by nutrient addition into aquatic systems pose serious risks to ecosystems and human health. Though there are established chemical, physical, and biological means of eradication, more efficient and environmentally friendly measures are desired. This study investigates the effect of potassium ferrate(VI) on the growth and intracellular and extracellular organic matter accumulations of the cyanobacterium Microcystis aeruginosa. Cultures were inoculated with three separate concentrations of potassium ferrate(VI) (3, 15, 30 mg L -1 ) and monitored by measuring chlorophyll-a (Chl-a) and intracellular/extracellular dissolved organic carbon. Results show that ferrate(VI) addition effectively removed the microalgae from the medium, as indicated by the reduction of Chl-a. Organic matter accumulation of the microalgae was also affected by ferrate(VI) treatment; fluorescence EEM spectra show details of changing intracellular dissolved organic matter (IDOM) and extracellular dissolved organic matter (EDOM). A new peak appeared in the EDOM indicating altered humic and proteinaceous compounds. This study demonstrates that ferrate(VI) is a potential treatment for the water contaminated with the toxic microalgae M. aeruginosa.

Graphene oxide alleviates the ecotoxicity of copper on the freshwater microalga Scenedesmus obliquus.

PubMed

Hu, Changwei; Hu, Naitao; Li, Xiuling; Zhao, Yongjun

2016-10-01

The extensive industrial application of graphene oxide (GO), has increased its exposure risk to various aquatic organisms and its potential to affect the toxicity of other environmental pollutants. In this study, we investigated the combined toxicity of GO and copper on the freshwater microalga Scenedesmus obliquus, using the MIXTOX model. The effects of low concentration (1mg/L) exposure to GO were investigated with environmentally relevant concentrations of copper by using a 12-d subacute toxicity test, with pre- and post-GO treatment. Results showed that there were significant antagonistic effects between GO and copper on S. obliquus, and GO was found to reduce ecotoxicity of copper even at low and environmentally relevant concentrations (1mg/L). Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of nutrient ratios and carbon dioxide bio-sequestration on biomass growth of Chlorella sp. in bubble column photobioreactor.

PubMed

Vo, Hoang-Nhat-Phong; Bui, Xuan-Thanh; Nguyen, Thanh-Tin; Nguyen, Dinh Duc; Dao, Thanh-Son; Cao, Ngoc-Dan-Thanh; Vo, Thi-Kim-Quyen

2018-08-01

Photobioreactor technology, especially bubble column configuration, employing microalgae cultivation (e.g., Chlorella sp.), is an ideal man-made environment to achieve sufficient microalgae biomass through its strictly operational control. Nutrients, typically N and P, are necessary elements in the cultivation process, which determine biomass yield and productivity. Specifically, N:P ratios have certain effects on microalgae's biomass growth. It is also attractive that microalgae can sequester CO 2 by using that carbon source for photosynthesis and, subsequently, reducing CO 2 emission. Therefore, this study aims to investigate the effect of N:P ratios on Chlorella sp.'s growth, and to study the dynamic of CO 2 fixation in the bubble column photobioreactor. According to our results, N:P ratio of 15:1 could produce the highest biomass yield (3568 ± 158 mg L -1 ). The maximum algae concentration was 105 × 10 6  cells mL -1 , receiving after 92 h. Chlorella sp. was also able to sequester CO 2 at 28 ± 1.2%, while the specific growth rate and carbon fixation rate were observed at 0.064 h -1 and 68.9 ± 1.91 mg L -1  h -1 , respectively. The types of carbon sources (e.g., organic and inorganic carbon) possessed potential impact on microalgae's cultivation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Development of a Two-Stage Microalgae Dewatering Process – A Life Cycle Assessment Approach

PubMed Central

Soomro, Rizwan R.; Zeng, Xianhai; Lu, Yinghua; Lin, Lu; Danquah, Michael K.

2016-01-01

Even though microalgal biomass is leading the third generation biofuel research, significant effort is required to establish an economically viable commercial-scale microalgal biofuel production system. Whilst a significant amount of work has been reported on large-scale cultivation of microalgae using photo-bioreactors and pond systems, research focus on establishing high performance downstream dewatering operations for large-scale processing under optimal economy is limited. The enormous amount of energy and associated cost required for dewatering large-volume microalgal cultures has been the primary hindrance to the development of the needed biomass quantity for industrial-scale microalgal biofuels production. The extremely dilute nature of large-volume microalgal suspension and the small size of microalgae cells in suspension create a significant processing cost during dewatering and this has raised major concerns towards the economic success of commercial-scale microalgal biofuel production as an alternative to conventional petroleum fuels. This article reports an effective framework to assess the performance of different dewatering technologies as the basis to establish an effective two-stage dewatering system. Bioflocculation coupled with tangential flow filtration (TFF) emerged a promising technique with total energy input of 0.041 kWh, 0.05 kg CO2 emissions and a cost of $ 0.0043 for producing 1 kg of microalgae biomass. A streamlined process for operational analysis of two-stage microalgae dewatering technique, encompassing energy input, carbon dioxide emission, and process cost, is presented. PMID:26904075

Toxicity and Fate Comparison between Several Brass and Titanium Dioxide Powders

DTIC Science & Technology

1993-07-01

the entire gut without showing any apparent effects . 14. UBJET TEMS1I. NUMBER OF PAGES 27 Daphnia Algae EC50 Aquatic toxicity 11T.PRICE CODE 9...levels of soluble copper and zinc in solution. 3. RESULTS The titanium dioxide ( TiO2 ) materials did not show any apparent toxic effects to daphnia up to...The extended exposure did not show any apparent toxic effects . Long term effects on aquatic org.rnisms exposed to TiO2 are not known. It is apparent

Nostoc sphaeroides Kütz, a candidate producer par excellence for CELSS

NASA Astrophysics Data System (ADS)

Wang, Gaohong; Hao, Zongjie; Liu, Yongding

A lot of aquatic organisms could be regarded as suitable candidates par excellence in the establishment of CELSS, since they are relatively easy and fast to grow and resistant to changes in environmental condition as well as providing nutritious, protein-and vitamin-rich foods for the crew, which can fulfill the main functions of CELSS, including supplying oxygen, water and food, removing carbon dioxide and making daily life waste reusable. Our labotory has developed mass culture of Nostoc sphaeroides Kütz, which is one of traditional healthy food in China and. The oxygen evolution rate of the cyanobacterium is about 150 molO2.mg-1.h-1, and it usually grows into colony with size between 2-20mm, which is easy to be harvested. It also can be cultured with high density, which show that the productivity of the cyanobacterium in limited volume is higher than other microalgae. We had measured the nutrient content of the cyanobacterium and developed some Chinese Dishes and Soups with Nostoc sphaeroides Kütz, which showed that it was a good food for crew. Using remote sensing technique, we also investigated its growth in Closed System under microgravity by SHENZHOU-2 spacecraft in January 2001. We plan to develop suitable bioreactor with the cyanobacterium for supplying oxygen and food to crew in future.

Using carbon dioxide in fisheries and aquatic invasive species management

USGS Publications Warehouse

Treanor, Hilary B.; Ray, Andrew M.; Layhee, Megan J.; Watten, Barnaby J.; Gross, Jason A.; Gresswell, Robert E.; Webb, Molly A. H.

2017-01-01

To restore native fish populations, fisheries programs often depend on active removal of aquatic invasive species. Chemical removal can be an effective method of eliminating aquatic invasive species, but chemicals can induce mortality in nontarget organisms and persist in the environment. Carbon dioxide (CO2) is an emerging alternative to traditional chemical control agents because it has been demonstrated to be toxic to fish, but is naturally occurring and readily neutralized. In addition, CO2 is a commercially available gas, is highly soluble, and has high absorption efficiency. When these characteristics are paired with advances in modern, large-scale gas delivery technologies, opportunities to use CO2 in natural or artificial (e.g., canals) waters to manage fish become increasingly feasible. Our objective is to describe the history of CO2 use in fisheries and outline potential future applications of CO2 to suppress and manipulate aquatic species in field and aquaculture settings.

An outdoor test facility for the large-scale production of microalgae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, D.A.; Weissman, J.; Goebel, R.

The goal of the US Department of EnergySolar Energy Research Institute's Aquatic Species Program is to develop the technology base to produce liquid fuels from microalgae. This technology is being initially developed for the desert Southwest. As part of this program an outdoor test facility has been designed and constructed in Roswell, New Mexico. The site has a large existing infrastructure, a suitable climate, and abundant saline groundwater. This facility will be used to evaluate productivity of microalgae strains and conduct large-scale experiments to increase biomass productivity while decreasing production costs. Six 3-m/sup 2/ fiberglass raceways were constructed. Several microalgaemore » strains were screened for growth, one of which had a short-term productivity rate of greater than 50 g dry wt m/sup /minus/2/ d/sup /minus/1/. Two large-scale, 0.1-ha raceways have also been built. These are being used to evaluate the performance trade-offs between low-cost earthen liners and higher cost plastic liners. A series of hydraulic measurements is also being carried out to evaluate future improved pond designs. Future plans include a 0.5-ha pond, which will be built in approximately 2 years to test a scaled-up system. This unique facility will be available to other researchers and industry for studies on microalgae productivity. 6 refs., 9 figs., 1 tab.« less

Effect of culture medium on toxic effect of ZnO nanoparticles to freshwater microalgae

NASA Astrophysics Data System (ADS)

Aravantinou, Andriana F.; Tsarpali, Vasiliki; Dailianis, Stefanos; Manariotis, Ioannis D.

2014-05-01

The widely use of nanoparticles (NPs) in many products, is increasing over time. The release of NPs into the environment may affect ecosystems, and therefore it is essential to study their impact on aquatic organisms. The aim of this work was to investigate the effect of zinc oxide (ZnO) NPs on microalgae, cultured in different mediums. Chlorococcum sp. and Scenedesmus rubescens were used as freshwater microalgae model species in order to investigate the toxic effects of ZnO NPs. Microalgae species exposed to ZnO NPs concentrations varying from 0.081 to 810 mg/L for different periods of time (24 to 96 h) and two different culture mediums. The aggregation level and particle size distribution of NPs were also determined during the experiments. The experimental results revealed significant differences on algae growth rates depending on the selected culture medium. Specifically, the toxic effect of ZnO NPs in Chlorococcum sp. was higher in cultures with 1/3N BG-11 medium than in BBM medium, despite the fact that the dissolved zinc concentration was higher in BBM medium. On the other hand, Scenedesmus rubescens exhibited the exact opposite behavior, with the highest toxic effect in cultures with BBM medium. Both species growth was significantly affected by the exposure time, the NPs concentrations, and mainly the culture medium.

The effect of naphthenic acids on physiological characteristics of the microalgae Phaeodactylum tricornutum and Platymonas helgolandica var. tsingtaoensis.

PubMed

Zhang, Huanxin; Tang, Xuexi; Shang, Jiagen; Zhao, Xinyu; Qu, Tongfei; Wang, Ying

2018-05-11

Naphthenic acids (NAs) account for 1-2% of crude oil and represent its main acidic component. However, the aquatoxic effects of NAs on marine phytoplankton and their ecological risks have remained largely unknown. Using the marine microalgae Phaeodactylum tricornutum and Platymonas helgolandica var. tsingtaoensis as the target, we studied the effects of NAs on their growth, cell morphology and physiological characteristics. The cell density decreased as the concentrations of NAs increased, indicating that they had an adverse effect on growth of the investigated algae in a concentration-dependent manner. Moreover, scanning electron microscopy revealed NAs exposure caused damage such as deformed cells, shrunken surface and ruptured cell structures. Exposure to NAs at higher concentrations for 48 h significantly increased the content of chlorophyll (Chl) a and b in P. tricornutum, but decreased their levels in P. helgolandica var. tsingtaoensis. NAs with concentrations no higher than 4 mg/L gradually enhanced the Chl fluorescence (ChlF) parameters and decreased the ChlF parameters at higher concentrations for the two marine microalgae. Additionally, NAs induced hormesis on photosynthetic efficiency of the two microalgae and also have the species difference in their aquatic toxicity. Overall, the results of this study provide a better understanding of the physiological responses of phytoplankton and will enable better risk assessments of NAs. Copyright © 2018 Elsevier Ltd. All rights reserved.

S-metolachlor promotes oxidative stress in green microalga Parachlorella kessleri - A potential environmental and health risk for higher organisms.

PubMed

Špoljarić Maronić, Dubravka; Štolfa Čamagajevac, Ivna; Horvatić, Janja; Žuna Pfeiffer, Tanja; Stević, Filip; Žarković, Neven; Waeg, Georg; Jaganjac, Morana

2018-05-08

The estimation of the toxic influences of herbicide products on non-target aquatic organisms is essential for evaluation of environmental contamination. We assessed the effects of the herbicide S-metolachlor (S-MET) on unicellular green microalga Parachlorella kessleri during 4-72 in vitro exposure to concentrations in the range 2-200μg/L. The results have shown that S-MET had a significant effect on algae, even in doses 10 and 20 times lower than the EC50 values obtained for P. kessleri (EC50-72h=1090μg/L). It generates reactive oxygen species in algae, decreases their growth and photosynthetic pigment concentration, changes their ultrastructure and alters the cellular antioxidant defence capacities. The levels of protein adducts with the reactive aldehyde 4-hydroxy-2-nonenal (HNE), the end-product of lipid peroxidation, were significantly elevated in S-MET treated cells revealing the insufficient effectiveness of P. kessleri antioxidant mechanisms and persistent lipid peroxidation. Since algae are fundamental aquatic food component, the damaged algal cells, still capable of dividing while having persistently increased content of HNE upon S-MET contamination could represent an important environmental toxic factor that might further affect higher organisms in the food chain. Copyright © 2018 Elsevier B.V. All rights reserved.

Change in Photosystem II Photochemistry During Algal Growth Phases of Chlorella vulgaris and Scenedesmus obliquus.

PubMed

Oukarroum, Abdallah

2016-06-01

Sensitivity of photosynthetic processes towards environmental stress is used as a bioanalytical tool to evaluate the responses of aquatic plants to a changing environment. In this paper, change of biomass density, chlorophyll a fluorescence and photosynthetic parameters during growth phases of two microalgae Chlorella vulgaris and Scenedesmus obliquus were studied. The photosynthetic growth behaviour changed significantly with cell age and algae species. During the exponential phase of growth, the photosynthesis capacity reached its maximum and decreased in ageing algal culture during stationary phase. In conclusion, the chlorophyll a fluorescence OJIP method and the derived fluorescence parameters would be an accurate method for obtaining information on maximum photosynthetic capacities and monitoring algal cell growth. This will contribute to more understanding, for example, of toxic actions of pollutants in microalgae test.

An effective device for gas-liquid oxygen removal in enclosed microalgae culture.

PubMed

Su, Zhenfeng; Kang, Ruijuan; Shi, Shaoyuan; Cong, Wei; Cai, Zhaoling

2010-01-01

A high-performance gas-liquid transmission device (HPTD) was described in this paper. To investigate the HPTD mass transfer characteristics, the overall volumetric mass transfer coefficients, K(A)(La,CO(2)) for the absorption of gaseous CO(2) and K(A)(La,O(2)) for the desorption of dissolved O(2) were determined, respectively, by titration and dissolved oxygen electrode. The mass transfer capability of carbon dioxide was compared with that of dissolved oxygen in the device, and the operating conditions were optimized to suit for the large-scale enclosed micro-algae cultivation. Based on the effectiveness evaluation of the HPTD applied in one enclosed flat plate Spirulina culture system, it was confirmed that the HPTD can satisfy the demand of the enclosed system for carbon supplement and excessive oxygen removal.

Switchable hydrophilicity solvents for lipid extraction from microalgae for biofuel production.

PubMed

Boyd, Alaina R; Champagne, Pascale; McGinn, Patrick J; MacDougall, Karen M; Melanson, Jeremy E; Jessop, Philip G

2012-08-01

A switchable hydrophilicity solvent (SHS) was studied for its effectiveness at extracting lipids from freeze-dried samples of Botryococcus braunii microalgae. The SHS N,N-dimethylcyclohexylamine extracted up to 22 wt.% crude lipid relative to the freeze-dried cell weight. The solvent was removed from the extract with water saturated with carbon dioxide at atmospheric pressure and recovered from the water upon de-carbonation of the mixture. Liquid chromatography-mass spectrometry (LC-MS) showed that the extracted lipids contained high concentrations of long chain tri-, di- and mono-acylglycerols, no phospholipids, and only 4-8% of residual solvent. Unlike extractions with conventional organic solvents, this new method requires neither distillation nor the use of volatile, flammable or chlorinated organic solvents. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of laser radiation on the cultivation rate of the microalga Chlorella sorokiniana as a source of biofuel

NASA Astrophysics Data System (ADS)

Politaeva, N.; Smyatskaya, Y.; Slugin, V.; Toumi, A.; Bouabdelli, M.

2018-01-01

This article studies the influence of laser radiation on the growth of micro-algal biomass of Chlorella sorokiniana. The composition of nutrient medium and the effect the laser beam (2 and 5 cm diameter, 1, 5, 10, 15 and 20 minutes exposure time) for accelerated cultivation of microalgal biomass were studied. The source of laser radiation (LR) was a helium-neon laser with a nominal output power of 1.6 mW and a wavelength of 0.63 μm. The greatest increase in biomass was observed when LR was applied to a suspension of microalga Chlorella sorokiniana with a beam of 5 cm diameter for a time of 10, 15 and 20 minutes. The results of the microscopic study of the microalga cells show a significant increase in the number of cells after an exposure to LR with a beam diameter of 5 cm in diameter. These cells were characterized by a large vacuole, a thickened lipid shell and a large accumulation of metabolites prone to agglutination. This study proposed to obtain valuable components (lipids, carotenoids, and pectin) from the obtained biomass by extraction method and to use the residual biomass formed wastes, after the extraction of valuable components, as a co-substrate for anaerobic digestion to produce biogas. The composition of biogas consists mainly of methane and carbon dioxide. Methane is recommended to be used for economic needs in supplying the whole process with heat and electricity. The carbon dioxide formed during fermentation and after combustion of methane for energy production, is planned to be used as a carbon source in the cultivation of Chlorella sorokiniana for photoautotrophic biomass production.

Evaluation on Microalgae Biomass for Bioethanol Production

NASA Astrophysics Data System (ADS)

Chng, L. M.; Lee, K. T.; Chan, D. C. J.

2017-06-01

The depletion of energy resources has triggered worldwide concern for alternative sources, especially renewable energy. Microalgae biomass offers the most promising feedstock for renewable energy because of their impressive efficient growing characteristics and valuable composition. Simple cell structure of the microalgae would simplify the pretreatment technology thus increase the cost-effectiveness of biofuel production. Scenedesmus dimorphus is a carbohydrate-rich microalgae that has potential as biomass for bioethanol. The cultivation of Scenedesmus dimorphus under aeration of carbon dioxide enriched air resulted 1.47 g/L of dry biomass with composition of 12 w/w total lipid, 53.7 w/w carbohydrate and 17.4 protein. Prior to ethanolic fermentation with Saccharomyces cerevisiae, various pre-treatment methods were investigated to release and degrade the complex carbohydrate in cell biomass thus obtaining the maximal amount of digestible sugar for ethanolic yeast. In this study, sulfuric acid was used as hydrolysis agent while amyloglucosidase as enzymatic agent. Dried biomass via hydrothermal acidic hydrolysis yielded sugar which is about 89 of total carbohydrate at reaction temperature of 125 °C and acid concentration of 4 v/v. While combination of organosolv treatment (mixture of methanol and chloroform) with enzymatic hydrolysis yielded comparable amount of sugar with 0.568 g glucose/g treated-biomass. In this study, the significant information in pre-treatment process ensures the sustainability of the biofuel produced.

Continuous cultivation of photosynthetic microorganisms: Approaches, applications and future trends.

PubMed

Fernandes, Bruno D; Mota, Andre; Teixeira, Jose A; Vicente, Antonio A

2015-11-01

The possibility of using photosynthetic microorganisms, such as cyanobacteria and microalgae, for converting light and carbon dioxide into valuable biochemical products has raised the need for new cost-efficient processes ensuring a constant product quality. Food, feed, biofuels, cosmetics and pharmaceutics are among the sectors that can profit from the application of photosynthetic microorganisms. Biomass growth in a photobioreactor is a complex process influenced by multiple parameters, such as photosynthetic light capture and attenuation, nutrient uptake, photobioreactor hydrodynamics and gas-liquid mass transfer. In order to optimize productivity while keeping a standard product quality, a permanent control of the main cultivation parameters is necessary, where the continuous cultivation has shown to be the best option. However it is of utmost importance to recognize the singularity of continuous cultivation of cyanobacteria and microalgae due to their dependence on light availability and intensity. In this sense, this review provides comprehensive information on recent breakthroughs and possible future trends regarding technological and process improvements in continuous cultivation systems of microalgae and cyanobacteria, that will directly affect cost-effectiveness and product quality standardization. An overview of the various applications, techniques and equipment (with special emphasis on photobioreactors) in continuous cultivation of microalgae and cyanobacteria are presented. Additionally, mathematical modeling, feasibility, economics as well as the applicability of continuous cultivation into large-scale operation, are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of antibacterial agents, levofloxacin and clarithromycin, on aquatic organisms.

PubMed

Yamashita, N; Yasojima, M; Nakada, N; Miyajima, K; Komori, K; Suzuki, Y; Tanaka, H

2006-01-01

Contamination of surface waters by pharmaceutical chemicals is an emerging environmental problem. This study evaluated the toxic effects of the antibacterial agents levofloxacin (LVFX) and clarithromycin (CAM), which are widely used in Japan, on aquatic organisms. Ecotoxicity tests using a bacterium, alga and crustacean were conducted. Microtox test using a marine fluorescent bacterium showed that LVFX and CAM have no acute toxicity to the bacterium. From the results of the Daphnia immobilisation test, LVFX and CAM did not show acute toxicity to the crustacean. Meanwhile, an algal growth inhibition test revealed that LVFX and CAM have high toxicity to the microalga. The phytotoxicity of CAM was about 100-fold higher than that of LVFX from a comparison of EC50 (median effective concentration) value. From the Daphnia reproduction test, LVFX and CAM also showed chronic toxicity to the crustacean. Concentrations of LVFX and CAM in the aquatic environment were compared with PNEC (predicted no effect concentration) to evaluate the ecological risk. As a result, the ecological risk of LVFX is considered to be low, but that of CAM is higher, suggesting that CAM discharged into an aquatic environment after therapeutic use may affect organisms in the aquatic environment.

Topical report on sources and systems for aquatic plant biomass as an energy resource

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldman, J.C.; Ryther, J.H.; Waaland, R.

1977-10-21

Background information is documented on the mass cultivation of aquatic plants and systems design that is available from the literature and through consultation with active research scientists and engineers. The biology of microalgae, macroalgae, and aquatic angiosperms is discussed in terms of morphology, life history, mode of existence, and ecological significance, as they relate to cultivation. The requirements for growth of these plants, which are outlined in the test, suggest that productivity rates are dependent primarily on the availability of light and nutrients. It is concluded that the systems should be run with an excess of nutrients and with lightmore » as the limiting factor. A historical review of the mass cultivation of aquatic plants describes the techniques used in commercial large-scale operations throughout the world and recent small-scale research efforts. This review presents information on the biomass yields that have been attained to date in various geographical locations with different plant species and culture conditions, emphasizing the contrast between high yields in small-scale operations and lower yields in large-scale operations.« less

Acute toxicity of anionic and non-ionic surfactants to aquatic organisms.

PubMed

Lechuga, M; Fernández-Serrano, M; Jurado, E; Núñez-Olea, J; Ríos, F

2016-03-01

The environmental risk of surfactants requires toxicity measurements. As different test organisms have different sensitivity to the toxics, it is necessary to establish the most appropriate organism to classify the surfactant as very toxic, toxic, harmful or safe, in order to establish the maximum permissible concentrations in aquatic ecosystems. We have determined the toxicity values of various anionic surfactants ether carboxylic derivatives using four test organisms: the freshwater crustacean Daphnia magna, the luminescent bacterium Vibrio fischeri, the microalgae Selenastrum capricornutum (freshwater algae) and Phaeodactylum tricornutum (seawater algae). In addition, in order to compare and classify the different families of surfactants, we have included a compilation of toxicity data of surfactants collected from literature. The results indicated that V. fischeri was more sensitive to the toxic effects of the surfactants than was D. magna or the microalgae, which was the least sensitive. This result shows that the most suitable toxicity assay for surfactants may be the one using V. fischeri. The toxicity data revealed considerable variation in toxicity responses with the structure of the surfactants regardless of the species tested. The toxicity data have been related to the structure of the surfactants, giving a mathematical relationship that helps to predict the toxic potential of a surfactant from its structure. Model-predicted toxicity agreed well with toxicity values reported in the literature for several surfactants previously studied. Predictive models of toxicity is a handy tool for providing a risk assessment that can be useful to establish the toxicity range for each surfactant and the different test organisms in order to select efficient surfactants with a lower impact on the aquatic environment. Copyright © 2015 Elsevier Inc. All rights reserved.

Does the photo-Fenton reaction work for microalgae control? A case study with Desmodesmus subspicatus.

PubMed

Torres, Mariana de Almeida; de Liz, Marcus Vinicius; Martins, Lucia Regina Rocha; Freitas, Adriane Martins

2018-04-18

Increased concentrations of nutrients in water bodies caused by effluent discharge, fertilizers and other inputs can lead to artificial eutrophication, increasing the primary productivity, bringing well-known and serious consequences to the environment (such as excessive macrophyte and microalgae growth). Most strategies for phytoplankton control in aquatic ecosystems result in metal accumulation or toxic by-product formation after chlorination. Concerning this matter, the photo-Fenton process (usually applied in wastewater treatment and degradation of a variety of contaminants) has been studied for water and effluent disinfection. However, its application in microalgae inactivation has not been reported until now. Therefore, this work aimed to evaluate the process effectiveness in inactivating microalgae, using Desmodesmus subspicatus as a model. Photo-Fenton experiments were carried out at the lab scale, at 105 cells per mL with 20 mg L-1 of H2O2 and 5 mg L-1 of Fe2+ (complexed with oxalic acid). The cell concentration and Growth Inhibition Test (GIT) were used to evaluate the process efficiency and Scanning Electron Microscopy (SEM) to analyze any alterations in the cell morphology. After performing the photo-Fenton reaction, the individual contribution of the reactants and radiation was investigated. The cell concentration was not significantly reduced during the photo-Fenton reaction, but SEM images indicated possible morphology alterations and the GIT showed the loss of cell viability after 30 minutes of exposure. Effects on the cell growth were also observed when exposed only to hydrogen peroxide.

Strategies and ecological roles of algicidal bacteria.

PubMed

Meyer, Nils; Bigalke, Arite; Kaulfuß, Anett; Pohnert, Georg

2017-11-01

In both freshwater and marine ecosystems, phytoplankton are the most dominant primary producers, contributing substantially to aquatic food webs. Algicidal bacteria that can associate to microalgae from the phytoplankton have the capability to control the proliferation and even to lyse them. These bacteria thus play an important role in shaping species composition in pelagic environments. In this review, we discuss and categorise strategies used by algicidal bacteria for the attack on microalgae. We highlight the complex regulation of algicidal activity and defence responses that govern alga-bacteria interactions. We also discuss how algicidal bacteria impact algal physiology and metabolism and survey the existing algicidal metabolites and enzymes. The review illustrates that the ecological role of algicidal bacteria is not yet fully understood and critically discusses the challenges in obtaining ecologically relevant data. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

An economical device for carbon supplement in large-scale micro-algae production.

PubMed

Su, Zhenfeng; Kang, Ruijuan; Shi, Shaoyuan; Cong, Wei; Cai, Zhaoling

2008-10-01

One simple but efficient carbon-supplying device was designed and developed, and the correlative carbon-supplying technology was described. The absorbing characterization of this device was studied. The carbon-supplying system proved to be economical for large-scale cultivation of Spirulina sp. in an outdoor raceway pond, and the gaseous carbon dioxide absorptivity was enhanced above 78%, which could reduce the production cost greatly.

Evaluation of photosynthetic efficacy and CO2 removal of microalgae grown in an enriched bicarbonate medium.

PubMed

Abinandan, S; Shanthakumar, S

2016-06-01

Bicarbonate species in the aqueous phase is the primary source for CO 2 for the growth of microalgae. The potential of carbon dioxide (CO 2 ) fixation by Chlorella pyrenoidosa in enriched bicarbonate medium was evaluated. In the present study, effects of parameters such as pH, sodium bicarbonate concentration and inoculum size were assessed for the removal of CO 2 by C. pyrenoidosa under mixotrophic condition. Central composite design tool from response surface methodology was used to validate statistical methods in order to study the influence of these parameters. The obtained results reveal that the maximum removal of CO 2 was attained at pH 8 with sodium bicarbonate concentration of 3.33 g/l, and inoculum size of 30 %. The experimental results were statistically significant with R 2 value of 0.9527 and 0.960 for CO 2 removal and accumulation of chlorophyll content, respectively. Among the various interactions, interactive effects between the parameters pH and inoculum size was statistically significant (P < 0.05) for CO 2 removal and chlorophyll accumulation. Based on the studies, the application of C. pyrenoidosa as a potential source for carbon dioxide removal at alkaline pH from bicarbonate source is highlighted.

Ability of an alkali-tolerant mutant strain of the microalga Chlorella sp. AT1 to capture carbon dioxide for increasing carbon dioxide utilization efficiency.

PubMed

Kuo, Chiu-Mei; Lin, Tsung-Hsien; Yang, Yi-Chun; Zhang, Wen-Xin; Lai, Jinn-Tsyy; Wu, Hsi-Tien; Chang, Jo-Shu; Lin, Chih-Sheng

2017-11-01

An alkali-tolerant Chlorella sp. AT1 mutant strain was screened by NTG mutagenesis. The strain grew well in pH 6-11 media, and the optimal pH for growth was 10. The CO 2 utilization efficiencies of Chlorella sp. AT1 cultured with intermittent 10% CO 2 aeration for 10, 20 and 30min at 3-h intervals were approximately 80, 42 and 30%, respectively. In alkaline medium (pH=11) with intermittent 10% CO 2 aeration for 30min at 3-, 6- and 12-h intervals, the medium pH gradually changed to 10, and the biomass productivities of Chlorella sp. AT1 were 0.987, 0.848 and 0.710gL -1 d -1 , respectively. When Chlorella sp. AT1 was aerated with 10% CO 2 intermittently for 30min at 3-h intervals in semi-continuous cultivation for 21days, the biomass concentration and biomass productivity were 4.35gL -1 and 0.726gL -1 d -1 , respectively. Our results show that CO 2 utilization efficiency can be markedly increased by intermittent CO 2 aeration and alkaline media as a CO 2 -capturing strategy for alkali-tolerant microalga cultivation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electromagnetic response of the protective pellicle of different unicellular microalgae

NASA Astrophysics Data System (ADS)

Inchaussandague, Marina E.; Skigin, Diana C.; Tolivia, Analía.; Fuertes Vila, Isabel; Conforti, Visitación

2014-03-01

Euglenoids are unicellular aquatic organisms. These microalgae show a typical surface structure that distinguishes them from the other protists. Most cells are naked and bounded by a plasma membrane surrounded by a pellicle formed by overlapping bands. It is well known that all terrestrial and aquatic organisms are exposed to UV-A and UV-B radiation. This radiation is potentially harmful to life and since it can penetrate up to 12 meters in the water, it can reduce survival, growth and production of phytoplankton. However, the organisms have developed numerous protection mechanisms intended to reduce such damage, such as the production of pigments and other repair mechanisms. However, the possible protection that could provide the first barriers before entering into the cell has not been explored yet. In this paper we investigate, from an electromagnetic point of view, the role played by the pellicle of euglenoids in the protection of the cell against UV radiation. To do so, we investigate the electromagnetic response of different species that exhibit different behaviors against the UV radiation. We solve the diffraction problem by using the Chandezon Method and obtain the reflectance of the pellicle for the UV wavelengths. The results show that the corrugated pellicle could contribute to increase the reflectance, thus reducing the penetration of the UV radiation within the cell and therefore, minimizing the damage and increasing the survival of these organisms.

A Review of Enzymatic Transesterification of Microalgal Oil-Based Biodiesel Using Supercritical Technology

PubMed Central

Taher, Hanifa; Al-Zuhair, Sulaiman; Al-Marzouqi, Ali H.; Haik, Yousef; Farid, Mohammed M.

2011-01-01

Biodiesel is considered a promising replacement to petroleum-derived diesel. Using oils extracted from agricultural crops competes with their use as food and cannot realistically satisfy the global demand of diesel-fuel requirements. On the other hand, microalgae, which have a much higher oil yield per hectare, compared to oil crops, appear to be a source that has the potential to completely replace fossil diesel. Microalgae oil extraction is a major step in the overall biodiesel production process. Recently, supercritical carbon dioxide (SC-CO2) has been proposed to replace conventional solvent extraction techniques because it is nontoxic, nonhazardous, chemically stable, and inexpensive. It uses environmentally acceptable solvent, which can easily be separated from the products. In addition, the use of SC-CO2 as a reaction media has also been proposed to eliminate the inhibition limitations that encounter biodiesel production reaction using immobilized enzyme as a catalyst. Furthermore, using SC-CO2 allows easy separation of the product. In this paper, conventional biodiesel production with first generation feedstock, using chemical catalysts and solvent-extraction, is compared to new technologies with an emphasis on using microalgae, immobilized lipase, and SC-CO2 as an extraction solvent and reaction media. PMID:21915372

Effects of various LED light wavelengths and intensities on microalgae-based simultaneous biogas upgrading and digestate nutrient reduction process.

PubMed

Zhao, Yongjun; Wang, Juan; Zhang, Hui; Yan, Cheng; Zhang, Yuejin

2013-05-01

Biogas is a well-known, primary renewable energy source, but its utilizations are possible only after upgrading. The microalgae-based bag photo-bioreactor utilized in this research could effectively upgrade biogas and simultaneously reduce the nutrient content in digestate. Red light was determined as the optimal light wavelength for microalgae growth, biogas upgrading, and digestate nutrient reduction. In the range of moderate light intensities (i.e., 800, 1200, 1600, and 2000 μmol m(-2) s(-1)), higher light intensities achieved higher biogas upgrade and larger digestate nutrient reduction. Methane content attained the highest value of 92.74±3.56% (v/v). The highest chemical oxygen demand, total nitrogen, and total phosphorus reduction efficiency of digestate were 85.35±1.04%, 77.98±1.84%, and 73.03±2.14%, respectively. Considering the reduction and economic efficiencies of the carbon dioxide content of biogas and digestate nutrient as well as the biogas upgrading standard, the optimal light intensity range was determined to be from 1200 to 1600 μmol m(-2) s(-1). Copyright © 2013 Elsevier Ltd. All rights reserved.

Feasibility of carbon dioxide sequestration by Spongiochloris sp microalgae during petroleum wastewater treatment in airlift bioreactor.

PubMed

Abid, Abdeldjalil; Saidane, Faten; Hamdi, Moktar

2017-06-01

The aim of this work was to study the ability of using Hydrocabonoclastic native microbial and Spongiochloris sp microalgae in airlift bioreactors couples in order to restore hydrocarbons wastewater and develop the capacity of natural systems to reduce greenhouse effect through maximal control of CO 2 gas emission in atmosphere. The kinetic parameters of CO 2 gas fixation level and conversion it into biological material by microalgae as the biodegradation process effect in hydrocarbon have been evaluated. The result present that maximum specific growth rate μ max of Spongiochloris sp was (0.87±0.04day -1 ) and the biomass productivity P max was attended (1.5±0.3gL -1 day -1 ) with maximal CO 2 biofixation rate RCO 2 (2.9205gL -1 day -1 ). At 30°C and pH (7.6-7.4) the bioreactor showed a good wastewater removal efficiency (99.18%) in total hydrocarbons with COD stabilized within (1.30g/L), this result obtained suggesting that, the bioreactor applied system represented a useful strategy for maximizing CO 2 bio-mitigation. Copyright © 2017. Published by Elsevier Ltd.

Impact of natural organic matter on particle behavior and phototoxicity of titanium dioxide nanoparticles

EPA Science Inventory

Due to their inherent phototoxicity and inevitable environmental release, titanium dioxide nanoparticles (nano-TiO2) are increasingly studied in the field of aquatic toxicology. One of the particular interests is the interactions between nano-TiO2 and natural organic matter (NOM)...

Photocatalytic effects of titanium dioxide nanoparticles on aquatic organisms-Current knowledge and suggestions for future research.

PubMed

Haynes, Vena N; Ward, J Evan; Russell, Brandon J; Agrios, Alexander G

2017-04-01

Nanoparticles are entering natural systems through product usage, industrial waste and post-consumer material degradation. As the production of nanoparticles is expected to increase in the next decade, so too are predicted environmental loads. Engineered metal-oxide nanomaterials, such as titanium dioxide, are known for their photocatalytic capabilities. When these nanoparticles are exposed to ultraviolet radiation in the environment, however, they can produce radicals that are harmful to aquatic organisms. There have been a number of studies that have reported the toxicity of titanium dioxide nanoparticles in the absence of light. An increasing number of studies are assessing the interactive effects of nanoparticles and ultraviolet light. However, most of these studies neglect environmentally-relevant experimental conditions. For example, researchers are using nanoparticle concentrations and light intensities that are too high for natural systems, and are ignoring water constituents that can alter the light field. The purpose of this review is to summarize the current knowledge of the photocatalytic effects of TiO 2 nanoparticles on aquatic organisms, discuss the limitations of these studies, and outline environmentally-relevant factors that need to be considered in future experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Selenium biotransformations in an engineered aquatic ecosystem for bioremediation of agricultural wastewater via brine shrimp production.

PubMed

Schmidt, Radomir; Tantoyotai, Prapakorn; Fakra, Sirine C; Marcus, Matthew A; Yang, Soo In; Pickering, Ingrid J; Bañuelos, Gary S; Hristova, Krassimira R; Freeman, John L

2013-05-21

An engineered aquatic ecosystem was specifically designed to bioremediate selenium (Se), occurring as oxidized inorganic selenate from hypersalinized agricultural drainage water while producing brine shrimp enriched in organic Se and omega-3 and omega-6 fatty acids for use in value added nutraceutical food supplements. Selenate was successfully bioremediated by microalgal metabolism into organic Se (seleno-amino acids) and partially removed via gaseous volatile Se formation. Furthermore, filter-feeding brine shrimp that accumulated this organic Se were removed by net harvest. Thriving in this engineered pond system, brine shrimp ( Artemia franciscana Kellogg) and brine fly (Ephydridae sp.) have major ecological relevance as important food sources for large populations of waterfowl, breeding, and migratory shore birds. This aquatic ecosystem was an ideal model for study because it mimics trophic interactions in a Se polluted wetland. Inorganic selenate in drainage water was metabolized differently in microalgae, bacteria, and diatoms where it was accumulated and reduced into various inorganic forms (selenite, selenide, or elemental Se) or partially incorporated into organic Se mainly as selenomethionine. Brine shrimp and brine fly larva then bioaccumulated Se from ingesting aquatic microorganisms and further metabolized Se predominately into organic Se forms. Importantly, adult brine flies, which hatched from aquatic larva, bioaccumulated the highest Se concentrations of all organisms tested.

Microalgal symbiosis in biotechnology.

PubMed

Santos, Carla A; Reis, Alberto

2014-07-01

This review provides an analysis of recent published work on interactions between microorganisms, especially the ones involving mainly nutrient exchanges and at least with one microalga species. Examples of microbial partners are given, with a remark to the potential application of cultures of an autotroph and a heterotroph, which grow simultaneously, taking advantage of the complementary metabolisms. These are particularly interesting, either due to economic or sustainable aspects, and some applications have already reached the commercial stage of development. The added advantages of these symbiotic cultures are biomass, lipid, and other products productivity enhancement a better utilization of resources and the reduction or even elimination of process residues (including carbon dioxide and other greenhouse gases) to conduct an increasingly greener biotechnology. Among the several symbiotic partners referred, the microalgae and yeast cultures are the most used. The interaction between these two microorganisms shows how to enhance the lipid production for biodiesel purposes compared with separated (stand-alone) cultures.

Composition and Structure of Microalgae Indicated in Raman and Hyperspectral Spectra and Scanning Electron Microscopy: from Cyanobacteria to Isolates from Coal-bed Methane Water Ponds

NASA Astrophysics Data System (ADS)

Zhou, X.; Zhou, Z.; Apple, M. E.; Spangler, L.

2017-12-01

Microalgae can be used for many potential applications for human's benefits. These potential applications included biofuel production from microalgae, biofiltering to cleaning water, chemical extraction as nutrients, etc. However, exploration for such applications is still in the early stages. For instance, many species and strains of microalgae have been investigated for their lipid content and growing conditions for efficient productions of lipids, but no specific species have yet been chosen as a fuel source for commercial production because of the huge biodiversity and subsequently a wide range of species that can potentially be exploited for biodiesel production, the great variability between species in their fuel precursor producing capabilities. Numerous coal-bed methane water ponds were established in the world as a consequence of coal-bed methane production from deep coal seams. Microalgae were isolated from such ponds and potentially these ponds can be used as venues for algal production. In this study, we characterized chemical composition and structure of the Cyanobacteria Anabaena cylindrica (UTEX # 1611) and isolates from coal-bed methane ponds Nannochloropsis gaditana and PW95 using Laser Raman Spectroscopy (LRS), hyperspectral spectra, and Scanning Electron Microscope (SEM). The objective is to seek bio-indicators for potential applications of these microalgae species. For instance, indicator of rich content lips shows the great potential for biofuel production. Fig.1 shows an example of the Raman spectra of the three species in desiccated form. The spectral peaks were isolated and the corresponding composition was identified. The insert at the right hand of the Raman spectrum of each species is the micrograph of the cell morphology under a microscope. The Raman spectra of cells in aquatic solutions were also obtained and compared with the desiccated form. The hyperspectral reflectances of the three species show quite different characteristics and the main absorption bands and scattering bands were located and their association with composition and structure were analyzed and discussed. SEM micrographs will be collected and the composition and structure derived from the SEM micrographs will be discussed and compared with those derived from the Raman spectra and hyperspectral spectra.

Characterization of water quality and biological communities, Fish Creek, Teton County, Wyoming, 2007-08

USGS Publications Warehouse

Eddy-Miller, Cheryl A.; Peterson, David A.; Wheeler, Jerrod D.; Leemon, Daniel J.

2010-01-01

Fish Creek, a tributary to the Snake River, is about 25 river kilometers long and is located in Teton County in western Wyoming near the town of Wilson. Public concern about nuisance growths of aquatic plants in Fish Creek have been increasing in recent years. To address this concern, the U.S. Geological Survey conducted a study in cooperation with the Teton Conservation District to characterize the water quality and biological communities in Fish Creek. Water-quality samples were collected for analyses of physical properties and water chemistry (nutrients, nitrate isotopes, and wastewater chemicals) between March 2007 and October 2008 from seven surface-water sites and three groundwater wells. During this same period, aquatic plant and macroinvertebrate samples were collected and habitat characteristics were measured at the surface-water sites. The main objectives of this study were to (1) evaluate nutrient concentrations (that influence biological indicators of eutrophication) and potential sources of nutrients by using stable isotope analysis and other indicator chemicals (such as caffeine and disinfectants) that could provide evidence of anthropogenic sources, such as wastewater or septic tank contamination in Fish Creek and adjacent groundwater, and (2) characterize the algal, macrophyte, and macroinvertebrate communities and habitat of Fish Creek. Nitrate was the dominant species of dissolved nitrogen present in all samples and was the only bioavailable species detected at concentrations greater than the laboratory reporting level in all surface-water samples. Average concentrations of dissolved nitrate in surface water were largest in samples collected from the two sites with seasonal flow near Teton Village and decreased downstream; the smallest concentration was at downstream site A-Wck. Concentrations of dissolved nitrate in groundwater were consistently greater than concentrations in corresponding surface-water sites during the same sampling event. Orthophosphate was the primary dissolved species of phosphorus present in all surface-water and groundwater samples. The average concentration of dissolved orthophosphate in surface water was largest in samples collected from near Teton Village; samples from all other sites had similar average concentrations. Concentrations of dissolved orthophosphate in groundwater also were typically greater than concentrations in corresponding surface-water sites during the same sampling event. The aquatic plant communities in Fish Creek typically were composed of a mixture of macrophytes, macroalgae, microalgae, and moss. The composition of the aquatic plant community in Fish Creek appeared to shift in the downstream direction in 2007. On average, the proportion of macrophytes ranged from about 1 percent at site A-R1U, the most upstream site, to 54 percent of the plant community at site A-R6D, the farthest downstream site sampled during 2007. The downstream increase in macrophytes was accompanied by a downstream decrease in microalgae. The average proportion of microalgae ranged from 80 percent at site A-R1U to 24 percent at site A-R6D. The proportion of the macroalgae Cladophora in the aquatic plant community was relatively high at sites A-Wck and A-R3D in both 2007 and 2008.

Water table and species identity outweigh carbon and nitrogen availability in a softwater plant community

NASA Astrophysics Data System (ADS)

Vanderhaeghe, Floris; Smolders, Alfons J. P.; Roelofs, Jan G. M.; Hoffmann, Maurice

2013-02-01

Performance of aquatic macrophytes is driven by many environmental factors, and a major challenge is to understand how aquatic macrophyte communities are structured in various environments. In softwater lakes in Western Europe, hydrological state (submersed/emersed), carbon dioxide and ammonium levels and species interactions are considered as driving forces in structuring amphibious plant communities. In this study we aimed at evaluating the relative importance of these factors for four species in a competitive neighbourhood. Softwater lake habitat was simulated during one growing season in laboratory conditions, mimicking water level fluctuation, photoperiod and temperature. Artificial communities consisted of small populations of four softwater macrophyte species: Luronium natans, Baldellia ranunculoides ssp. repens, Eleocharis multicaulis and Hydrocotyle vulgaris. These communities were subjected to two levels of carbon dioxide and ammonium. Additionally, monocultures of Baldellia and Eleocharis were grown at a higher nutrient level combination in order to measure their competitive response in a community. Time (hydrological state) and species identity turned out to be the only consistently significant factors determining community composition. Plant performance was clearly species-dependent, while carbon dioxide and ammonium did not have major effects. The competitive response was significant in both Eleocharis and Baldellia. Competition intensity was highest in the emersed state. Carbon dioxide had a supplementary effect on the within-species performance in Luronium, Baldellia and Eleocharis, with high carbon dioxide level mainly resulting in more flowers and more stolons. Community outcomes and competitive responses in aquatic macrophytes appear difficult to predict, because of mixed life strategies and morphological and functional plasticity. We conclude that hydrological state was the only important environmental factor. The identity of the species that were present—implying species interactions—largely determined community outcome.

Estimating the capability of microalgae to physiological acclimatization and genetic adaptation to petroleum and diesel oil contamination.

PubMed

Romero-Lopez, Julia; Lopez-Rodas, Victoria; Costas, Eduardo

2012-11-15

There is increasing scientific interest in how phytoplankton reacts to petroleum contamination, since crude oil and its derivatives are generating extensive contamination of aquatic environments. However, toxic effects of short-term petroleum exposure are more widely known than the adaptation of phytoplankton to long-term petroleum exposure. An analysis of short-term and long-term effects of petroleum exposure was done using experimental populations of freshwater (Scenedesmus intermedius and Microcystis aeruginosa) and marine (Dunaliella tertiolecta) microalgae isolated from pristine sites without crude oil product contamination. These strains were exposed to increased levels of petroleum and diesel oil. Short-term exposure to petroleum or diesel oil revealed a rapid inhibition of photosynthetic performance and cell proliferation in freshwater and marine phytoplankton species. A broad degree of inter-specific variation in lethal contamination level was observed. When different strains were exposed to petroleum or diesel oil over the long-term, the cultures showed massive destruction of the sensitive cells. Nonetheless, after further incubation, some cultures were able to grow again due to cells that were resistant to the toxins. By means of a fluctuation analysis, discrimination between cells that had become resistant due to physiological acclimatization and resistant cells arising from rare spontaneous mutations was accomplished. In addition, an analysis was done as to the maximum capacity of adaptation to a gradual contamination process. An experimental ratchet protocol was used, which maintains a strong selection pressure in a temporal scale up to several months over very large experimental populations of microalgae. Microalgae are able to survive to petroleum contamination as a result of physiological acclimatization without genetic changes. However, when petroleum concentration exceeds the physiological limits, survival depends exclusively on the occurrence on mutations that confer resistance and subsequent selection of these mutants. Finally, it is certain that further mutations and selection will ultimately determine adaptation of microalgae to the environmental forcing. Copyright © 2012 Elsevier B.V. All rights reserved.

Quantification of Concentration of Microalgae Anabaena Cylindrica, Coal-bed Methane Water Isolates Nannochloropsis Gaditana and PW-95 in Aquatic Solutions through Hyperspectral Reflectance Measurement and Analytical Model Establishment

NASA Astrophysics Data System (ADS)

Zhou, Z.; Zhou, X.; Apple, M. E.; Spangler, L.

2017-12-01

Three species of microalgae, Anabaena cylindrica (UTEX # 1611), coal-bed methane water isolates Nannochloropsis gaditana and PW-95 were cultured for the measurements of their hyperspectral profiles in different concentrations. The hyperspectral data were measured by an Analytical Spectral Devices (ASD) spectroradiomter with the spectral resolution of 1 nanometer over the wavelength ranges from 350nm to 1050 nm for samples of microalgae of different concentration. Concentration of microalgae was measured using a Hemocytometer under microscope. The objective of this study is to establish the relation between spectral reflectance and micro-algal concentration so that microalgae concentration can be measured remotely by space- or airborne hyperspectral or multispectral sensors. Two types of analytical models, linear reflectance-concentration model and Lamber-Beer reflectance-concentration model, were established for each species. For linear modeling, the wavelength with the maximum correlation coefficient between the reflectance and concentrations of algae was located and then selected for each species of algae. The results of the linear models for each species are shown in Fig.1(a), in which Refl_1, Refl_2, and Refl_3 represent the reflectance of Anabaena, N. Gaditana, and PW-95 respectively. C1, C2, and C3 represent the Concentrations of Anabaena, N. Gaditana, and PW-95 respectively. The Lamber-Beer models were based on the Lambert-Beer Law, which states that the intensity of light propagating in a substance dissolved in a fully transmitting solvent is directly proportional to the concentration of the substance and the path length of the light through the solution. Thus, for the Lamber-Beer modeling, a wavelength with large absorption in red band was selected for each species. The results of Lambert-Beer models for each species are shown in Fig.1(b). Based on the Lamber-Beer models, the absorption coefficient for the three different species will be quantified.

Anaerobic digestion of the microalga Spirulina at extreme alkaline conditions: biogas production, metagenome, and metatranscriptome

PubMed Central

Nolla-Ardèvol, Vímac; Strous, Marc; Tegetmeyer, Halina E.

2015-01-01

A haloalkaline anaerobic microbial community obtained from soda lake sediments was used to inoculate anaerobic reactors for the production of methane rich biogas. The microalga Spirulina was successfully digested by the haloalkaline microbial consortium at alkaline conditions (pH 10, 2.0 M Na+). Continuous biogas production was observed and the obtained biogas was rich in methane, up to 96%. Alkaline medium acted as a CO2 scrubber which resulted in low amounts of CO2 and no traces of H2S in the produced biogas. A hydraulic retention time (HRT) of 15 days and 0.25 g Spirulina L−1 day−1 organic loading rate (OLR) were identified as the optimal operational parameters. Metagenomic and metatranscriptomic analysis showed that the hydrolysis of the supplied substrate was mainly carried out by Bacteroidetes of the “ML635J-40 aquatic group” while the hydrogenotrophic pathway was the main producer of methane in a methanogenic community dominated by Methanocalculus. PMID:26157422

Applications of Microalgal Biotechnology for Disease Control in Aquaculture.

PubMed

Charoonnart, Patai; Purton, Saul; Saksmerprome, Vanvimon

2018-04-12

Aquaculture industries, and in particular the farming of fish and crustaceans, are major contributors to the economy of many countries and an increasingly important component in global food supply. However, the severe impact of aquatic microbial diseases on production performance remains a challenge to these industries. This article considers the potential applications of microalgal technology in the control of such diseases. At the simplest level, microalgae offer health-promoting benefits as a nutritional supplement in feed meal because of their digestibility and high content of proteins, lipids and essential nutrients. Furthermore, some microalgal species possess natural anti-microbial compounds or contain biomolecules that can serve as immunostimulants. In addition, emerging genetic engineering technologies in microalgae offer the possibility of producing 'functional feed additives' in which novel and specific bioactives, such as fish growth hormones, anti-bacterials, subunit vaccines, and virus-targeted interfering RNAs, are components of the algal supplement. The evaluation of such technologies for farm applications is an important step in the future development of sustainable aquaculture.

Simulating CO₂ leakages from CCS to determine Zn toxicity using the marine microalgae Pleurochrysis roscoffensis.

PubMed

Bautista-Chamizo, Esther; De Orte, Manoela Romanó; DelValls, Tomás Ángel; Riba, Inmaculada

2016-02-01

Due to the current climate change and ocean acidification, a new technology for CO2 mitigation has been proposed, the Carbon dioxide Capture and Storage (CCS). However, there is an ecological risk associated with potential CO2 leakages from the sub-seabed storages sites. To evaluate the effects related to CO2 leakages, laboratory-scales experiments were performed using the marine microalgae Pleurochrysis roscoffensis. Five Zn concentrations were tested at different pHs to study Zn toxicity under acidified conditions. Seawater was collected and submitted to acidification by means of CO2 injection and by HCl addition. Results showed differences between both acidification techniques: while microalgae growth was enhanced by CO2 supply, reaching the optimal growth at pH 6.5 and full inhibition at pH 5.5, HCl acidification growth was inhibited at pH 6.5. Although small concentrations of Zn were positive for P. roscoffensis growth, Zn toxicity increased at lower pHs, and more severely on samples acidified with HCl. The conclusions obtained in this work are useful to address the potential effects on the marine ecosystem related to changes in metal bioavailability during CO2 leakages scenarios. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantification of Heavy Metals and Other Inorganic Contaminants on the Productivity of Microalgae.

PubMed

Napan, Katerine; Hess, Derek; McNeil, Brian; Quinn, Jason C

2015-07-10

Increasing demand for renewable fuels has researchers investigating the feasibility of alternative feedstocks, such as microalgae. Inherent advantages include high potential yield, use of non-arable land and integration with waste streams. The nutrient requirements of a large-scale microalgae production system will require the coupling of cultivation systems with industrial waste resources, such as carbon dioxide from flue gas and nutrients from wastewater. Inorganic contaminants present in these wastes can potentially lead to bioaccumulation in microalgal biomass negatively impact productivity and limiting end use. This study focuses on the experimental evaluation of the impact and the fate of 14 inorganic contaminants (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, V and Zn) on Nannochloropsis salina growth. Microalgae were cultivated in photobioreactors illuminated at 984 µmol m(-2) sec(-1) and maintained at pH 7 in a growth media polluted with inorganic contaminants at levels expected based on the composition found in commercial coal flue gas systems. Contaminants present in the biomass and the medium at the end of a 7 day growth period were analytically quantified through cold vapor atomic absorption spectrometry for Hg and through inductively coupled plasma mass spectrometry for As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Sn, V and Zn. Results show N. salina is a sensitive strain to the multi-metal environment with a statistical decrease in biomass yieldwith the introduction of these contaminants. The techniques presented here are adequate for quantifying algal growth and determining the fate of inorganic contaminants.

Quantification of Heavy Metals and Other Inorganic Contaminants on the Productivity of Microalgae

PubMed Central

Napan, Katerine; Hess, Derek; McNeil, Brian; Quinn, Jason C.

2015-01-01

Increasing demand for renewable fuels has researchers investigating the feasibility of alternative feedstocks, such as microalgae. Inherent advantages include high potential yield, use of non-arable land and integration with waste streams. The nutrient requirements of a large-scale microalgae production system will require the coupling of cultivation systems with industrial waste resources, such as carbon dioxide from flue gas and nutrients from wastewater. Inorganic contaminants present in these wastes can potentially lead to bioaccumulation in microalgal biomass negatively impact productivity and limiting end use. This study focuses on the experimental evaluation of the impact and the fate of 14 inorganic contaminants (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, V and Zn) on Nannochloropsis salina growth. Microalgae were cultivated in photobioreactors illuminated at 984 µmol m-2 sec-1 and maintained at pH 7 in a growth media polluted with inorganic contaminants at levels expected based on the composition found in commercial coal flue gas systems. Contaminants present in the biomass and the medium at the end of a 7 day growth period were analytically quantified through cold vapor atomic absorption spectrometry for Hg and through inductively coupled plasma mass spectrometry for As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Sn, V and Zn. Results show N. salina is a sensitive strain to the multi-metal environment with a statistical decrease in biomass yieldwith the introduction of these contaminants. The techniques presented here are adequate for quantifying algal growth and determining the fate of inorganic contaminants. PMID:26274060

Occurrence of β-N-methylamino-l-alanine (BMAA) and Isomers in Aquatic Environments and Aquatic Food Sources for Humans

PubMed Central

Arnich, Nathalie; Maignien, Thomas; Biré, Ronel

2018-01-01

The neurotoxin β-N-methylamino-l-alanine (BMAA), a non-protein amino acid produced by terrestrial and aquatic cyanobacteria and by micro-algae, has been suggested to play a role as an environmental factor in the neurodegenerative disease Amyotrophic Lateral Sclerosis-Parkinsonism-Dementia complex (ALS-PDC). The ubiquitous presence of BMAA in aquatic environments and organisms along the food chain potentially makes it public health concerns. However, the BMAA-associated human health risk remains difficult to rigorously assess due to analytical challenges associated with the detection and quantification of BMAA and its natural isomers, 2,4-diamino butyric acid (DAB), β-amino-N-methyl-alanine (BAMA) and N-(2-aminoethyl) glycine (AEG). This systematic review, reporting the current knowledge on the presence of BMAA and isomers in aquatic environments and human food sources, was based on a selection and a score numbering of the scientific literature according to various qualitative and quantitative criteria concerning the chemical analytical methods used. Results from the best-graded studies show that marine bivalves are to date the matrix containing the higher amount of BMAA, far more than most fish muscles, but with an exception for shark cartilage. This review discusses the available data in terms of their use for human health risk assessment and identifies knowledge gaps requiring further investigations. PMID:29443939

Morpho-physiological effects of ibuprofen on Scenedesmus rubescens.

PubMed

Moro, Isabella; Matozzo, Valerio; Piovan, Anna; Moschin, Emanuela; Vecchia, Francesca Dalla

2014-09-01

The pollution of aquatic bodies by drugs is an emerging environmental problem, because of their extensive use in animal and human context. Ibuprofen, 2-[4-(2-methylpropyl)phenyl]propanoic acid, is the non-steroidal anti-inflammatory drug mainly present both in wastewater and in rivers and lakes in Europe. Since in literature there is little information about the effects of ibuprofen on microalgae, in this paper we presented the results on the effects of this molecule at different concentrations (62.5μgL(-1), 250μgL(-1) and 1000μgL(-1)) on cultures of the freshwater microalga Scenedesmus rubescens (P.J.L. Dangeard) E. Kesslet et al. Ibuprofen effects on the alga were assayed at first through analyses of the growth curve. Moreover, analyses of cell morphology, ultrastructure, and photosynthetic pigments were additionally performed. The first negative effect of the drug was on the microalga growth, suggesting a drug action dose-dependent mechanism type, more evident at the concentration of 1000μgL(-1) ibuprofen and in the last phase of the growth curve. In support of this, following ibuprofen exposure, the cells exhibited morphological and ultrastructural alterations, mainly consisting in large cytoplasmic inclusions, probably of lipids and/or carotenoids. The decrease of chlorophyll amounts and, on the contrary, the increase of carotenoids were correlated with a stressful condition induced by drug. Copyright © 2014 Elsevier B.V. All rights reserved.

The use of probiotics in aquaculture.

PubMed

Hai, N V

2015-10-01

This study aims to present comprehensive notes for the use of probiotics in aquaculture. Probiotics have been proven to be positive promoters of aquatic animal growth, survival and health. In aquaculture, intestines, gills, the skin mucus of aquatic animals, and habitats or even culture collections and commercial products, can be sources for acquiring appropriate probiotics, which have been identified as bacteria (Gram-positive and Gram-negative) and nonbacteria (bacteriophages, microalgae and yeasts). While a bacterium is a pathogen to one aquatic animal, it can bring benefits to another fish species; a screening process plays a significant role in making a probiotic species specific. The administration of probiotics varies from oral/water routine to feed additives, of which the latter is commonly used in aquaculture. Probiotic applications can be either mono or multiple strains, or even in combination with prebiotic, immunostimulants such as synbiotics and synbiotism, and in live or dead forms. Encapsulating probiotics with live feed is a suitable approach to convey probiotics to aquatic animals. Dosage and duration of time are significant factors in providing desired results. Several modes of actions of probiotics are presented, while some others are not fully understood. Suggestions for further studies on the effects of probiotics in aquaculture are proposed. © 2015 The Society for Applied Microbiology.

Cu toxicity on growth and chlorophyll-a of Chaetoceros sp.

NASA Astrophysics Data System (ADS)

Puspitasari, R.; Suratno; Purbonegoro, T.; Agustin, A. T.

2018-02-01

Phytoplankton is a primary producer in marine aquatic ecosystem. Their sensitivity to metal makes them important to study to predict the environmental impact of pollution. Copper is an essential nutrient for aquatic life as micronutrients on an organism but toxic at high levels. The focus of this study was to assess the toxicity of copper to Chaetoceros sp. on growth and chlorophyll-a content. The result shows that inhibition concentration (IC50) of copper on the microalgae, Chaetoceros sp. was 30.25 μg L-1. Growth of Chaetoceros sp. decreased 16.84% in 16 μg L-1 and 81.97% in 44 μg L-1. Chlorophyll-a content decreased dramatically at 44 μg L-1 compared to control. Increase of the cell size, deformation of cell wall and loss of setae were observed at higher concentration of copper.

Evaluation of High Rate Algae Ponds for treatment of anaerobically digested wastewater: Effect of CO2 addition and modification of dilution rate.

PubMed

de Godos, I; Arbib, Z; Lara, E; Rogalla, F

2016-11-01

High Rate Algae Ponds (HRAP) are the simplest way to grow microalgae biomass and an interesting alternative for wastewater treatment. In this work the performance of these systems was evaluated using anaerobically digested wastewater as culture medium. Two variables were studied in long-term mode: the carbon dioxide supply and the modification of the dilution rates. The results showed that CO2 supply increases the productivity but less than expected considering the potential biomass generation calculated based on the ratios of carbon to nitrogen of microalgae and wastewater. The assimilation into biomass only accounted for 57% of the inlet nitrogen under the best conditions because nitrification and volatilization reduced the availability of this element. The operation under short hydraulic retention times presented a more interesting performance with higher biomass productivities. The biomass produced was efficiently harvested with in a Dissolved Air Flotation (DAF) unit. Copyright © 2016 Elsevier Ltd. All rights reserved.

Carbon dioxide utilisation of Dunaliella tertiolecta for carbon bio-mitigation in a semicontinuous photobioreactor.

PubMed

Farrelly, Damien J; Brennan, Liam; Everard, Colm D; McDonnell, Kevin P

2014-04-01

Bio-fixation of carbon dioxide (CO2) by microalgae has been recognised as an attractive approach to offset anthropogenic emissions. Biological carbon mitigation is the process whereby autotrophic organisms, such as microalgae, convert CO2 into organic carbon and O2 through photosynthesis; this process through respiration produces biomass. In this study Dunaliella tertiolecta was cultivated in a semicontinuous culture to investigate the carbon mitigation rate of the system. The algae were produced in 1.2-L Roux bottles with a working volume of 1 L while semicontinuous production commenced on day 4 of cultivation when the carbon mitigation rate was found to be at a maximum for D. tertiolecta. The reduction in CO2 between input and output gases was monitored to predict carbon fixation rates while biomass production and microalgal carbon content are used to calculate the actual carbon mitigation potential of D. tertiolecta. A renewal rate of 45 % of flask volume was utilised to maintain the culture in exponential growth with an average daily productivity of 0.07 g L(-1) day(-1). The results showed that 0.74 g L(-1) of biomass could be achieved after 7 days of semicontinuous production while a total carbon mitigation of 0.37 g L(-1) was achieved. This represented an increase of 0.18 g L(-1) in carbon mitigation rate compared to batch production of D. tertiolecta over the same cultivation period.

Microalgal biomass production pathways: evaluation of life cycle environmental impacts.

PubMed

Zaimes, George G; Khanna, Vikas

2013-06-20

Microalgae are touted as an attractive alternative to traditional forms of biomass for biofuel production, due to high productivity, ability to be cultivated on marginal lands, and potential to utilize carbon dioxide (CO2) from industrial flue gas. This work examines the fossil energy return on investment (EROIfossil), greenhouse gas (GHG) emissions, and direct Water Demands (WD) of producing dried algal biomass through the cultivation of microalgae in Open Raceway Ponds (ORP) for 21 geographic locations in the contiguous United States (U.S.). For each location, comprehensive life cycle assessment (LCA) is performed for multiple microalgal biomass production pathways, consisting of a combination of cultivation and harvesting options. Results indicate that the EROIfossil for microalgae biomass vary from 0.38 to 1.08 with life cycle GHG emissions of -46.2 to 48.9 (g CO2 eq/MJ-biomass) and direct WDs of 20.8 to 38.8 (Liters/MJ-biomass) over the range of scenarios analyzed. Further anaylsis reveals that the EROIfossil for production pathways is relatively location invariant, and that algae's life cycle energy balance and GHG impacts are highly dependent on cultivation and harvesting parameters. Contrarily, algae's direct water demands were found to be highly sensitive to geographic location, and thus may be a constraining factor in sustainable algal-derived biofuel production. Additionally, scenarios with promising EROIfossil and GHG emissions profiles are plagued with high technological uncertainty. Given the high variability in microalgae's energy and environmental performance, careful evaluation of the algae-to-fuel supply chain is necessary to ensure the long-term sustainability of emerging algal biofuel systems. Alternative production scenarios and technologies may have the potential to reduce the critical demands of biomass production, and should be considered to make algae a viable and more efficient biofuel alternative.

Photobioreactor cultivation strategies for microalgae and cyanobacteria.

PubMed

Johnson, Tylor J; Katuwal, Sarmila; Anderson, Gary A; Gu, Liping; Zhou, Ruanbao; Gibbons, William R

2018-03-08

The current burden on fossil-derived chemicals and fuels combined with the rapidly increasing global population has led to a crucial need to develop renewable and sustainable sources of chemicals and biofuels. Photoautotrophic microorganisms, including cyanobacteria and microalgae, have garnered a great deal of attention for their capability to produce these chemicals from carbon dioxide, mineralized water, and solar energy. While there have been substantial amounts of research directed at scaling-up production from these microorganisms, several factors have proven difficult to overcome, including high costs associated with cultivation, photobioreactor construction, and artificial lighting. Decreasing these costs will substantially increase the economic feasibility of these production processes. Thus, the purpose of this review is to describe various photobioreactor designs, and then provide an overview on lighting systems, mixing, gas transfer, and the hydrodynamics of bubbles. These factors must be considered when the goal of a production process is economic feasibility. Targets for improving microalgae and cyanobacteria cultivation media, including water reduction strategies will also be described. As fossil fuel reserves continue to be depleted and the world population continues to increase, it is imperative that renewable chemical and biofuel production processes be developed toward becoming economically feasible. Thus, it is essential that future research is directed toward improving these processes. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018. © 2018 American Institute of Chemical Engineers.

CO2 Biofixation by the Cyanobacterium Spirulina sp. LEB 18 and the Green Alga Chlorella fusca LEB 111 Grown Using Gas Effluents and Solid Residues of Thermoelectric Origin.

PubMed

da Silva Vaz, Bruna; Costa, Jorge Alberto Vieira; de Morais, Michele Greque

2016-01-01

The concentration of carbon dioxide (CO2) in the atmosphere has increased from 280 to 400 ppm in the last 10 years, and the coal-fired power plants are responsible for approximately 22 % of these emissions. The burning of fossil fuel also produces a great amount of solid waste that causes serious industrial and environmental problems. The biological processes become interesting alternative in combating pollution and developing new products. The objective of this study was to evaluate the CO2 biofixation potential of microalgae that were grown using gaseous effluents and solid residues of thermoelectric origin. The microalgae Chlorella fusca LEB 111 presented higher rate of CO2 biofixation (42.8 %) (p < 0.01) than did Spirulina sp. LEB 18. The values for the CO2 biofixation rates and the kinetic parameters of Spirulina and Chlorella cells grown using combustion gas did not differ significantly from those of cells grown using CO2 and a carbon source in the culture media. These microalgae could be grown using ash derived from coal combustion, using the minerals present in this residue as the source of the essential metals required for their growth and the CO2 derived from the combustion gas as their carbon source.

Potential risk of biochar-amended soil to aquatic systems: an evaluation based on aquatic bioassays.

PubMed

Bastos, A C; Prodana, M; Abrantes, N; Keizer, J J; Soares, A M V M; Loureiro, S

2014-11-01

It is vital to address potential risks to aquatic ecosystems exposed to runoff and leachates from biochar-amended soils, before large scale applications can be considered. So far, there are no established approaches for such an assessment. This study used a battery of bioassays and representative aquatic organisms for assessing the acute toxicity of water-extractable fractions of biochar-amended soil, at reported application rates (80 t ha(-1)). Biochar-amended aqueous soil extracts contained cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), zinc (Zn), nickel (Ni), lead (Pb), arsenic (As) and mercury (Hg) (Σmetals 96.3 µg l(-1)) as well as the 16 priority PAHs defined by the U.S. Environmental Protection Agency (Σ16PAHs 106 ng l(-1)) at contents in the range of current EU regulations for surface waters. Nevertheless, acute exposure to soil-biochar (SB) extracts resulted in species-specific effects and dose-response patterns. While the bioluminescent marine bacterium Vibrio fischeri was the most sensitive organism to aqueous SB extracts, there were no effects on the growth of the microalgae Pseudokirchneriella subcapitata. In contrast, up to 20 and 25% mobility impairment was obtained for the invertebrate Daphnia magna upon exposure to 50 and 100% SB extract concentrations (respectively). Results suggest that a battery of rapid and cost-effective aquatic bioassays that account for ecological representation can complement analytical characterization of biochar-amended soils and risk assessment approaches for surface and groundwater protection.

Toxicity of single-walled carbon nanotubes on green microalga Chromochloris zofingiensis

NASA Astrophysics Data System (ADS)

Wang, Yan; Yang, Kaijing

2013-03-01

Nanoparticles, or particles in size of 1-100 nm, are extensively used in the world in different applications. For instance, single-walled carbon nanotubes (SWCNTs) are commonly used in consumer products, such as biosensors, drug and vaccine delivery transporters, and novel biomaterials. Although nanoparticles do not cause safety concerns to consumers who use nanoparticle-containing products, these small particles are potentially harmful for workers who produce them in factories or in cases of discharge to aquatic ecosystems. SWCNTs do not have a natural analogue, so the effects on health of their disposal remain largely unknown. In this study, we evaluated the effects of SWCNTs on a population of the green microalga Chromochloris zofingiensis and the profile and production of pigments and fatty acids. The alga was incubated with SWCNTs for 6 days in 0 (control), 40, 80, 160, or 320 mg/L concentrations. SWCNTs showed both positive and negative effects on the growth of C. zofingiensis, with a biomass enhancement at low levels (40-160 mg/L) but inhibition at high levels (320 mg/L). By contrast, a decreased accumulation of fatty acids and pigments of C. zofingiensis was observed over the range of the tested concentrations. These results indicate that the markers on the inhibitive toxicity of SWCNTs are increasingly sensitive in the following order: biomass and fatty acids < primary carotenoids < chlorophylls < secondary carotenoids. C. zofingiensis is a suitable microalga for evaluating the ecotoxicological hazards of SWCNTs, especially in terms of pigmentation response.

Development of Green Fuels From Algae - The University of Tulsa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crunkleton, Daniel; Price, Geoffrey; Johannes, Tyler

The general public has become increasingly aware of the pitfalls encountered with the continued reliance on fossil fuels in the industrialized world. In response, the scientific community is in the process of developing non-fossil fuel technologies that can supply adequate energy while also being environmentally friendly. In this project, we concentrate on green fuels which we define as those capable of being produced from renewable and sustainable resources in a way that is compatible with the current transportation fuel infrastructure. One route to green fuels that has received relatively little attention begins with algae as a feedstock. Algae are amore » diverse group of aquatic, photosynthetic organisms, generally categorized as either macroalgae (i.e. seaweed) or microalgae. Microalgae constitute a spectacularly diverse group of prokaryotic and eukaryotic unicellular organisms and account for approximately 50% of global organic carbon fixation. The PI's have subdivided the proposed research program into three main research areas, all of which are essential to the development of commercially viable algae fuels compatible with current energy infrastructure. In the fuel development focus, catalytic cracking reactions of algae oils is optimized. In the species development project, genetic engineering is used to create microalgae strains that are capable of high-level hydrocarbon production. For the modeling effort, the construction of multi-scaled models of algae production was prioritized, including integrating small-scale hydrodynamic models of algae production and reactor design and large-scale design optimization models.« less

Semifield testing of a bioremediation tool for atrazine-contaminated soils: evaluating the efficacy on soil and aquatic compartments.

PubMed

Chelinho, Sónia; Moreira-Santos, Matilde; Silva, Cátia; Costa, Catarina; Viana, Paula; Viegas, Cristina A; Fialho, Arsénio M; Ribeiro, Rui; Sousa, José Paulo

2012-07-01

The present study evaluated the bioremediation efficacy of a cleanup tool for atrazine-contaminated soils (Pseudomonas sp. ADP plus citrate [P. ADP + CIT]) at a semifield scale, combining chemical and ecotoxicological information. Three experiments representing worst-case scenarios of atrazine contamination for soil, surface water (due to runoff), and groundwater (due to leaching) were performed in laboratory simulators (100 × 40 × 20 cm). For each experiment, three treatments were set up: bioremediated, nonbioremediated, and a control. In the first, the soil was sprayed with 10 times the recommended dose (RD) for corn of Atrazerba and with P. ADP + CIT at day 0 and a similar amount of P. ADP at day 2. The nonbioremediated treatment consisted of soil spraying with 10 times the RD of Atrazerba (day 0). After 7 d of treatment, samples of soil (and eluates), runoff, and leachate were collected for ecotoxicological tests with plants (Avena sativa and Brassica napus) and microalgae (Pseudokirchneriella subcapitata) species. In the nonbioremediated soils, atrazine was very toxic to both plants, with more pronounced effects on plant growth than on seed emergence. The bioremediation tool annulled atrazine toxicity to A. sativa (86 and 100% efficacy, respectively, for seed emergence and plant growth). For B. napus, results point to incomplete bioremediation. For the microalgae, eluate and runoff samples from the nonbioremediated soils were extremely toxic; a slight toxicity was registered for leachates. After only 7 d, the ecotoxicological risk for the aquatic compartments seemed to be diminished with the application of P. ADP + CIT. In aqueous samples obtained from the bioremediated soils, the microalgal growth was similar to the control for runoff samples and slightly lower than control (by 11%) for eluates. Copyright © 2012 SETAC.

Performance of Raphidocelis subcapitata exposed to heavy metal mixtures.

PubMed

Expósito, Nora; Kumar, Vikas; Sierra, Jordi; Schuhmacher, Marta; Giménez Papiol, Gemma

2017-12-01

Microalgae growth inhibition assays are candidates for referent ecotoxicological assays, and are a fundamental part in the strategy to reduce the use of fish and other animal models in aquatic toxicology. In the present work, the performance of Raphidocelis subcapitata exposed to heavy metals following standardized growth inhibition assays has been assessed in three different scenarios: 1) dilutions of single heavy metals, 2) artificial mixture of heavy metals at similar levels than those found in natural rivers and, 3) natural samples containing known mixtures of contaminants (heavy metals). Chemical speciation of heavy metals has been estimated with Eh-pH diagram and Visual MINTEQ software; heavy metal and free heavy metal ion concentrations were used as input data, together with microalgae growth inhibition, for Dr. Fit software. The final goal was to assess the suitability of the ecotoxicological test based on the growth inhibition of microalgae cultures, and the mathematic models based on these results, for regulatory and decision-making purposes. The toxicity of a given heavy metal is not only determined by its chemical speciation; other chemical and biological interaction play an important role in the final toxicity. Raphidocelis subcapitata 48h-h-EC50 for tested heavy metals (especially Cu and Zn) were in agreement with previous studies, when ion metal bioavailability was assumed to be 100%. Nevertheless, the calculated growth inhibition was not in agreement with the obtained inhibition when exposed to the artificial mixture of heavy metals or the natural sample. Interactions between heavy metal ions and the compounds of the culture media and/or the natural sample determine heavy metal bioavailability, and eventually their toxicity. More research is needed for facing the challenge posed by pollutant mixtures as they are present in natural environments, and make microalgae-based assays suitable for pollution management and regulatory purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of indigenous fresh water microalga Scenedesmus obtusus for feed and fuel applications: Effect of carbon dioxide, light and nutrient sources on growth and biochemical characteristics.

PubMed

Sarat Chandra, T; Deepak, R S; Maneesh Kumar, M; Mukherji, S; Chauhan, V S; Sarada, R; Mudliar, S N

2016-05-01

Scenedesmus obtusus, a freshwater microalga, was evaluated for its growth and biochemical characteristics under various culture conditions. S. obtusus was tolerant at all tested CO2 concentrations up to 20%. Among the different nitrogen sources, urea showed enhanced biomass productivities up to 2-fold compared to control, where the nitrogen source was sodium nitrate. Light intensity and photoperiod had a significant effect on growth rate and biomass productivity. The growth rate was observed maximum under continuous light exposure at the light intensities, 30μmolm(-2)sec(-1) and 60μmolm(-2)sec(-1) The species was able to tolerate the salinity levels up to 25mM NaCl, where, the increase in the concentration of NaCl suppressed the growth. Ammonium acetate and glycine showed better growth rate and biomass productivity indicating mixotrophic ability of S. obtusus. Supplementation of acetate and bicarbonate significantly enhanced the biomass productivity. Biodiesel properties of S. obtusus cultivated at various culture conditions were estimated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ciliates in chalk-stream habitats congregate in biodiversity hot spots.

PubMed

Bradley, Mark W; Esteban, Genoveva F; Finlay, Bland J

2010-09-01

Free-living ciliates are a diverse group of microbial eukaryotes that inhabit aquatic environments. They have a vital role within the 'microbial loop', being consumers of microscopic prey such as bacteria, micro-algae, and flagellates, and representing a link between the microscopic and macroscopic components of aquatic food webs. This investigation describes the ciliate communities of four habitats located in the catchment of the River Frome, the major chalk-stream in southern Britain. The ciliate communities were characterised in terms of community assemblage, species abundance and size classes. The ciliate communities investigated proved to be highly diverse, yielding a total of 114 active species. An additional 15 'cryptic' ciliate species were also uncovered. Heterogeneity in the ciliate communities was evident at multiple spatial scales, revealing hot spots of species richness, both within and between habitats. The ciliate communities of habitats with flowing water were composed of smaller ciliates compared to the still-water habitats examined. Copyright 2010 Elsevier Masson SAS. All rights reserved.

Review: ecotoxicity of organic and organo-metallic antifouling co-biocides and implications for environmental hazard and risk assessments in aquatic ecosystems.

PubMed

Martins, Samantha Eslava; Fillmann, Gilberto; Lillicrap, Adam; Thomas, Kevin V

2018-01-01

Hazard assessments of Irgarol 1051, diuron, 2-(thiocyanomethylthio)benzothiazole (TCMTB), dichloro-octylisothiazolin (DCOIT), chlorothalonil, dichlofluanid, thiram, zinc pyrithione, copper pyrithione, triphenylborane pyridine (TPBP), capsaicin, nonivamide, tralopyril and medetomidine were performed to establish robust environmental quality standards (EQS), based on predicted no effect concentrations (PNECs). Microalgae, zooplankton, fish and amphibians were the most sensitive ecological groups to all the antifoulants evaluated, especially in the early life stages. No differences were identified between freshwater and seawater species. The use of toxicity tests with non-standard species is encouraged because they increase the datasets, allowing EQS to be derived from probabilistic-based PNECs whilst reducing uncertainties. The global ban of tributyltin (TBT) has been heralded as a major environmental success; however, substitute antifoulants may also pose risks to aquatic ecosystems. Environmental risk assessments (ERAs) have driven decision-makings for regulating antifouling products, but in many countries there is still a lack of regulation of antifouling biocides which should be addressed.

Physiological and biochemical responses of Chlorella vulgaris to Congo red.

PubMed

Hernández-Zamora, Miriam; Perales-Vela, Hugo Virgilio; Flores-Ortíz, César Mateo; Cañizares-Villanueva, Rosa Olivia

2014-10-01

Extensive use of synthetic dyes in many industrial applications releases large volumes of wastewater. Wastewaters from dying industries are considered hazardous and require careful treatment prior to discharge into receiving water bodies. Dyes can affect photosynthetic activities of aquatic flora and decrease dissolved oxygen in water. The aim of this study was to evaluate the effect of Congo red on growth and metabolic activity of Chlorella vulgaris after 96h exposure. Exposure of the microalga to Congo red reduced growth rate, photosynthesis and respiration. Analysis of chlorophyll a fluorescence emission showed that the donor side of photosystem II was affected at high concentrations of Congo red. The quantum yield for electron transport (φEo), the electron transport rate (ETR) and the performance index (PI) also decreased. The reduction in the ability to absorb and use the quantum energy increased non-photochemical (NPQ) mechanisms for thermal dissipation. Overall, Congo red affects growth and metabolic activity in photosynthetic organisms in aquatic environments. Copyright © 2014 Elsevier Inc. All rights reserved.

The biosynthesis of nitrous oxide in the green alga Chlamydomonas reinhardtii.

PubMed

Plouviez, Maxence; Wheeler, David; Shilton, Andy; Packer, Michael A; McLenachan, Patricia A; Sanz-Luque, Emanuel; Ocaña-Calahorro, Francisco; Fernández, Emilio; Guieysse, Benoit

2017-07-01

Over the last decades, several studies have reported emissions of nitrous oxide (N 2 O) from microalgal cultures and aquatic ecosystems characterized by a high level of algal activity (e.g. eutrophic lakes). As N 2 O is a potent greenhouse gas and an ozone-depleting pollutant, these findings suggest that large-scale cultivation of microalgae (and possibly, natural eutrophic ecosystems) could have a significant environmental impact. Using the model unicellular microalga Chlamydomonas reinhardtii, this study was conducted to investigate the molecular basis of microalgal N 2 O synthesis. We report that C. reinhardtii supplied with nitrite (NO 2 - ) under aerobic conditions can reduce NO 2 - into nitric oxide (NO) using either a mitochondrial cytochrome c oxidase (COX) or a dual enzymatic system of nitrate reductase (NR) and amidoxime-reducing component, and that NO is subsequently reduced into N 2 O by the enzyme NO reductase (NOR). Based on experimental evidence and published literature, we hypothesize that when nitrate (NO 3 - ) is the main Nitrogen source and the intracellular concentration of NO 2 - is low (i.e. under physiological conditions), microalgal N 2 O synthesis involves the reduction of NO 3 - to NO 2 - by NR followed by the reduction of NO 2 - to NO by the dual system involving NR. This microalgal N 2 O pathway has broad implications for environmental science and algal biology because the pathway of NO 3 - assimilation is conserved among microalgae, and because its regulation may involve NO. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Ionic liquids toxicity on fresh water microalgae, Scenedesmus quadricauda, Chlorella vulgaris &Botryococcus braunii; selection criterion for use in a two-phase partitioning bioreactor (TPPBR).

PubMed

Quraishi, Khurrum Shehzad; Bustam, Mohamad Azmi; Krishnan, Sooridarsan; Aminuddin, Noor Fathanah; Azeezah, Noraisyah; Ghani, Noraini Abd; Uemura, Yoshimitsu; Lévêque, Jean Marc

2017-10-01

A promising method of Carbon dioxide (CO 2 ) valorization is to use green microalgae photosynthesis to process biofuel. Two Phase Partitioning Bioreactors (TPPBR) offer the possibility to use non-aqueous phase liquids (NAPL) to enhance CO 2 solubility; thus making CO 2 available to maximize algae growth. This requires relatively less toxic hydrophobic Ionic Liquids (ILs) that comprise a new class of ionic compounds with remarkable physicochemical properties and thus qualifies them as NAPL candidates. This paper concerns the synthesis of ILs with octyl and butyl chains as well as different cations containing aromatic (imidazolium, pyridinium) and non-aromatic (piperidinum, pyrrolidinium) rings for CO 2 absorption studies. The authors measured their respective toxicity levels on microalgae species, specifically, Scenedesmus quadricauda, Chlorella vulgaris and Botryococcus braunii. Results revealed that octyl-based ILs were more toxic than butyl-based analogues. Such was the case for bmim-PF6 at double saturation with an absorbance of 0.11, compared to Omim-PF6 at 0.17, bmim-NTf2 at 0.02, and Omim-NTf2 at 0.14, respectively. CO 2 uptake results for ILs bearing octyl-based chains compared to the butyl analog were 54% (nCO 2 /nIL) (i.e., moles of CO 2 moles of IL) and 38% (nCO 2 /nIL), respectively. Conclusively, 1-butyl-1-methylpiperidinium absorbed 13% (nCO 2 /nIL) and appeared the least toxic, having an absorbance of 0.25 at 688 nm (double saturation at 7 d) compared to 1-butyl-3-methylimidazolium, which showed the highest toxicity with zero absorbance. Accordingly, these findings suggest that 1-butyl-1-methylpiperidinium is capable of transporting CO 2 to a system containing green microalgae without causing significant harm; thus allowing its use in TPPBR technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bioremoval of the azo dye Congo Red by the microalga Chlorella vulgaris.

PubMed

Hernández-Zamora, Miriam; Cristiani-Urbina, Eliseo; Martínez-Jerónimo, Fernando; Perales-Vela, Hugo Virgilio; Ponce-Noyola, Teresa; Montes-Horcasitas, María del Carmen; Cañizares-Villanueva, Rosa Olivia

2015-07-01

Discharge of dye-containing wastewater by the textile industry can adversely affect aquatic ecosystems and human health. Bioremoval is an alternative to industrial processes for detoxifying water contaminated with dyes. In this work, active and inactive biomass of the microalga Chlorella vulgaris was assayed for the ability to remove Congo Red (CR) dye from aqueous solutions. Through biosorption and biodegradation processes, Chlorella vulgaris was able to remove 83 and 58 % of dye at concentrations of 5 and 25 mg L(-1), respectively. The maximum adsorption capacity at equilibrium was 200 mg g(-1). The Langmuir model best described the experimental equilibrium data. The acute toxicity test (48 h) with two species of cladocerans indicated that the toxicity of the dye in the effluent was significantly decreased compared to the initial concentrations in the influent. Daphnia magna was the species less sensitive to dye (EC50 = 17.0 mg L(-1)), followed by Ceriodaphnia dubia (EC50 = 3.32 mg L(-1)). These results show that Chlorella vulgaris significantly reduced the dye concentration and toxicity. Therefore, this method may be a viable option for the treatment of this type of effluent.

Constraints to commercialization of algal fuels.

PubMed

Chisti, Yusuf

2013-09-10

Production of algal crude oil has been achieved in various pilot scale facilities, but whether algal fuels can be produced in sufficient quantity to meaningfully displace petroleum fuels, has been largely overlooked. Limitations to commercialization of algal fuels need to be understood and addressed for any future commercialization. This review identifies the major constraints to commercialization of transport fuels from microalgae. Algae derived fuels are expensive compared to petroleum derived fuels, but this could change. Unfortunately, improved economics of production are not sufficient for an environmentally sustainable production, or its large scale feasibility. A low-cost point supply of concentrated carbon dioxide colocated with the other essential resources is necessary for producing algal fuels. An insufficiency of concentrated carbon dioxide is actually a major impediment to any substantial production of algal fuels. Sustainability of production requires the development of an ability to almost fully recycle the phosphorous and nitrogen nutrients that are necessary for algae culture. Development of a nitrogen biofixation ability to support production of algal fuels ought to be an important long term objective. At sufficiently large scale, a limited supply of freshwater will pose a significant limitation to production even if marine algae are used. Processes for recovering energy from the algal biomass left after the extraction of oil, are required for achieving a net positive energy balance in the algal fuel oil. The near term outlook for widespread use of algal fuels appears bleak, but fuels for niche applications such as in aviation may be likely in the medium term. Genetic and metabolic engineering of microalgae to boost production of fuel oil and ease its recovery, are essential for commercialization of algal fuels. Algae will need to be genetically modified for improved photosynthetic efficiency in the long term. Copyright © 2013 Elsevier B.V. All rights reserved.

Challenges and opportunities for hydrogen production from microalgae.

PubMed

Oey, Melanie; Sawyer, Anne Linda; Ross, Ian Lawrence; Hankamer, Ben

2016-07-01

The global population is predicted to increase from ~7.3 billion to over 9 billion people by 2050. Together with rising economic growth, this is forecast to result in a 50% increase in fuel demand, which will have to be met while reducing carbon dioxide (CO2 ) emissions by 50-80% to maintain social, political, energy and climate security. This tension between rising fuel demand and the requirement for rapid global decarbonization highlights the need to fast-track the coordinated development and deployment of efficient cost-effective renewable technologies for the production of CO2 neutral energy. Currently, only 20% of global energy is provided as electricity, while 80% is provided as fuel. Hydrogen (H2 ) is the most advanced CO2 -free fuel and provides a 'common' energy currency as it can be produced via a range of renewable technologies, including photovoltaic (PV), wind, wave and biological systems such as microalgae, to power the next generation of H2 fuel cells. Microalgae production systems for carbon-based fuel (oil and ethanol) are now at the demonstration scale. This review focuses on evaluating the potential of microalgal technologies for the commercial production of solar-driven H2 from water. It summarizes key global technology drivers, the potential and theoretical limits of microalgal H2 production systems, emerging strategies to engineer next-generation systems and how these fit into an evolving H2 economy. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

The influence of natural dissolved organic matter on herbicide toxicity to marine microalgae is species-dependent.

PubMed

Coquillé, Nathalie; Ménard, Dominique; Rouxel, Julien; Dupraz, Valentin; Éon, Mélissa; Pardon, Patrick; Budzinski, Hélène; Morin, Soizic; Parlanti, Édith; Stachowski-Haberkorn, Sabine

2018-05-01

Microalgae, which are the foundation of aquatic food webs, may be the indirect target of herbicides used for agricultural and urban applications. Microalgae also interact with other compounds from their environment, such as natural dissolved organic matter (DOM), which can itself interact with herbicides. This study aimed to evaluate the influence of natural DOM on the toxicity of three herbicides (diuron, irgarol and S-metolachlor), singly and in ternary mixtures, to two marine microalgae, Chaetoceros calcitrans and Tetraselmis suecica, in monospecific, non-axenic cultures. Effects on growth, photosynthetic efficiency (Ф' M ) and relative lipid content were evaluated. The chemical environment (herbicide and nutrient concentrations, dissolved organic carbon and DOM optical properties) was also monitored to assess any changes during the experiments. The results show that, without DOM, the highest irgarol concentration (I0.5: 0.5 mg.L -1 ) and the strongest mixture (M2: irgarol 0.5 μg.L -1  + diuron 0.5 μg.L -1  + S-metolachlor 5.0 μg.L -1 ) significantly decreased all parameters for both species. Similar impacts were induced by I0.5 and M2 in C. calcitrans (around -56% for growth, -50% for relative lipid content and -28% for Ф' M ), but a significantly higher toxicity of M2 was observed in T. suecica (-56% and -62% with I0.5 and M2 for growth, respectively), suggesting a possible interaction between molecules. With DOM added to the culture media, a significant inhibition of these three parameters was also observed with I0.5 and M2 for both species. Furthermore, DOM modulated herbicide toxicity, which was decreased for C. calcitrans (-51% growth at I0.5 and M2) and increased for T. suecica (-64% and -75% growth at I0.5 and M2, respectively). In addition to the direct and/or indirect (via their associated bacteria) use of molecules present in natural DOM, the characterization of the chemical environment showed that the toxic effects observed on microalgae were accompanied by modifications of DOM composition and the quantity of dissolved organic carbon excreted and/or secreted by microorganisms. This toxicity modulation in presence of DOM could be explained by (i) the modification of herbicide bioavailability, (ii) a difference in cell wall composition between the two species, and/or (iii) a higher detoxification capacity of C. calcitrans by the use of molecules contained in DOM. This study therefore demonstrated, for the first time, the major modulating role of natural DOM on the toxicity of herbicides to marine microalgae. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessment of agglomeration, co-sedimentation and trophic transfer of titanium dioxide nanoparticles in a laboratory-scale predator-prey model system

NASA Astrophysics Data System (ADS)

Gupta, Govind Sharan; Kumar, Ashutosh; Shanker, Rishi; Dhawan, Alok

2016-08-01

Nano titanium dioxide (nTiO2) is the most abundantly released engineered nanomaterial (ENM) in aquatic environments. Therefore, it is prudent to assess its fate and its effects on lower trophic-level organisms in the aquatic food chain. A predator-and-prey-based laboratory microcosm was established using Paramecium caudatum and Escherichia coli to evaluate the effects of nTiO2. The surface interaction of nTiO2 with E. coli significantly increased after the addition of Paramecium into the microcosm. This interaction favoured the hetero-agglomeration and co-sedimentation of nTiO2. The extent of nTiO2 agglomeration under experimental conditions was as follows: combined E. coli and Paramecium > Paramecium only > E. coli only > without E. coli or Paramecium. An increase in nTiO2 internalisation in Paramecium cells was also observed in the presence or absence of E. coli cells. These interactions and nTiO2 internalisation in Paramecium cells induced statistically significant (p < 0.05) effects on growth and the bacterial ingestion rate at 24 h. These findings provide new insights into the fate of nTiO2 in the presence of bacterial-ciliate interactions in the aquatic environment.

Assessment of agglomeration, co-sedimentation and trophic transfer of titanium dioxide nanoparticles in a laboratory-scale predator-prey model system

PubMed Central

Gupta, Govind Sharan; Kumar, Ashutosh; Shanker, Rishi; Dhawan, Alok

2016-01-01

Nano titanium dioxide (nTiO2) is the most abundantly released engineered nanomaterial (ENM) in aquatic environments. Therefore, it is prudent to assess its fate and its effects on lower trophic-level organisms in the aquatic food chain. A predator-and-prey-based laboratory microcosm was established using Paramecium caudatum and Escherichia coli to evaluate the effects of nTiO2. The surface interaction of nTiO2 with E. coli significantly increased after the addition of Paramecium into the microcosm. This interaction favoured the hetero-agglomeration and co-sedimentation of nTiO2. The extent of nTiO2 agglomeration under experimental conditions was as follows: combined E. coli and Paramecium > Paramecium only > E. coli only > without E. coli or Paramecium. An increase in nTiO2 internalisation in Paramecium cells was also observed in the presence or absence of E. coli cells. These interactions and nTiO2 internalisation in Paramecium cells induced statistically significant (p < 0.05) effects on growth and the bacterial ingestion rate at 24 h. These findings provide new insights into the fate of nTiO2 in the presence of bacterial-ciliate interactions in the aquatic environment. PMID:27530102

Removal and Biodegradation of 17β-Estradiol and Diethylstilbestrol by the Freshwater Microalgae Raphidocelis subcapitata

PubMed Central

Chen, Qi; Sun, Kaifeng; Sun, Dong; Wu, Xiaoqing; Duan, Shunshan

2018-01-01

Natural steroidal and synthetic non-steroidal estrogens such as 17β-estradiol (E2) and diethylstilbestrol (DES) have been found in natural water, which can potentially endanger public health and aquatic ecosystems. The removal and biodegradation of E2 and DES by Raphidocelis subcapitata were studied in bacteria-free cultures exposed to single and mixture treatments at different concentrations for 96 h. The results showed that R. subcapitata exhibited a rapid and strong ability to remove E2 and DES in both single and mixture treatments by biodegradation. At the end of 96 h, the removal percentage of single E2 and DES achieved 82.0%, 80.4%, 74.6% and 89.9%, 73.4%, 54.1% in 0.1, 0.5, and 1.5 mg·L−1, respectively. With the exception of the 0.1 mg·L−1 treatment at 96 h, the removal capacity of E2 was more efficient than that of DES by R. subcapitata. Furthermore, the removal percentage of mixture E2 and DES achieved 88.5%, 82.9%, 84.3% and 87.2%, 71.8%, 51.1% in 0.1, 0.5, and 1.5 mg·L−1, respectively. The removal percentage of mixed E2 was significantly higher than that of the single E2. The presence of DES could accelerate the removal of E2 from the mixture treatments in equal concentrations. In addition, the removal was mainly attributed to the biodegradation or biotransformation process by the microalgae cells rather than simple sorption and accumulation in the cells. The microalgae R. subcapitata demonstrated a high capability for the removal of the E2 and DES indicating future prospects for its application. PMID:29510598

Bioremediation of wastewater using microalgae

NASA Astrophysics Data System (ADS)

Chalivendra, Saikumar

Population expansion and industrial development has deteriorated the quality of freshwater reservoirs around the world and has caused freshwater shortages in certain areas. Discharge of industrial effluents containing toxic heavy metals such as Cd and Cr into the environment have serious impact on human, animal and aquatic life. In order to solve these problems, the present study was focused on evaluating and demonstrating potential of microalgae for bioremediation of wastewater laden with nitrogen (N) in the form of nitrates, phosphorous (P) in the form of phosphates, chromium (Cr (VI)) and cadmium (Cd (II)). After screening several microalgae, Chlorella vulgaris and algae taken from Pleasant Hill Lake were chosen as candidate species for this study. The viability of the process was demonstrated in laboratory bioreactors and various experimental parameters such as contact time, initial metal concentration, algae concentration, pH and temperature that would affect remediation rates were studied. Based on the experimental results, correlations were developed to enable customizing and designing a commercial Algae based Wastewater Treatment System (AWTS). A commercial AWTS system that can be easily customized and is suitable for integration into existing wastewater treatment facilities was developed, and capital cost estimates for system including installation and annual operating costs were determined. The work concludes that algal bioremediation is a viable alternate technology for treating wastewater in an economical and sustainable way when compared to conventional treatment processes. The annual wastewater treatment cost to remove N,P is ~26x lower and to remove Cr, Cd is 7x lower than conventional treatment processes. The cost benefit analysis performed shows that if this technology is implemented at industrial complexes, Air Force freight and other Department of Defense installations with wastewater treatment plants, it could lead to millions of dollars in savings that could be repurposed for meeting other needs.

Influence of variable water depth and turbidity on microalgae production in a shallow estuarine lake system - A modelling study

NASA Astrophysics Data System (ADS)

Tirok, Katrin; Scharler, Ursula M.

2014-06-01

Strongly varying water levels and turbidities are typical characteristics of the large shallow estuarine lake system of St. Lucia, one of the largest on the African continent. This theoretical study investigated the combined effects of variable water depth and turbidity on seasonal pelagic and benthic microalgae production using a mathematical model, in order to ascertain productivity levels during variable and extreme conditions. Simulated pelagic and benthic net production varied between 0.3 and 180 g C m-2 year-1 and 0 and 220 g C m-2 year-1, respectively, dependent on depth, turbidity, and variability in turbidity. Although not surprising production and biomass decreased with increasing turbidity and depth. A high variability in turbidity, i.e. an alteration of calm and windy days, could reduce or enhance the seasonal pelagic and benthic production by more than 30% compared to a low variability. The day-to-day variability in wind-induced turbidity therefore influences production in the long term. On the other hand, varying water depth within a year did not significantly influence the seasonal production for turbidities representative of Lake St. Lucia. Reduced lake area and volume as observed during dry periods in Lake St. Lucia did not reduce primary production of the entire system since desiccation resulted in lower water depth and thus increased light availability. This agrees with field observations suggesting little light limitation and high areal microalgal biomass during a period with below average rainfall (2005-2011). Thus, microalgae potentially fulfil their function in the lake food-web even under extreme drought conditions. We believe that these results are of general interest to shallow aquatic ecosystems that are sensitive to drought periods due to either human or natural causes.

Genome and methylome of the oleaginous diatom Cyclotella cryptica reveal genetic flexibility toward a high lipid phenotype

DOE Office of Scientific and Technical Information (OSTI.GOV)

Traller, Jesse C.; Cokus, Shawn J.; Lopez, David A.

Here, improvement in the performance of eukaryotic microalgae for biofuel and bioproduct production is largely dependent on characterization of metabolic mechanisms within the cell. The marine diatom Cyclotella cryptica, which was originally identified in the Aquatic Species Program, is a promising strain of microalgae for large-scale production of biofuel and bioproducts, such as omega-3 fatty acids. As a result, we sequenced the nuclear genome and methylome of this oleaginous diatom to identify the genetic traits that enable substantial accumulation of triacylglycerol. The genome is comprised of highly methylated repetitive sequence, which does not significantly change under silicon starved lipid induction,more » and data further suggests the primary role of DNA methylation is to suppress DNA transposition. Annotation of pivotal glycolytic, lipid metabolism, and carbohydrate degradation processes reveal an expanded enzyme repertoire in C. cryptica that would allow for an increased metabolic capacity toward triacylglycerol production. Identification of previously unidentified genes, including those involved in carbon transport and chitin metabolism, provide potential targets for genetic manipulation of carbon flux to further increase its lipid phenotype. New genetic tools were developed, bringing this organism on a par with other microalgae in terms of genetic manipulation and characterization approaches. Furthermore, functional annotation and detailed cross-species comparison of key carbon rich processes in C. cryptica highlights the importance of enzymatic subcellular compartmentation for regulation of carbon flux, which is often overlooked in photosynthetic microeukaryotes. The availability of the genome sequence, as well as advanced genetic manipulation tools enable further development of this organism for deployment in large-scale production systems.« less

Copper uptake, intracellular localization, and speciation in marine microalgae measured by synchrotron radiation X-ray fluorescence and absorption microspectroscopy

DOE PAGES

Adams, Merrin S.; Dillon, Carolyn T.; Vogt, Stefan; ...

2016-07-20

Metal toxicity to aquatic organisms depends on the speciation of the metal and its binding to the critical receptor site(s) (biotic ligand) of the organism. The intracellular nature of the biotic ligand for Cu in microalgal cells was investigated using the high elemental sensitivity of microprobe synchrotron radiation X-ray fluorescence (SR-XRF) and X-ray absorption near-edge spectroscopy (XANES). The marine microalgae, Ceratoneis closterium, Phaeodactylum tricornutum, and Tetraselmis sp. were selected based on their varying sensitivities to Cu (72-h 50% population growth inhibitions of 8–47 μg Cu/L). Intracellular Cu in control cells was similar for all three species (2.5–3.2 × 10–15 gmore » Cu/cell) and increased 4-fold in C. closterium and Tetraselmis sp. when exposed to copper, but was unchanged in P. tricornutum (72-h exposure to 19, 40, and 40 μg Cu/L, respectively). Whole cell microprobe SR-XRF identified endogenous Cu in the central compartment (cytoplasm) of control (unexposed) cells. After Cu exposure, Cu was colocated with organelles/granules dense in P, S, Ca, and Si and this was clearly evident in thin sections of Tetraselmis sp. XANES indicated coexistence of Cu(I) and Cu(II) in control and Cu-exposed cells, with the Cu ligand (e.g., phytochelatin) in P. tricornutum different from that in C. closterium and Tetraselmis sp. Here, this study supports the hypothesis that Cu(II) is reduced to Cu(I) and that polyphosphate bodies and phytochelatins play a significant role in the internalization and detoxification of Cu in marine microalgae.« less

Genome and methylome of the oleaginous diatom Cyclotella cryptica reveal genetic flexibility toward a high lipid phenotype

DOE PAGES

Traller, Jesse C.; Cokus, Shawn J.; Lopez, David A.; ...

2016-11-25

Here, improvement in the performance of eukaryotic microalgae for biofuel and bioproduct production is largely dependent on characterization of metabolic mechanisms within the cell. The marine diatom Cyclotella cryptica, which was originally identified in the Aquatic Species Program, is a promising strain of microalgae for large-scale production of biofuel and bioproducts, such as omega-3 fatty acids. As a result, we sequenced the nuclear genome and methylome of this oleaginous diatom to identify the genetic traits that enable substantial accumulation of triacylglycerol. The genome is comprised of highly methylated repetitive sequence, which does not significantly change under silicon starved lipid induction,more » and data further suggests the primary role of DNA methylation is to suppress DNA transposition. Annotation of pivotal glycolytic, lipid metabolism, and carbohydrate degradation processes reveal an expanded enzyme repertoire in C. cryptica that would allow for an increased metabolic capacity toward triacylglycerol production. Identification of previously unidentified genes, including those involved in carbon transport and chitin metabolism, provide potential targets for genetic manipulation of carbon flux to further increase its lipid phenotype. New genetic tools were developed, bringing this organism on a par with other microalgae in terms of genetic manipulation and characterization approaches. Furthermore, functional annotation and detailed cross-species comparison of key carbon rich processes in C. cryptica highlights the importance of enzymatic subcellular compartmentation for regulation of carbon flux, which is often overlooked in photosynthetic microeukaryotes. The availability of the genome sequence, as well as advanced genetic manipulation tools enable further development of this organism for deployment in large-scale production systems.« less

Dual-mode cultivation of Chlorella protothecoides applying inter-reactors gas transfer improves microalgae biodiesel production.

PubMed

Santos, C A; Nobre, B; Lopes da Silva, T; Pinheiro, H M; Reis, A

2014-08-20

Chlorella protothecoides, a lipid-producing microalga, was grown heterotrophically and autotrophically in separate reactors, the off-gases exiting the former being used to aerate the latter. Autotrophic biomass productivity with the two-reactor association, 0.0249gL(-1)h(-1), was 2.2-fold the value obtained in a control autotrophic culture, aerated with ambient air. Fatty acid productivity was 1.7-fold the control value. C. protothecoides heterotrophic biomass productivity was 0.229gL(-1)h(-1). This biomass' fatty acid content was 34.5% (w/w) with a profile suitable for biodiesel production, according to European Standards. The carbon dioxide fixed by the autotrophic biomass was 45mgCO2L(-1)h(-1) in the symbiotic arrangement, 2.1 times the control reactor value. The avoided CO2 atmospheric emission represented 30% of the CO2 produced in the heterotrophic stage, while the released O2 represented 49% of the oxygen demand in that stage. Thus, an increased efficiency in the glucose carbon source use and a higher environmental sustainability were achieved in microalgal biodiesel production using the proposed assembly. Copyright © 2014 Elsevier B.V. All rights reserved.

A comparison of six different ballast water treatment systems based on UV radiation, electrochlorination and chlorine dioxide.

PubMed

Stehouwer, Peter Paul; Buma, Anita; Peperzak, Louis

2015-01-01

The spread of aquatic invasive species through ballast water is a major ecological and economical threat. Because of this, the International Maritime Organization (IMO) set limits to the concentrations of organisms allowed in ballast water. To meet these limits, ballast water treatment systems (BWTSs) were developed. The main techniques used for ballast water treatment are ultraviolet (UV) radiation and electrochlorination (EC). In this study, phytoplankton regrowth after treatment was followed for six BWTSs. Natural plankton communities were treated and incubated for 20 days. Growth, photosystem II efficiency and species composition were followed. The three UV systems all showed similar patterns of decrease in phytoplankton concentrations followed by regrowth. The two EC and the chlorine dioxide systems showed comparable results. However, UV- and chlorine-based treatment systems showed significantly different responses. Overall, all BWTSs reduced phytoplankton concentrations to below the IMO limits, which represents a reduced risk of aquatic invasions through ballast water.

A novel portable filtration system for sampling and concentration of microorganisms: Demonstration on marine microalgae with subsequent quantification using IC-NASBA.

PubMed

Loukas, Christos-Moritz; Mowlem, Matthew C; Tsaloglou, Maria-Nefeli; Green, Nicolas G

2018-05-01

This paper presents a novel portable sample filtration/concentration system, designed for use on samples of microorganisms with very low cell concentrations and large volumes, such as water-borne parasites, pathogens associated with faecal matter, or toxic phytoplankton. The example application used for demonstration was the in-field collection and concentration of microalgae from seawater samples. This type of organism is responsible for Harmful Algal Blooms (HABs), an example of which is commonly referred to as "red tides", which are typically the result of rapid proliferation and high biomass accumulation of harmful microalgal species in the water column or at the sea surface. For instance, Karenia brevis red tides are the cause of aquatic organism mortality and persistent blooms may cause widespread die-offs of populations of other organisms including vertebrates. In order to respond to, and adequately manage HABs, monitoring of toxic microalgae is required and large-volume sample concentrators would be a useful tool for in situ monitoring of HABs. The filtering system presented in this work enables consistent sample collection and concentration from 1 L to 1 mL in five minutes, allowing for subsequent benchtop sample extraction and analysis using molecular methods such as NASBA and IC-NASBA. The microalga Tetraselmis suecica was successfully detected at concentrations ranging from 2 × 10 5  cells/L to 20 cells/L. Karenia brevis was also detected and quantified at concentrations between 10 cells/L and 10 6  cells/L. Further analysis showed that the filter system, which concentrates cells from very large volumes with consequently more reliable sampling, produced samples that were more consistent than the independent non-filtered samples (benchtop controls), with a logarithmic dependency on increasing cell numbers. This filtering system provides simple, rapid, and consistent sample collection and concentration for further analysis, and could be applied to a wide range of different samples and target organisms in situations lacking laboratories. Copyright © 2018. Published by Elsevier B.V.

Imaging Spectrometry of Inland and Coastal Waters: State of the Art, Achievements and Perspectives

NASA Astrophysics Data System (ADS)

Giardino, C.; Brando, V. E.; Gege, P.; Pinnel, N.; Hochberg, E.; Knaeps, E.; Reusen, I.; Doerffer, R.; Bresciani, M.; Braga, F.; Foerster, S.; Champollion, N.; Dekker, A.

2018-06-01

Imaging spectrometry of non-oceanic aquatic ecosystems has been in development since the late 1980s when the first airborne hyperspectral sensors were deployed over lakes. Most water quality management applications were, however, developed using multispectral mid-spatial resolution satellites or coarse spatial resolution ocean colour satellites till now. This situation is about to change with a suite of upcoming imaging spectrometers being deployed from experimental satellites or from the International Space Station. We review the science of developing applications for inland and coastal aquatic ecosystems that often are a mixture of optically shallow and optically deep waters, with gradients of clear to turbid and oligotrophic to hypertrophic productive waters and with varying bottom visibility with and without macrophytes, macro-algae, benthic micro-algae or corals. As the spaceborne, airborne and in situ optical sensors become increasingly available and appropriate for aquatic ecosystem detection, monitoring and assessment, the science-based applications will need to be further developed to an operational level. The Earth Observation-derived information products will range from more accurate estimates of turbidity and transparency measures, chlorophyll, suspended matter and coloured dissolved organic matter concentration, to more sophisticated products such as particle size distributions, phytoplankton functional types or distinguishing sources of suspended and coloured dissolved matter, estimating water depth and mapping types of heterogeneous substrates. We provide an overview of past science, current state of the art and future directions so that early career scientists as well as aquatic ecosystem managers and associated industry groups may be prepared for the imminent deluge of imaging spectrometry data.

Transport and Use of Bicarbonate in Plants: Current Knowledge and Challenges Ahead.

PubMed

Poschenrieder, Charlotte; Fernández, José Antonio; Rubio, Lourdes; Pérez, Laura; Terés, Joana; Barceló, Juan

2018-05-03

Bicarbonate plays a fundamental role in the cell pH status in all organisms. In autotrophs, HCO₃ − may further contribute to carbon concentration mechanisms (CCM). This is especially relevant in the CO₂-poor habitats of cyanobacteria, aquatic microalgae, and macrophytes. Photosynthesis of terrestrial plants can also benefit from CCM as evidenced by the evolution of C₄ and Crassulacean Acid Metabolism (CAM). The presence of HCO₃ − in all organisms leads to more questions regarding the mechanisms of uptake and membrane transport in these different biological systems. This review aims to provide an overview of the transport and metabolic processes related to HCO₃ − in microalgae, macroalgae, seagrasses, and terrestrial plants. HCO₃ − transport in cyanobacteria and human cells is much better documented and is included for comparison. We further comment on the metabolic roles of HCO₃ − in plants by focusing on the diversity and functions of carbonic anhydrases and PEP carboxylases as well as on the signaling role of CO₂/HCO₃ − in stomatal guard cells. Plant responses to excess soil HCO₃ − is briefly addressed. In conclusion, there are still considerable gaps in our knowledge of HCO₃ − uptake and transport in plants that hamper the development of breeding strategies for both more efficient CCM and better HCO₃ − tolerance in crop plants.

Tiny Stowaways: Analyzing the Economic Benefits of a U.S. Environmental Protection Agency Permit Regulating Ballast Water Discharges

NASA Astrophysics Data System (ADS)

Lovell, Sabrina J.; Drake, Lisa A.

2009-03-01

The U.S. Environmental Protection Agency has proposed permitting ballast water discharges—a benefit of which would be to reduce the economic damages associated with the introduction and spread of aquatic invasive species. Research on ship-borne aquatic invasive species has been conducted in earnest for decades, but determining the economic damages they cause remains troublesome. Furthermore, with the exception of harmful algal blooms, the economic consequences of microscopic invaders have not been studied, despite their potentially great negative effects. In this paper, we show how to estimate the economic benefits of preventing the introduction and spread of harmful bacteria, microalgae, and viruses delivered in U.S. waters. Our calculations of net social welfare show the damages from a localized incident, cholera-causing bacteria found in shellfish in the Gulf of Mexico, to be approximately 706,000 (2006). On a larger scale, harmful algal species have the potential to be transported in ships’ ballast tanks, and their effects in the United States have been to reduce commercial fisheries landings and impair water quality. We examine the economic repercussions of one bloom-forming species. Finally, we consider the possible translocation within the Great Lakes of a virus that has the potential to harm commercial and recreational fisheries. These calculations illustrate an approach to quantifying the benefits of preventing invasive aquatic microorganisms from controls on ballast water discharges.

Tiny stowaways: analyzing the economic benefits of a U.S. Environmental Protection Agency permit regulating ballast water discharges.

PubMed

Lovell, Sabrina J; Drake, Lisa A

2009-03-01

The U.S. Environmental Protection Agency has proposed permitting ballast water discharges--a benefit of which would be to reduce the economic damages associated with the introduction and spread of aquatic invasive species. Research on ship-borne aquatic invasive species has been conducted in earnest for decades, but determining the economic damages they cause remains troublesome. Furthermore, with the exception of harmful algal blooms, the economic consequences of microscopic invaders have not been studied, despite their potentially great negative effects. In this paper, we show how to estimate the economic benefits of preventing the introduction and spread of harmful bacteria, microalgae, and viruses delivered in U.S. waters. Our calculations of net social welfare show the damages from a localized incident, cholera-causing bacteria found in shellfish in the Gulf of Mexico, to be approximately $706,000 (2006$). On a larger scale, harmful algal species have the potential to be transported in ships' ballast tanks, and their effects in the United States have been to reduce commercial fisheries landings and impair water quality. We examine the economic repercussions of one bloom-forming species. Finally, we consider the possible translocation within the Great Lakes of a virus that has the potential to harm commercial and recreational fisheries. These calculations illustrate an approach to quantifying the benefits of preventing invasive aquatic microorganisms from controls on ballast water discharges.

TiO2, SiO2 and ZrO2 Nanoparticles Synergistically Provoke Cellular Oxidative Damage in Freshwater Microalgae

PubMed Central

Liu, Yinghan; Ye, Nan; Fang, Hao; Wang, Degao

2018-01-01

Metal-based nanoparticles (NPs) are the most widely used engineered nanomaterials. The individual toxicities of metal-based NPs have been plentifully studied. However, the mixture toxicity of multiple NP systems (n ≥ 3) remains much less understood. Herein, the toxicity of titanium dioxide (TiO2) nanoparticles (NPs), silicon dioxide (SiO2) NPs and zirconium dioxide (ZrO2) NPs to unicellular freshwater algae Scenedesmus obliquus was investigated individually and in binary and ternary combination. Results show that the ternary combination systems of TiO2, SiO2 and ZrO2 NPs at a mixture concentration of 1 mg/L significantly enhanced mitochondrial membrane potential and intracellular reactive oxygen species level in the algae. Moreover, the ternary NP systems remarkably increased the activity of the antioxidant defense enzymes superoxide dismutase and catalase, together with an increase in lipid peroxidation products and small molecule metabolites. Furthermore, the observation of superficial structures of S. obliquus revealed obvious oxidative damage induced by the ternary mixtures. Taken together, the ternary NP systems exerted more severe oxidative stress in the algae than the individual and the binary NP systems. Thus, our findings highlight the importance of the assessment of the synergistic toxicity of multi-nanomaterial systems. PMID:29419775

Prediction of dissolved oxygen and carbon dioxide concentration profiles in tubular photobioreactors for microalgal culture

PubMed

Rubio; Fernandez; Perez; Camacho; Grima

1999-01-05

A model is developed for prediction of axial concentration profiles of dissolved oxygen and carbon dioxide in tubular photobioreactors used for culturing microalgae. Experimental data are used to verify the model for continuous outdoor culture of Porphyridium cruentum grown in a 200-L reactor with 100-m long tubular solar receiver. The culture was carried out at a dilution rate of 0.05 h-1 applied only during a 10-h daylight period. The quasi-steady state biomass concentration achieved was 3.0 g. L-1, corresponding to a biomass productivity of 1.5 g. L-1. d-1. The model could predict the dissolved oxygen level in both gas disengagement zone of the reactor and at the end of the loop, the exhaust gas composition, the amount of carbon dioxide injected, and the pH of the culture at each hour. In predicting the various parameters, the model took into account the length of the solar receiver tube, the rate of photosynthesis, the velocity of flow, the degree of mixing, and gas-liquid mass transfer. Because the model simulated the system behavior as a function of tube length and operational variables (superficial gas velocity in the riser, composition of carbon dioxide in the gas injected in the solar receiver and its injection rate), it could potentially be applied to rational design and scale-up of photobioreactors. Copyright 1999 John Wiley & Sons, Inc.

Extraction of urea and ammonium ion

NASA Technical Reports Server (NTRS)

Anselmi, R. T.; Husted, R. R.; Schulz, J. R.

1977-01-01

Water purification system keeps urea and ammonium ion concentration below toxic limits in recirculated water of closed loop aquatic habitat. Urea is first converted to ammonium ions and carbon dioxide by enzygmatic action. Ammonium ions are removed by ion exchange. Bioburden is controlled by filtration through 0.45 micron millipore filters.

A Killer Lake

ERIC Educational Resources Information Center

Horvath, Thomas

2005-01-01

In 1986, Lake Nyos, a volcanic lake in Cameroon, released a huge amount of carbon dioxide gas, killing over 1,700 people in the surrounding area. This case study, developed for use in a limnology or aquatic biology course, explores that event, introducing students to concepts relating to lake formation, thermal stratification, and dissolved gases.…

Phototoxicity and Dosimetry of Nano-scaleTitanium Dioxide in Aquatic Organisms

EPA Science Inventory

We have been testing nanoscale TiO2 (primarily Evonik P25) in acute exposures to identify and quantify its phototoxicity under solar simulated radiation (SSR), and to develop dose metrics reflective of both nano-scale properties and the photon component of its potency. Several e...

Phototoxicity and Dosimetry of Nano-scale Titanium Dioxide in Aquatic Organisms

EPA Science Inventory

We have been testing nanoscale TiO2 (primarily Evonik P25) in acute exposures to identify and quantify its phototoxicity under solar simulated radiation (SSR), and to develop dose metrics reflective of both nano-scale properties and the photon component of its potency. Several e...

Algae biofuels: versatility for the future of bioenergy.

PubMed

Jones, Carla S; Mayfield, Stephen P

2012-06-01

The world continues to increase its energy use, brought about by an expanding population and a desire for a greater standard of living. This energy use coupled with the realization of the impact of carbon dioxide on the climate, has led us to reanalyze the potential of plant-based biofuels. Of the potential sources of biofuels the most efficient producers of biomass are the photosynthetic microalgae and cyanobacteria. These versatile organisms can be used for the production of bioethanol, biodiesel, biohydrogen, and biogas. In fact, one of the most economic methods for algal biofuels production may be the combined biorefinery approach where multiple biofuels are produced from one biomass source. Copyright © 2011 Elsevier Ltd. All rights reserved.

Marine Organisms with Anti-Diabetes Properties

PubMed Central

Lauritano, Chiara; Ianora, Adrianna

2016-01-01

Diabetes is a chronic degenerative metabolic disease with high morbidity and mortality rates caused by its complications. In recent years, there has been a growing interest in looking for new bioactive compounds to treat this disease, including metabolites of marine origin. Several aquatic organisms have been screened to evaluate their possible anti-diabetes activities, such as bacteria, microalgae, macroalgae, seagrasses, sponges, corals, sea anemones, fish, salmon skin, a shark fusion protein as well as fish and shellfish wastes. Both in vitro and in vivo screenings have been used to test anti-hyperglycemic and anti-diabetic activities of marine organisms. This review summarizes recent discoveries in anti-diabetes properties of several marine organisms as well as marine wastes, existing patents and possible future research directions in this field. PMID:27916864

Net acidity indicates the whole effluent toxicity of pH and dissolved metals in metalliferous saline waters.

PubMed

Degens, Bradley P; Krassoi, Rick; Galvin, Lynette; Reynolds, Brad; Micevska, Tina

2018-05-01

Measurements of potential acidity in water are used to manage aquatic toxicity risks of discharge from acid sulfate soils or acid mine drainage. Net acidity calculated from pH, dissolved metals and alkalinity is a common measurement of potential acidity but the relevance of current risk thresholds to aquatic organisms are unclear. Aquatic toxicity testing was carried out using four halophytic organisms with water from four saline sources in southern Western Australia (3 acidic drains and one alkaline river; 39-40 g TDS/L) where acidity was varied by adjusting pH to 4.5-6.5. The test species were brine shrimps (Artemia salina), locally sourced ostracods (Platycypris baueri), microalgae (Dunaliella salina) and amphipods (Allorchestes compressa). Testing found the EC 10 and IC 10 of net acidity ranged from -7.8 to 10.5 mg CaCO 3 /L with no survival or growth of any species at >47 mg CaCO 3 /L. Reduced net acidity indicated reduced whole effluent toxicity more reliably than increased pH alone with organisms tolerating pH up to 1.1 units lower in the absence of dissolved metals. Variation in toxicity indicated by net acidity was mostly attributed to reduced concentrations of dissolved Al and Fe combined with higher pH and alkalinity and some changes in speciation of Al and Fe with pH. These results indicate that rapid in-field assessments of net acidity in acidic, Al dominated waters may be an indicator of potential acute and sub-chronic impacts on aquatic organisms. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

Ecotoxicological risks of the abandoned F-Ba-Pb-Zn mining area of Osor (Spain).

PubMed

Bori, Jaume; Vallès, Bettina; Navarro, Andrés; Riva, Maria Carme

2017-06-01

Due to its potential toxic properties, metal mobilization is of major concern in areas surrounding Pb-Zn mines. In the present study, metal contents and toxicity of soils, aqueous extracts from soils and mine drainage waters from an abandoned F-Ba-Pb-Zn mining area in Osor (Girona, NE Spain) were evaluated through chemical extractions and ecotoxicity bioassays. Toxicity assessment in the terrestrial compartment included lethal and sublethal endpoints on earthworms Eisenia fetida, arthropods Folsomia candida and several plant species, whereas aquatic tests involved bacteria Vibrio fischeri, microalgae Raphidocelis subcapitata and crustaceans Daphnia magna. Total concentrations of Ba (250-5110 mg kg -1 ), Pb (940 to >5000 mg kg -1 ) and Zn (2370-11,300 mg kg -1 ) in soils exceeded intervention values to protect human health. Risks for the aquatic compartment were identified in the release of drainage waters and in the potential leaching and runoff of metals from contaminated soils, with Cd (1.98-9.15 µg L -1 ), Pb (2.11-326 µg L -1 ) and Zn (280-2900 µg L -1 ) concentrations in filtered water samples surpassing US EPA Water Quality Criteria (2016a, b). Terrestrial ecotoxicity tests were in accordance with metal quantifications and identified the most polluted soil as the most toxic. Avoidance and reproduction tests with earthworms showed the highest sensitivity to metal contamination. Aquatic bioassays performed in aqueous extracts from soils confirmed the results from terrestrial tests and also detected toxic effects caused by the mine drainage waters. Algal growth inhibition was the most sensitive aquatic endpoint. In view of the results, the application of a containment or remediative procedure in the area is encouraged.

Toxicity of diesel water accommodated fraction toward microalgae, Pseudokirchneriella subcapitata and Chlorella sp. MM3.

PubMed

Ramadass, Kavitha; Megharaj, Mallavarapu; Venkateswarlu, Kadiyala; Naidu, Ravi

2017-08-01

Diesel is a commonly used fuel and a key pollutant on water surface through leaks and accidental spills, thus creating risk directly to planktons as well as other aquatic organisms. We assessed the toxicty of diesel and its water accommodated fraction (WAF) towards two microalgal species, Pseudokirchneriella subcapitata and Chlorella sp. MM3. The toxicity criteria included were: chlorophyll a content as a growth parameter and induction of enzyme activities linked to oxidative stress. Increase in concentrations of diesel or its WAF significantly increased toxicity towards growth, measured in terms of chlorophyll a content in both the algae. Activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) in response to addition of diesel or diesel WAF to the microalgal cultures were dose-dependent. Diesel WAF was more toxic than diesel itself, suggesting that use of WAF may be more relevant for environmental risk assessment of diesel. The overall response of the antioxidant enzymes to toxicants' stress followed the order: POX≥SOD>CAT. The present study clearly demonstrated the use of SOD, POX and CAT as suitable biomarkers for assessing diesel pollution in aquatic ecosystem. Copyright © 2017 Elsevier Inc. All rights reserved.

The Dinner Menu: Spatial Distribution of Organic Carbon Composition Across the San Francisco Bay-Delta

NASA Astrophysics Data System (ADS)

Harfmann, J.; Hernes, P.; Bergamaschi, B. A.

2016-12-01

The San Francisco Bay-Delta is a dynamic tidal system with multiple sources of carbon, both autochthonous (e.g. phytoplankton, submersed or floating aquatic vegetation, or non-phytoplankton microalgae) and allochthonous (e.g. riverine detritus, agricultural drainage, and urban runoff). Spatial variability in organic carbon (OC) sources translates into varying degrees of food quantity and quality for the aquatic food web, and yet surprisingly little is known about the implications of carbon source variability on the health of zooplankton populations, which form the base of the lower food chain. Particulate organic carbon (POC) is a critical component of zooplankton diet, and with the assistance of the microbial loop, dissolved organic carbon (DOC) may supplement their food. As part of a larger study linking OC sources with zooplankton growth, we collected water samples along a transect from San Pablo Bay to the Sacramento-San Joaquin Delta. Samples were analyzed for bulk POC and DOC, lignin, chlorophyll a, δ13C, and δ15N. Feeding experiments with the calanoid copepod Eurytemora affinis will be conducted in order to assess the relative bioavailability of collected OC across the transect.

Plant pigment types, distributions, and influences on shallow water submerged aquatic vegetation mapping

NASA Astrophysics Data System (ADS)

Hall, Carlton R.; Bostater, Charles R., Jr.; Virnstein, Robert

2004-11-01

Development of robust protocols for use in mapping shallow water habitats using hyperspectral imagery requires knowledge of absorbing and scattering features present in the environment. These include, but are not limited to, water quality parameters, phytoplankton concentrations and species, submerged aquatic vegetation (SAV) species and densities, epiphytic growth on SAV, benthic microalgae and substrate reflectance characteristics. In the Indian River Lagoon, Fl. USA we conceptualize the system as having three possible basic layers, water column and SAV bed above the bottom. Each layer is occupied by plants with their associated light absorbing pigments that occur in varying proportions and concentrations. Phytoplankton communities are composed primarily of diatoms, dinoflagellates, and picoplanktonic cyanobacteria. SAV beds, including flowering plants and green, red, and brown macro-algae exist along density gradients ranging in coverage from 0-100%. SAV beds may be monotypic, or more typically, mixtures of the several species that may or may not be covered in epiphytes. Shallow water benthic substrates are colonized by periphyton communities that include diatoms, dinoflagellates, chlorophytes and cyanobacteria. Inflection spectra created form ASIA hyperspectral data display a combination of features related to water and select plant pigment absorption peaks.

Profiling physicochemical and planktonic features from discretely/continuously sampled surface water.

PubMed

Oita, Azusa; Tsuboi, Yuuri; Date, Yasuhiro; Oshima, Takahiro; Sakata, Kenji; Yokoyama, Akiko; Moriya, Shigeharu; Kikuchi, Jun

2018-04-24

There is an increasing need for assessing aquatic ecosystems that are globally endangered. Since aquatic ecosystems are complex, integrated consideration of multiple factors utilizing omics technologies can help us better understand aquatic ecosystems. An integrated strategy linking three analytical (machine learning, factor mapping, and forecast-error-variance decomposition) approaches for extracting the features of surface water from datasets comprising ions, metabolites, and microorganisms is proposed herein. The three developed approaches can be employed for diverse datasets of sample sizes and experimentally analyzed factors. The three approaches are applied to explore the features of bay water surrounding Odaiba, Tokyo, Japan, as a case study. Firstly, the machine learning approach separated 681 surface water samples within Japan into three clusters, categorizing Odaiba water into seawater with relatively low inorganic ions, including Mg, Ba, and B. Secondly, the factor mapping approach illustrated Odaiba water samples from the summer as rich in multiple amino acids and some other metabolites and poor in inorganic ions relative to other seasons based on their seasonal dynamics. Finally, forecast-error-variance decomposition using vector autoregressive models indicated that a type of microalgae (Raphidophyceae) grows in close correlation with alanine, succinic acid, and valine on filters and with isobutyric acid and 4-hydroxybenzoic acid in filtrate, Ba, and average wind speed. Our integrated strategy can be used to examine many biological, chemical, and environmental physical factors to analyze surface water. Copyright © 2018. Published by Elsevier B.V.

A suite of microplate reader-based colorimetric methods to quantify ammonium, nitrate, orthophosphate and silicate concentrations for aquatic nutrient monitoring.

PubMed

Ringuet, Stephanie; Sassano, Lara; Johnson, Zackary I

2011-02-01

A sensitive, accurate and rapid analysis of major nutrients in aquatic systems is essential for monitoring and maintaining healthy aquatic environments. In particular, monitoring ammonium (NH(4)(+)) concentrations is necessary for maintenance of many fish stocks, while accurate monitoring and regulation of ammonium, orthophosphate (PO(4)(3-)), silicate (Si(OH)(4)) and nitrate (NO(3)(-)) concentrations are required for regulating algae production. Monitoring of wastewater streams is also required for many aquaculture, municipal and industrial wastewater facilities to comply with local, state or federal water quality effluent regulations. Traditional methods for quantifying these nutrient concentrations often require laborious techniques or expensive specialized equipment making these analyses difficult. Here we present four alternative microcolorimetric assays that are based on a standard 96-well microplate format and microplate reader that simplify the quantification of each of these nutrients. Each method uses small sample volumes (200 µL), has a detection limit ≤ 1 µM in freshwater and ≤ 2 µM in saltwater, precision of at least 8% and compares favorably with standard analytical procedures. Routine use of these techniques in the laboratory and at an aquaculture facility to monitor nutrient concentrations associated with microalgae growth demonstrates that they are rapid, accurate and highly reproducible among different users. These techniques offer an alternative to standard nutrient analyses and because they are based on the standard 96-well format, they significantly decrease the cost and time of processing while maintaining high precision and sensitivity.

Using agro-industrial wastes for the cultivation of microalgae and duckweeds: Contamination risks and biomass safety concerns.

PubMed

Markou, Giorgos; Wang, Liang; Ye, Jianfeng; Unc, Adrian

Aquatic organisms, such as microalgae (Chlorella, Arthrospira (Spirulina), Tetrasselmis, Dunalliela etc.) and duckweed (Lemna spp., Wolffia spp. etc.) are a potential source for the production of protein-rich biomass and for numerous other high-value compounds (fatty acids, pigments, vitamins etc.). Their cultivation using agro-industrial wastes and wastewater (WaW) is of particular interest in the context of a circular economy, not only for recycling valuable nutrients but also for reducing the requirements for fresh water for the production of biomass. Recovery and recycling of nutrients is an unavoidable long-term approach for securing future food and feed production. Agro-industrial WaW are rich in nutrients and have been widely considered as a potential nutrient source for the cultivation of microalgae/duckweed. However, they commonly contain various hazardous contaminants, which could potentially taint the produced biomass, raising various concerns about the safety of their consumption. Herein, an overview of the most important contaminants, including heavy metals and metalloids, pathogens (bacteria, viruses, parasites etc.), and xenobiotics (hormones, antibiotics, parasiticides etc.) is given. It is concluded that pretreatment and processing of WaW is a requisite step for the removal of several contaminants. Among the various technologies, anaerobic digestion (AD) is widely used in practice and offers a technologically mature approach for WaW treatment. During AD, various organic and biological contaminants are significantly removed. Further removal of contaminants could be achieved by post-treatment and processing of digestates (solid/liquid separation, dilution etc.) to further decrease the concentration of contaminants. Moreover, during cultivation an additional removal may occur through various mechanisms, such as precipitation, degradation, and biotransformation. Since many jurisdictions regulate the presence of various contaminants in feed or food setting strict safety monitoring processes, it would be of particular interest to initiate a multi-disciplinary discussion whether agro-industrial WaW ought to be used to cultivate microalgae/duckweed for feed or food production and identify most feasible options for doing this safely. Based on the current body of knowledge it is estimated that AD and post-treatment of WaW can lower significantly the risks associated with heavy metals and pathogens, but it is yet unclear to what extent this is the case for certain persistent xenobiotics. Copyright © 2018 Elsevier Inc. All rights reserved.

The Potential for Microalgae as Bioreactors to Produce Pharmaceuticals

PubMed Central

Yan, Na; Fan, Chengming; Chen, Yuhong; Hu, Zanmin

2016-01-01

As photosynthetic organisms, microalgae can efficiently convert solar energy into biomass. Microalgae are currently used as an important source of valuable natural biologically active molecules, such as carotenoids, chlorophyll, long-chain polyunsaturated fatty acids, phycobiliproteins, carotenoids and enzymes. Significant advances have been achieved in microalgae biotechnology over the last decade, and the use of microalgae as bioreactors for expressing recombinant proteins is receiving increased interest. Compared with the bioreactor systems that are currently in use, microalgae may be an attractive alternative for the production of pharmaceuticals, recombinant proteins and other valuable products. Products synthesized via the genetic engineering of microalgae include vaccines, antibodies, enzymes, blood-clotting factors, immune regulators, growth factors, hormones, and other valuable products, such as the anticancer agent Taxol. In this paper, we briefly compare the currently used bioreactor systems, summarize the progress in genetic engineering of microalgae, and discuss the potential for microalgae as bioreactors to produce pharmaceuticals. PMID:27322258

Selenium accumulation and metabolism in algae.

PubMed

Schiavon, Michela; Ertani, Andrea; Parrasia, Sofia; Vecchia, Francesca Dalla

2017-08-01

Selenium (Se) is an intriguing element because it is metabolically required by a variety of organisms, but it may induce toxicity at high doses. Algae primarily absorb selenium in the form of selenate or selenite using mechanisms similar to those reported in plants. However, while Se is needed by several species of microalgae, the essentiality of this element for plants has not been established yet. The study of Se uptake and accumulation strategies in micro- and macro-algae is of pivotal importance, as they represent potential vectors for Se movement in aquatic environments and Se at high levels may affect their growth causing a reduction in primary production. Some microalgae exhibit the capacity of efficiently converting Se to less harmful volatile compounds as a strategy to cope with Se toxicity. Therefore, they play a crucial role in Se-cycling through the ecosystem. On the other side, micro- or macro-algae enriched in Se may be used in Se biofortification programs aimed to improve Se content in human diet via supplementation of valuable food. Indeed, some organic forms of selenium (selenomethionine and methylselenocysteine) are known to act as anticarcinogenic compounds and exert a broad spectrum of beneficial effects in humans and other mammals. Here, we want to give an overview of the developments in the current understanding of Se uptake, accumulation and metabolism in algae, discussing potential ecotoxicological implications and nutritional aspects. Copyright © 2017 Elsevier B.V. All rights reserved.

Bioremediation of oxytetracycline in seawater by living and dead biomass of the microalga Phaeodactylum tricornutum.

PubMed

Santaeufemia, Sergio; Torres, Enrique; Mera, Roi; Abalde, Julio

2016-12-15

Due to its use, a large amount of Oxytetracycline (OTC) is released into water, which has a detrimental impact on aquatic ecosystems and human health. Although there are different physicochemical methods (mainly photodegradation) to remove OTC, there is increasing interest in the use of bioremediation. The sorption characteristics of OTC using living and dead biomass of the microalga Phaeodactylum tricornutum have been investigated in this study. Kinetics, isotherms and maximum elimination capacity were tested and discussed. Kinetic studies showed that the OTC removal by living biomass followed a sigmoidal model. However, the dead biomass followed a pseudo-first order model. The living biomass showed higher efficiency than the dead biomass with maximum sorption capacities of 29.18mgg -1 and 4.54mgg -1 , respectively. Combination of living biomass and photodegradation under the culture conditions eliminated 13.2mgL -1 of OTC during 11h of culture and with an initial OTC concentration of 15mgL -1 . With an initial OTC concentration of 2.5mgL -1 , 97% of OTC was removed. This removal was mainly caused by bioremediation than by photodegradation. The results proved the potential practical application of the living P. tricornutum biomass for a low-cost and efficient removal of OTC from seawater. Copyright © 2016 Elsevier B.V. All rights reserved.

Mechanisms of Phosphorus Acquisition and Lipid Class Remodeling under P Limitation in a Marine Microalga1[OPEN

PubMed Central

Winge, Per; El Assimi, Aimen; Jouhet, Juliette; Vadstein, Olav

2017-01-01

Molecular mechanisms of phosphorus (P) limitation are of great interest for understanding algal production in aquatic ecosystems. Previous studies point to P limitation-induced changes in lipid composition. As, in microalgae, the molecular mechanisms of this specific P stress adaptation remain unresolved, we reveal a detailed phospholipid-recycling scheme in Nannochloropsis oceanica and describe important P acquisition genes based on highly corresponding transcriptome and lipidome data. Initial responses to P limitation showed increased expression of genes involved in P uptake and an expansion of the P substrate spectrum based on purple acid phosphatases. Increase in P trafficking displayed a rearrangement between compartments by supplying P to the chloroplast and carbon to the cytosol for lipid synthesis. We propose a novel phospholipid-recycling scheme for algae that leads to the rapid reduction of phospholipids and synthesis of the P-free lipid classes. P mobilization through membrane lipid degradation is mediated mainly by two glycerophosphoryldiester phosphodiesterases and three patatin-like phospholipases A on the transcriptome level. To compensate for low phospholipids in exponential growth, N. oceanica synthesized sulfoquinovosyldiacylglycerol and diacylglyceroltrimethylhomoserine. In this study, it was shown that an N. oceanica strain has a unique repertoire of genes that facilitate P acquisition and the degradation of phospholipids compared with other stramenopiles. The novel phospholipid-recycling scheme opens new avenues for metabolic engineering of lipid composition in algae. PMID:29051196

Enhanced removal of Zn(2+) or Cd(2+) by the flocculating Chlorella vulgaris JSC-7.

PubMed

Alam, Md Asraful; Wan, Chun; Zhao, Xin-Qing; Chen, Li-Jie; Chang, Jo-Shu; Bai, Feng-Wu

2015-05-30

Microalgae are attracting attention due to their potentials in mitigating CO2 emissions and removing environmental pollutants. However, harvesting microalgal biomass from diluted cultures is one of the bottlenecks for developing economically viable processes for this purpose. Microalgal cells can be harvested by cost-effective sedimentation when flocculating strains are used. In this study, the removal of Zn(2+) and Cd(2+) by the flocculating Chlorella vulgaris JSC-7 was studied. The experimental results indicated that more than 80% Zn(2+) and 60% Cd(2+) were removed by the microalgal culture within 3 days in the presence up to 20.0mg/L Zn(2+) and 4.0mg/L Cd(2+), respectively, which were much higher than that observed with the culture of the non-flocculating C. vulgaris CNW11. Furthermore, the mechanism underlying this phenomenon was explored by investigating the effect of Zn(2+) and Cd(2+) on the growth and metabolic activities of the microalgal strains. It was found that the flocculation of the microalga improved its growth, synthesis of photosynthetic pigments and antioxidation activity under the stressful conditions, indicating a better tolerance to the heavy metal ions for a potential in removing them more efficiently from contaminated wastewaters, together with a bioremediation of other nutritional components contributed to the eutrophication of aquatic ecosystems. Copyright © 2015 Elsevier B.V. All rights reserved.

Isolation, Preliminary Characterization and Preliminary Assessment of Scale-Up Potential of Photosynthetic Microalgae for the Production of Both Biofuels and Bio-Active Molecules in the U.S. and Canada: Cooperative Research and Development Final Report, CRADA Number CRD-10-372

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pienkos, P.

2012-09-01

Combustion flue gases are a major contributor to carbon dioxide emissions into the Earth's atmosphere, a factor that has been linked to the possible global climate change. It is, therefore, critical to begin thinking seriously about ways to reduce this influx into the atmosphere. Using carbon dioxide from fossil fuel combustion as a feedstock for the growth, photosynthetic microorganisms can provide a large sink for carbon assimilation as well as a feedstock for the production of significant levels of biofuels. Combining microalgal farming with fossil fuel energy production has great potential to diminish carbon dioxide releases into the atmosphere, asmore » well as contribute to the production of biofuels (e.g., biodiesel, renewable diesel and gasoline and jet fuel) as well as valuable co-products such as animal feeds and green chemicals. CO2 capture may be a regulatory requirement in future new coal or natural gas power plants and will almost certainly become an opportunity for commerce, the results of such studies may provide industries in the US and Canada with both regulatory relief and business opportunities as well as the ability to meet environmental and regulatory requirements, and to produce large volumes of fuels and co-products.« less

Batch anaerobic co-digestion of waste activated sludge and microalgae (Chlorella sorokiniana) at mesophilic temperature.

PubMed

Beltrán, Carolina; Jeison, David; Fermoso, Fernando G; Borja, Rafael

2016-08-23

The microalgae Chlorella sorokiniana are used as co-substrate for waste activated sludge (WAS) anaerobic digestion. The specific objective of this research was to evaluate the feasibility of improving methane production from anaerobic digestion of WAS in co-digestion with this microalga, based on an optimized mixture percentage. Thus, the anaerobic co-digestion of both substrates aims to overcome the drawbacks of the anaerobic digestion of single WAS, simultaneously improving its management. Different co-digestion mixtures (0% WAS-100% microalgae; 25% WAS-75% microalgae; 50% WAS-50% microalgae; 75% WAS-25% microalgae; 100% WAS-0% microalgae) were studied. The highest methane yield (442 mL CH4/g VS) was obtained for the mixture with 75% WAS and 25% microalgae. This value was 22% and 39% higher than that obtained in the anaerobic digestion of the sole substrates WAS and microalgae, respectively, as well as 16% and 25% higher than those obtained for the co-digestion mixtures with 25% WAS and 75% microalgae and 50% WAS and 50% microalgae, respectively. The kinetic constant of the process increased 42%, 42% and 12%, respectively, for the mixtures with 25%, 50% and 75% of WAS compared to the substrate without WAS. Anaerobic digestion of WAS, together with C. sorokiniana, has been clearly improved by ensuring its viability, suitability and efficiency.

Greenhouse gas efflux from an impacted Malaysian tropical peat swamp (Invited)

NASA Astrophysics Data System (ADS)

Waldron, S.; Vihermaa, L. E.; Evers, S.; Garnett, M.; Newton, J.; Padfield, R.

2013-12-01

Tropical peatlands constitute ~11% of global peatland area and ~12% of the global peat C pool. Malaysia alone contains 10% of tropical peats. Due to rising global demands for food and biofuels, SE-Asia peat swamp forest ecosystems are threatened by increasing amounts of drainage, fire and conversion to plantation. These processes can change the GHG emissions and thus net ecosystem C balance. However, in comparison to temperate and boreal peatlands, there is a lack of data on terrestrial-aquatic-atmospheric carbon transfer from tropical peatlands, both those that are little disturbed and those facing anthropogenic pressures. Lateral transport of soil-respired carbon, and fluvial respiration or UV-oxidation of terrestrial DOC primes atmospheric carbon dioxide efflux. We now know that DOC lost from disturbed tropical peat swamp forests can be centuries to millennia old and originates deep within the peat column - this carbon may fuel efflux of old carbon dioxide and so anthropogenic land-use change renders the older, slower carbon cycles shorter and faster. Currently we have no knowledge of how significant ';older-slower' terrestrial-aquatic-atmospheric cycles are in disturbed tropical peatlands. Further, in some areas for commercial reasons, or by conservation bodies trying to minimise peat habitat loss, logged peats have been left to regenerate. Consequently, unpicking the legacy of multiple land uses on magnitude, age and source of GHG emissions is challenging but required to support land management decisions and projections of response to a changing climate. Here, we present the results of our first field campaign in July 2013 to the Raja Musa and Sungai Karang Peat Swamp Forest Reserves in North Selangor, Malaysia. This is one of Malaysia's largest oceanic peat swamps, and has been selectively logged and drained for 80 years, but is now subject to a 30 year logging ban to aid forest regeneration and build up wood stocks. From sites subject to different land use, we will present measurements of i) spatial variation in fluvial carbon dioxide and methane concentrations and associated efflux rates, and ii) the stable carbon isotopic composition of DIC and novel determination of the age of the effluxed carbon dioxide. From this we can consider if younger-faster or older-slower carbon cycling dominates the terrestrial-aquatic-atmospheric C transfer during this dry period sampling.

Atmospheric dry deposition of sulfur and nitrogen in the Athabasca Oil Sands Region, Alberta, Canada

Treesearch

Yu-Mei Hsu; Andrzej Bytnerowicz; Mark E. Fenn; Kevin E. Percy

2016-01-01

Due to the potential ecological effects on terrestrial and aquatic ecosystems from atmospheric deposition in the Athabasca Oil Sands Region (AOSR), Alberta, Canada, this study was implemented to estimate atmospheric nitrogen (N) and sulfur (S) inputs. Passive samplers were used to measure ambient concentrations of ammonia (NH3), nitrogen dioxide...

Long-chain polyunsaturated fatty acid sources and evaluation of their nutritional and functional properties

PubMed Central

Abedi, Elahe; Sahari, Mohammad Ali

2014-01-01

Recent studies have clearly shown the importance of polyunsaturated fatty acids (as essential fatty acids) and their nutritional value for human health. In this review, various sources, nutritional properties, and metabolism routes of long-chain polyunsaturated fatty acids (LC-PUFA) are introduced. Since the conversion efficiency of linoleic acid (LA) to arachidonic acid (AA) and also α-linolenic acid (ALA) to docosahexaenoic acid (DHA) and eicosatetraenoic acid (EPA) is low in humans, looking for the numerous sources of AA, EPA and EPA fatty acids. The sources include aquatic (fish, crustaceans, and mollusks), animal sources (meat, egg, and milk), plant sources including 20 plants, most of which were weeds having a good amount of LC-PUFA, fruits, herbs, and seeds; cyanobacteria; and microorganisms (bacteria, fungi, microalgae, and diatoms). PMID:25473503

Establishment of a Bioenergy-Focused Microalgae Strain Collection Using Rapid, High-Throughput Methodologies: Cooperative Research and Development Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pienkos, Philip T.

2013-11-01

This project is part of the overall effort by and among NREL, Colorado State University, University of Colorado, and Colorado School of Mines known as the Colorado Center for Biorefining and Biofuels. This is part of a larger statewide effort provided for in House Bill 06-1322, establishing a Colorado Collaboratory that envisions these four institutions working together as part of the state'senergy plan. This individual project with Colorado School of Mines is the first of many envisioned in this overall effort. The project focuses on development of high throughput procedures aimed at rapidly isolating and purifying novel microalgal strains (specificallymore » green alga and diatoms) from water samples obtained from unique aquatic environments.« less

Current Concepts and Future Directions of CELSS

NASA Technical Reports Server (NTRS)

Macelroy, R. D.; Bredt, J.

1985-01-01

Bioregenerative life support systems for use in space were studied. Concepts of such systems include the use of higher plants and/or microalgae as sources of food, potable water and oxygen, and as sinks for carbon dioxide and metabolic wastes. Recycling of materials within the system will require processing of food organism and crew wastes using microbiological and/or physical chemical techniques. The dynamics of material flow within the system will require monitoring, control, stabilization and maintenance imposed by computers. Studies included higher plant and algal physiology, environmental responses, and control; flight experiments for testing responses of organisms to weightlessness and increased radiation levels; and development of ground based facilities for the study of recycling within a bioregenerative life support system.

Climate-driven basin-scale decadal oscillations of oceanic phytoplankton.

PubMed

Martinez, Elodie; Antoine, David; D'Ortenzio, Fabrizio; Gentili, Bernard

2009-11-27

Phytoplankton--the microalgae that populate the upper lit layers of the ocean--fuel the oceanic food web and affect oceanic and atmospheric carbon dioxide levels through photosynthetic carbon fixation. Here, we show that multidecadal changes in global phytoplankton abundances are related to basin-scale oscillations of the physical ocean, specifically the Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation. This relationship is revealed in approximately 20 years of satellite observations of chlorophyll and sea surface temperature. Interaction between the main pycnocline and the upper ocean seasonal mixed layer is one mechanism behind this correlation. Our findings provide a context for the interpretation of contemporary changes in global phytoplankton and should improve predictions of their future evolution with climate change.

A geographical assessment of vegetation carbon stocks and greenhouse gas emissions on potential microalgae-based biofuel facilities in the United States.

PubMed

Quiroz Arita, Carlos; Yilmaz, Özge; Barlak, Semin; Catton, Kimberly B; Quinn, Jason C; Bradley, Thomas H

2016-12-01

The microalgae biofuels life cycle assessments (LCA) present in the literature have excluded the effects of direct land use change (DLUC) from facility construction under the assumption that DLUC effects are negligible. This study seeks to model the greenhouse gas (GHG) emissions of microalgae biofuels including DLUC by quantifying the CO 2 equivalence of carbon released to the atmosphere through the construction of microalgae facilities. The locations and types of biomass and Soil Organic Carbon that are disturbed through microalgae cultivation facility construction are quantified using geographical models of microalgae productivity potential including consideration of land availability. The results of this study demonstrate that previous LCA of microalgae to biofuel processes have overestimated GHG benefits of microalgae-based biofuels production by failing to include the effect of DLUC. Previous estimations of microalgae biofuel production potential have correspondingly overestimated the volume of biofuels that can be produced in compliance with U.S. environmental goals. Copyright © 2016 Elsevier Ltd. All rights reserved.

Adsorption behavior of lead on aquatic sediments contaminated with cerium dioxide nanoparticles.

PubMed

Wang, Chao; Fan, Xiulei; Wang, Peifang; Hou, Jun; Ao, Yanhui; Miao, Lingzhan

2016-12-01

Aquatic sediments serve as an important sink for engineered nanomaterials (ENMs), such as metal oxide nanoparticles (MeO NPs) and carbon nanotubes (CNTs). Owing to their remarkable properties, ENMs demonstrate significant potential to disturb the adsorption behavior of other contaminants in aquatic sediments, thereby altering the bioavailability and toxicity of these contaminants. Thus far, most studies have investigated the effect of CNTs on the adsorption of other contaminants on sediments. Cerium dioxide nanoparticles (CeO 2 NPs), as one of the important MeO NPs, are also inevitably discharged into aquatic sediments because of their widespread use. In this study, we investigated the adsorption behavior of Pb 2+ on sediments spiked with CeO 2 NPs at a weight ratio of 5.0%. The results showed that the adsorption rates at three stages occurring during adsorption clearly increase for sediments contaminated with CeO 2 NPs. Moreover, the results obtained from the adsorption isotherms indicated that the Langmuir isotherm model best fits the isotherm data for both sediments and those contaminated with CeO 2 NPs. After spiking the sediments with CeO 2 NPs, the theoretical maximum monolayer adsorption capacity (Q max ) for Pb 2+ increased from 4.433 to 4.995 mg/g and the Langmuir isotherm coefficient (K L ) decreased from 8.813 to 7.730 L/g. The effects of CeO 2 NPs on the surface charge and pore surface properties of sediments were also studied as these properties affect the adsorption of several chemicals in sediments. The results showed that pH zpc , S BET , S ext , and average pore size of sediments clearly decrease for sediments contaminated with CeO 2 NPs. Hence, the strong adsorption capacity of CeO 2 NPs and the changes of sediment surface charge and pore surface properties caused by CeO 2 NPs are important factors affecting the adsorption behavior of Pb 2+ . The potential risk of Pb 2+ in aquatic environment may increase with CeO 2 NPs buried in sediments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Removal of metal from acid mine drainage using a hybrid system including a pipes inserted microalgae reactor.

PubMed

Park, Young-Tae; Lee, Hongkyun; Yun, Hyun-Shik; Song, Kyung-Guen; Yeom, Sung-Ho; Choi, Jaeyoung

2013-12-01

In this study, the microalgae culture system to combined active treatment system and pipe inserted microalgae reactor (PIMR) was investigated. After pretreated AMD in active treatment system, the effluent load to PIMR in order to Nephroselmis sp. KGE 8 culture. In experiment, effect of iron on growth and lipid accumulation in microalgae were inspected. The 2nd pretreatment effluent was economic feasibility of microalgae culture and lipid accumulation. The growth kinetics of the microalgae are modeled using logistic growth model and the model is primarily parameterized from data obtained through an experimental study where PIMR were dosed with BBM, BBM added 10 mg L(-1) iron and 2nd pretreatment effluent. Moreover, the continuous of microalgae culture in PIMR can be available. Overall, this study indicated that the use of pretreated AMD is a viable method for culture microalgae and lipid accumulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Airborne Microalgae: Insights, Opportunities, and Challenges

PubMed Central

Skjøth, Carsten Ambelas; Šantl-Temkiv, Tina; Löndahl, Jakob

2016-01-01

Airborne dispersal of microalgae has largely been a blind spot in environmental biological studies because of their low concentration in the atmosphere and the technical limitations in investigating microalgae from air samples. Recent studies show that airborne microalgae can survive air transportation and interact with the environment, possibly influencing their deposition rates. This minireview presents a summary of these studies and traces the possible route, step by step, from established ecosystems to new habitats through air transportation over a variety of geographic scales. Emission, transportation, deposition, and adaptation to atmospheric stress are discussed, as well as the consequences of their dispersal on health and the environment and state-of-the-art techniques to detect and model airborne microalga dispersal. More-detailed studies on the microalga atmospheric cycle, including, for instance, ice nucleation activity and transport simulations, are crucial for improving our understanding of microalga ecology, identifying microalga interactions with the environment, and preventing unwanted contamination events or invasions. PMID:26801574

Characterization of water quality and biological communities, Fish Creek, Teton County, Wyoming, 2007-2011

USGS Publications Warehouse

Eddy-Miller, Cheryl A.; Peterson, David A.; Wheeler, Jerrod D.; Edmiston, C. Scott; Taylor, Michelle L.; Leemon, Daniel J.

2013-01-01

Fish Creek, an approximately 25-kilometer-long tributary to Snake River, is located in Teton County in western Wyoming near the town of Wilson. Fish Creek is an important water body because it is used for irrigation, fishing, and recreation and adds scenic value to the Jackson Hole properties it runs through. Public concern about nuisance growths of aquatic plants in Fish Creek has been increasing since the early 2000s. To address these concerns, the U.S. Geological Survey conducted a study in cooperation with the Teton Conservation District to characterize the hydrology, water quality, and biologic communities of Fish Creek during 2007–11. The hydrology of Fish Creek is strongly affected by groundwater contributions from the area known as the Snake River west bank, which lies east of Fish Creek and west of Snake River. Because of this continuous groundwater discharge to the creek, land-use activities in the west bank area can affect the groundwater quality. Evaluation of nitrate isotopes and dissolved-nitrate concentrations in groundwater during the study indicated that nitrate was entering Fish Creek from groundwater, and that the source of nitrate was commonly a septic/sewage effluent or manure source, or multiple sources, potentially including artificial nitrogen fertilizers, natural soil organic matter, and mixtures of sources. Concentrations of dissolved nitrate and orthophosphate, which are key nutrients for growth of aquatic plants, generally were low in Fish Creek and occasionally were less than reporting levels (not detected). One potential reason for the low nutrient concentrations is that nutrients were being consumed by aquatic plant life that increases during the summer growing season, as a result of the seasonal increase in temperature and larger number of daylight hours. Several aspects of Fish Creek’s hydrology contribute to higher productivity and biovolume of aquatic plants in Fish Creek than typically observed in streams of its size in Wyoming. Especially in the winter, the proportionately large, continuous gain of groundwater into Fish Creek in the perennial section keeps most of the creek free of ice. Because sunlight can still reach the streambed in Fish Creek and the water is still flowing, aquatic plants continue to photosynthesize in the winter, albeit at a lower level of productivity. Additionally, the cobble and large gravel substrate in Fish Creek provides excellent attachment points for aquatic plants, and when combined with Fish Creek’s channel stability allows rapid growth of aquatic plants once conditions allow during the spring. The aquatic plant community of Fish Creek was different than most streams in Wyoming in that it contains many different macrophytes—including macroalgae such as long streamers of Cladophora, aquatic vascular plants, and moss; most other streams in the state contain predominantly algae. From the banks of Fish Creek, the bottom of the stream sometimes appeared to be a solid green carpet. A shift was observed from higher amounts of microalgae in April/May to higher amounts macrophytes in August and October, and differences in the relative abundance of microalgae and macrophytes were statistically significant between seasons. Differences in dissolved-nitrate concentrations and in the nitrogen-to-phosphorus ratio were significantly different between seasons, as concentrations of dissolved nitrate decreased from April/May to August and October. It is likely that dissolved-nitrate concentrations in Fish Creek were lower in August and October because macrophytes were quickly utilizing the nutrient, and a negative correlation between macro-phytes and nitrate was found. Macroinvertebrates also were sampled because of their role as indicators of water quality and their documented responses to perturbation such as degradation of water quality and habitat. Statistically significant seasonal differences were noted in the macroinvertebrate community. Taxa richness and relative abundance of Ephemeroptera, Plecoptera, and Trichoptera, which tend to be intolerant of water-quality degradation, decreased from April/May to August; the same time period saw a corresponding increase in Diptera and noninsects, particularly Oligochaeta (worms) that are more tolerant. Seasonal changes in macroinvertebrate functional feeding groups were significantly different. The relative abundance of gatherer-collector and scraper feeding groups decreased from April/May to August, accompanied by an increase in filterer-collector and shredders feeding groups. Seasonal changes in feeding groups might be due to the seasonal shift in aquatic plant communities, as indicated by comparison with other streams in the area that had fewer aquatic macrophytes than Fish Creek. Statistical tests of macroinvertebrate metrics indicated few differences between years or biological sampling sites on Fish Creek, although the site farthest upstream sometimes was different not only in terms of macroinvertebrates but also in streamflow, water quality, and aquatic plants. Potential effects of contributions of additional nutrients to the Fish Creek ecosystem beyond the conditions sampled during the study period are not known. However, because virtually all of the detectable dissolved nitrate commonly was consumed by aquatic plants in August (leaving dissolved nitrate less than the reporting level in water samples), it is possible that increased nutrient contributions could cause increased growth of aquatic plants. Additional long-term monitoring of the stream, with concurrent data analysis and interpretation would be needed to determine the effects of additional nutrients on the aquatic plant community and on higher levels of the food chain.

A mathematical model of microalgae growth in cylindrical photobioreactor

NASA Astrophysics Data System (ADS)

Bakeri, Noorhadila Mohd; Jamaian, Siti Suhana

2017-08-01

Microalgae are unicellular organisms, which exist individually or in chains or groups but can be utilized in many applications. Researchers have done various efforts in order to increase the growth rate of microalgae. Microalgae have a potential as an effective tool for wastewater treatment, besides as a replacement for natural fuel such as coal and biodiesel. The growth of microalgae can be estimated by using Geider model, which this model is based on photosynthesis irradiance curve (PI-curve) and focused on flat panel photobioreactor. Therefore, in this study a mathematical model for microalgae growth in cylindrical photobioreactor is proposed based on the Geider model. The light irradiance is the crucial part that affects the growth rate of microalgae. The absorbed photon flux will be determined by calculating the average light irradiance in a cylindrical system illuminated by unidirectional parallel flux and considering the cylinder as a collection of differential parallelepipeds. Results from this study showed that the specific growth rate of microalgae increases until the constant level is achieved. Therefore, the proposed mathematical model can be used to estimate the rate of microalgae growth in cylindrical photobioreactor.

Harvesting of microalgae biomass from the phycoremediation process of greywater.

PubMed

Atiku, Hauwa; Mohamed, R M S R; Al-Gheethi, A A; Wurochekke, A A; Kassim, Amir Hashim M

2016-12-01

The wide application of microalgae in the field of wastewater treatment and bioenergy source has improved research studies in the past years. Microalgae represent a good source of biomass and bio-products which are used in different medical and industrial activities, among them the production of high-valued products and biofuels. The present review focused on greywater treatment through the application of phycoremediation technique with microalgae and presented recent advances in technologies used for harvesting the microalgae biomass. The advantages and disadvantages of each method are discussed. The microbiological aspects of production, harvesting and utilization of microalgae biomass are viewed.

Detection of viability of micro-algae cells by optofluidic hologram pattern.

PubMed

Wang, Junsheng; Yu, Xiaomei; Wang, Yanjuan; Pan, Xinxiang; Li, Dongqing

2018-03-01

A rapid detection of micro-algae activity is critical for analysis of ship ballast water. A new method for detecting micro-algae activity based on lens-free optofluidic holographic imaging is presented in this paper. A compact lens-free optofluidic holographic imaging device was developed. This device is mainly composed of a light source, a small through-hole, a light propagation module, a microfluidic chip, and an image acquisition and processing module. The excited light from the light source passes through a small hole to reach the surface of the micro-algae cells in the microfluidic chip, and a holographic image is formed by the diffraction light of surface of micro-algae cells. The relation between the characteristics in the hologram pattern and the activity of micro-algae cells was investigated by using this device. The characteristics of the hologram pattern were extracted to represent the activity of micro-algae cells. To demonstrate the accuracy of the presented method and device, four species of micro-algae cells were employed as the test samples and the comparison experiments between the alive and dead cells of four species of micro-algae were conducted. The results show that the developed method and device can determine live/dead microalgae cells accurately.

Microalgal biomass production pathways: evaluation of life cycle environmental impacts

PubMed Central

2013-01-01

Background Microalgae are touted as an attractive alternative to traditional forms of biomass for biofuel production, due to high productivity, ability to be cultivated on marginal lands, and potential to utilize carbon dioxide (CO2) from industrial flue gas. This work examines the fossil energy return on investment (EROIfossil), greenhouse gas (GHG) emissions, and direct Water Demands (WD) of producing dried algal biomass through the cultivation of microalgae in Open Raceway Ponds (ORP) for 21 geographic locations in the contiguous United States (U.S.). For each location, comprehensive life cycle assessment (LCA) is performed for multiple microalgal biomass production pathways, consisting of a combination of cultivation and harvesting options. Results Results indicate that the EROIfossil for microalgae biomass vary from 0.38 to 1.08 with life cycle GHG emissions of −46.2 to 48.9 (g CO2 eq/MJ-biomass) and direct WDs of 20.8 to 38.8 (Liters/MJ-biomass) over the range of scenarios analyzed. Further anaylsis reveals that the EROIfossil for production pathways is relatively location invariant, and that algae’s life cycle energy balance and GHG impacts are highly dependent on cultivation and harvesting parameters. Contrarily, algae’s direct water demands were found to be highly sensitive to geographic location, and thus may be a constraining factor in sustainable algal-derived biofuel production. Additionally, scenarios with promising EROIfossil and GHG emissions profiles are plagued with high technological uncertainty. Conclusions Given the high variability in microalgae’s energy and environmental performance, careful evaluation of the algae-to-fuel supply chain is necessary to ensure the long-term sustainability of emerging algal biofuel systems. Alternative production scenarios and technologies may have the potential to reduce the critical demands of biomass production, and should be considered to make algae a viable and more efficient biofuel alternative. PMID:23786775

Application of Biotechnology to Construct a Sustainable Biodiesel Production System on Wastewater

NASA Astrophysics Data System (ADS)

Wu, Xiaodan; Liu, Yuhuan; Xu, Erni; Liu, Jianqiang; Ruan, Roger; Fu, Guiming

2010-11-01

The potential of microalgae biodiesel is unlimited. The ingenious combination of microalgae biomass exploitation, decontamination of municipal wastewater, and CO2 fixation may gestate the ultimate hope for solving the problem of liquid alternative fuel. However, the municipal wastewater has some characteristics, such as high content of nitrogen and phosphorus, low C/N ratio, fluctuation of loading rate, toxicity of heavy metal, etc. To overcome these problems, studies are currently underway in our laboratory. In this paper, an idea of constructing a sustainable biodiesel production system from microalgae on wastewater is assumed. The system could realize CO2 fixation, decontamination of municipal wastewater, and production of high value-added biodiesel by microalgae. Firstly, municipal wastewater is used as the cultivation media and CO2 as gaseous fertilizer for mass culture of Shuihua microalgae. So with the harvest of large quantities of low-price Shuihua microalgae, the nitrogen, phosphorus and heavy metals can be removed from the wastewater, and the emission of greenhouse gas can be reduced. Secondly, try to breed a high-oil content engineering microalgae by heterotrophic cultivation which could realize high-density growth through the conjunction of the advanced methods of fermentation engineering with the microalgae breeding technology. Finally, make the high-oil content engineering microalgae cultivated on the decomposed Shuihua microalgae cells, and try to make the high-oil content engineering microalgae grow rapidly in the initial stage and start oil accumulation when nitrogen is exhausted by controlling the conditions of fermentation.

Catalytic deoxygenation of microalgae oil to green hydrocarbons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Chen; Bruck, Thomas; Lercher, Johannes A.

2013-05-14

Microalgae are high potential raw biomass material for triglyceride feedstock, due to their high oil content and rapid growth rate, and because algae cultivation does not compete with edible food on arable land. This review addresses first the microalgae cultivation with an overview of the productivity and growth of microalgae, the recovery of lipids from the microalgae, and chemical compositions of microalgae biomass and microalgal oil. Second, three basic approaches are discussed to downstream processing for the production of green gasoline and diesel hydrocarbons from microalgae oil, including cracking with zeolite, hydrotreating with supported sulfided catalysts and hydrodeoxygenation with non-sulfidemore » metal catalysts. For the triglyceride derived bio-fuels, only “drop-in” gasoline and diesel range components are discussed in this review.« less

Nanosilver microalgae biosynthesis: cell appearance based on SEM and EDX methods

NASA Astrophysics Data System (ADS)

Pancasakti Kusumaningrum, Hermin; Zainuri, Muhammad; Marhaendrajaya, Indras; Subagio, Agus

2018-05-01

Microbial contamination has caused public health problems in the world population. This problem has spurred the development of methods to overcome and prevent microbial invasion. The extensive use of antibiotics has facilitated the continued emergence and spread of resistant organisms. Synthesized of silver nanoparticle (AgNPs) on microalgae Chlorella pyrenoidosa offer environmentally safe antimicrobial agent. The present study is focused on the biosynthesis of AgNPs using microalgae C. pyrenoidosa. The research methods was conducted by insertion of nanosilver particle into microalgae cells with and without agitation to speed up the process of formation nanosilver microalgae. The formation of microalgae SNP was analyzes by UV-Vis spectrophotometer, Scanning Electron Micrograph (SEM) and Energy-dispersive X-ray spectroscopy (EDX) methods. The research result showed that nanosilver microalgae biosynthesis using the agitation treatment was exhibited better performance in particle insertion and cell stability, comparing with no agitation treatment. However, synthesis of nanosilver microalgae tend to reduce the cell size.

TiO2 nanoparticles in seawater: Aggregation and interactions with the green alga Dunaliella tertiolecta.

PubMed

Morelli, Elisabetta; Gabellieri, Edi; Bonomini, Alessandra; Tognotti, Danika; Grassi, Giacomo; Corsi, Ilaria

2018-02-01

Titanium dioxide nanoparticles (TiO 2 NPs) have been widely employed in industrial applications, thus rising concern about their impact in the aquatic environment. In this study we investigated the chemical behaviour of TiO 2 NPs in the culture medium and its effect on the green alga Dunaliella tertiolecta, in terms of growth inhibition, oxidative stress, ROS (Reactive Oxygen Species) accumulation and chlorophyll content. In addition, the influence of exopolymeric substances (EPS) excreted by the microalgae on the stability of NPs has been evaluated. The physicochemical characterization showed a high propensity of TiO 2 NPs to form micrometric-sized aggregates within 30min, large enough to partially settle to the bottom of the test vessel. Indeed, an increasing amount of TiO 2 particles settled out with time, but the presence of EPS seemed to mitigate this behaviour in the first 6h of exposure where the main effects in D. tertiolecta were observed. TiO 2 NPs did not inhibit the 72-h growth rate of D. tertiolecta, nor affected the cellular chlorophyll concentration in the range 0.01-10mgL -1 . The time-course of ROS production showed an initial transient increase of ROS in TiO 2 NP-exposed algae compared to the control, concomitant with an enhancement of catalase activity. Interestingly, intracellular ROS was a small fraction of total ROS, the highest amount being extracellular. The occurrence of cell-mediated chemical transformations of TiO 2 NPs in the external medium, related to the presence of EPS, has been evaluated. Our results showed that carbohydrates were the major component of EPS, whereas proteins of medium molecular weight (20-80kDa) were preferentially bound to TiO 2 NPs, likely influencing their biological fate. Copyright © 2017 Elsevier Inc. All rights reserved.

Mixotrophic cultivation of microalgae for biodiesel production: status and prospects.

PubMed

Wang, Jinghan; Yang, Haizhen; Wang, Feng

2014-04-01

Biodiesel from microalgae provides a promising alternative for biofuel production. Microalgae can be produced under three major cultivation modes, namely photoautotrophic cultivation, heterotrophic cultivation, and mixotrophic cultivation. Potentials and practices of biodiesel production from microalgae have been demonstrated mostly focusing on photoautotrophic cultivation; mixotrophic cultivation of microalgae for biodiesel production has rarely been reviewed. This paper summarizes the mechanisms and virtues of mixotrophic microalgae cultivation through comparison with other major cultivation modes. Influencing factors of microalgal biodiesel production under mixotrophic cultivation are presented, development of combining microalgal biodiesel production with wastewater treatment is especially reviewed, and bottlenecks and strategies for future commercial production are also identified.

Survey of the occurrence of desiccation-induced quenching of basal fluorescence in 28 species of green microalgae.

PubMed

Wieners, Paul Christian; Mudimu, Opayi; Bilger, Wolfgang

2018-05-30

Desiccation-induced chlorophyll fluorescence quenching seems to be an indispensable part of desiccation resistance in the surveyed 28 green microalgal species. Lichens are desiccation tolerant meta-organisms. In the desiccated state photosynthesis is inhibited rendering the photobionts potentially sensitive to photoinhibition. As a photoprotective mechanism, strong non-radiative dissipation of absorbed light leading to quenching of chlorophyll fluorescence has been proposed. Desiccation-induced quenching affects not only variable fluorescence, but also the so-called basal fluorescence, F 0 . This phenomenon is well-known for intact lichens and some free living aero-terrestrial algae, but it was often absent in isolated lichen algae. Therefore, a thorough screening for the appearance of desiccation-induced quenching was undertaken with 13 different aero-terrestrial microalgal species and lichen photobionts. They were compared with 15 aquatic green microalgal species, among them also three marine species. We asked the following questions: Do isolated lichen algae show desiccation-induced quenching? Are aero-terrestrial algae different in this respect to aquatic algae and is the potential for desiccation-induced quenching coupled to desiccation tolerance? How variable is desiccation-induced quenching among species? Most of the aero-terrestrial algae, including all lichen photobionts, showed desiccation-induced quenching, although highly variable in extent, whereas most of the aquatic algae did not. All algae displaying quenching were also desiccation tolerant, whereas all algae unable to perform desiccation-induced quenching were desiccation intolerant. Desiccation-induced fluorescence quenching seems to be an indispensable part of desiccation resistance in the investigated species.

Incorporation of Chlorella vulgaris and Spirulina maxima biomass in pasta products. Part 1: Preparation and evaluation.

PubMed

Fradique, Mónica; Batista, Ana Paula; Nunes, M Cristiana; Gouveia, Luísa; Bandarra, Narcisa M; Raymundo, Anabela

2010-08-15

Microalgae are able to enhance the nutritional content of conventional foods and hence to positively affect human health, due to their original chemical composition. The aim of the present study was to prepare fresh spaghetti enriched with different amounts of microalgae biomass (Chlorella vulgaris and Spirulina maxima) and to compare the quality parameters (optimal cooking time, cooking losses, swelling index and water absorption), chemical composition, instrumental texture and colour of the raw and cooked pasta enriched with microalgae biomass with standard semolina spaghetti. The incorporation of microalgae results in an increase of quality parameters when compared to the control sample. The colour of microalgae pastas remained relatively stable after cooking. The addition of microalgae resulted in an increase in the raw pasta firmness when compared to the control sample. Of all the microalgae studied, an increase in the biomass concentration (0.5-2.0%) resulted in a general tendency of an increase in the pasta firmness. Sensory analysis revealed that microalgae pastas had higher acceptance scores by the panellists than the control pasta. Microalgae pastas presented very appellative colours, such as orange and green, similar to pastas produced with vegetables, with nutritional advantages, showing energetic values similar to commercial pastas. The use of microalgae biomass can enhance the nutritional and sensorial quality of pasta, without affecting its cooking and textural properties. Copyright (c) 2010 Society of Chemical Industry.

Simulation of temperature effect on microalgae culture in a tubular photo bioreactor for local solar irradiance

NASA Astrophysics Data System (ADS)

Shahriar, M.; Deb, Ujjwal Kumar; Rahman, Kazi Afzalur

2017-06-01

Microalgae based biofuel is now an emerging source of renewable energy alternative to the fossil fuel. This paper aims to present computational model of microalgae culture taking effect of solar irradiance and corresponding temperature in a photo bioreactor (PBR). As microalgae is a photosynthetic microorganism, so irradiance of sunlight is one of the important limiting factors for the proper growth of microalgae cells as temperature is associated with it. We consider the transient behaviour of temperature inside the photo bioreactor for a microalgae culture. The optimum range of temperature for outdoor cultivation of microalgae is about 16-35°c and out of this range the cell growth inhibits. Many correlations have already been established to investigate the heat transfer phenomena inside a tubular PBR. However, none of them are validated yet numerically by using a user defined function in a simulated model. A horizontal tubular PBR length 20.5m with radius 0.05m has taken account to investigate the temperature effect for the growth of microalgae cell. As the solar irradiance varies at any geographic latitude for a year so an empirical relation is established between local solar irradiance and temperature to simulate the effect. From our simulation, we observed that the growth of microalgae has a significant effect of temperature and the solar irradiance of our locality is suitable for the culture of microalgae.

Microalgae community shifts during the biogas upgrading in an alkaline open photobioreactor.

PubMed

Granada-Moreno, C I; Aburto-Medina, A; de Los Cobos Vasconcelos, D; González-Sánchez, A

2017-10-01

To achieve the functional specialization of a microalgae community through operational tuning of an open photobioreactor used for biogas upgrading under alkaline conditions. An open photobioreactor was inoculated with an indigenous microalgae sample from the Texcoco Soda Lake. A microalgae community was adapted to fix CO 2 from synthetic biogas through different culture conditions reaching a maximum of 220 mg CO 2  l -1 per day. Picochlorum sp. and Scenedesmus sp. were identified as the prominent microalgae genera by molecular fingerprinting (partial sequencing of 16S rRNA and 18S rRNA genes) but only the first was detected by microscopy screening. Changes in the microalgae community profile were monitored by a range-weighted richness index, reaching the lowest value when biogas was upgraded. A robust microalgae community in the open photobioreactor was obtained after different culture conditions. The specialization of microalgae community for CO 2 fixation under H 2 S presence was driven by biogas upgrading conditions. The alkaline conditions enhance the CO 2 absorption from biogas and could optimize specialized microalgae communities in the open photobioreactor. Denaturing gradient gel electrophoresis fingerprinting and richness index comparison are useful methods for the evaluation of microalgae community shifts and photosynthetic activity performance, particularly in systems intended for CO 2 removal from biogas where the CO 2 assimilation potential can be related to the microbial richness. © 2017 The Society for Applied Microbiology.

The role of algae and cyanobacteria in the production and release of odorants in water.

PubMed

Lee, Jechan; Rai, Prabhat Kumar; Jeon, Young Jae; Kim, Ki-Hyun; Kwon, Eilhann E

2017-08-01

This review covers literatures pertaining to algal and cyanobacterial odor problems that have been published over the last five decades. Proper evaluation of algal and cyanobacterial odors may help establish removal strategies for hazardous metabolites while enhancing the recyclability of water. A bloom of microalgae is a sign of an anthropogenic disturbance in aquatic systems and can lead to diverse changes in ecosystems along with increased production of odorants. In general, because algal and cyanobacterial odors vary in chemistry and intensity according to blooming pattern, it is necessary to learn more about the related factors and processes (e.g., changes due to differences in taxa). This necessitates systematic and transdisciplinary approaches that require the cooperation of chemists, biologists, engineers, and policy makers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Aquatic insect community of lake, Phulbari anua in Cachar, Assam.

PubMed

Gupta, Susmita; Narzary, Rupali

2013-05-01

An investigation on the water quality and aquatic insect community of an oxbow lake (Phulbari anua) of south Assam, North-East India was carried out during February to April, 2010. Aquatic insect community of the oxbow lake was represented by 9 species belonging to 9 families and 4 orders during the study period. Order Ephemeroptera and Hemiptera were found to be dominant. Record of 5 species and 5 families from the order Hemiptera showed that this is the largest order in terms of aquatic insect diversity of the lake. Computation of dominance status of different species of aquatic insects of the lake based on Engelmann's Scale revealed that Anisops lundbladiana and Cloeon sp. were eudominant in the system. The Shannon- Weiner's Diversity Index (H') and Shannon evenness values (J') were found to range from 0.3-0.69 and 0.53 -0.97, respectively indicating perturbation of the system. Again in terms of physico-chemical properties of water the lake is in a satisfactory condition where all the parameters are well within the range of IS 10500. The DO values were found to range from 6.8 to 14.8 mgl(-1). Free CO2 fluctuated from 1 to 4.98 mgl(-1) and nitrate in water ranged from 0.4 to 2.1 mgl(-1). Margalef's water quality index values of most of the samplings also indicated clean water condition of the lake. Correlation coefficient analyses of the environmental variables, aquatic insect diversity and density of the lake revealed that aquatic insect diversity of the lake is mainly governed by dissolved oxygen, nitrate, and free carbon dioxide.

Microalgal production--a close look at the economics.

PubMed

Norsker, Niels-Henrik; Barbosa, Maria J; Vermuë, Marian H; Wijffels, René H

2011-01-01

Worldwide, microalgal biofuel production is being investigated. It is strongly debated which type of production technology is the most adequate. Microalgal biomass production costs were calculated for 3 different micro algal production systems operating at commercial scale today: open ponds, horizontal tubular photobioreactors and flat panel photobioreactors. For the 3 systems, resulting biomass production costs including dewatering, were 4.95, 4.15 and 5.96 € per kg, respectively. The important cost factors are irradiation conditions, mixing, photosynthetic efficiency of systems, medium- and carbon dioxide costs. Optimizing production with respect to these factors, a price of € 0.68 per kg resulted. At this cost level microalgae become a promising feedstock for biodiesel and bulk chemicals. Photobioreactors may become attractive for microalgal biofuel production. Copyright © 2010 Elsevier Inc. All rights reserved.

Biotoxicity of nickel oxide nanoparticles and bio-remediation by microalgae Chlorella vulgaris.

PubMed

Gong, Ning; Shao, Kuishuang; Feng, Wei; Lin, Zhengzhi; Liang, Changhua; Sun, Yeqing

2011-04-01

Adverse effects of manufactured nickel oxide nanoparticles on the microalgae Chlorellavulgaris were determined by algal growth-inhibition test and morphological observation via transmission electron microscopy (TEM). Results showed that the NiO nanoparticles had severe impacts on the algae, with 72 h EC(50) values of 32.28 mg NiOL(-1). Under the stress of NiO nanoparticles, C. vulgaris cells showed plasmolysis, cytomembrane breakage and thylakoids disorder. NiO nanoparticles aggregated and deposited in algal culture media. The presence of algal cells accelerated aggregation of nanoparticles. Moreover, about 0.14% ionic Ni was released when NiO NPs were added into seawater. The attachment of aggregates to algal cell surface and the presence of released ionic Ni were likely responsible for the toxic effects. Interestingly, some NiO nanoparticles were reduced to zero valence nickel as determined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The maximum ratios of nickel reduction was achieved at 72 h of exposure, in accordance with the time-course of changes in soluble protein content of treated C. vulgaris, implying that some proteins of algae are involved in the process. Our results indicate that the toxicity and bioavailability of NiO nanoparticles to marine algae are reduced by aggregation and reduction of NiO. Thus, marine algae have the potential for usage in nano-pollution bio-remediation in aquatic system. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

Response of cellular stoichiometry and phosphorus storage of the cyanobacteria Aphanizomenon flos-aquae to small-scale turbulence

NASA Astrophysics Data System (ADS)

Li, Zhe; Xiao, Yan; Yang, Jixiang; Li, Chao; Gao, Xia; Guo, Jinsong

2017-11-01

Turbulent mixing, in particular on a small scale, affects the growth of microalgae by changing diffusive sublayers and regulating nutrient fluxes of cells. We tested the nutrient flux hypothesis by evaluating the cellular stoichiometry and phosphorus storage of microalgae under different turbulent mixing conditions. Aphanizomenon flos-aquae were cultivated in different stirring batch reactors with turbulent dissipation rates ranging from 0.001 51 m2/s3 to 0.050 58 m2/s3, the latter being the highest range observed in natural aquatic systems. Samples were taken in the exponential growth phase and compared with samples taken when the reactor was completely stagnant. Results indicate that, within a certain range, turbulent mixing stimulates the growth of A. flos-aquae. An inhibitory effect on growth rate was observed at the higher range. Photosynthesis activity, in terms of maximum effective quantum yield of PSII (the ratio of F v/ F m) and cellular chlorophyll a, did not change significantly in response to turbulence. However, Chl a/C mass ratio and C/N molar ratio, showed a unimodal response under a gradient of turbulent mixing, similar to growth rate. Moreover, we found that increases in turbulent mixing might stimulate respiration rates, which might lead to the use of polyphosphate for the synthesis of cellular constituents. More research is required to test and verify the hypothesis that turbulent mixing changes the diffusive sublayer, regulating the nutrient flux of cells.

Mechanisms of Phosphorus Acquisition and Lipid Class Remodeling under P Limitation in a Marine Microalga.

PubMed

Mühlroth, Alice; Winge, Per; El Assimi, Aimen; Jouhet, Juliette; Maréchal, Eric; Hohmann-Marriott, Martin F; Vadstein, Olav; Bones, Atle M

2017-12-01

Molecular mechanisms of phosphorus (P) limitation are of great interest for understanding algal production in aquatic ecosystems. Previous studies point to P limitation-induced changes in lipid composition. As, in microalgae, the molecular mechanisms of this specific P stress adaptation remain unresolved, we reveal a detailed phospholipid-recycling scheme in Nannochloropsis oceanica and describe important P acquisition genes based on highly corresponding transcriptome and lipidome data. Initial responses to P limitation showed increased expression of genes involved in P uptake and an expansion of the P substrate spectrum based on purple acid phosphatases. Increase in P trafficking displayed a rearrangement between compartments by supplying P to the chloroplast and carbon to the cytosol for lipid synthesis. We propose a novel phospholipid-recycling scheme for algae that leads to the rapid reduction of phospholipids and synthesis of the P-free lipid classes. P mobilization through membrane lipid degradation is mediated mainly by two glycerophosphoryldiester phosphodiesterases and three patatin-like phospholipases A on the transcriptome level. To compensate for low phospholipids in exponential growth, N. oceanica synthesized sulfoquinovosyldiacylglycerol and diacylglyceroltrimethylhomoserine. In this study, it was shown that an N. oceanica strain has a unique repertoire of genes that facilitate P acquisition and the degradation of phospholipids compared with other stramenopiles. The novel phospholipid-recycling scheme opens new avenues for metabolic engineering of lipid composition in algae. © 2017 American Society of Plant Biologists. All Rights Reserved.

Evaluation of Arthrobacter aurescens Strain TC1 as Bioaugmentation Bacterium in Soils Contaminated with the Herbicidal Substance Terbuthylazine

PubMed Central

Silva, Vera P.; Moreira-Santos, Matilde; Mateus, Carla; Teixeira, Tânia; Ribeiro, Rui; Viegas, Cristina A.

2015-01-01

In the last years the chloro-s-triazine active substance terbuthylazine has been increasingly used as an herbicide and may leave residues in the environment which can be of concern. The present study aimed at developing a bioaugmentation tool based on the soil bacterium Arthrobacter aurescens strain TC1 for the remediation of terbuthylazine contaminated soils and at examining its efficacy for both soil and aquatic compartments. First, the feasibility of growing the bioaugmentation bacterium inocula on simple sole nitrogen sources (ammonium and nitrate) instead of atrazine, while still maintaining its efficiency to biodegrade terbuthylazine was shown. In sequence, the successful and quick (3 days) bioremediation efficacy of ammonium-grown A. aurescens TC1 cells was proven in a natural soil freshly spiked or four-months aged with commercial terbuthylazine at a dose 10× higher than the recommended in corn cultivation, to mimic spill situations. Ecotoxicity assessment of the soil eluates towards a freshwater microalga supported the effectiveness of the bioaugmentation tool. Obtained results highlight the potential to decontaminate soil while minimizing terbuthylazine from reaching aquatic compartments via the soil-water pathway. The usefulness of this bioaugmentation tool to provide rapid environment decontamination is particularly relevant in the event of accidental high herbicide contamination. Its limitations and advantages are discussed. PMID:26662024

Advances in Microalgae-Derived Phytosterols for Functional Food and Pharmaceutical Applications

PubMed Central

Luo, Xuan; Su, Peng; Zhang, Wei

2015-01-01

Microalgae contain a variety of bioactive lipids with potential applications in aquaculture feed, biofuel, food and pharmaceutical industries. While microalgae-derived polyunsaturated fatty acid (PUFA) and their roles in promoting human health have been extensively studied, other lipid types from this resource, such as phytosterols, have been poorly explored. Phytosterols have been used as additives in many food products such as spread, dairy products and salad dressing. This review focuses on the recent advances in microalgae-derived phytosterols with functional bioactivities and their potential applications in functional food and pharmaceutical industries. It highlights the importance of microalgae-derived lipids other than PUFA for the development of an advanced microalgae industry. PMID:26184233

Advances in Microalgae-Derived Phytosterols for Functional Food and Pharmaceutical Applications.

PubMed

Luo, Xuan; Su, Peng; Zhang, Wei

2015-07-09

Microalgae contain a variety of bioactive lipids with potential applications in aquaculture feed, biofuel, food and pharmaceutical industries. While microalgae-derived polyunsaturated fatty acid (PUFA) and their roles in promoting human health have been extensively studied, other lipid types from this resource, such as phytosterols, have been poorly explored. Phytosterols have been used as additives in many food products such as spread, dairy products and salad dressing. This review focuses on the recent advances in microalgae-derived phytosterols with functional bioactivities and their potential applications in functional food and pharmaceutical industries. It highlights the importance of microalgae-derived lipids other than PUFA for the development of an advanced microalgae industry.

Sensitivity of aquatic ecosystems to climatic and anthropogenic changes: The basin and range, American Southwest and Mexico

USGS Publications Warehouse

Grimm, N. B.; Chacon, A.; Dahm, Clifford N.; Hostetler, S.W.; Lind, O.T.; Starkweather, P.L.; Wurtsbaugh, W.W.

1997-01-01

Variability and unpredictability are characteristics of the aquatic ecosystems, hydrological patterns and climate of the largely dryland region that encompasses the Basin and Range, American Southwest and western Mexico. Neither hydrological nor climatological models for the region are sufficiently developed to describe the magnitude or direction of change in response to increased carbon dioxide; thus, an attempt to predict specific responses of aquatic ecosystems is premature. Instead, we focus on the sensitivity of rivers, streams, springs, wetlands, reservoirs, and lakes of the region to potential changes in climate, especially those inducing a change in hydrological patterns such as amount, timing and predictability of stream flow. The major sensitivities of aquatic ecosystems are their permanence and even existence in the face of potential reduced net basin supply of water, stability of geomorphological structure and riparian ecotones with alterations in disturbance regimes, and water quality changes resulting from a modified water balance. In all of these respects, aquatic ecosystems of the region are also sensitive to the extensive modifications imposed by human use of water resources, which underscores the difficulty of separating this type of anthropogenic change from climate change. We advocate a focus in future research on reconstruction and analysis of past climates and associated ecosystem characteristics, long-term studies to discriminate directional change vs. year to year variability (including evidence of aquatic ecosystem responses or sensitivity to extremes), and studies of ecosystems affected by human activity. ?? 1997 by John Wiley & Sons, Ltd.

Effects of CO2 concentration and light intensity on photosynthesis of a rootless submerged plant, Ceratophyllum demersum L., used for aquatic food production in bioregenerative life support systems

NASA Technical Reports Server (NTRS)

Kitaya, Y.; Okayama, T.; Murakami, K.; Takeuchi, T.

2003-01-01

In addition to green microalgae, aquatic higher plants are likely to play an important role in aquatic food production modules in bioregenerative systems for producing feed for fish, converting CO2 to O2 and remedying water quality. In the present study, the effects of culture conditions on the net photosynthetic rate of a rootless submerged plant, Ceratophyllum demersum L., was investigated to determine the optimum culture conditions for maximal function of plants in food production modules including both aquatic plant culture and fish culture systems. The net photosynthetic rate in plants was determined by the increase in dissolved O2 concentrations in a closed vessel containing a plantlet and water. The water in the vessel was aerated sufficiently with a gas containing a known concentration of CO2 gas mixed with N2 gas before closing the vessel. The CO2 concentrations in the aerating gas ranged from 0.3 to 10 mmol mol-1. Photosynthetic photon flux density (PPFD) in the vessel ranged from 0 (dark) to 1.0 mmol m-2 s-1, which was controlled with a metal halide lamp. Temperature was kept at 28 degrees C. The net photosynthetic rate increased with increasing PPFD levels and was saturated at 0.2 and 0.5 mmol m-2 s-1 PPFD under CO2 levels of 1.0 and 3.0 mmol mol-1, respectively. The net photosynthetic rate increased with increasing CO2 levels from 0.3 to 3.0 mmol mol-1 showing the maximum value, 75 nmol O2 gDW-1 s-1, at 2-3 mmol mol-1 CO2 and gradually decreased with increasing CO2 levels from 3.0 to 10 mmol mol-1. The results demonstrate that C. demersum could be an efficient CO2 to O2 converter under a 2.0 mmol mol-1 CO2 level and relatively low PPFD levels in aquatic food production modules. c2003 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Effects of Co2 Concentrations and light intensity on photosynthesis of a rootless submerged plant, ceratophyllum demersum L., used for aquatic food production in bioregenerative life support systems

NASA Astrophysics Data System (ADS)

Kitaya, Y.; Okayama, T.; Murakami, K.; Takeuchi, T.

Aquatic higher plants are likely to play an important role in aquatic food production modules in bioregenerative systems for producing feeds for fish, converting CO2 to O2 and remedying water quality in addition to green microalgae. In the present study, the effects of culture conditions on the net photosynthetic rate of a rootless submerged plant, Ceratophyllum demersum L., was investigated to determine the optimum culture conditions for plant function in aquatic food production modules including both plant culture and fish culture systems . The net photosynthetic rate in plants was determined by the increase in dissolved O2 concentrations in a closed vessel containing a plantlet and water. The water in the vessel was aerated sufficiently with a gas containing a known level CO 2 gas mixed with N2 gas before closing the vessel. The CO 2 concentrations in the aerating gas ranged from 0.3 to 100 mmol mol-1 . Photosynthetic photon flux density (PPFD) in the vessel ranged from 0 (dark) to 1.0 mmol m-2 s-1 , which was controlled with a metal halide lamp. Temperature was kept at 28 C. The net photosynthetic rate increased with increasing PPFD levels and was saturated at 0.2 and 0.5 mmol m-2 s-1 PPFD under CO 2 levels of 1.0 and 3.0 mmol mol-1 , respectively. The net photosynthetic rate increased with increasing CO2 levels from 0.3 to 3.0 mmol mol-1 showing the maximum value, 70 nmolO 2 gDW s at 3.0 mmol mol-1 CO2 and gradually decreased with increasing CO 2 levels from 3.0 to 100 mmol mol-1 . The results demonstrate that Ceratophyllum demersum L. could be an efficient CO 2 to O2 converter under a 3.0 mmol mol-1 CO2 level and relatively low PPFD levels in aquatic food production modules.

Effects of CO 2 concentration and light intensity on photosynthesis of a rootless submerged plant, Ceratophyllumdemersum L., used for aquatic food production in bioregenerative life support systems

NASA Astrophysics Data System (ADS)

Kitaya, Y.; Okayama, T.; Murakami, K.; Takeuchi, T.

In addition to green microalgae, aquatic higher plants are likely to play an important role in aquatic food production modules in bioregenerative systems for producing feed for fish, converting CO 2 to O 2 and remedying water quality. In the present study, the effects of culture conditions on the net photosynthetic rate of a rootless submerged plant, Ceratophyllum demersum L., was investigated to determine the optimum culture conditions for maximal function of plants in food production modules including both aquatic plant culture and fish culture systems. The net photosynthetic rate in plants was determined by the increase in dissolved O 2 concentrations in a closed vessel containing a plantlet and water. The water in the vessel was aerated sufficiently with a gas containing a known concentration of CO 2 gas mixed with N 2 gas before closing the vessel. The CO 2 concentrations in the aerating gas ranged from 0.3 to 10 mmol mol -1. Photosynthetic photon flux density (PPFD) in the vessel ranged from 0 (dark) to 1.0 mmol M -2 s -1, which was controlled with a metal halide lamp. Temperature was kept at 28°C. The net photosynthetic rate increased with increasing PPFD levels and was saturated at 0.2 and 0.5 mmol m -2 s -1 PPFD under CO 2 levels of 1.0 and 3.0 mmol mol -1, respectively. The net photosynthetic rate increased with increasing CO 2 levels from 0.3 to 3.0 mmol mol -1 showing the maximum value, 75 nmolO 2 gDW -1 s -1, at 2-3 mmol mol -1 CO 2 and gradually decreased with increasing CO 2 levels from 3.0 to 10 mmol mol -1. The results demonstrate that C. demersum could be an efficient CO 2 to O 2 converter under a 2.0 mmol mol -1 CO 2 level and relatively low PPFD levels in aquatic food production modules.

Application of agar liquid-gel transition in cultivation and harvesting of microalgae for biodiesel production.

PubMed

Kumar, Vinod; Nanda, Manisha; Verma, Monu

2017-11-01

In order to increase microalgal biomass productivity efficient cultivation and harvesting methods are needed against the available traditional methods. The present study focuses on the same by harvesting microalgae using agar gel. Agar medium containing bold's basal medium (BBM) undergoes a thermoreversible gel transition. As compared to the traditional protocols, this gel is used to cultivate microalgae without even affecting the total productivity. To develop the gel for microalgae cultivation, agar was boiled in BBM. Then the agar was cooled to 35°C and microalgae culture was added to it. After seeding the microalgae the temperature of the agar was further decreased by 10°C to induce gelation. Instead of isolated cells microalgae were grown in clusters within the agar gel. Microalgal clusters gravimetrically settle at the bottom within 2h. In this method agar can be reused. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biotechnological production of value-added carotenoids from microalgae: Emerging technology and prospects.

PubMed

Wichuk, Kristine; Brynjólfsson, Sigurður; Fu, Weiqi

2014-01-01

We recently evaluated the relationship between abiotic environmental stresses and lutein biosynthesis in the green microalga Dunaliella salina and suggested a rational design of stress-driven adaptive evolution experiments for carotenoids production in microalgae. Here, we summarize our recent findings regarding the biotechnological production of carotenoids from microalgae and outline emerging technology in this field. Carotenoid metabolic pathways are characterized in several representative algal species as they pave the way for biotechnology development. The adaptive evolution strategy is highlighted in connection with enhanced growth rate and carotenoid metabolism. In addition, available genetic modification tools are described, with emphasis on model species. A brief discussion on the role of lights as limiting factors in carotenoid production in microalgae is also included. Overall, our analysis suggests that light-driven metabolism and the photosynthetic efficiency of microalgae in photobioreactors are the main bottlenecks in enhancing biotechnological potential of carotenoid production from microalgae.

A Label-Free Microfluidic Biosensor for Activity Detection of Single Microalgae Cells Based on Chlorophyll Fluorescence

PubMed Central

Wang, Junsheng; Sun, Jinyang; Song, Yongxin; Xu, Yongyi; Pan, Xinxiang; Sun, Yeqing; Li, Dongqing

2013-01-01

Detection of living microalgae cells is very important for ballast water treatment and analysis. Chlorophyll fluorescence is an indicator of photosynthetic activity and hence the living status of plant cells. In this paper, we developed a novel microfluidic biosensor system that can quickly and accurately detect the viability of single microalgae cells based on chlorophyll fluorescence. The system is composed of a laser diode as an excitation light source, a photodiode detector, a signal analysis circuit, and a microfluidic chip as a microalgae cell transportation platform. To demonstrate the utility of this system, six different living and dead algae samples (Karenia mikimotoi Hansen, Chlorella vulgaris, Nitzschia closterium, Platymonas subcordiformis, Pyramidomonas delicatula and Dunaliella salina) were tested. The developed biosensor can distinguish clearly between the living microalgae cells and the dead microalgae cells. The smallest microalgae cells that can be detected by using this biosensor are 3 μm ones. Even smaller microalgae cells could be detected by increasing the excitation light power. The developed microfluidic biosensor has great potential for in situ ballast water analysis. PMID:24287532

Study of cultivation and growth rate kinetic for mixed cultures of local microalgae as third generation (G-3) bioethanol feedstock in thin layer photobioreactor

NASA Astrophysics Data System (ADS)

Prihastuti Yuarrina, Wahyu; Surya Pradana, Yano; Budiman, Arief; Majid, Akmal Irfan; Indarto; Agus Suyono, Eko

2018-05-01

The increasing use of fossil fuels causes the depletion in supply and contributes to climate change by GHG emissions into the atmosphere. Microalgae indicate as renewable and sustainable energy sources as they have a high potential for producing large amounts of biomass for third-generation biofuels (bioethanol and biodiesel) feedstock. However, there are several parameters which should be considered for microalgae cultivation, such as environmental conditions, medium composition and microalgae species. The aim of this research was to study cultivation of mixed microalgae cultures (Glagah consortium and Arthrospira maxima) in a thin layer photobioreactor. Farmpion medium, Bold’s Basal Medium (BBM) and Thoriq Eko Arief (TEA) medium were investigated as cultivation medium for bioethanol feedstock for 7 days. The results showed that the highest dry weight concentration of microalgae was in Farmpion medium (0.35 mg/ml) and the highest carbohydrate concentration of microalgae was in BBM (0.14 mg/ml). Thus, the optimum medium of microalgae cultivation for bioethanol feedstock was BBM because of the highest carbohydrate-dry weight ratio (0.88). In addition, mathematical approach by using Contois model was used to find out the growth rate of microalgae cultivation in each medium.

Flotation: A promising microalgae harvesting and dewatering technology for biofuels production.

PubMed

Ndikubwimana, Theoneste; Chang, Jingyu; Xiao, Zongyuan; Shao, Wenyao; Zeng, Xianhai; Ng, I-Son; Lu, Yinghua

2016-03-01

Microalgal biomass as renewable energy source is believed to be of great potential for reliable and sustainable biofuels production. However, microalgal biomass production is pinned by harvesting and dewatering stage thus hindering the developing and growing microalgae biotechnology industries. Flotation technology applied in mineral industry could be potentially applied in microalgae harvesting and dewatering, however substantial knowledge on different flotation units is essential. This paper presents an overview on different flotation units as promising cost-effective technologies for microalgae harvesting thus bestowing for further research in development and commercialization of microalgae based biofuels. Dispersed air flotation was found to be less energy consuming. Moreover, Jameson cell flotation and dispersed ozone flotation are believed to be energy efficient microalgae flotation approaches. Microalgae harvesting and dewatering by flotation is still at embryonic stage, therefore extended studies with the focus on life cycle assessment, sustainability of the flotation unit, optimization of the operating parameters using different algal species is imperative. Though there are a number of challenges in microalgae harvesting and dewatering, with well designed and developed cultivation, harvesting/dewatering, extraction and conversion technologies, progressively, microalgae technology will be of great potential for biological carbon sequestration, biofuels and biochemicals production. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Binary culture of microalgae as an integrated approach for enhanced biomass and metabolites productivity, wastewater treatment, and bioflocculation.

PubMed

Rashid, Naim; Park, Won-Kun; Selvaratnam, Thinesh

2018-03-01

Ecological studies of microalgae have revealed their potential to co-exist in the natural environment. It provides an evidence of the symbiotic relationship of microalgae with other microorganisms. The symbiosis potential of microalgae is inherited with distinct advantages, providing a venue for their scale-up applications. The deployment of large-scale microalgae applications is limited due to the technical challenges such as slow growth rate, low metabolites yield, and high risk of biomass contamination by unwanted bacteria. However, these challenges can be overcome by exploring symbiotic potential of microalgae. In a symbiotic system, photosynthetic microalgae co-exist with bacteria, fungi, as well as heterotrophic microalgae. In this consortium, they can exchange nutrients and metabolites, transfer gene, and interact with each other through complex metabolic mechanism. Microalgae in this system, termed as a binary culture, are reported to exhibit high growth rate, enhanced bio-flocculation, and biochemical productivity without experiencing contamination. Binary culture also offers interesting applications in other biotechnological processes including bioremediation, wastewater treatment, and production of high-value metabolites. The focus of the study is to provide a perspective to enhance the understanding about microalgae binary culture. In this review, the mechanism of binary culture, its potential, and limitations are briefly discussed. A number of queries are evolved through this study, which needs to be answered by executing future research to assess the real potential of binary culture. Copyright © 2017 Elsevier Ltd. All rights reserved.

Are Aquatic Viruses a Biological Archive of Genetic Information from Universe?

NASA Astrophysics Data System (ADS)

Toparceanu, F.; Negoita, Gh. T.; Nita, I. I.; Sava, D.

2009-04-01

After 1990, when the viruses were admited as the most abundant lifeforms from aquatic environments, it became obvious that viral lysis had an essential role on release and recycling of nutrients. Studies on cellular cultures and modeling suggest that this is an important quantitative process. The viruses from oceans represent the widest source of genetic diversity on the Earth, uncharacterized yet. The ancient lifeforms records stretching back a million years are locked in ice caps. The trend of glaciers melting as effect of actual climate change will promote the release of ancient viruses from ice caps. The increasing of the freshwater layer led to the replace of some algae species by others. Law-Racovitza Station (69o23'S 76o23'E) from East Antarctica (Larsemann Hills Oasis) offers opportunities to study the Antarctic marine ecosystem, as well as archaic aquatic ecosystems from this area ( 150 lakes and waterways resulted from ice and snow melting during the austral summer). According to Law-Racovitza Station Scientific Program, we are performing studies regarding the effect of climate changes on virus-algae host relationship in these aquatic ecosystems. Phycodnaviruses, that infect the eukaryote algae, are comprised of ancient genes and they are considered a "peek" of genetic diversity useful in biological studies and exobiology regarding the evolution of genetic sequencing. The latest discoveries of the giant aquatic viruses open the unexpected perspectives for understanding the role of viral infection in global ecosystem; beyond the old concept which considered that the viruses were only etiological agents of human, animals and plants illnesses. The aquatic viruses which infect microalgae contain similar genes of other viruses, bacteria, arhebacteria and eukaryotes, all of them being on the same genome. Which is the signification of enormous abundance of viruses and excessive diversity of genetic information encoded by viruses? There is the possibility that the viruses to be a biological archive which contains all genetic information of the whole Earth? So, there are a lot of questions and we are attempting to find answers in the present work which will be examined in the framework of the project entitled ,,The structure and dynamics of polar ecosystems: interhemispheric comparisons of micro, macroflora and biogeochemical processes in relation to climate change" (PolarCLIMATE programme of ESF PP-039/24.11.2008) coordinated by Romania.

Structural, functional, and evolutionary aspects of galectins in aquatic mollusks: From a sweet tooth to the Trojan horse

PubMed Central

Vasta, GR; Feng, C; Bianchet, MA; Bachvaroff, TR; Tasumi, S

2015-01-01

Galectins constitute a conserved and widely distributed lectin family characterized by their binding affinity for β-galactosides and a unique binding site sequence motif in the carbohydrate recognition domain (CRD). In spite of their structural conservation, galectins display a remarkable functional diversity, by participating in developmental processes, cell adhesion and motility, regulation of immune homeostasis, and recognition of glycans on the surface of viruses, bacteria and protozoan parasites. In contrast with mammals, and other vertebrate and invertebrate taxa, the identification and characterization of bona fide galectins in aquatic mollusks has been relatively recent. Most of the studies have focused on the identification and domain organization of galectin-like transcripts or proteins in diverse tissues and cell types, including hemocytes, and their expression upon environmental or infectious challenge. Lectins from the eastern oyster Crassostrea virginica, however, have been characterized in their molecular, structural and functional aspects and some notable features have become apparent in the galectin repertoire of aquatic mollusks. These including less diversified galectin repertoires and different domain organizations relative to those observed in vertebrates, carbohydrate specificity for blood group oligosaccharides, and up regulation of galectin expression by infectious challenge, a feature that supports their proposed role(s) in innate immune responses. Although galectins from some aquatic mollusks have been shown to recognize microbial pathogens and parasites and promote their phagocytosis, they can also selectively bind to phytoplankton components, suggesting that they also participate in uptake and intracellular digestion of microalgae. In addition, the experimental evidence suggests that the protozoan parasite Perkinsus marinus has co-evolved with the oyster host to be selectively recognized by the oyster hemocyte galectins over algal food or bacterial pathogens, thereby subverting the oyster’s innate immune/feeding recognition mechanisms to gain entry into the host cells. PMID:25982395

Regulation of Oil Biosynthesis in Algae

DTIC Science & Technology

2014-10-06

renewed interest in microalgae as potential feed stock for renewable fuels including high energy density aviation fuels. Microalgae accumulate large...mechanisms of TAG accumulation relevant to other microalgae and perhaps dedicated biofuel crop plants. Knowledge and understanding of algal model systems...energy density liquid fuels. Long Term Objectives. Under permissive conditions, i.e. nutrient deprivation, many microalgae accumulate oils (TAGs

Optimization of Biofuel Production From Transgenic Microalgae

DTIC Science & Technology

2013-02-27

AFRL-OSR-VA-TR-2013-0145 OPTIMIZATION OF BIOFUEL PRODUCTION FROM TRANSGENIC MICROALGAE Richard Sayre Donald Danforth...Technical 20080815 to 20120630 OPTIMIZATION OF BIOFUEL PRODUCTION FROM TRANSGENIC MICROALGAE FA9550-08-1-0451 Richard Sayre Donald Danforth Plant...BIOFUEL PRODUCTION FROM TRANSGENIC MICROALGAE Grant/Contract Number: FA9550-08-1-0451 Reporting Period: Final Report Abstract: We have compared the

Highly valuable microalgae: biochemical and topological aspects.

PubMed

Pignolet, Olivier; Jubeau, Sébastien; Vaca-Garcia, Carlos; Michaud, Philippe

2013-08-01

The past decade has seen a surge in the interest in microalgae culture for biodiesel production and other applications as renewable biofuels as an alternative to petroleum transport fuels. The development of new technologies for the culture of these photosynthetic microorganisms and improved knowledge of their biochemical composition has spurred innovation in the field of high-value biomolecules. These developments are only economically viable if all the microalgae fractions are valorized in a biorefinery strategy. Achieving this objective requires an understanding of microalgae content and the cellular localization of the main biomolecular families in order to develop efficient harvest and sequential recovery technologies. This review summarizes the state of the art in microalgae compositions and topologies using some examples of the main industrially farmed microalgae.

Regulation of Oil Biosynthesis in Algae

DTIC Science & Technology

2011-03-14

transportation fuels can potentially be addressed by exploring oil (triacylglycerol) biosynthesis in microalgae . Many microalgae , including Chlamydomonas...biosynthesis in microalgae have not been studied at the molecular level. Chlamydomonas is being used as a microalgal model to identify genes and regulatory...of this phenomenon will shed light on the physiological significance of oil production in microalgae . A first paper describing this interesting

Impact of Microalgae-Bacteria Interactions on the Production of Algal Biomass and Associated Compounds

PubMed Central

Fuentes, Juan Luis; Garbayo, Inés; Cuaresma, María; Montero, Zaida; González-del-Valle, Manuel; Vílchez, Carlos

2016-01-01

A greater insight on the control of the interactions between microalgae and other microorganisms, particularly bacteria, should be useful for enhancing the efficiency of microalgal biomass production and associated valuable compounds. Little attention has been paid to the controlled utilization of microalgae-bacteria consortia. However, the studies of microalgal-bacterial interactions have revealed a significant impact of the mutualistic or parasitic relationships on algal growth. The algal growth, for instance, has been shown to be enhanced by growth promoting factors produced by bacteria, such as indole-3-acetic acid. Vitamin B12 produced by bacteria in algal cultures and bacterial siderophores are also known to be involved in promoting faster microalgal growth. More interestingly, enhancement in the intracellular levels of carbohydrates, lipids and pigments of microalgae coupled with algal growth stimulation has also been reported. In this sense, massive algal production might occur in the presence of bacteria, and microalgae-bacteria interactions can be beneficial to the massive production of microalgae and algal products. This manuscript reviews the recent knowledge on the impact of the microalgae-bacteria interactions on the production of microalgae and accumulation of valuable compounds, with an emphasis on algal species having application in aquaculture. PMID:27213407

The promising future of microalgae: current status, challenges, and optimization of a sustainable and renewable industry for biofuels, feed, and other products.

PubMed

Khan, Muhammad Imran; Shin, Jin Hyuk; Kim, Jong Deog

2018-03-05

Microalgae have recently attracted considerable interest worldwide, due to their extensive application potential in the renewable energy, biopharmaceutical, and nutraceutical industries. Microalgae are renewable, sustainable, and economical sources of biofuels, bioactive medicinal products, and food ingredients. Several microalgae species have been investigated for their potential as value-added products with remarkable pharmacological and biological qualities. As biofuels, they are a perfect substitute to liquid fossil fuels with respect to cost, renewability, and environmental concerns. Microalgae have a significant ability to convert atmospheric CO 2 to useful products such as carbohydrates, lipids, and other bioactive metabolites. Although microalgae are feasible sources for bioenergy and biopharmaceuticals in general, some limitations and challenges remain, which must be overcome to upgrade the technology from pilot-phase to industrial level. The most challenging and crucial issues are enhancing microalgae growth rate and product synthesis, dewatering algae culture for biomass production, pretreating biomass, and optimizing the fermentation process in case of algal bioethanol production. The present review describes the advantages of microalgae for the production of biofuels and various bioactive compounds and discusses culturing parameters.

Crayfish behavioral changes with CO2

NASA Astrophysics Data System (ADS)

Ellis, J.

2017-12-01

Changes in carbon dioxide (CO2) could have a major impact on aquatic life. We examined the effects of different levels of CO2 on the behavior of crayfish. The shelter treatments showed that crayfish became less active with increased CO2. The predator treatments showed that crayfish became more aggressive with increased CO2. From these experiments, we conclude that the roles of crayfish in the ecosystem could change.

Sustainable microalgae for the simultaneous synthesis of carbon quantum dots for cellular imaging and porous carbon for CO2 capture.

PubMed

Guo, Li-Ping; Zhang, Yan; Li, Wen-Cui

2017-05-01

Microalgae biomass is a sustainable source with the potential to produce a range of products. However, there is currently a lack of practical and functional processes to enable the high-efficiency utilization of the microalgae. We report here a hydrothermal process to maximize the utilizability of microalgae biomass. Specifically, our concept involves the simultaneous conversion of microalgae to (i) hydrophilic and stable carbon quantum dots and (ii) porous carbon. The synthesis is easily scalable and eco-friendly. The microalgae-derived carbon quantum dots possess a strong two-photon fluorescence property, have a low cytotoxicity and an efficient cellular uptake, and show potential for high contrast bioimaging. The microalgae-based porous carbons show excellent CO 2 capture capacities of 6.9 and 4.2mmolg -1 at 0 and 25°C respectively, primarily due to the high micropore volume (0.59cm 3 g -1 ) and large specific surface area (1396m 2 g -1 ). Copyright © 2017 Elsevier Inc. All rights reserved.

Microalgae biorefinery: High value products perspectives.

PubMed

Chew, Kit Wayne; Yap, Jing Ying; Show, Pau Loke; Suan, Ng Hui; Juan, Joon Ching; Ling, Tau Chuan; Lee, Duu-Jong; Chang, Jo-Shu

2017-04-01

Microalgae have received much interest as a biofuel feedstock in response to the uprising energy crisis, climate change and depletion of natural sources. Development of microalgal biofuels from microalgae does not satisfy the economic feasibility of overwhelming capital investments and operations. Hence, high-value co-products have been produced through the extraction of a fraction of algae to improve the economics of a microalgae biorefinery. Examples of these high-value products are pigments, proteins, lipids, carbohydrates, vitamins and anti-oxidants, with applications in cosmetics, nutritional and pharmaceuticals industries. To promote the sustainability of this process, an innovative microalgae biorefinery structure is implemented through the production of multiple products in the form of high value products and biofuel. This review presents the current challenges in the extraction of high value products from microalgae and its integration in the biorefinery. The economic potential assessment of microalgae biorefinery was evaluated to highlight the feasibility of the process. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparative study of bio-oils from pyrolysis of microalgae and oil seed waste in a fluidized bed.

PubMed

Kim, Sung Won; Koo, Bon Seok; Lee, Dong Hyun

2014-06-01

The pyrolysis of Scenedesmus sp. and Jatropha seedshell cake (JSC) was investigated under similar operating condition in a fluidized bed reactor for comparison of pyrolytic behaviors from different species of lipids-containing biomass. Microalgae showed a narrower main peak in differential thermogravimetric curve compared to JSC due to different constituents. Pyrolysis liquid yields were similar; liquid's oil proportion of microalgae is higher than JSC. Microalgae bio-oil was characterized by similar carbon and hydrogen contents and higher H/C and O/C molar ratios compared to JSC due to compositional difference. The pyrolytic oils from microalgae and JSC contained more oxygen and nitrogen and less sulfur than petroleum and palm oils. The pyrolytic oils showed high yields of fatty oxygenates and nitrogenous compounds. The microalgae bio-oil features in high concentrations of aliphatic compounds, fatty acid alkyl ester, alcohols and nitriles. Microalgae showed potentials for alternative feedstock for green diesel, and commodity and valuable chemicals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pyrolysis characteristics and kinetics of microalgae via thermogravimetric analysis (TGA): A state-of-the-art review.

PubMed

Bach, Quang-Vu; Chen, Wei-Hsin

2017-12-01

Pyrolysis is a promising route for biofuels production from microalgae at moderate temperatures (400-600°C) in an inert atmosphere. Depending on the operating conditions, pyrolysis can produce biochar and/or bio-oil. In practice, knowledge for thermal decomposition characteristics and kinetics of microalgae during pyrolysis is essential for pyrolyzer design and pyrolysis optimization. Recently, the pyrolysis kinetics of microalgae has become a crucial topic and received increasing interest from researchers. Thermogravimetric analysis (TGA) has been employed as a proven technique for studying microalgae pyrolysis in a kinetic control regime. In addition, a number of kinetic models have been applied to process the TGA data for kinetic evaluation and parameters estimation. This paper aims to provide a state-of-the art review on recent research activities in pyrolysis characteristics and kinetics of various microalgae. Common kinetic models predicting the thermal degradation of microalgae are examined and their pros and cons are illustrated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biodiesel from wet microalgae: extraction with hexane after the microwave-assisted transesterification of lipids.

PubMed

Cheng, Jun; Huang, Rui; Li, Tao; Zhou, Junhu; Cen, Kefa

2014-10-01

A chloroform-free novel process for the efficient production of biodiesel from wet microalgae is proposed. Crude biodiesel is produced through extraction with hexane after microwave-assisted transesterification (EHMT) of lipids in wet microalgae. Effects of different parameters, including reaction temperature, reaction time, methanol dosage, and catalyst dosage, on fatty acids methyl esters (FAMEs) yield are investigated. The yield of FAME extracted into the hexane from the wet microalgae is increased 6-fold after the transesterification of lipids. The yield of FAME obtained through EHMT of lipids in wet microalgae is comparable to that obtained through direct transesterification of dried microalgae biomass with chloroform; however, FAME content in crude biodiesel obtained through EHMT is 86.74%, while that in crude biodiesel obtained through the chloroform-based process is 75.93%. EHMT ensures that polar pigments present in microalgae are not extracted into crude biodiesel, which leads to a 50% reduction in nitrogen content in crude biodiesel. Copyright © 2014 Elsevier Ltd. All rights reserved.

Efficient harvesting of marine Chlorella vulgaris microalgae utilizing cationic starch nanoparticles by response surface methodology.

PubMed

Bayat Tork, Mahya; Khalilzadeh, Rasoul; Kouchakzadeh, Hasan

2017-11-01

Harvesting involves nearly thirty percent of total production cost of microalgae that needs to be done efficiently. Utilizing inexpensive and highly available biopolymer-based flocculants can be a solution for reducing the harvest costs. Herein, flocculation process of Chlorella vulgaris microalgae using cationic starch nanoparticles (CSNPs) was evaluated and optimized through the response surface methodology (RSM). pH, microalgae and CSNPs concentrations were considered as the main independent variables. Under the optimum conditions of microalgae concentration 0.75gdry weight/L, CSNPs concentration 7.1mgdry weight/L and pH 11.8, the maximum flocculation efficiency (90%) achieved. Twenty percent increase in flocculation efficiency observed with the use of CSNPs instead of the non-particulate starch which can be due to the more electrostatic interactions between the cationic nanoparticles and the microalgae. Therefore, the synthesized CSNPs can be employed as a convenient and economical flocculants for efficient harvest of Chlorella vulgaris microalgae at large scale. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of different artificial neural network architectures in modeling of Chlorella sp. flocculation.

PubMed

Zenooz, Alireza Moosavi; Ashtiani, Farzin Zokaee; Ranjbar, Reza; Nikbakht, Fatemeh; Bolouri, Oberon

2017-07-03

Biodiesel production from microalgae feedstock should be performed after growth and harvesting of the cells, and the most feasible method for harvesting and dewatering of microalgae is flocculation. Flocculation modeling can be used for evaluation and prediction of its performance under different affective parameters. However, the modeling of flocculation in microalgae is not simple and has not performed yet, under all experimental conditions, mostly due to different behaviors of microalgae cells during the process under different flocculation conditions. In the current study, the modeling of microalgae flocculation is studied with different neural network architectures. Microalgae species, Chlorella sp., was flocculated with ferric chloride under different conditions and then the experimental data modeled using artificial neural network. Neural network architectures of multilayer perceptron (MLP) and radial basis function architectures, failed to predict the targets successfully, though, modeling was effective with ensemble architecture of MLP networks. Comparison between the performances of the ensemble and each individual network explains the ability of the ensemble architecture in microalgae flocculation modeling.

Lipid-Derived Biofuels: Determination of Factors that Control Triglyceride Accumulation in Microalgae

DTIC Science & Technology

2012-10-30

Accumulation in Microalgae Principal Investigator Dr. K.E. Cooksey Department of Microbiology 109 Lewis Hall Montana State University...cultures to find the extent to which previously published results can be considered general for microalgae . Task 2. Quantify growth kinetics and...diatoms cultures to find the extent to which previous results can be found to be general for microalgae . Before this project, detailed

Optimization of Chlorella vulgaris and bioflocculant-producing bacteria co-culture: enhancing microalgae harvesting and lipid content.

PubMed

Wang, Y; Yang, Y; Ma, F; Xuan, L; Xu, Y; Huo, H; Zhou, D; Dong, S

2015-05-01

Microalgae are a sustainable bioresource, and the biofuel they produce is widely considered to be an alternative to limited natural fuel resources. However, microalgae harvesting is a bottleneck in the development of technology. Axenic Chlorella vulgaris microalgae exhibit poor harvesting, as expressed by a flocculation efficiency of 0·2%. This work optimized the co-culture conditions of C. vulgaris and bioflocculant-producing bacteria in synthetic wastewater using response surface methodology (RSM), thus aiming to enhance C. vulgaris harvesting and lipid content. Three significant process variables- inoculation ratio of bacteria and microalgae, initial glucose concentration, and co-culture time- were proposed in the RSM model. F-values (3·98/8·46) and R(2) values (0·7817/0·8711) both indicated a reasonable prediction by the RSM model. The results showed that C. vulgaris harvesting efficiency reached 45·0-50·0%, and the lipid content was over 21·0% when co-cultured with bioflocculant-producing bacteria under the optimized culture conditions of inoculation ratio of bacteria and microalgae of 0·20-0·25, initial glucose concentration of <1·5 kg m(-3) and co-culture time of 9-14 days. This work provided new insights into microalgae harvesting and cost-effective microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production. This work optimized the co-culture conditions of microalgae (C. vulgaris) and bioflocculant-producing bacteria (F2, Rhizobium radiobacter) in synthetic wastewater using response surface methodology, aiming to enhance C. vulgaris harvesting and lipid produced content. Bioflocculant-producing microbes are environmentally friendly functional materials. They avoid the negative effects of traditional chemical flocculants. This work provided new insights into microalgae harvesting and cost-effective production of microalgal bioproducts, and confirmed the promising prospect of introducing bioflocculant-producing bacteria into microalgae bioenergy production. © 2015 The Society for Applied Microbiology.

Induction of Photosynthetic Carbon Fixation in Anoxia Relies on Hydrogenase Activity and Proton-Gradient Regulation-Like1-Mediated Cyclic Electron Flow in Chlamydomonas reinhardtii.

PubMed

Godaux, Damien; Bailleul, Benjamin; Berne, Nicolas; Cardol, Pierre

2015-06-01

The model green microalga Chlamydomonas reinhardtii is frequently subject to periods of dark and anoxia in its natural environment. Here, by resorting to mutants defective in the maturation of the chloroplastic oxygen-sensitive hydrogenases or in Proton-Gradient Regulation-Like1 (PGRL1)-dependent cyclic electron flow around photosystem I (PSI-CEF), we demonstrate the sequential contribution of these alternative electron flows (AEFs) in the reactivation of photosynthetic carbon fixation during a shift from dark anoxia to light. At light onset, hydrogenase activity sustains a linear electron flow from photosystem II, which is followed by a transient PSI-CEF in the wild type. By promoting ATP synthesis without net generation of photosynthetic reductants, the two AEF are critical for restoration of the capacity for carbon dioxide fixation in the light. Our data also suggest that the decrease in hydrogen evolution with time of illumination might be due to competition for reduced ferredoxins between ferredoxin-NADP(+) oxidoreductase and hydrogenases, rather than due to the sensitivity of hydrogenase activity to oxygen. Finally, the absence of the two alternative pathways in a double mutant pgrl1 hydrogenase maturation factor G-2 is detrimental for photosynthesis and growth and cannot be compensated by any other AEF or anoxic metabolic responses. This highlights the role of hydrogenase activity and PSI-CEF in the ecological success of microalgae in low-oxygen environments. © 2015 American Society of Plant Biologists. All Rights Reserved.

Cellulose degradation and assimilation by the unicellular phototrophic eukaryote Chlamydomonas reinhardtii.

PubMed

Blifernez-Klassen, Olga; Klassen, Viktor; Doebbe, Anja; Kersting, Klaudia; Grimm, Philipp; Wobbe, Lutz; Kruse, Olaf

2012-01-01

Plants convert sunlight to biomass, which is primarily composed of lignocellulose, the most abundant natural biopolymer and a potential feedstock for fuel and chemical production. Cellulose assimilation has so far only been described for heterotrophic organisms that rely on photosynthetically active primary producers of organic compounds. Among phototrophs, the unicellular green microalga Chlamydomonas reinhardtii is widely known as one of the best established model organisms. It occupies many habitats, including aquatic and soil ecosystems. This ubiquity underscores the versatile metabolic properties of this microorganism. Here we present yet another paradigm of adaptation for C. reinhardtii, highlighting its photoheterotrophic ability to utilize cellulose for growth in the absence of other carbon sources. When grown under CO(2)-limiting conditions in the light, secretion of endo-β-1,4-glucanases by the cell causes digestion of exogenous cellulose, followed by cellobiose uptake and assimilation. Phototrophic microbes like C. reinhardtii may thus serve as biocatalysts for cellulosic biofuel production.

Competition of Invertebrates Mixed Culture in the Closed Aquatic System

NASA Astrophysics Data System (ADS)

Pisman, Tamara

The study considers the experimental model of interactions between invertebrates (the cilates Paramecium caudatum, Paramecium bursaria and the rotifers Brachionis plicatilis) in the closed aquatic system. The infusoria P.caudatum can feed on yeast, bacteria and chlorella; in this experiment growth and reproduction were maintained by bacteria only. The P.bursaria - zoochlorella endosymbiosis is a natural model of a simple biotic cycle. P.bursaria consumes glucose and oxygen released by zoochlorella in the process of biosynthesis and releases nitrogenous compounds and carbon dioxide necessary for algal photosynthesis. The rotifers Br. plicatilis can consume algae, bacteria and detritus. Thus in experiment with the mixed culture of invertebrates they can use different food sources. However with any initial percentage of the invertebrates the end portion of P.bursaria reaches 90-99

Harvesting of freshwater microalgae biomass by Scenedesmus sp. as bioflocculant

NASA Astrophysics Data System (ADS)

Rinanti, A.; Purwadi, R.

2018-01-01

This study is particularly expected to provide information on the diversity of microalgae as the flocculant agent that gives the highest biomass yield. Bioflocculation was done by using one of the flocculating microalgae i.e. Scenedesmus obliquus to concentrate on non-flocculating microalgae Chlorella vulgaris. The freshwater microalgae S. obliquus tested it ability to harvest other non-flocculating microalgae, increased sedimentation rate in the flocculation process and increased biomass yield. The flocculation of biomass microalgae with chemical flocculant as comparison was done by adding alum (K2SO4·Al2 (SO4)3·24H2O). The addition of alum (K2SO4·Al2 (SO4)3·24H2O) as flocculant at pH 11 and S. obliquus sp. as bioflocculant caused significant alteration of nutrition of microalgae. Overall, the essential content produced by flocculation method with addition of alum or with bioflocculation (%, mg/100 mg dry weight) are lipid 31,64; 38,69, protein 30,79; 38.50%, and chlorophyll 0.6253; 0.8420). Harvesting with bioflocculation methods conducted at the end of the cultivation period increase the amount of biomass significantly and can accelerate the settling time of biomass. Harvesting microalgae cells by bioflocculation method becomes an economically competitive harvesting method compared to alum as a chemical flocculant because of the cheaper cost of flocculant, not toxic so it does not require further water treatment after harvesting due to the use of alum as chemical flocculants.

The interactive effects of microcystin-LR and cylindrospermopsin on the growth rate of the freshwater algae Chlorella vulgaris.

PubMed

Pinheiro, Carlos; Azevedo, Joana; Campos, Alexandre; Vasconcelos, Vítor; Loureiro, Susana

2016-05-01

Microcystin-LR (MC-LR) and cylindrospermopsin (CYN) are the most representative cyanobacterial cyanotoxins. They have been simultaneously detected in aquatic systems, but their combined ecotoxicological effects to aquatic organisms, especially microalgae, is unknown. In this study, we examined the effects of these cyanotoxins individually and as a binary mixture on the growth rate of the freshwater algae Chlorella vulgaris. Using the MIXTOX tool, the reference model concentration addition (CA) was selected to evaluate the combined effects of MC-LR and CYN on the growth of the freshwater green algae due to its conservative prediction of mixture effect for putative similar or dissimilar acting chemicals. Deviations from the CA model such as synergism/antagonism, dose-ratio and dose-level dependency were also assessed. In single exposures, our results demonstrated that MC-LR and CYN had different impacts on the growth rates of C. vulgaris at the highest tested concentrations, being CYN the most toxic. In the mixture exposure trial, MC-LR and CYN showed a synergistic deviation from the conceptual model CA as the best descriptive model. MC-LR individually was not toxic even at high concentrations (37 mg L(-1)); however, the presence of MC-LR at much lower concentrations (0.4-16.7 mg L(-1)) increased the CYN toxicity. From these results, the combined exposure of MC-LR and CYN should be considered for risk assessment of mixtures as the toxicity may be underestimated when looking only at the single cyanotoxins and not their combination. This study also represents an important step to understand the interactions among MC-LR and CYN detected previously in aquatic systems.

Allelopathy as a potential strategy to improve microalgae cultivation.

PubMed

Bacellar Mendes, Leonardo Brantes; Vermelho, Alane Beatriz

2013-10-21

One of the main obstacles for continuous productivity in microalgae cultivation is the presence of biological contaminants capable of eliminating large numbers of cells in a matter of days or even hours. However, a number of strategies are being used to combat and prevent contamination in microalgae cultivation. These strategies include the use of extreme conditions in the culture media such as high salinity and high pH to create an unfavorable environment for the competitive organisms or predators of the microalgae. Numerous studies have explored the potential of naturally occurring bioactive secondary metabolites, which are natural products from plants and microorganisms, as a source of such compounds. Some of these compounds are herbicides, and marine and freshwater microalgae are a source of these compounds. Microalgae produce a remarkable diversity of biologically active metabolites. Results based on the allelopathic potential of algae have only been described for laboratory-scale production and not for algae cultivation on a pilot scale. The adoption of allelopathy on microalgal strains is an unexplored field and may be a novel solution to improve algae production. Here we present information showing the diversity of allelochemicals from microalgae and the use of an allelopathic approach to control microalgae cultivation on a pilot scale based on R&D activities being carried out in Brazil for biodiesel production.

Microalgae population dynamics in photobioreactors with secondary sewage effluent as culture medium

PubMed Central

Marchello, Adriano E.; Lombardi, Ana T.; Dellamano-Oliveira, Maria José; de Souza, Clovis W.O.

2015-01-01

Nitrogen and phosphorus present in sewage can be used for microalgae growth, possibiliting cost reduction in the production of microalgae at the same time that it decreases the eutrophication potential of the effluent. This research aimed at monitoring the native community of microalgae and coliform bacteria in a secondary effluent from anaerobic municipal sewage treatment. Two treatments (aerated and non-aerated) were performed to grow microalgae under semi-controlled conditions in semi-closed photobioreactors in a greenhouse. The results showed no significant pH and coliforms (total and Escherichia coli ) variation between treatments. Nutrient concentrations were reduced supporting microalgae growth up to 10 7 cells.mL −1 independent of aeration. Exponential growth was obtained from the first day for the non-aerated, but a 5 day lag phase of growth was obtained for the aerated. Chlorella vulgaris was the dominant microalgae (99.9%) in both treatments. In the aerated, 5 algae classes were detected (Chlorophyceae, Cyanophyceae, Chrysophyceae, Bacillariophyceae and Euglenophyceae), with 12 taxa, whereas in the non-aerated, 2 classes were identified (Chlorophyceae and Cyanophyceae), with 5 taxa. We concluded that effluent is viable for microalgae growth, especially Chlorella vulgaris, at the same time that the eutrophication potential and coliforms are decreased, contributing for better quality of the final effluent. PMID:26221091

Allelopathy as a potential strategy to improve microalgae cultivation

PubMed Central

2013-01-01

One of the main obstacles for continuous productivity in microalgae cultivation is the presence of biological contaminants capable of eliminating large numbers of cells in a matter of days or even hours. However, a number of strategies are being used to combat and prevent contamination in microalgae cultivation. These strategies include the use of extreme conditions in the culture media such as high salinity and high pH to create an unfavorable environment for the competitive organisms or predators of the microalgae. Numerous studies have explored the potential of naturally occurring bioactive secondary metabolites, which are natural products from plants and microorganisms, as a source of such compounds. Some of these compounds are herbicides, and marine and freshwater microalgae are a source of these compounds. Microalgae produce a remarkable diversity of biologically active metabolites. Results based on the allelopathic potential of algae have only been described for laboratory-scale production and not for algae cultivation on a pilot scale. The adoption of allelopathy on microalgal strains is an unexplored field and may be a novel solution to improve algae production. Here we present information showing the diversity of allelochemicals from microalgae and the use of an allelopathic approach to control microalgae cultivation on a pilot scale based on R&D activities being carried out in Brazil for biodiesel production. PMID:24499580

Purification of microalgae from bacterial contamination using a disposable inertia-based microfluidic device

NASA Astrophysics Data System (ADS)

Godino, Neus; Jorde, Felix; Lawlor, Daryl; Jaeger, Magnus; Duschl, Claus

2015-08-01

Microalgae are a promising source of bioactive ingredients for the food, pharmaceutical and cosmetic industries. Every microalgae research group or production facility is facing one major problem regarding the potential contamination of the algal cell with bacteria. Prior to the storage of the microalgae in strain collections or to cultivation in bioreactors, it is necessary to carry out laborious purification procedures to separate the microalgae from the undesired bacterial cells. In this work, we present a disposable microfluidic cartridge for the high-throughput purification of microalgae samples based on inertial microfluidics. Some of the most relevant microalgae strains have a larger size than the relatively small, few micron bacterial cells, so making them distinguishable by size. The inertial microfluidic cartridge was fabricated with inexpensive materials, like pressure sensitive adhesive (PSA) and thin plastic layers, which were patterned using a simple cutting plotter. In spite of fabrication restrictions and the intrinsic difficulties of biological samples, the separation of microalgae from bacteria reached values in excess of 99%, previously only achieved using conventional high-end and high cost lithography methods. Moreover, due to the simple and high-throughput characteristic of the separation, it is possible to concatenate serial purification to exponentially decrease the absolute amount of bacteria in the final purified sample.

Photosynthetic aeration in biological wastewater treatment using immobilized microalgae-bacteria symbiosis.

PubMed

Praveen, Prashant; Loh, Kai-Chee

2015-12-01

Chlorella vulgaris encapsulated in alginate beads were added into a bioreactor treating synthetic wastewater using Pseudomonas putida. A symbiotic CO2/O2 gas exchange was established between the two microorganisms for photosynthetic aeration of wastewater. During batch operation, glucose removal efficiency in the bioreactor improved from 50% in 12 h without aeration to 100% in 6 h, when the bioreactor was aerated photosynthetically. During continuous operation, the bioreactor was operated at a low hydraulic retention time of 3.3 h at feed concentrations of 250 and 500 mg/L glucose. The removal efficiency at 500 mg/L increased from 73% without aeration to 100% in the presence of immobilized microalgae. The initial microalgae concentration was critical to achieve adequate aeration, and the removal rate increased with increasing microalgae concentration. The highest removal rate of 142 mg/L-h glucose was achieved at an initial microalgae concentration of 190 mg/L. Quantification of microalgae growth in the alginate beads indicated an exponential growth during symbiosis, indicating that the bioreactor performance was limited by oxygen production rates. Under symbiotic conditions, the chlorophyll content of the immobilized microalgae increased by more than 30%. These results indicate that immobilized microalgae in symbiosis with heterotrophic bacteria are promising in wastewater aeration.

Lipid extraction from microalgae using a single ionic liquid

DOEpatents

Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo

2013-05-28

A one-step process for the lysis of microalgae cell walls and separation of the cellular lipids for use in biofuel production by utilizing a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium. The hydrophilic ionic liquid both lyses the microalgae cell walls and forms two immiscible layers, one of which consists of the lipid contents of the lysed cells. After mixture of the hydrophilic ionic liquid with a suspension of microalgae cells, gravity causes a hydrophobic lipid phase to move to a top phase where it is removed from the mixture and purified. The hydrophilic ionic liquid is recycled to lyse new microalgae suspensions.

[Trends of microalgal biotechnology: a view from bibliometrics].

PubMed

Yang, Xiaoqiu; Wu, Yinsong; Yan, Jinding; Song, Haigang; Fan, Jianhua; Li, Yuanguang

2015-10-01

Microalgae is a single-cell organism with the characteristics of high light energy utilization rate, fast growth rate, high-value bioactive components and high energy material content. Therefore, microalgae has broad application prospects in food, feed, bioenergy, carbon sequestration, wastewater treatment and other fields. In this article, the microalgae biotechnology development in recent years were fully consulted, through analysis from the literature and patent. The progress of microalgal biotechnology at home and abroad is compared and discussed. Furthermore, the project layout, important achievements and development bottlenecks of microalgae biotechnology in our country were also summarized. At last, future development directions of microalgae biotechnology were discussed.

The potential of transgenic green microalgae; a robust photobioreactor to produce recombinant therapeutic proteins.

PubMed

Akbari, Fariba; Eskandani, Morteza; Khosroushahi, Ahmad Yari

2014-11-01

Microalgae have been used in food, cosmetic, and biofuel industries as a natural source of lipids, vitamins, pigments and antioxidants for a long time. Green microalgae, as potent photobioreactors, can be considered as an economical expression system to produce recombinant therapeutical proteins at large-scale due to low cost of production and scaling-up capitalization owning to the inexpensive medium requirement, fast growth rate, and the ease of manipulation. These microalgae possess all benefit eukaryotic expression systems including the ability of post-translational modifications required for proper folding and stability of active proteins. Among the many items regarded as recombinant protein production, this review compares the different expression systems with green microalgae like Dunaliella by viewing the nuclear/chloroplast transformation challenges/benefits, related selection markers/reporter genes, and crucial factors/strategies affecting the increase of foreign protein expression in microalgae transformants. Some important factors were discussed regarding the increase of protein yielding in microalgae transformants including: transformation-associated genotypic modifications, endogenous regulatory factors, promoters, codon optimization, enhancer elements, and milking of recombinant protein.

Marine Microalgae with Anti-Cancer Properties.

PubMed

Martínez Andrade, Kevin A; Lauritano, Chiara; Romano, Giovanna; Ianora, Adrianna

2018-05-15

Cancer is the leading cause of death globally and finding new therapeutic agents for cancer treatment remains a major challenge in the pursuit for a cure. This paper presents an overview on microalgae with anti-cancer activities. Microalgae are eukaryotic unicellular plants that contribute up to 40% of global primary productivity. They are excellent sources of pigments, lipids, carotenoids, omega-3 fatty acids, polysaccharides, vitamins and other fine chemicals, and there is an increasing demand for their use as nutraceuticals and food supplements. Some microalgae are also reported as having anti-cancer activity. In this review, we report the microalgal species that have shown anti-cancer properties, the cancer cell lines affected by algae and the concentrations of compounds/extracts tested to induce arrest of cell growth. We also report the mediums used for growing microalgae that showed anti-cancer activity and compare the bioactivity of these microalgae with marine anticancer drugs already on the market and in phase III clinical trials. Finally, we discuss why some microalgae can be promising sources of anti-cancer compounds for future development.

Fermentative hydrogen production using pretreated microalgal biomass as feedstock.

PubMed

Wang, Jianlong; Yin, Yanan

2018-02-14

Microalgae are simple chlorophyll containing organisms, they have high photosynthetic efficiency and can synthesize and accumulate large quantities of carbohydrate biomass. They can be cultivated in fresh water, seawater and wastewater. They have been used as feedstock for producing biodiesel, bioethanol and biogas. The production of these biofuels can be integrated with CO 2 mitigation, wastewater treatment, and the production of high-value chemicals. Biohydrogen from microalgae is renewable. Microalgae have several advantages compared to terrestrial plants, such as higher growth rate with superior CO 2 fixation capacity; they do not need arable land to grow; they do not contain lignin. In this review, the biology of microalgae and the chemical composition of microalgae were briefly introduced, the advantages and disadvantages of hydrogen production from microalgae were discussed, and the pretreatment of microalgal biomass and the fermentative hydrogen production from microalgal biomass pretreated by different methods (including physical, chemical, biological and combined methods) were summarized and evaluated. For the production of biohydrogen from microalgae, the economic feasibility remains the most important aspect to consider. Several technological and economic issues must be addressed to achieve success on a commercial scale.

Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2-).

PubMed

Chhetri, Ravi Kumar; Baun, Anders; Andersen, Henrik Rasmus

2017-05-01

Environmental effect evaluation of disinfection of combined sewer overflow events with alternative chemical disinfectants requires that the environmental toxicity of the disinfectants and the main by-products of their use are known. Many disinfectants degrade quickly in water which should be included in the evaluation of both their toxicity as determined in standardized tests and their possible negative effect in the water environment. Here we evaluated according to the standardized ISO 8692 test the toxicity towards the green microalgae, Pseudokirchneriella subcapitata, of three disinfectants: performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO 2 ) as well as two by-products of their use: hydrogen peroxide (H 2 O 2 ) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC 50 values ranged from 0.16 to 2.9mg/L based on nominal concentrations leading to the labeling of the chemicals as either toxic or very toxic. The five investigated chemicals decreased in toxicity in the order chlorine dioxide, performic acid, peracetic acid, chlorite and hydrogen peroxide. The stability of the chemicals increased in the same order as the toxicity decrease. This indicates that even though ClO 2 has the highest environmental hazard potential, it may still be suitable as an alternative disinfectant due to its rapid degradation in water. Copyright © 2016 Elsevier GmbH. All rights reserved.

Modeling of the Kinetics of Supercritical Fluid Extraction of Lipids from Microalgae with Emphasis on Extract Desorption

PubMed Central

Sovová, Helena; Nobre, Beatriz P.; Palavra, António

2016-01-01

Microalgae contain valuable biologically active lipophilic substances such as omega-3 fatty acids and carotenoids. In contrast to the recovery of vegetable oils from seeds, where the extraction with supercritical CO2 is used as a mild and selective method, economically viable application of this method on similarly soluble oils from microalgae requires, in most cases, much higher pressure. This paper presents and verifies hypothesis that this difference is caused by high adsorption capacity of microalgae. Under the pressures usually applied in supercritical fluid extraction from plants, microalgae bind a large fraction of the extracted oil, while under extremely high CO2 pressures their adsorption capacity diminishes and the extraction rate depends on oil solubility in supercritical CO2. A mathematical model for the extraction from microalgae was derived and applied to literature data on the extraction kinetics in order to determine model parameters. PMID:28773546

Nutrient recycle from defatted microalgae (Aurantiochytrium) with hydrothermal treatment for microalgae cultivation.

PubMed

Aida, Taku Michael; Maruta, Ryouma; Tanabe, Yuuhiko; Oshima, Minori; Nonaka, Toshiyuki; Kujiraoka, Hiroki; Kumagai, Yasuaki; Ota, Masaki; Suzuki, Iwane; Watanabe, Makoto M; Inomata, Hiroshi; Smith, Richard L

2017-03-01

Defatted heterotrophic microalgae (Aurantiochytrium limacinum SR21) was treated with high temperature water (175-350°C, 10-90min) to obtain nitrogen and phosphorous nutrients as a water soluble fraction (WS). Yields of nitrogen and phosphorous recovered in WS varied from 38 to 100% and from 57 to 99%, respectively. Maximum yields of nitrogen containing compounds in WS were proteins (43%), amino acids (12%) and ammonia (60%) at treatment temperatures of 175, 250 and 350°C, respectively. Maximum yield of phosphorous in WS was 99% at a treatment temperature of 250°C. Cultivation experiments of microalgae (A. limacinum SR21) using WS obtained at 200 and 250°C showed positive growth. Water soluble fractions from hydrothermal treatment of defatted microalgae are effective nitrogen and phosphorous nutrient sources for microalgae cultivation. Copyright © 2016 Elsevier Ltd. All rights reserved.

From lab to full-scale ultrafiltration in microalgae harvesting

NASA Astrophysics Data System (ADS)

Wenten, I. G.; Steven, S.; Dwiputra, A.; Khoiruddin; Hakim, A. N.

2017-07-01

Ponding system is generally used for microalgae cultivation. However, selection of appropriate technology for the harvesting process is challenging due to the low cell density of cultivated microalgae from the ponding system and the large volume of water to be handled. One of the promising technologies for microalgae harvesting is ultrafiltration (UF). In this study, the performance of UF during harvesting of microalgae in a lab- and a full-scale test is investigated. The performances of both scales are compared and analyzed to provide an understanding of several aspects which affect the yield produced from lab and actual conditions. Furthermore, a unique self-standing non-modular UF is introduced in the full-scale test. The non-modular UF exhibits several advantages, such as simple piping and connection, single pump for filtration and backwashing, and smaller footprint. With those advantages, the non-modular UF could be a promising technology for microalgae harvesting in industrial-scale.

Physiological-phased kinetic characteristics of microalgae Chlorella vulgaris growth and lipid synthesis considering synergistic effects of light, carbon and nutrients.

PubMed

Liao, Qiang; Chang, Hai-Xing; Fu, Qian; Huang, Yun; Xia, Ao; Zhu, Xun; Zhong, Nianbing

2018-02-01

To comprehensively understand kinetic characteristics of microalgae growth and lipid synthesis in different phases, a phase-feeding strategy was proposed to simultaneously regulate light, carbon and nutrients in adaption, growth and stationary phases of microalgae cultivation. Physiological-phased kinetic characteristics of microalgae Chlorella vulgaris growth and lipid synthesis under synergistic effects of light, carbon and nutrients were investigated, and supply-demand relationships of electrons and energy between light and dark reactions of photosynthesis process were discussed. Finally, the optimized cultivation strategy for microalgae in various phases were obtained, under which the lipid productivity was significantly improved from 130.11 mg/L/d to 163.42 mg/L/d. The study provided some important guidance for the large-scale production of biofuels from microalgae. Copyright © 2017 Elsevier Ltd. All rights reserved.

Possible nutrient limiting factor in long term operation of closed aquatic ecosystem

NASA Astrophysics Data System (ADS)

Hao, Zongjie; Li, Yanhui; Cai, Wenkai; Wu, Peipei; Liu, Yongding; Wang, Gaohong

2012-03-01

To investigate nutrient limitation effect on the community metabolism of closed aquatic ecosystem and possible nutrient limiting factors in the experimental food chains, depletion of inorganic chemicals including carbon, nitrogen and phosphorous was tested. A closed aquatic ecosystem lab module consisting of Chlorella pyrenoidosa and Chlamydomonas reinhardtii, Daphnia magna and associated unidentified microbes was established. Closed ecological systems receive no carbon dioxide; therefore, we presumed carbon as a first limiting factor. The results showed that the algae population in the nutrient saturated group was statistically higher than that in the nutrient limited groups, and that the chlorophyll a content of algae in the phosphorus limited group was the highest among the limited groups. However, the nitrogen limited group supported the most Daphnia, followed by the carbon limited group, the nutrient saturated group and the phosphorus limited group. Redundancy analysis showed that the total phosphorus contents were correlated significantly with the population of algae, and that the amount of soluble carbohydrate as feedback of nutrient depletion was correlated with the number of Daphnia. Thus, these findings suggest that phosphorus is the limiting factor in the operation of closed aquatic ecosystem. The results presented herein have important indications for the future construction of long term closed ecological system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams, Merrin S.; Dillon, Carolyn T.; Vogt, Stefan

Metal toxicity to aquatic organisms depends on the speciation of the metal and its binding to the critical receptor site(s) (biotic ligand) of the organism. The intracellular nature of the biotic ligand for Cu in microalgal cells was investigated using the high elemental sensitivity of microprobe synchrotron radiation X-ray fluorescence (SR-XRF) and X-ray absorption near-edge spectroscopy (XANES). The marine microalgae, Ceratoneis closterium, Phaeodactylum tricornutum, and Tetraselmis sp. were selected based on their varying sensitivities to Cu (72-h 50% population growth inhibitions of 8–47 μg Cu/L). Intracellular Cu in control cells was similar for all three species (2.5–3.2 × 10–15 gmore » Cu/cell) and increased 4-fold in C. closterium and Tetraselmis sp. when exposed to copper, but was unchanged in P. tricornutum (72-h exposure to 19, 40, and 40 μg Cu/L, respectively). Whole cell microprobe SR-XRF identified endogenous Cu in the central compartment (cytoplasm) of control (unexposed) cells. After Cu exposure, Cu was colocated with organelles/granules dense in P, S, Ca, and Si and this was clearly evident in thin sections of Tetraselmis sp. XANES indicated coexistence of Cu(I) and Cu(II) in control and Cu-exposed cells, with the Cu ligand (e.g., phytochelatin) in P. tricornutum different from that in C. closterium and Tetraselmis sp. Here, this study supports the hypothesis that Cu(II) is reduced to Cu(I) and that polyphosphate bodies and phytochelatins play a significant role in the internalization and detoxification of Cu in marine microalgae.« less

PhytoREF: a reference database of the plastidial 16S rRNA gene of photosynthetic eukaryotes with curated taxonomy.

PubMed

Decelle, Johan; Romac, Sarah; Stern, Rowena F; Bendif, El Mahdi; Zingone, Adriana; Audic, Stéphane; Guiry, Michael D; Guillou, Laure; Tessier, Désiré; Le Gall, Florence; Gourvil, Priscillia; Dos Santos, Adriana L; Probert, Ian; Vaulot, Daniel; de Vargas, Colomban; Christen, Richard

2015-11-01

Photosynthetic eukaryotes have a critical role as the main producers in most ecosystems of the biosphere. The ongoing environmental metabarcoding revolution opens the perspective for holistic ecosystems biological studies of these organisms, in particular the unicellular microalgae that often lack distinctive morphological characters and have complex life cycles. To interpret environmental sequences, metabarcoding necessarily relies on taxonomically curated databases containing reference sequences of the targeted gene (or barcode) from identified organisms. To date, no such reference framework exists for photosynthetic eukaryotes. In this study, we built the PhytoREF database that contains 6490 plastidial 16S rDNA reference sequences that originate from a large diversity of eukaryotes representing all known major photosynthetic lineages. We compiled 3333 amplicon sequences available from public databases and 879 sequences extracted from plastidial genomes, and generated 411 novel sequences from cultured marine microalgal strains belonging to different eukaryotic lineages. A total of 1867 environmental Sanger 16S rDNA sequences were also included in the database. Stringent quality filtering and a phylogeny-based taxonomic classification were applied for each 16S rDNA sequence. The database mainly focuses on marine microalgae, but sequences from land plants (representing half of the PhytoREF sequences) and freshwater taxa were also included to broaden the applicability of PhytoREF to different aquatic and terrestrial habitats. PhytoREF, accessible via a web interface (http://phytoref.fr), is a new resource in molecular ecology to foster the discovery, assessment and monitoring of the diversity of photosynthetic eukaryotes using high-throughput sequencing. © 2015 John Wiley & Sons Ltd.

Microalgae as healthy ingredients for functional food: a review.

PubMed

Matos, J; Cardoso, C; Bandarra, N M; Afonso, C

2017-08-01

Microalgae are very interesting and valuable natural sources of highly valuable bioactive compounds, such as vitamins, essential amino acids, polyunsaturated fatty acids, minerals, carotenoids, enzymes and fibre. Due to their potential, microalgae have become some of the most promising and innovative sources of new food and functional products. Moreover, microalgae can be used as functional ingredients to enhance the nutritional value of foods and, thus, to favourably affect human health by improving the well-being and quality of life, but also by curtailing disease and illness risks. This review provides an overview of the current knowledge of the health benefits associated with the consumption of microalgae, bioactive compounds, functional ingredients, and health foods.

The role of microalgae as biodiesel feedstock in a tropical setting: Economics, agro-energy competitiveness, and potential impacts on regional agricultural feedstock production

NASA Astrophysics Data System (ADS)

Boll, Matias G.

The objective of this study is to obtain a realistic evaluation of the potential role of microalgae as a biodiesel feedstock in a tropical setting. First, microalgae economics are estimated, including the detailed design of a 400 ha microalgae open pond production farm together with the microalgae biomass and crude oil production costs calculations. Sensitivity analysis and a stochastic evaluation of the microalgae venture chances for profit are also included. Next, microalgae potential for biodiesel production is compared to traditional oil crops such as soybeans and African palm. This comparison is performed using the Northeast Region (NER) of Brazil as background. Six potential biodiesel feedstock sources produced in the NER and microalgae are compared considering selected environmental, economic and social sustainability indicators. Finally, in the third chapter, the study proposes a cropland allocation model for the NER. The model aims to offer insights to the decision maker concerning biofuel development strategies and their impact on regional agricultural feedstock production. In the model, cropland allocation among three agriculture feedstock sectors, namely staple food, commodity export and biofuel is optimized through the use of the multiple objective technique referred to as compromise programming (CP). Our results indicate a projected microalgae total production cost of R 78,359 ha-1 (US43,533), which has a breakdown as follows: R 34,133 ha-1 (US18,963) for operating costs and R 44,226 ha-1 (US24,570) for overhead (ownership) costs. Our stochastic analysis indicates that microalgae production under the conditions assumed in the baseline scenario of this study has a 0% chance to present a positive NPV for a microalgae crude oil price of R 1.86. This price corresponds to an international oil price around US 77 bbl-1. To obtain a reasonable investment return (IRR = 12%) from the microalgae farm, an international oil price as high as US 461 bbl-1 is required. Despite the advantage of using about 14 times less cropland area (0.13 ha boe-1 ), microalgae presented significant disadvantages as compared to some of the traditional oil crops. Among these is the significant amount of N fertilizer and water demanded by microalgae production, namely 205 kg and 4,990 boe -1, about 132% and 30% higher than the second highest value among the crops compared in this study, respectively. Optimized CP scenarios expanded annual cropland allocation to 14.58 million ha in the NER, year 2017, compared to 11.04 and 12.81 million ha in current (2007) and baseline (2017) scenarios, respectively. In comparison to the baseline scenario, cropland expansions allied to the shift of the commodities export dedicated cropland to the biofuel production sector in CP scenarios significantly increased the NER fuel autonomy (95%) and reduced its R 5,126 million reais deficit baseline comprehensive feedstock trade balance by 79%. Contrary to the concerns usually referred to biofuel development, our model indicates that in the NER case, it is the commodity export, rather than the staple food agriculture feedstock production sector, that is mostly affected by the biofuel cropland allocation demand. When compared to traditional oil crops, microalgae-based biodiesel scenarios could not significantly improve regional staple food autonomy, increasing this objective by 1% only. The NER fuel autonomy, in its turn, is positively impacted in the microalgae scenarios, but the increment as compared to the traditional oil crops is rather small, namely 2% and 7% in the B5 and B10 levels, respectively. These results indicate that the potential advantages expected for the microalgae-based biodiesel introduction did not materialize for the NER. It is concluded that the adoption of microalgae-based biodiesel is not an interesting biofuel alternative for the NER of Brazil for the next ten years.

Temporal scaling of the growth dependent optical properties of microalgae

NASA Astrophysics Data System (ADS)

Zhao, J. M.; Ma, C. Y.; Liu, L. H.

2018-07-01

The optical properties of microalgae are basic parameters for analyzing light field distribution in photobioreactors (PBRs). With the growth of microalgae cell, their optical properties will vary with growth time due to accumulation of pigment and lipid, cell division and metabolism. In this work, we report a temporal scaling behavior of the growth dependent optical properties of microalgae cell suspensions with both experimental and theoretical evidence presented. A new concept, the temporal scaling function (TSF), defined as the ratio of absorption or scattering cross-sections at growth phase to that at stationary phase, is introduced to characterize the temporal scaling behavior. The temporal evolution and temporal scaling characteristics of the absorption and scattering cross-sections of three example microalgae species, Chlorella vulgaris, Chlorella pyrenoidosa, and Chlorella protothecoides, were experimentally studied at spectral range 380-850 nm. It is shown that the TSFs of the absorption and scattering cross-sections for different microalgae species are approximately constant at different wavelength, which confirms theoretical predictions very well. With the aid of the temporal scaling relation, the optical properties at any growth time can be calculated based on those measured at stationary phase, hence opens a new way to determine the time-dependent optical properties of microalgae. The findings of this work will help the understanding of time dependent optical properties of microalgae and facilitate their applications in light field analysis in PBRs design.

Combined toxicities of copper nanoparticles with carbon nanotubes on marine microalgae Skeletonema costatum.

PubMed

Zhang, Cai; Chen, Xiaohua; Tan, Liju; Wang, Jinagtao

2018-05-01

To investigate the combined toxicities of copper nanoparticles (nano-Cu) with carbon nanotubes (CNTs) on marine microalgae Skeletonema costatum, algal growth inhibition tests were carried out. Toxicities of nano-Cu with CNTs and without CNTs on microalgae were determined, respectively. Chlorophyll content and photosynthetic efficiency (ΦPSII) were determined to compare negative effects of nano-Cu with CNTs and without CNTs on photosynthesis. The concentration of Cu 2+ released by nano-Cu into the medium was determined, and interactions between nano-Cu and CNTs were analyzed to study toxic mechanisms of combined toxicities of nano-Cu with CNTs. It was found that both nano-Cu and CNTs could inhibit the growth of the microalgae; however, the toxicity of CNTs on the microalgae was far lower than that of nano-Cu. The maximum growth inhibition ratio (IR) of nano-Cu on the microalgae was 86% appearing at 96 h under 1.0 mg/L nano-Cu treatment, while the maximum IR of CNTs on the microalgae was 58% at 96 h under 200 mg/L CNT treatment. CNTs could reduce the toxicity of nano-Cu on the microalgae in processes of growth and photosynthesis. Adsorption of Cu 2+ on CNTs and aggregate between Cu and CNTs in the medium were main reasons for attenuation of toxicity of nano-Cu with adding CNTs.

Lipid extraction of wet BLT0404 microalgae for biofuel application

NASA Astrophysics Data System (ADS)

Mansur, Dieni; Fitriady, Muhammad Arifuddin; Susilaningsih, Dwi; Simanungkalit, Sabar Pangihutan; Agustian, Egi

2017-01-01

Recently, research and development of microalgae for biodiesel production were conducted by researchers in the world. This research becomes popular because of an exponential growth of the microalgae under nutrient limitation. Lipid of microalgae grows faster than oil producing land crops. Therefore, microalgae lipid content could improve the economics of biodiesel production. The aim of this study was to investigate yield of lipid extract and chemicals compounds containing in non-acylglycerol neutral lipid from BLT 0404 microalga. The study was conducted because lipid extraction was an important step for biodiesel as well as biofuel production. The extraction was carried out using polar and non-polar mixture solvents. The polar solvent was methanol and non-polar one was chloroform. Process extraction was conducted under various stirring time between the microalgae and methanol and volume ratio between the methanol and chloroform. Methanol as a polar solvent was able to extract polar lipid (phospholipid and glycolipid) because it removed polar membrane lipid and lipid-associated to polar molecule. Moreover, the non-polar solvent was used for extraction non-acylglycerol neutral lipid (hydrocarbons, sterols, ketones, free fatty acids, carotenes, and chlorophylls) for biofuel production. Under ratio of microalgae: methanol: chloroform of 0.8: 4: 2 that stirring time of the microalgae with methanol was 30 min yielded 58% of total lipid extract. The yield value consisted of 14.5% of non-acylglycerol neutral lipid and 43.5% of polar lipid. The non-acylglycerol neutral lipid will be converted into biofuel. Therefore, analysis of its chemical compounds was required. The non-acylglycerol neutral lipid was analyzed by GCMS and found that the extract contained long chains of hydrocarbon compounds. The hydrocarbons consisted of C18-C30 that high peaks with larger percentage area were C20-C26. The results suggested that stirring between microalgae and methanol for 30 min was needed before additional of chloroform. Moreover, the ratio of methanol must be higher than chloroform due to the higher portion of polar lipid content in the microalgae.

Sludge-grown algae for culturing aquatic organisms: Part I. Algal growth in sludge extracts

NASA Astrophysics Data System (ADS)

Hung, K. M.; Chiu, S. T.; Wong, M. H.

1996-05-01

This project is aimed at studying the feasibility of using sewage sludge to prepare culture media for microalgae ( Chlorella-HKBU) and the use of the sludge-grown algae as a feed for some aquatic organisms. Part I of the project included results on preparing sludge extracts and their use on algal culture. By comparing two culturing techniques, “aeration” and “shaking,” it was noted that both lag and log phases were shortened in the aeration system. A subsequent experiment noted that algal growth subject to aeration rates of 1.0 and 1.5 liters/min had similar lag and log phases. In addition, both aeration rates had a significantly higher ( P < 0.05) final cell density than that of 0.5 liters/min. A detailed study on the variation of growth conditions on the algal growth was done. The results indicated that pH values of all the cultures declined below 5 at day 12. The removal rates of ammonia N ranged from 62% to 70%. The sludge-grown algae contained a rather substantial amount of heavy metals (µg/g): Zn 289 581, Cu 443 682, Ni 310 963, Mn 96 126, Cr 25 118, and Fe 438 653. This implied that the rather high levels of heavy metals may impose adverse effects on higher trophic organisms.

Benefits of Microalgae for Human Space Exploration

NASA Technical Reports Server (NTRS)

Verrecchia, Angelique; Bebout, Brad M.; Murphy, Thomas

2015-01-01

Algae have long been known to offer a number of benefits to support long duration human space exploration. Algae contain proteins, essential amino acids, vitamins, and lipids needed for human consumption, and can be produced using waste streams, while consuming carbon dioxide, and producing oxygen. In comparison with higher plants, algae have higher growth rates, fewer environmental requirements, produce far less "waste" tissue, and are resistant to digestion and/or biodegradation. As an additional benefit, algae produce many components (fatty acids, H2, etc.) which are useful as biofuels. On Earth, micro-algae survive in many harsh environments including low humidity, extremes in temperature, pH, and as well as high salinity and solar radiation. Algae have been shown to survive inmicro-gravity, and can adapt to high and low light intensity while retaining their ability to perform nitrogen fixation and photosynthesis. Studies have demonstrated that some algae are resistant to the space radiation environment, including solar ultraviolet radiation. It remains to be experimentally demonstrated, however, that an algal-based system could fulfil the requirements for a space-based Bioregenerative Life Support System (BLSS) under comparable spaceflight power, mass, and environmental constraints. Two specific challenges facing algae cultivation in space are that (i) conventional growth platforms require large masses of water, which in turn require a large amount of propulsion fuel, and (ii) most nutrient delivery mechanisms (predominantly bubbling) are dependent on gravity. To address these challenges, we have constructed a low water biofilm based bioreactor whose operation is enabled by capillary forces. Preliminary characterization of this Surface Adhering BioReactor (SABR) suggests that it can serve as a platform for cultivating algae in space which requires about 10 times less mass than conventional reactors without sacrificing growth rate. Further work is necessary to compare the performance of microalgae-based systems, including SABR, with systems based on higher plants, as well as conventional physicochemical-based systems. Ongoing and future work in our laboratory is therefore directed determining the feasibility of using algae as a component of a BLSS in space.

Enhanced performance of the microalga Chlorella sorokiniana remotely induced by the plant growth-promoting bacteria Azospirillum brasilense and Bacillus pumilus

PubMed Central

Amavizca, Edgar; Bashan, Yoav; Ryu, Choong-Min; Farag, Mohamed A.; Bebout, Brad M.; de-Bashan, Luz E.

2017-01-01

Remote effects (occurring without physical contact) of two plant growth-promoting bacteria (PGPB) Azospirillum brasilense Cd and Bacilus pumilus ES4 on growth of the green microalga Chlorella sorokiniana UTEX 2714 were studied. The two PGPB remotely enhanced the growth of the microalga, up to six-fold, and its cell volume by about three-fold. In addition to phenotypic changes, both bacteria remotely induced increases in the amounts of total lipids, total carbohydrates, and chlorophyll a in the cells of the microalga, indicating an alteration of the microalga’s physiology. The two bacteria produced large amounts of volatile compounds, including CO2, and the known plant growth-promoting volatile 2,3-butanediol and acetoin. Several other volatiles having biological functions in other organisms, as well as numerous volatile compounds with undefined biological roles, were detected. Together, these bacteria-derived volatiles can positively affect growth and metabolic parameters in green microalgae without physical attachment of the bacteria to the microalgae. This is a new paradigm on how PGPB promote growth of microalgae which may serve to improve performance of Chlorella spp. for biotechnological applications. PMID:28145473

Algicidal microorganisms and secreted algicides: New tools to induce microalgal cell disruption.

PubMed

Demuez, Marie; González-Fernández, Cristina; Ballesteros, Mercedes

2015-12-01

Cell disruption is one of the most critical steps affecting the economy and yields of biotechnological processes for producing biofuels from microalgae. Enzymatic cell disruption has shown competitive results compared to mechanical or chemical methods. However, the addition of enzymes implies an associated cost in the overall production process. Recent studies have employed algicidal microorganisms to perform enzymatic cell disruption and degradation of microalgae biomass in order to reduce this associated cost. Algicidal microorganisms induce microalgae growth inhibition, death and subsequent lysis. Secreted algicidal molecules and enzymes produced by bacteria, cyanobacteria, viruses and the microalga themselves that are capable of inducing algal death are classified, and the known modes of action are described along with insights into cell-to-cell interaction and communication. This review aims to provide information regarding microalgae degradation by microorganisms and secreted algicidal substances that would be useful for microalgae cell breakdown in biofuels production processes. A better understanding of algae-to-algae communication and the specific mechanisms of algal cell lysis is expected to be an important breakthrough for the broader application of algicidal microorganisms in biological cell disruption and the production of biofuels from microalgae biomass. Copyright © 2015 Elsevier Inc. All rights reserved.

Microalgae as sustainable renewable energy feedstock for biofuel production.

PubMed

Medipally, Srikanth Reddy; Yusoff, Fatimah Md; Banerjee, Sanjoy; Shariff, M

2015-01-01

The world energy crisis and increased greenhouse gas emissions have driven the search for alternative and environmentally friendly renewable energy sources. According to life cycle analysis, microalgae biofuel is identified as one of the major renewable energy sources for sustainable development, with potential to replace the fossil-based fuels. Microalgae biofuel was devoid of the major drawbacks associated with oil crops and lignocelluloses-based biofuels. Algae-based biofuels are technically and economically viable and cost competitive, require no additional lands, require minimal water use, and mitigate atmospheric CO2. However, commercial production of microalgae biodiesel is still not feasible due to the low biomass concentration and costly downstream processes. The viability of microalgae biodiesel production can be achieved by designing advanced photobioreactors, developing low cost technologies for biomass harvesting, drying, and oil extraction. Commercial production can also be accomplished by improving the genetic engineering strategies to control environmental stress conditions and by engineering metabolic pathways for high lipid production. In addition, new emerging technologies such as algal-bacterial interactions for enhancement of microalgae growth and lipid production are also explored. This review focuses mainly on the problems encountered in the commercial production of microalgae biofuels and the possible techniques to overcome these difficulties.

Bioenergetic strategy of microalgae for the biodegradation of tyrosol and hydroxytyrosol.

PubMed

Papazi, Aikaterini; Ioannou, Andreas; Symeonidi, Myrto; Doulis, Andreas G; Kotzabasis, Kiriakos

2017-05-01

Olive mill wastewater has significant polluting properties due to its high phenolic content [mainly tyrosol (trs) and hydroxytyrosol (htrs)]. Growth kinetics and a series of fluorescence induction measurements for Scenedesmus obliquus cultures showed that microalgae can be tolerant of these phenolic compounds. Changes in the cellular energy reserves and concentration of the phenolic compounds adjust the "toxicity" of these compounds to the microalgae and are, therefore, the main parameters that affect biodegradation. Autotrophic growth conditions of microalgae and high concentrations of trs or htrs induce higher biodegradation compared with mixotrophic conditions and lower phenolic concentrations. When microalgae face trs and htrs simultaneously, biodegradation begins from htrs, the more energetically demanding compound. All these lead to the conviction that microalgae have a "rational" management of cellular energy balance. Low toxicity levels lead to higher growth and lower biodegradation, whereas higher toxicity levels lead to lower growth and higher biodegradation. The selection of appropriate conditions (compatible to the bioenergetic strategies of microalgae) seems to be the key for a successful biodegradation of a series of toxic compounds, thus paving the way for future biotechnological applications for solving complicated pollution problems, like the detoxification of olive mill wastewater.

Rapid Characterization of Microalgae and Microalgae Mixtures Using Matrix-Assisted Laser Desorption Ionization Time-Of-Flight Mass Spectrometry (MALDI-TOF MS)

PubMed Central

Barbano, Duane; Diaz, Regina; Zhang, Lin; Sandrin, Todd; Gerken, Henri; Dempster, Thomas

2015-01-01

Current molecular methods to characterize microalgae are time-intensive and expensive. Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) may represent a rapid and economical alternative approach. The objectives of this study were to determine whether MALDI-TOF MS can be used to: 1) differentiate microalgae at the species and strain levels and 2) characterize simple microalgal mixtures. A common protein extraction sample preparation method was used to facilitate rapid mass spectrometry-based analysis of 31 microalgae. Each yielded spectra containing between 6 and 56 peaks in the m/z 2,000 to 20,000 range. The taxonomic resolution of this approach appeared higher than that of 18S rDNA sequence analysis. For example, two strains of Scenedesmus acutus differed only by two 18S rDNA nucleotides, but yielded distinct MALDI-TOF mass spectra. Mixtures of two and three microalgae yielded relatively complex spectra that contained peaks associated with members of each mixture. Interestingly, though, mixture-specific peaks were observed at m/z 11,048 and 11,230. Our results suggest that MALDI-TOF MS affords rapid characterization of individual microalgae and simple microalgal mixtures. PMID:26271045

Perspectives on engineering strategies for improving biofuel production from microalgae--a critical review.

PubMed

Ho, Shih-Hsin; Ye, Xiaoting; Hasunuma, Tomohisa; Chang, Jo-Shu; Kondo, Akihiko

2014-12-01

Although the potential for biofuel production from microalgae via photosynthesis has been intensively investigated, information on the selection of a suitable operation strategy for microalgae-based biofuel production is lacking. Many published reports describe competitive strains and optimal culture conditions for use in biofuel production; however, the major impediment to further improvements is the absence of effective engineering strategies for microalgae cultivation and biofuel production. This comprehensive review discusses recent advances in understanding the effects of major environmental stresses and the characteristics of various engineering operation strategies on the production of biofuels (mainly biodiesel and bioethanol) using microalgae. The performances of microalgae-based biofuel-producing systems under various environmental stresses (i.e., irradiance, temperature, pH, nitrogen depletion, and salinity) and cultivation strategies (i.e., fed-batch, semi-continuous, continuous, two-stage, and salinity-gradient) are compared. The reasons for variations in performance and the underlying theories of the various production strategies are also critically discussed. The aim of this review is to provide useful information to facilitate development of innovative and feasible operation technologies for effectively increasing the commercial viability of microalgae-based biofuel production. Copyright © 2014 Elsevier Inc. All rights reserved.

Microalgae as Sustainable Renewable Energy Feedstock for Biofuel Production

PubMed Central

Yusoff, Fatimah Md.; Shariff, M.

2015-01-01

The world energy crisis and increased greenhouse gas emissions have driven the search for alternative and environmentally friendly renewable energy sources. According to life cycle analysis, microalgae biofuel is identified as one of the major renewable energy sources for sustainable development, with potential to replace the fossil-based fuels. Microalgae biofuel was devoid of the major drawbacks associated with oil crops and lignocelluloses-based biofuels. Algae-based biofuels are technically and economically viable and cost competitive, require no additional lands, require minimal water use, and mitigate atmospheric CO2. However, commercial production of microalgae biodiesel is still not feasible due to the low biomass concentration and costly downstream processes. The viability of microalgae biodiesel production can be achieved by designing advanced photobioreactors, developing low cost technologies for biomass harvesting, drying, and oil extraction. Commercial production can also be accomplished by improving the genetic engineering strategies to control environmental stress conditions and by engineering metabolic pathways for high lipid production. In addition, new emerging technologies such as algal-bacterial interactions for enhancement of microalgae growth and lipid production are also explored. This review focuses mainly on the problems encountered in the commercial production of microalgae biofuels and the possible techniques to overcome these difficulties. PMID:25874216

Bare Iron Oxide Nanoparticles for Magnetic Harvesting of Microalgae: From Interaction Behavior to Process Realization.

PubMed

Fraga-García, Paula; Kubbutat, Peter; Brammen, Markus; Schwaminger, Sebastian; Berensmeier, Sonja

2018-05-01

Microalgae continue to gain in importance as a bioresource, while their harvesting remains a major challenge at the moment. This study presents findings on microalgae separation using low-cost, easy-to-process bare iron oxide nanoparticles with the additional contribution of the upscaling demonstration of this simple, adhesion-based process. The high affinity of the cell wall for the inorganic surface enables harvesting efficiencies greater than 95% for Scenedesmus ovalternus and Chlorella vulgaris . Successful separation is possible in a broad range of environmental conditions and primarily depends on the nanoparticle-to-microalgae mass ratio, whereas the effect of pH and ionic strength are less significant when the mass ratio is chosen properly. The weakening of ionic concentration profiles at the interphase due to the successive addition of deionized water leads the microalgae to detach from the nanoparticles. The process works efficiently at the liter scale, enabling complete separation of the microalgae from their medium and the separate recovery of all materials (algae, salts, and nanoparticles). The current lack of profitable harvesting processes for microalgae demands innovative approaches to encourage further development. This application of magnetic nanoparticles is an example of the prospects that nanobiotechnology offers for biomass exploitation.

The Second State of the Carbon Cycle Report: A Scientific Basis for Policy and Management Decisions

NASA Astrophysics Data System (ADS)

Birdsey, R.; Mayes, M. A.; Reed, S.; Najjar, R.; Romero-Lankao, P.

2017-12-01

The second "State of the Carbon Cycle of North America Report" (SOCCR-2) includes an overview of the North American carbon budget and future projections, the consequences of changes to the carbon budget, details of the carbon budget in major terrestrial and aquatic ecosystems (including coastal ocean waters), information about anthropogenic drivers, and implications for policy and carbon management. SOCCR-2 includes new focus areas such as soil carbon, arctic and boreal ecosystems, tribal lands, and greater emphasis on aquatic systems and the role of societal drivers and decision making on the carbon cycle. In addition, methane is considered to a greater extent than before. SOCCR-2 will contribute to the next U.S. National Climate Assessment, as well as providing information to support science-based management decisions and policies that include climate change mitigation and adaptation in Canada, the United States, and Mexico. Although the Report is still in the review process, preliminary findings indicate that North America is a net emitter of carbon dioxide and methane to the atmosphere, and that natural sinks offset about 25% of emitted carbon dioxide. Combustion of fossil fuels represents the largest source of emissions, but show a decreasing trend over the last decade and a lower share (20%) of the global total compared with the previous decade. Forests, soils, grasslands, and coastal oceans comprise the largest carbon sinks, while emissions from inland waters are a significant source of carbon dioxide. The Report also documents the lateral transfers of carbon among terrestrial ecosystems and from terrestrial to near-coastal ecosystems, to complete the carbon cycle accounting. Further, the Report explores the consequences of rising atmospheric carbon dioxide on terrestrial and oceanic systems, and the capacity of these systems to continue to act as carbon sinks based on the drivers of future carbon cycle changes, including carbon-climate feedbacks, atmospheric composition, nutrient availability, and human activity and management decisions. SOCCR-2 highlights key data gaps in carbon accounting frameworks, uncertainties in modeling and estimation approaches, and integrated frameworks for improving our understanding of the North American carbon cycle.

Chemical composition of microalgae Heterochlorella luteoviridis and Dunaliella tertiolecta with emphasis on carotenoids.

PubMed

Diprat, Andressa Bacalau; Menegol, Tania; Boelter, Juliana Ferreira; Zmozinski, Ariane; Rodrigues Vale, Maria Goreti; Rodrigues, Eliseu; Rech, Rosane

2017-08-01

Microalgae have been used as food supplements owing to their high protein, polyunsaturated fatty acid and carotenoid contents. As different carotenoids have distinct properties and the carotenoid composition of microalgae has been poorly explored in the literature, this study determined the complete carotenoid composition of two microalgae species, Heterochlorella luteoviridis and Dunaliella tertiolecta, using high-performance liquid chromatography coupled with diode array detection and tandem mass spectrometry (HPLC-DAD/MS 2 ). Additionally, the proximate composition and major minerals were evaluated. The carotenoid composition of the two microalgae was similar, with 13 carotenoids being found in H. luteoviridis and 12 in D. tertiolecta. The major carotenoids were all-trans-lutein (1.18 mg g -1 in H. luteoviridis and 1.59 mg g -1 in D. tertiolecta), all-trans-violaxanthin (0.52 mg g -1 in H. luteoviridis and 0.45 mg g -1 in D. tertiolecta) and all-trans-β-carotene (0.50 mg g -1 in H. luteoviridis and 0.62 mg g -1 in D. tertiolecta). All-trans-lutein was the predominant carotenoid in both microalgae, representing around 40% (mass fraction) of the total carotenoids. The lutein content found in these microalgae was significantly higher (2-40 times) than that in other important food sources of lutein (e.g. parsley, carrot, red pepper and broccoli). The microalgae H. luteoviridis and D. tertiolecta are excellent sources of lutein that could be commercially exploited by the food and pharmaceutical industries. Moreover, it was confirmed that both microalgae are good sources of protein, lipids and calcium. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Combination pulsed electric field with ethanol solvent for Nannochloropsis sp. extraction

NASA Astrophysics Data System (ADS)

Nafis, Ghazy Ammar; Mumpuni, Perwitasari Yekti; Indarto, Budiman, Arief

2015-12-01

Nowadays, energy is one of human basic needs. As the human population increased, energy consumption also increased. This condition causes energy depletion. In case of the situation, alternative energy is needed to replace existing energy. Microalgae is chosen to become one of renewable energy resource, especially biodiesel, because it contains high amount of lipid instead of other feedstock which usually used. Fortunately, Indonesia has large area of water and high intensity of sunlight so microalgae cultivation becomes easier. Nannochloropsis sp., one of microalgae species, becomes the main focus because of its high lipid content. Many ways to break the cell wall of microalgae so the lipid content inside the microalgae will be released, for example conventional extraction, ultrasonic wave extraction, pressing, and electrical method. The most effective way for extraction is electrical method such as pulsed electric field method (PEF). The principal work of this method is by draining the electrical current into parallel plate. Parallel plate will generate the electrical field to break microalgae cell wall and the lipid will be released. The aim of this work is to evaluate two-stage procedure for extraction of useful components from microalgae Nannochloropsis sp. The first stage of this procedure includes pre-treatment of microalgae by ethanol solvent extraction and the second stage applies the PEF extraction using a binary mixture of water and ethanol solvent. Ethanol is chosen as solvent because it's safer to be used and easier to be handled than other solvent. Some variables that used to study the most effective operation conditions are frequency and duty cycle for microalgae. The optimum condition based on this research are at frequency 1 Hz and duty cycle 13%.

Preliminary Study on the Location Selection of Microalgae Cultivation In Nusa Tenggara Region As A Potential Feedstock For Bioavtur

NASA Astrophysics Data System (ADS)

Anggraini, Citrae Permata Kusuma; Sasongko, Nugroho Adi; Kuntjoro, Yanif Dwi

2018-02-01

NTT is a province located in strategic areas between Bali and South Sulawesi which has economic growth 5,08% in 2016. This causes air transportation in NTT to grow rapidly so the need for avtur is increased by 6% per year. To meet the needs of avtur in NTT would require energy diversification with bioavtur development in which one of them comes from microalgae. The content of lipid and hydrocarbon in microalgae can be used as a source of bioavtur feedstock. The suitability of location for cultivation will influence the success of microalgae cultivation that will be used as a source of bioavtur feedstock. The purpose of this research is to choose the best location for microalgae cultivation in NTT by AHP method. The criteria used in this research are nutrient, water and technology. Sub criteria of nutrient elements are coal power plant emission, cement industry emission and synthetic fertilizers, sub criteria from water that is sea water, brackish water and fresh water, while sub criteria of technology are Photobioreactor, Open Raceway Pond and membrane. The result of AHP analysis shows the selection of microalgae cultivation location in Kupang with the weight of 0.308, with the source of nutrient derived from coal power plant emission, the type of water used is sea water and the technology used is Photobioreactor. Microalgae species used were Nannochloropsis sp with a lipid content of 31-68%. Based on the author assumption, microalgae have the productivity for bioavtur manufacture which amount of 24.489kL/ha/ yr. That can be used to meet the needs of 2% avtur in NTT which amount of 1.052,22 kL/yr and the area requirement for microalgae cultivation is 2,14 hectare.

Effect of Metals, Metalloids and Metallic Nanoparticles on Microalgae Growth and Industrial Product Biosynthesis: A Review

PubMed Central

Miazek, Krystian; Iwanek, Waldemar; Remacle, Claire; Richel, Aurore; Goffin, Dorothee

2015-01-01

Microalgae are a source of numerous compounds that can be used in many branches of industry. Synthesis of such compounds in microalgal cells can be amplified under stress conditions. Exposure to various metals can be one of methods applied to induce cell stress and synthesis of target products in microalgae cultures. In this review, the potential of producing diverse biocompounds (pigments, lipids, exopolymers, peptides, phytohormones, arsenoorganics, nanoparticles) from microalgae cultures upon exposure to various metals, is evaluated. Additionally, different methods to alter microalgae response towards metals and metal stress are described. Finally, possibilities to sustain high growth rates and productivity of microalgal cultures in the presence of metals are discussed. PMID:26473834

Concurrent extraction and reaction for the production of biodiesel from wet microalgae.

PubMed

Im, Hanjin; Lee, HanSol; Park, Min S; Yang, Ji-Won; Lee, Jae W

2014-01-01

This work addresses a reliable in situ transesterification process which integrates lipid extraction from wet microalgae, and its conversion to biodiesel, with a yield higher than 90 wt.%. This process enables single-step production of biodiesel from microalgae by mixing wet microalgal cells with solvent, methanol, and acid catalyst; and then heating them in one pot. The effects of reaction parameters such as reaction temperature, wet cell weight, reaction time, and catalyst volume on the conversion yield are investigated. This simultaneous extraction and transesterification of wet microalgae may enable a significant reduction in energy consumption by eliminating the drying process of algal cells and realize the economic production of biodiesel using wet microalgae. Copyright © 2013 Elsevier Ltd. All rights reserved.

Magnetophoretic harvesting of oleaginous Chlorella sp. by using biocompatible chitosan/magnetic nanoparticle composites.

PubMed

Lee, Kyubock; Lee, So Yeun; Na, Jeong-Geol; Jeon, Sang Goo; Praveenkumar, Ramasamy; Kim, Dong-Myung; Chang, Won-Seok; Oh, You-Kwan

2013-12-01

The consumption of energy and resources such as water in the cultivation and harvesting steps should be minimized to reduce the overall cost of biodiesel production from microalgae. Here we present a biocompatible and rapid magnetophoretic harvesting process of oleaginous microalgae by using chitosan-Fe3O4 nanoparticle composites. Over 99% of microalgae was harvested by using the composites and the external magnetic field without changing the pH of culture medium so that it may be reused for microalgal culture without adverse effect on the cell growth. Depending on the working volume (20-500 mL) and the strength of surface magnetic-field (3400-9200 G), the process of harvesting microalgae took only 2-5 min. The method presented here not only utilizes permanent magnets without additional energy for fast harvesting but also recycles the medium effectively for further cultivation of microalgae, looking ahead to a large scale economic microalgae-based biorefinement. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quorum sensing molecules in activated sludge could trigger microalgae lipid synthesis.

PubMed

Zhang, Chaofan; Li, Qingcheng; Fu, Liang; Zhou, Dandan; Crittenden, John C

2018-05-18

Cultivating microalgae using wastewater is an economical strategy to produce biofuel; however, microbial contamination has to be controlled strictly. Microalgae lipid accumulation can be triggered by environmental pressures, and here, we studied whether microbial contamination is the pressure for microalgae. We hypothesized this pressure was forced via cell-to-cell communication with quorum sensing molecules (QSMs). In this work, we verified the impacts of QSMs produced by activated sludge (wastewater-born microbial consortiums) on both lipid content and biomass production of the microalgae Chlorophyta sp., since in combination, they determined lipid productivity. With QSMs stress, the lipid content of Chlorophyta sp. increased by ∼84%, while biomass production decreased only slightly. Consistently, enzymes on the fatty acid synthesis pathways were generally up-regulated, while they were slightly down-regulated for DNA replication. In summary, the total lipid production improved by 86%. These results revealed the positive effects of microbial contamination on microalgae biofuel production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Life-cycle analysis on biodiesel production from microalgae: water footprint and nutrients balance.

PubMed

Yang, Jia; Xu, Ming; Zhang, Xuezhi; Hu, Qiang; Sommerfeld, Milton; Chen, Yongsheng

2011-01-01

This research examines the life-cycle water and nutrients usage of microalgae-based biodiesel production. The influence of water types, operation with and without recycling, algal species, geographic distributions are analyzed. The results confirm the competitiveness of microalgae-based biofuels and highlight the necessity of recycling harvested water and using sea/wastewater as water source. To generate 1 kg biodiesel, 3726 kg water, 0.33 kg nitrogen, and 0.71 kg phosphate are required if freshwater used without recycling. Recycling harvest water reduces the water and nutrients usage by 84% and 55%. Using sea/wastewater decreases 90% water requirement and eliminates the need of all the nutrients except phosphate. The variation in microalgae species and geographic distribution are analyzed to reflect microalgae biofuel development in the US. The impacts of current federal and state renewable energy programs are also discussed to suggest suitable microalgae biofuel implementation pathways and identify potential bottlenecks. Copyright © 2010 Elsevier Ltd. All rights reserved.

Enhancement of growth and lipid production from microalgae using fluorescent paint under the solar radiation.

PubMed

Seo, Yeong Hwan; Cho, Changsoon; Lee, Jung-Yong; Han, Jong-In

2014-12-01

Solar radiation has intensity that is too high to inhibit microalgae activity and is composed of wide light spectrum including ultraviolet (UV) range which cannot be utilized for microalgae. For these reasons, the modification of solar radiation is required for effective microalgae cultivation, and to do that, fluorescent paint was used for not only blocking excessive solar energy but also converting UV to visible light. With fluorescent aqueous layer, microalgae was protected from photoinhibition and could grow well, but there was difference in growth and lipid accumulation efficiencies depending on the color; maximum dry weight of 1.7 g/L was achieved in red paint, whereas best lipid content of 30% was obtained in blue one. This phenomenon was due to the different light spectrum made by colors. With simple process using fluorescent paint, modification of light was successfully done and allowing microalgae to grow under strong radiation such as solar radiation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microalgae-based biorefinery--from biofuels to natural products.

PubMed

Yen, Hong-Wei; Hu, I-Chen; Chen, Chun-Yen; Ho, Shih-Hsin; Lee, Duu-Jong; Chang, Jo-Shu

2013-05-01

The potential for biodiesel production from microalgal lipids and for CO2 mitigation due to photoautotrophic growth of microalgae have recently been recognized. Microalgae biomass also has other valuable components, including carbohydrates, long chain fatty acids, pigments and proteins. The microalgae-based carbohydrates consist mainly of cellulose and starch without lignin; thus they can be ready carbon source for the fermentation industry. Some microalgae can produce long chain fatty acids (such as DHA and EPA) as valuable health food supplements. In addition, microalgal pigments and proteins have considerable potential for many medical applications. This review article presents comprehensive information on the current state of these commercial applications, as well as the utilization and characteristics of the microalgal components, in addition to the key factors and challenges that should be addressed during the production of these materials, and thus provides a useful report that can aid the development of an efficient microalgae-based biorefinery process. Copyright © 2012 Elsevier Ltd. All rights reserved.

An overview of microalgae industrial phycology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benemann, J.R.

1992-01-01

Microalgae, Chlorella, production for health foods has been an established industry in the Far East for over twenty five years. Since the mid-1970's, commercial Spirulina production has been carried out, first in Mexico, and since then by several companies, including two located in the United States. Spirulina is sold not only in the health food trade, but is also used in the extraction of food coloring agents and aquaculture feeds. Since the early 1980's, Dunaliella has been produced in the US, Australia, and Israel for its beta-carotene content. Microalgae are also being produced at a small scale for aquaculture feedsmore » and several companies are developing processes for the controlled cultivation of microalgae in bioreactors for speciality products, including essential fatty acids, pigments, diagnostic reagents, etc. The commercial applications of microalgae extend to wastewater treatment, including heavy metals removal. The steady progress of microalgae industrial phycology promises to continue in the coming years and decades.« less

The role of biochemical engineering in the production of biofuels from microalgae.

PubMed

Costa, Jorge Alberto Vieira; de Morais, Michele Greque

2011-01-01

Environmental changes that have occurred due to the use of fossil fuels have driven the search for alternative sources that have a lower environmental impact. First-generation biofuels were derived from crops such as sugar cane, corn and soybean, which contribute to water scarcity and deforestation. Second-generation biofuels originated from lignocellulose agriculture and forest residues, however these needed large areas of land that could be used for food production. Based on technology projections, the third generation of biofuels will be derived from microalgae. Microalgae are considered to be an alternative energy source without the drawbacks of the first- and second-generation biofuels. Depending upon the growing conditions, microalgae can produce biocompounds that are easily converted into biofuels. The biofuels from microalgae are an alternative that can keep the development of human activity in harmony with the environment. This study aimed to present the main biofuels that can be derived from microalgae. Copyright © 2010 Elsevier Ltd. All rights reserved.

Nutritional evaluation of microalgae oils rich in omega-3 long chain polyunsaturated fatty acids as an alternative for fish oil.

PubMed

Ryckebosch, Eline; Bruneel, Charlotte; Termote-Verhalle, Romina; Goiris, Koen; Muylaert, Koenraad; Foubert, Imogen

2014-10-01

The purpose of this work was to evaluate the nutritional value of the total lipid extract of different omega-3 long chain polyunsaturated fatty acids producing photoautotrophic microalgae in one study. It was shown that microalgae oils from Isochrysis, Nannochloropsis, Phaeodactylum, Pavlova and Thalassiosira contain sufficient omega-3 LC-PUFA to serve as an alternative for fish oil, which was used as the 'golden standard'. In the microalgae oils an important part of the omega-3 long chain polyunsaturated fatty acids are present in the polar lipid fraction, which may be favourable from a bioavailability and stability viewpoint. Consumption of microalgae oil ensures intake of sterols and carotenoids. The intake of sterols, including cholesterol and phytosterols, is probably not relevant. The intake of carotenoids is however definitely significant and could give the microalgae oils a nutritional added value compared to fish oil. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microalgae cultivation in sugarcane vinasse: Selection, growth and biochemical characterization.

PubMed

Santana, Hugo; Cereijo, Carolina R; Teles, Valérya C; Nascimento, Rodrigo C; Fernandes, Maiara S; Brunale, Patrícia; Campanha, Raquel C; Soares, Itânia P; Silva, Flávia C P; Sabaini, Priscila S; Siqueira, Félix G; Brasil, Bruno S A F

2017-03-01

Sugarcane ethanol is produced at large scale generating wastes that could be used for microalgae biomass production in a biorefinery strategy. In this study, forty microalgae strains were screened for growth in sugarcane vinasse at different concentrations. Two microalgae strains, Micractinium sp. Embrapa|LBA32 and C. biconvexa Embrapa|LBA40, presented vigorous growth in a light-dependent manner even in undiluted vinasse under non-axenic conditions. Microalgae strains presented higher biomass productivity in vinasse-based media compared to standard Bold's Basal Medium in cultures performed using 15L airlift flat plate photobioreactors. Chemical composition analyses showed that proteins and carbohydrates comprise the major fractions of algal biomass. Glucose was the main monosaccharide detected, ranging from 46% to 76% of the total carbohydrates content according to the strain and culture media used. This research highlights the potential of using residues derived from ethanol plants to cultivate microalgae for the production of energy and bioproducts. Copyright © 2016 Elsevier Ltd. All rights reserved.

In Metabolic Engineering of Eukaryotic Microalgae: Potential and Challenges Come with Great Diversity

PubMed Central

Gimpel, Javier A.; Henríquez, Vitalia; Mayfield, Stephen P.

2015-01-01

The great phylogenetic diversity of microalgae is corresponded by a wide arrange of interesting and useful metabolites. Nonetheless metabolic engineering in microalgae has been limited, since specific transformation tools must be developed for each species for either the nuclear or chloroplast genomes. Microalgae as production platforms for metabolites offer several advantages over plants and other microorganisms, like the ability of GMO containment and reduced costs in culture media, respectively. Currently, microalgae have proved particularly well suited for the commercial production of omega-3 fatty acids and carotenoids. Therefore most metabolic engineering strategies have been developed for these metabolites. Microalgal biofuels have also drawn great attention recently, resulting in efforts for improving the production of hydrogen and photosynthates, particularly triacylglycerides. Metabolic pathways of microalgae have also been manipulated in order to improve photosynthetic growth under specific conditions and for achieving trophic conversion. Although these pathways are not strictly related to secondary metabolites, the synthetic biology approaches could potentially be translated to this field and will also be discussed. PMID:26696985

Characterization of the flocculating agent from the spontaneously flocculating microalga Chlorella vulgaris JSC-7.

PubMed

Alam, Md Asraful; Wan, Chun; Guo, Suo-Lian; Zhao, Xin-Qing; Huang, Zih-You; Yang, Yu-Liang; Chang, Jo-Shu; Bai, Feng-Wu

2014-07-01

High cost of biomass recovery is one of the bottlenecks for developing cost-effective processes with microalgae, particularly for the production of biofuels and bio-based chemicals through biorefinery, and microalgal biomass recovery through cell flocculation is a promising strategy. Some microalgae are naturally flocculated whose cells can be harvested by simple sedimentation. However, studies on the flocculating agents synthesized by microalgae cells are still very limited. In this work, the cell flocculation of a spontaneously flocculating microalga Chlorella vulgaris JSC-7 was studied, and the flocculating agent was identified to be cell wall polysaccharides whose crude extract supplemented at low dosage of 0.5 mg/L initiated the more than 80% flocculating rate of freely suspended microalgae C. vulgaris CNW11 and Scenedesmus obliquus FSP. Fourier transform infrared (FTIR) analysis revealed a characteristic absorption band at 1238 cm(-1), which might arise from PO asymmetric stretching vibration of [Formula: see text] phosphodiester. The unique cell wall-associated polysaccharide with molecular weight of 9.86×10(3) g/mol, and the monomers consist of glucose, mannose and galactose with a molecular ratio of 5:5:2. This is the first time to our knowledge that the flocculating agent from C. vulgaris has been characterized, which could provide basis for understanding the cell flocculation of microalgae and breeding of novel flocculating microalgae for cost-effective biomass harvest. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Biorefineries of carbon dioxide: From carbon capture and storage (CCS) to bioenergies production.

PubMed

Cheah, Wai Yan; Ling, Tau Chuan; Juan, Joon Ching; Lee, Duu-Jong; Chang, Jo-Shu; Show, Pau Loke

2016-09-01

Greenhouse gas emissions have several adverse environmental effects, like pollution and climate change. Currently applied carbon capture and storage (CCS) methods are not cost effective and have not been proven safe for long term sequestration. Another attractive approach is CO2 valorization, whereby CO2 can be captured in the form of biomass via photosynthesis and is subsequently converted into various form of bioenergy. This article summarizes the current carbon sequestration and utilization technologies, while emphasizing the value of bioconversion of CO2. In particular, CO2 sequestration by terrestrial plants, microalgae and other microorganisms are discussed. Prospects and challenges for CO2 conversion are addressed. The aim of this review is to provide comprehensive knowledge and updated information on the current advances in biological CO2 sequestration and valorization, which are essential if this approach is to achieve environmental sustainability and economic feasibility. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biodiesels from microbial oils: Opportunity and challenges.

PubMed

Ma, Yingqun; Gao, Zhen; Wang, Qunhui; Liu, Yu

2018-05-08

Although biodiesel has been extensively explored as an important renewable energy source, the raw materials-associated cost poses a serious challenge on its large-scale commercial production. The first and second generations of biodiesel are mainly produced from usable raw materials, e.g. edible oils, crops etc. Such a situation inevitably imposes higher demands on land and water usage, which in turn compromise future food and water supply. Obviously, there is an urgent need to explore alternative feedstock, e.g. microbial oils which can be produced by many types of microorganisms including microalgae, fungi and bacteria with the advantages of small footprint, high lipid content and efficient uptake of carbon dioxide. Therefore, this review offers a comprehensive picture of microbial oil-based technology for biodiesel production. The perspectives and directions forward are also outlined for future biodiesel production and commercialization. Copyright © 2018 Elsevier Ltd. All rights reserved.

Millennial-scale plankton regime shifts in the subtropical North Pacific Ocean.

PubMed

McMahon, Kelton W; McCarthy, Matthew D; Sherwood, Owen A; Larsen, Thomas; Guilderson, Thomas P

2015-12-18

Climate change is predicted to alter marine phytoplankton communities and affect productivity, biogeochemistry, and the efficacy of the biological pump. We reconstructed high-resolution records of changing plankton community composition in the North Pacific Ocean over the past millennium. Amino acid-specific δ(13)C records preserved in long-lived deep-sea corals revealed three major plankton regimes corresponding to Northern Hemisphere climate periods. Non-dinitrogen-fixing cyanobacteria dominated during the Medieval Climate Anomaly (950-1250 Common Era) before giving way to a new regime in which eukaryotic microalgae contributed nearly half of all export production during the Little Ice Age (~1400-1850 Common Era). The third regime, unprecedented in the past millennium, began in the industrial era and is characterized by increasing production by dinitrogen-fixing cyanobacteria. This picoplankton community shift may provide a negative feedback to rising atmospheric carbon dioxide concentrations. Copyright © 2015, American Association for the Advancement of Science.

Biology and Industrial Applications of Chlorella: Advances and Prospects.

PubMed

Liu, Jin; Chen, Feng

2016-01-01

Chlorella represents a group of eukaryotic green microalgae that has been receiving increasing scientific and commercial interest. It possesses high photosynthetic ability and is capable of growing robustly under mixotrophic and heterotrophic conditions as well. Chlorella has long been considered as a source of protein and is now industrially produced for human food and animal feed. Chlorella is also rich in oil, an ideal feedstock for biofuels. The exploration of biofuel production by Chlorella is underway. Chlorella has the ability to fix carbon dioxide efficiently and to remove nutrients of nitrogen and phosphorous, making it a good candidate for greenhouse gas biomitigation and wastewater bioremediation. In addition, Chlorella shows potential as an alternative expression host for recombinant protein production, though challenges remain to be addressed. Currently, omics analyses of certain Chlorella strains are being performed, which will help to unravel the biological implications of Chlorella and facilitate the future exploration of industrial applications.

Methane and Carbon Dioxide Concentrations and Fluxes in Amazon Floodplains

NASA Astrophysics Data System (ADS)

Melack, J. M.; MacIntyre, S.; Forsberg, B.; Barbosa, P.; Amaral, J. H.

2016-12-01

Field studies on the central Amazon floodplain in representative aquatic habitats (open water, flooded forests, floating macrophytes) combine measurements of methane and carbon dioxide concentrations and fluxes to the atmosphere over diel and seasonal times with deployment of meteorological sensors and high-resolution thermistors and dissolved oxygen sondes. A cavity ringdown spectrometer is used to determine gas concentrations, and floating chambers and bubble collectors are used to measure fluxes. To further understand fluxes, we measured turbulence as rate of dissipation of turbulent kinetic energy based on microstructure profiling. These results allow calculations of vertical mixing within the water column and of air-water exchanges using surface renewal models. Methane and carbon dioxide fluxes varied as a function of season, habitat and water depth. High CO2 fluxes at high water are related to high pCO2; low pCO2 levels at low water result from increased phytoplankton uptake. CO2 fluxes are highest at turbulent open water sites, and pCO2 is highest in macrophyte beds. Fluxes and pCH4 are high in macrophyte beds.

Flotation of algae for water reuse and biomass production: role of zeta potential and surfactant to separate algal particles.

PubMed

Kwak, Dong-Heui; Kim, Mi-Sug

2015-01-01

The effect of chemical coagulation and biological auto-flocculation relative to zeta potential was examined to compare flotation and sedimentation separation processes for algae harvesting. Experiments revealed that microalgae separation is related to auto-flocculation of Anabaena spp. and requires chemical coagulation for the whole period of microalgae cultivation. In addition, microalgae separation characteristics which are associated with surfactants demonstrated optimal microalgae cultivation time and separation efficiency of dissolved CO2 flotation (DCF) as an alternative to dissolved air flotation (DAF). Microalgae were significantly separated in response to anionic surfactant rather than cationic surfactant as a function of bubble size and zeta potential. DAF and DCF both showed slightly efficient flotation; however, application of anionic surfactant was required when using DCF.

Biologically Active Metabolites Synthesized by Microalgae

PubMed Central

Costa, Jorge Alberto Vieira

2015-01-01

Microalgae are microorganisms that have different morphological, physiological, and genetic traits that confer the ability to produce different biologically active metabolites. Microalgal biotechnology has become a subject of study for various fields, due to the varied bioproducts that can be obtained from these microorganisms. When microalgal cultivation processes are better understood, microalgae can become an environmentally friendly and economically viable source of compounds of interest, because production can be optimized in a controlled culture. The bioactive compounds derived from microalgae have anti-inflammatory, antimicrobial, and antioxidant activities, among others. Furthermore, these microorganisms have the ability to promote health and reduce the risk of the development of degenerative diseases. In this context, the aim of this review is to discuss bioactive metabolites produced by microalgae for possible applications in the life sciences. PMID:26339647

Current progress and future prospect of microalgal biomass harvest using various flocculation technologies.

PubMed

Wan, Chun; Alam, Md Asraful; Zhao, Xin-Qing; Zhang, Xiao-Yue; Guo, Suo-Lian; Ho, Shih-Hsin; Chang, Jo-Shu; Bai, Feng-Wu

2015-05-01

Microalgae have been extensively studied for the production of various valuable products. Application of microalgae for the production of renewable energy has also received increasing attention in recent years. However, high cost of microalgal biomass harvesting is one of the bottlenecks for commercialization of microalgae-based industrial processes. Considering harvesting efficiency, operation economics and technological feasibility, flocculation is a superior method to harvest microalgae from mass culture. In this article, the latest progress of various microalgal cell harvesting methods via flocculation is reviewed with the emphasis on the current progress and prospect in environmentally friendly bio-based flocculation. Harvesting microalgae through bio-based flocculation is a promising component of the low-cost microalgal biomass production technology. Copyright © 2014 Elsevier Ltd. All rights reserved.

Growth of locally isolated microalga in POME to produce lipid as alternative energy sources

NASA Astrophysics Data System (ADS)

Elvitriana; Munir, E.; Delvian; Wahyuningsih, H.

2018-04-01

Purpose of this study was to find the best growth of locally isolated microalgae that produce lipids from Palm Oil Mill Effluent (POME) as an alternative energy source. Microalgae was cultivated in POME in glass vessel at room temperature using a lighting intensity of 13,000 lux and continuously aeration for 24 and 12 hours, respectively. Biomass of microalgae were analyzed daily to get their growth by spectrophotometry at 624 nm wavelength, whereas Modified Bligh and Dyer method determined lipid content. Results show that the best growth occurred at 10% inoculum with lighting cycle and aeration of 24 hours (on/off) and resulting highest biomass content of 0.99 g dry weight/L followed by the decrease of organic substances in POME. The percentage reduction of COD, BOD, TSS, and oil at POME reached above 92%, while phosphate concentration reached 89.2%. Cultivation of microalgae in POME for 12 days showed its ability to reduce organic substances and nutrients in POME and produced biomass with lipid content of 35%. These results reached to the conclusion that locally isolated microalgae has an ability to treat POME safely for environment and POME can be used as a growing medium of microalgae that produces lipids.

Microalgae-activated sludge treatment of molasses wastewater in sequencing batch photo-bioreactor.

PubMed

Tsioptsias, Costas; Lionta, Gesthimani; Samaras, Petros

2017-05-01

The aim of this work was the examination of the treatment potential of molasses wastewater, by the utilization of activated sludge and microalgae. The systems used included a sequencing batch bioreactor and a similar photo-bioreactor, favoring microalgae growth. The microalgae treatment of molasses wastewater mixture resulted in a considerable reduction in the total nitrogen content. A reduction in the ammonium and nitrate content was observed in the photo-bioreactor, while the effluent's total nitrogen consisted mainly of 50% organic nitrogen. The transformation of the nitrogen forms in the photo-bioreactor was attributed to microalgae activity, resulting in the production of a better quality effluent. Lower COD removal was observed for the photo-bioreactor than the control, which however increased, by the replacement of the anoxic phase by a long aeration period. The mechanism of nitrogen removal included both the denitrification process during the anoxic stage and the microalgae activities, as the replacement of the anoxic stage resulted in low total nitrogen removal capacities. A decrease in the photobioreactor performance was observed after 35 days of operation due to biofilm formation on the light tube surface, while the operation at higher temperature accelerated microalgae growth, resulting thus in the early failure of the photoreactor.

Bare Iron Oxide Nanoparticles for Magnetic Harvesting of Microalgae: From Interaction Behavior to Process Realization

PubMed Central

Brammen, Markus; Berensmeier, Sonja

2018-01-01

Microalgae continue to gain in importance as a bioresource, while their harvesting remains a major challenge at the moment. This study presents findings on microalgae separation using low-cost, easy-to-process bare iron oxide nanoparticles with the additional contribution of the upscaling demonstration of this simple, adhesion-based process. The high affinity of the cell wall for the inorganic surface enables harvesting efficiencies greater than 95% for Scenedesmus ovalternus and Chlorella vulgaris. Successful separation is possible in a broad range of environmental conditions and primarily depends on the nanoparticle-to-microalgae mass ratio, whereas the effect of pH and ionic strength are less significant when the mass ratio is chosen properly. The weakening of ionic concentration profiles at the interphase due to the successive addition of deionized water leads the microalgae to detach from the nanoparticles. The process works efficiently at the liter scale, enabling complete separation of the microalgae from their medium and the separate recovery of all materials (algae, salts, and nanoparticles). The current lack of profitable harvesting processes for microalgae demands innovative approaches to encourage further development. This application of magnetic nanoparticles is an example of the prospects that nanobiotechnology offers for biomass exploitation. PMID:29723963

Microalgae: a robust "green bio-bridge" between energy and environment.

PubMed

Chen, Yimin; Xu, Changan; Vaidyanathan, Seetharaman

2018-05-01

Microalgae are a potential candidate for biofuel production and environmental treatment because of their specific characteristics (e.g. fast growth, carbon neutral, and rich lipid accumulations). However, several primary bottlenecks still exist in current technologies, including low biomass conversion efficiency, bio-invasion from the external environment, limited or costly nutrient sources, and high energy and capital input for harvest, and stalling its industrial progression. Coupling biofuel production with environmental treatment renders microalgae a more feasible feedstock. This review focuses on microalgae biotechnologies for both bioenergy generation and environmental treatment (e.g. CO 2 sequestration and wastewater reclamation). Different intelligent technologies have been developed, especially during the last decade, to eliminate the bottlenecks, including mixotrophic/heterotrophic cultivation, immobilization, and co-cultivation. It has been realized that any single purpose for the cultivation of microalgae is not an economically feasible option. Combinations of applications in biorefineries are gradually reckoned to be necessary as it provides more economically feasible and environmentally sustainable operations. This presents microalgae as a special niche occupier linking the fields of energy and environmental sciences and technologies. The integrated application of microalgae is also proven by most of the life-cycle analysis studies. This study summarizes the latest development of primary microalgal biotechnologies in the two areas that will bring researchers a comprehensive view towards industrialization with an economic perspective.

Microalgae harvesting techniques: A review.

PubMed

Singh, Gulab; Patidar, S K

2018-07-01

Microalgae with wide range of commercial applications have attracted a lot of attention of the researchers in the last few decades. However, microalgae utilization is not economically sustainable due to high cost of harvesting. A wide range of solid - liquid separation techniques are available for microalgae harvesting. The techniques include coagulation and flocculation, flotation, centrifugation and filtration or a combination of various techniques. Despite the importance of harvesting to the economics and energy balance, there is no universal harvesting technique for microalgae. Therefore, this review focuses on assessing technical, economical and application potential of various harvesting techniques so as to allow selection of an appropriate technology for cost effectively harvesting of microalgae from their culture medium. Various harvesting and concentrating techniques of microalgae were reviewed to suggest order of suitability of the techniques for four main microalgae applications i.e biofuel, human and animal food, high valued products, and water quality restoration. For deciding the order of suitability, a comparative analysis of various harvesting techniques based on the six common criterions (i.e biomass quality, cost, biomass quantity, processing time, species specific and toxicity) has been done. Based on the order of various techniques vis-a-vis various criteria and preferred order of criteria for various applications, order of suitability of harvesting techniques for various applications has been decided. Among various harvesting techniques, coagulation and flocculation, centrifugation and filtration were found to be most suitable for considered applications. These techniques may be used alone or in combination for increasing the harvesting efficiency. Copyright © 2018 Elsevier Ltd. All rights reserved.

Methods on observation of fluorescence micro-imaging for microalgae

NASA Astrophysics Data System (ADS)

Ou, Lin; Zhuang, Hui-ru; Chen, Rong; Lei, Jin-pin; Liao, Xiao-hua; Lin, Wen-suo

2007-11-01

Objective: Auto-fluorescence micro-imaging of microalgae are observed by using of laser scanning confocal microscopy (LSCM) and fluorescence microscopy, so as to investigate the effect of auto fluorescence alteration on growth of irradiated microalgae irradiated, meanwhile, the method of microalgae cells stained also to be studied. Methods: Platymonas subcordiformis, Phaeodactylum tricormutum and Isochyrsis zhanjiangensis cells are stained with acridine orange, and observed by fluorescence microscopy; the three types microalgae mentioned above are irradiated by Nd:YAP laser with 10w at 1341nm, irradiating time:12s, 30s, 35s and 55s, than to be cultured 6 days, and the auto fluorescence images and fluorescence spectra of algae cells are obtained by LSCM on lambda scan mode, at excitation 488nm (Ar + laser). Results: It is showed that the shapes and the structural features of microalgae cells stained can be seen clearly, and the cytoplasm and nucleus also can be observed. The chloroplasts in cell is bigger on promoting effects, conversely, it is to be mutilated, deformation and shrink. Contrast to the CK, the peak positions of fluorescence of algae cells irradiated is similar to the whole while the peak light intensity alters. On irradiation of promoting dose, however, the auto fluorescence intensity is enhanced more than control. Conclusions: The method of cell stained can be used to observed genetic material in microalgae. There are obvious effects for laser irradiating to chloroplasts in cells, the bigger chloroplasts the greater fluorescence intensity. Physiological incentive effects of microalgae irradiated can be given expression on fluorescence characteristics and fluorescence intensity alteration of cells.

Controls on microalgal community structures in cryoconite holes upon high Arctic glaciers, Svalbard

NASA Astrophysics Data System (ADS)

Vonnahme, T. R.; Devetter, M.; Žárský, J. D.; Šabacká, M.; Elster, J.

2015-07-01

Glaciers are known to harbor surprisingly complex ecosystems. On their surface, distinct cylindrical holes filled with meltwater and sediments are considered as hot spots for microbial life. The present paper addresses possible biological interactions within the community of prokaryotic cyanobacteria and eukaryotic microalgae (microalgae) and relations to their potential grazers, additional to their environmental controls. Svalbard glaciers with substantial allochthonous input of material from local sources reveal high microalgal densities. Small valley glaciers with high sediment coverages and high impact of birds show high biomasses and support a high biological diversity. Invertebrate grazer densities do not show any significant negative correlation with microalgal abundances, but a positive correlation with eukaryotic microalgae. Most microalgae found in this study form large colonies (< 10 cells, or > 25 μm), which may protect them against invertebrate grazing. This finding rather indicates grazing as a positive control on eukaryotic microalgae by nutrient recycling. Density differences between the eukaryotic microalgae and prokaryotic cyanobacteria and their high distinction in RDA and PCA analyses indicate that these two groups are in strong contrast. Eukaryotic microalgae occurred mainly in unstable cryoconite holes with high sediment loads, high N : P ratios, and a high impact of bird guano, as a proxy for nutrients. In these environments autochthonous nitrogen fixation appears to be negligible. Selective wind transport of Oscillatoriales via soil and dust particles is proposed to explain their dominance in cryoconites further away from the glacier margins. We propose that, for the studied glaciers, nutrient levels related to recycling of limiting nutrients is the main factor driving variation in the community structure of microalgae and grazers.

Biofouling in photobioreactors for marine microalgae.

PubMed

Zeriouh, Ouassim; Reinoso-Moreno, José Vicente; López-Rosales, Lorenzo; Cerón-García, María Del Carmen; Sánchez-Mirón, Asterio; García-Camacho, Francisco; Molina-Grima, Emilio

2017-12-01

The economic and/or energetic feasibility of processes based on using microalgae biomass requires an efficient cultivation system. In photobioreactors (PBRs), the adhesion of microalgae to the transparent PBR surfaces leads to biofouling and reduces the solar radiation penetrating the PBR. Light reduction within the PBR decreases biomass productivity and, therefore, the photosynthetic efficiency of the cultivation system. Additionally, PBR biofouling leads to a series of further undesirable events including changes in cell pigmentation, culture degradation, and contamination by invasive microorganisms; all of which can result in the cultivation process having to be stopped. Designing PBR surfaces with proper materials, functional groups or surface coatings, to prevent microalgal adhesion is essential for solving the biofouling problem. Such a significant advance in microalgal biotechnology would enable extended operational periods at high productivity and reduce maintenance costs. In this paper, we review the few systematic studies performed so far and applied the existing thermodynamic and colloidal theories for microbial biofouling formation in order to understand microalgal adhesion on PBR surfaces and the microalgae-microalgae cell interactions. Their relationship to the physicochemical properties of the solid PBR surface, the microalgae cell surfaces, and the ionic strength of the culture medium is discussed. The suitability and the applicability of such theories are reviewed. To this end, an example of biofouling formation on a commercial glass surface is presented for the marine microalgae Nannochloropsis gaditana. It highlights the adhesion dynamics and the inaccuracies of the process and the need for further refinement of previous theories so as to apply them to flowing systems, such as is the case for PBRs used to culture microalgae.

Aquatic export of young dissolved and gaseous carbon from a pristine boreal fen: Implications for peat carbon stock stability.

PubMed

Campeau, Audrey; Bishop, Kevin H; Billett, Michael F; Garnett, Mark H; Laudon, Hjalmar; Leach, Jason A; Nilsson, Mats B; Öquist, Mats G; Wallin, Marcus B

2017-12-01

The stability of northern peatland's carbon (C) store under changing climate is of major concern for the global C cycle. The aquatic export of C from boreal peatlands is recognized as both a critical pathway for the remobilization of peat C stocks as well as a major component of the net ecosystem C balance (NECB). Here, we present a full year characterization of radiocarbon content ( 14 C) of dissolved organic carbon (DOC), carbon dioxide (CO 2 ), and methane (CH 4 ) exported from a boreal peatland catchment coupled with 14 C characterization of the catchment's peat profile of the same C species. The age of aquatic C in runoff varied little throughout the year and appeared to be sustained by recently fixed C from the atmosphere (<60 years), despite stream DOC, CO 2 , and CH 4 primarily being sourced from deep peat horizons (2-4 m) near the mire's outlet. In fact, the 14 C content of DOC, CO 2 , and CH 4 across the entire peat profile was considerably enriched with postbomb C compared with the solid peat material. Overall, our results demonstrate little to no mobilization of ancient C stocks from this boreal peatland and a relatively large resilience of the source of aquatic C export to forecasted hydroclimatic changes. © 2017 The Authors Global Change Biology Published by John Wiley & Sons Ltd.

Efficient Anaerobic Digestion of Microalgae Biomass: Proteins as a Key Macromolecule.

PubMed

Magdalena, Jose Antonio; Ballesteros, Mercedes; González-Fernandez, Cristina

2018-05-06

Biogas generation is the least complex technology to transform microalgae biomass into bioenergy. Since hydrolysis has been pointed out as the rate limiting stage of anaerobic digestion, the main challenge for an efficient biogas production is the optimization of cell wall disruption/hydrolysis. Among all tested pretreatments, enzymatic treatments were demonstrated not only very effective in disruption/hydrolysis but they also revealed the impact of microalgae macromolecular composition in the anaerobic process. Although carbohydrates have been traditionally recognized as the polymers responsible for the low microalgae digestibility, protease addition resulted in the highest organic matter solubilization and the highest methane production. However, protein solubilization during the pretreatment can result in anaerobic digestion inhibition due to the release of large amounts of ammonium nitrogen. The possible solutions to overcome these negative effects include the reduction of protein biomass levels by culturing the microalgae in low nitrogen media and the use of ammonia tolerant anaerobic inocula. Overall, this review is intended to evidence the relevance of microalgae proteins in different stages of anaerobic digestion, namely hydrolysis and methanogenesis.

Combustion characteristics and air pollutant formation during oxy-fuel co-combustion of microalgae and lignite.

PubMed

Gao, Yuan; Tahmasebi, Arash; Dou, Jinxiao; Yu, Jianglong

2016-05-01

Oxy-fuel combustion of solid fuels is seen as one of the key technologies for carbon capture to reduce greenhouse gas emissions. The combustion characteristics of lignite coal, Chlorella vulgaris microalgae, and their blends under O2/N2 and O2/CO2 conditions were studied using a Thermogravimetric Analyzer-Mass Spectroscopy (TG-MS). During co-combustion of blends, three distinct peaks were observed and were attributed to C. vulgaris volatiles combustion, combustion of lignite, and combustion of microalgae char. Activation energy during combustion was calculated using iso-conventional method. Increasing the microalgae content in the blend resulted in an increase in activation energy for the blends combustion. The emissions of S- and N-species during blend fuel combustion were also investigated. The addition of microalgae to lignite during air combustion resulted in lower CO2, CO, and NO2 yields but enhanced NO, COS, and SO2 formation. During oxy-fuel co-combustion, the addition of microalgae to lignite enhanced the formation of gaseous species. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microalgal biofactories: a promising approach towards sustainable omega-3 fatty acid production

PubMed Central

2012-01-01

Omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) provide significant health benefits and this has led to an increased consumption as dietary supplements. Omega-3 fatty acids EPA and DHA are found in animals, transgenic plants, fungi and many microorganisms but are typically extracted from fatty fish, putting additional pressures on global fish stocks. As primary producers, many marine microalgae are rich in EPA (C20:5) and DHA (C22:6) and present a promising source of omega-3 fatty acids. Several heterotrophic microalgae have been used as biofactories for omega-3 fatty acids commercially, but a strong interest in autotrophic microalgae has emerged in recent years as microalgae are being developed as biofuel crops. This paper provides an overview of microalgal biotechnology and production platforms for the development of omega-3 fatty acids EPA and DHA. It refers to implications in current biotechnological uses of microalgae as aquaculture feed and future biofuel crops and explores potential applications of metabolic engineering and selective breeding to accumulate large amounts of omega-3 fatty acids in autotrophic microalgae. PMID:22830315

Carotenoids, Phenolic Compounds and Tocopherols Contribute to the Antioxidative Properties of Some Microalgae Species Grown on Industrial Wastewater.

PubMed

Safafar, Hamed; van Wagenen, Jonathan; Møller, Per; Jacobsen, Charlotte

2015-12-11

This study aimed at investigating the potential of microalgae species grown on industrial waste water as a new source of natural antioxidants. Six microalgae from different classes, including Phaeodactylum sp. (Bacillariophyceae), Nannochloropsis sp. (Eustigmatophyceae), Chlorella sp., Dunaniella sp., and Desmodesmus sp. (Chlorophyta), were screened for their antioxidant properties using different in vitro assays. Natural antioxidants, including pigments, phenolics, and tocopherols, were measured in methanolic extracts of microalgae biomass. Highest and lowest concentrations of pigments, phenolic compounds, and tocopherols were found in Desmodesmus sp. and Phaeodactylum tricornuotom microalgae species, respectively. The results of each assay were correlated to the content of natural antioxidants in microalgae biomass. Phenolic compounds were found as major contributors to the antioxidant activity in all antioxidant tests while carotenoids were found to contribute to the 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activity, ferrous reduction power (FRAP), and ABTS-radical scavenging capacity activity. Desmodesmus sp. biomass represented a potentially rich source of natural antioxidants, such as carotenoids (lutein), tocopherols, and phenolic compounds when cultivated on industrial waste water as the main nutrient source.

Carotenoids, Phenolic Compounds and Tocopherols Contribute to the Antioxidative Properties of Some Microalgae Species Grown on Industrial Wastewater

PubMed Central

Safafar, Hamed; van Wagenen, Jonathan; Møller, Per; Jacobsen, Charlotte

2015-01-01

This study aimed at investigating the potential of microalgae species grown on industrial waste water as a new source of natural antioxidants. Six microalgae from different classes, including Phaeodactylum sp. (Bacillariophyceae), Nannochloropsis sp. (Eustigmatophyceae), Chlorella sp., Dunaniella sp., and Desmodesmus sp. (Chlorophyta), were screened for their antioxidant properties using different in vitro assays. Natural antioxidants, including pigments, phenolics, and tocopherols, were measured in methanolic extracts of microalgae biomass. Highest and lowest concentrations of pigments, phenolic compounds, and tocopherols were found in Desmodesmus sp. and Phaeodactylum tricornuotom microalgae species, respectively. The results of each assay were correlated to the content of natural antioxidants in microalgae biomass. Phenolic compounds were found as major contributors to the antioxidant activity in all antioxidant tests while carotenoids were found to contribute to the 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activity, ferrous reduction power (FRAP), and ABTS-radical scavenging capacity activity. Desmodesmus sp. biomass represented a potentially rich source of natural antioxidants, such as carotenoids (lutein), tocopherols, and phenolic compounds when cultivated on industrial waste water as the main nutrient source. PMID:26690454

Lipid for biodiesel production from attached growth Chlorella vulgaris biomass cultivating in fluidized bed bioreactor packed with polyurethane foam material.

PubMed

Mohd-Sahib, Ainur-Assyakirin; Lim, Jun-Wei; Lam, Man-Kee; Uemura, Yoshimitsu; Isa, Mohamed Hasnain; Ho, Chii-Dong; Kutty, Shamsul Rahman Mohamed; Wong, Chung-Yiin; Rosli, Siti-Suhailah

2017-09-01

The potential to grow attached microalgae Chlorella vulgaris in fluidized bed bioreactor was materialized in this study, targeting to ease the harvesting process prior to biodiesel production. The proposed thermodynamic mechanism and physical property assessment of various support materials verified polyurethane to be suitable material favouring the spontaneous adhesion by microalgae cells. The 1-L bioreactor packed with only 2.4% (v/v) of 1.00-mL polyurethane foam cubes could achieve the highest attached growth microalgae biomass and lipid weights of 812±122 and 376±37mg, respectively, in comparison with other cube sizes. The maturity of attached growth microalgae biomass for harvesting could also be determined from the growth trend of suspended microalgae biomass. Analysis of FAME composition revealed that the harvested microalgae biomass was dominated by C16-C18 (>60%) and mixture of saturated and mono-unsaturated fatty acids (>65%), satiating the biodiesel standard with adequate cold flow property and oxidative stability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thermogravimetric analysis of co-combustion between microalgae and textile dyeing sludge.

PubMed

Peng, Xiaowei; Ma, Xiaoqian; Xu, Zhibin

2015-03-01

The synergistic interaction and kinetics of microalgae, textile dyeing sludge and their blends were investigated under combustion condition by thermogravimetric analysis. The textile dyeing sludge was blended with microalgae in the range of 10-90wt.% to investigate their co-combustion behavior. Results showed that the synergistic interaction between microalgae and textile dyeing sludge improved the char catalytic effect and alkali metals melt-induced effect on the decomposition of textile dyeing sludge residue at high temperature of 530-800°C. As the heating rate increasing, the entire combustion process was delayed but the combustion intensity was enhanced. The lowest average activation energy was obtained when the percentage of microalgae was 60%, which was 227.1kJ/mol by OFW and 227.4kJ/mol by KAS, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

Heterotrophic cultivation of microalgae for production of biodiesel.

PubMed

Mohamed, Mohd Shamzi; Wei, Lai Zee; Ariff, Arbakariya B

2011-08-01

High cell density cultivation of microalgae via heterotrophic growth mechanism could effectively address the issues of low productivity and operational constraints presently affecting the solar driven biodiesel production. This paper reviews the progress made so far in the development of commercial-scale heterotrophic microalgae cultivation processes. The review also discusses on patentable concepts and innovations disclosed in the past four years with regards to new approaches to microalgal cultivation technique, improvisation on the process flow designs to economically produced biodiesel and genetic manipulation to confer desirable traits leading to much valued high lipid-bearing microalgae strains.

Performance, insulin sensitivity, carcass characteristics, and fatty acid profile of beef from steers fed microalgae.

PubMed

Carvalho, J R R; Brennan, K M; Ladeira, M M; Schoonmaker, J P

2018-05-25

Heterotrophic production of microalgae biomass provides a consistent, high quality source of docosahexaenoic acid (DHA; C22:6 n-3) in triglyceride oils that could be used as a ration supplement for feedlot steers to improve nutritional qualities of beef. Sixty Angus × Simmental steers (438 ± 6.4 kg) were allotted to 2 treatments (30 steers each, 6 pens, 5 steers/pen) to determine the effects of ForPLUS (DHA-rich microalgae Aurantiochytrium limacinum; 63.6 % fat; 17.9% DHA; 30 mg/kg Sel-Plex; Alltech Inc.) on performance, insulin sensitivity, LM fatty acid composition, and meat quality. Steers were fed basal diets containing 45% corn, 30% distillers dried grains with solubles, 20% corn silage, and 5% supplement. Basal diets were formulated to contain 16.1% CP and 1.32 Mcal/kg NEg. Treatments were delivered to steers in a ground corn based top-dress (454 g total/steer) and contained no microalgae for control steers or 100 g/steer daily of ForPLUS for microalgae steers. A glucose tolerance test (GTT) was performed 10 d prior to slaughter. Steers were slaughtered when a target pen BW of 621 kg was achieved. Fatty acid oxidation potential was determined by measuring thiobarbituric acid reactive substances (TBARS) on LM samples collected 24 h after slaughter and aged for 48 h or 21 d. Weight and BW gain did not differ during the study (P ≥ 0.13); however, steers fed microalgae remained in the feedlot 7 more d compared to steers fed the control diet (111 vs. 104 d; P = 0.04). Overall DMI decreased (P = 0.002) and G:F increased during the second half of the study (P = 0.04) in steers fed microalgae compared to steers fed the control diet. Steers fed microalgae secreted less insulin (P = 0.01) and took longer to clear glucose (P = 0.01) during a 2 h GTT. Carcass traits did not differ between treatments (P ≥ 0.23). Microalgae had no effect on n-6 content (P = 0.67), but more than doubled the n-3 fatty acid percentage and the n3:n6 ratio of the LM (P < 0.0001). The percentage of n-3 fatty acids C20:5 and C22:6 were increased (P < 0.0001) 4-fold and 6.25-fold, respectively, by microalgae supplementation. Concentration of TBARS did not differ in LM aged for 48 h (P = 0.91); however, when aged for 21 d, steers fed microalgae tended to produce LM with greater TBARS concentration compared to steers fed the control diet (P = 0.08). In conclusion, DHA-rich microalgae decreased DMI of steers, and increased n-3 fatty acids and beef oxidation in steaks aged for 21 d.

Chlorella sorokiniana UTEX 2805, a heat and intense, sunlight-tolerant microalga with potential for removing ammonium from wastewater.

PubMed

de-Bashan, Luz E; Trejo, Adan; Huss, Volker A R; Hernandez, Juan-Pablo; Bashan, Yoav

2008-07-01

In the summer of 2003, a microalga strain was isolated from a massive green microalgae bloom in wastewater stabilization ponds at the treatment facility of La Paz, B.C.S., Mexico. Prevailing environmental conditions were air temperatures over 40 degrees C, water temperature of 37 degrees C, and insolation of up to 2400 micromol m2 s(-1) at midday for several hours at the water surface for four months. The microalga was identified as Chlorella sorokiniana Shih. et Krauss, based on sequencing its entire 18S rRNA gene. In a controlled photo-bioreactor, this strain can grow to high population densities in synthetic wastewater at temperatures of 40-42 degrees C and light intensity of 2500 micromol m2 s(-1) for 5h daily and efficiently remove ammonium from the wastewater under these conditions better than under normal lower temperature (28 degrees C) and lower light intensity (60 micromol m2 s(-1)). When co-immobilized with the bacterium Azospirillum brasilense that promotes growth of microalgae, the population of microalga grew faster and removed even more ammonium. Under exposure to extreme growth conditions, the quantity of four photosynthetic pigments increased in the co-immobilized cultures. This strain of microalga has potential as a wastewater treatment agent under extreme conditions of temperature and light intensity.

Antioxidant activity of some Moroccan marine microalgae: Pufa profiles, carotenoids and phenolic content.

PubMed

Maadane, Amal; Merghoub, Nawal; Ainane, Tarik; El Arroussi, Hicham; Benhima, Redouane; Amzazi, Saaid; Bakri, Youssef; Wahby, Imane

2015-12-10

In order to promote Moroccan natural resources, this study aims to evaluate the potential of microalgae isolated from Moroccan coastlines, as new source of natural antioxidants. Different extracts (ethanolic, ethanol/water and aqueous) obtained from 9 microalgae strains were screened for their in vitro antioxidant activity using DPPH free radical-scavenging assay. The highest antioxidant potentials were obtained in Dunalliela sp., Tetraselmis sp. and Nannochloropsis gaditana extracts. The obtained results indicate that ethanol extract of all microalgae strains exhibit higher antioxidant activity, when compared to water and ethanol/water extracts. Therefore, total phenolic and carotenoid content measurement were performed in active ethanol extracts. The PUFA profiles of ethanol extracts were also determined by GC/MS analysis. The studied microalgae strains displayed high PUFA content ranging from 12.9 to 76.9 %, total carotenoids content varied from 1.9 and 10.8mg/g of extract and total polyphenol content varied from 8.1 to 32.0mg Gallic acid Equivalent/g of extract weight. The correlation between the antioxidant capacities and the phenolic content and the carotenoids content were found to be insignificant, indicating that these compounds might not be major contributor to the antioxidant activity of these microalgae. The microalgae extracts exerting the high antioxidant activity are potential new source of natural antioxidants. Copyright © 2015 Elsevier B.V. All rights reserved.

Magnetic-Nanoflocculant-Assisted Water-Nonpolar Solvent Interface Sieve for Microalgae Harvesting.

PubMed

Lee, Kyubock; Na, Jeong-Geol; Seo, Jung Yoon; Shim, Tae Soup; Kim, Bohwa; Praveenkumar, Ramasamy; Park, Ji-Yeon; Oh, You-Kwan; Jeon, Sang Goo

2015-08-26

Exploitation of magnetic flocculants is regarded as a very promising energy-saving approach to microalgae harvesting. However, its practical applicability remains limited, mainly because of the problem of the postharvest separation of magnetic flocculants from microalgal flocs, which is crucial both for magnetic-flocculant recycling and high-purity microalgal biomasses, but which is also a very challenging and energy-consuming step. In the present study, we designed magnetic nanoflocculants dually functionalizable by two different organosilane compounds, (3-aminopropyl)triethoxysilane (APTES) and octyltriethoxysilane (OTES), which flocculate negatively charged microalgae and are readily detachable at the water-nonpolar organic solvent (NOS) interface only by application of an external magnetic field. APTES functionalization imparts a positive zeta potential charge (29.6 mV) to magnetic nanoflocculants, thereby enabling microalgae flocculation with 98.5% harvesting efficiency (with a dosage of 1.6 g of dMNF/g of cells). OTES functionalization imparts lipophilicity to magnetic nanoflocculants to make them compatible with NOS, thus effecting efficient separation of magnetic flocculants passing through the water-NOS interface sieve from hydrophilic microalgae. Our new energy-saving approach to microalgae harvesting concentrates microalgal cultures (∼1.5 g/L) up to 60 g/L, which can be directly connected to the following process of NOS-assisted wet lipid extraction or biodiesel production, and therefore provides, by simplifying multiple downstream processes, a great potential cost reduction in microalgae-based biorefinement.

C-13 dynamics in benthic algae: Effects of light, phosphorus, and biomass development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, Walter; Fanta, S.E.; Roberts, Brian J

2008-07-01

We performed three experiments in indoor streams and one experiment in a natural stream to investigate the effects of growth factors on {delta}{sup 13}C levels in benthic microalgae. In the indoor streams, algae grown under conditions of high light and high phosphorus had {delta}{sup 13}C values that were 16% higher than those in algae grown under conditions of low light and low phosphorus. Light effects were much stronger than phosphorus effects. The effects of both factors increased in strength as algal biomass accrued, and by the end of the experiments, algal {delta}{sup 13}C and biomass were highly correlated. In themore » natural stream, algae exposed to direct sunlight were enriched 15% over shaded algae, corroborating the strong effect of light in the indoor streams. Growth factors such as light and nutrients probably reduce discrimination against {delta}{sup 13}C (raising {delta}{sup 13}C values) in benthic microalgae by causing CO{sub 2} depletion both within individual cells and within the assemblage matrix. However, because the most marked fractionation occurred in older and thicker assemblages, CO{sub 2} depletion within the assemblage matrix appeared to be more important than depletion within individual cells. In the absence of carbon-concentrating mechanisms, elevated {delta}{sup 13}C suggests that inorganic carbon may limit the growth of benthic algae. The extensive range of d13C values (-14{per_thousand} to -36{per_thousand}) created by light and nutrient manipulations in this study easily encompassed the mean {delta}{sup 13}C values of both C{sub 3} and C{sub 4} terrestrial plants, indicating the challenge aquatic ecologists face in identifying carbon sources for higher trophic levels when light and nutrient conditions vary.« less

Metallomics and NMR-based metabolomics of Chlorella sp. reveal the synergistic role of copper and cadmium in multi-metal toxicity and oxidative stress.

PubMed

Zhang, Wenlin; Tan, Nicole G J; Fu, Baohui; Li, Sam F Y

2015-03-01

Industrial wastewaters often contain high levels of metal mixtures, in which metal mixtures may have synergistic or antagonistic effects on aquatic organisms. A combination of metallomics and nuclear magnetic resonance spectroscopy (NMR)-based metabolomics was employed to understand the consequences of multi-metal systems (Cu, Cd, Pb) on freshwater microalgae. Morphological characterization, cell viability and chlorophyll a determination of metal-spiked Chlorella sp. suggested synergistic effects of Cu and Cd on growth inhibition and toxicity. While Pb has no apparent effect on Chlorella sp. metabolome, a substantial decrease of sucrose, amino acid content and glycerophospholipid precursors in Cu-spiked microalgae revealed Cu-induced oxidative stress. Addition of Cd to Cu-spiked cultures induced more drastic metabolic perturbations, hence we confirmed that Cu and Cd synergistically influenced photosynthesis inhibition, oxidative stress and membrane degradation. Total elemental analysis revealed a significant decrease in K, and an increase in Na, Mg, Zn and Mn concentrations in Cu-spiked cultures. This indicated that Cu is more toxic to Chlorella sp. as compared to Cd or Pb, and the combination of Cu and Cd has a strong synergistic effect on Chlorella sp. oxidative stress induction. Oxidative stress is confirmed by liquid chromatography tandem mass spectrometry analysis, which demonstrated a drastic decrease in the GSH/GSSG ratio solely in Cu-spiked cultures. Interestingly, we observed Cu-facilitated Cd and Pb bioconcentration in Chlorella sp. The absence of phytochelatins and an increment of extracellular polymeric substances (EPS) yields in Cu-spiked cultures suggested that the mode of bioconcentration of Cd and Pb is through adsorption of free metals onto the algal EPS rather than intracellular chelation to phytochelatins.

Microalgae-based advanced municipal wastewater treatment for reuse in water bodies.

PubMed

Wang, Jing-Han; Zhang, Tian-Yuan; Dao, Guo-Hua; Xu, Xue-Qiao; Wang, Xiao-Xiong; Hu, Hong -Ying

2017-04-01

Reuse of secondary municipal effluent from wastewater treatment plants in water bodies could effectively alleviate freshwater resource shortage. However, excessive nutrients must be efficiently removed to prevent eutrophication. Compared with other means of advanced wastewater treatment, microalgae-based processes display overwhelming advantages including efficient and simultaneous N and P removal, no requirement of additional chemicals, O 2 generation, CO 2 mitigation, and potential value-added products from harvested biomass. One particular challenge of microalgae-based advanced municipal wastewater treatment compared to treatment of other types of wastewater is that concentrations of nutrients and N:P ratios in secondary municipal effluent are much lower and imbalanced. Therefore, there should be comprehensive considerations on nutrient removal from this specific type of effluent. Removal of nutrients and organic substances, and other environmental benefits of microalgae-based advanced municipal wastewater treatment systems were summarized. Among the existing studies on microalgal advanced nutrient removal, much information on major parameters is absent, rendering performances between studies not really comparable. Mechanisms of microalgae-based nitrogen and phosphorus removal were respectively analyzed to better understand advanced nutrient removal from municipal secondary effluent. Factors influencing microalgae-based nutrient removal were divided into intrinsic, environmental, and operational categories; several factors were identified in each category, and their influences on microalgal nutrient removal were discussed. A multiplicative kinetic model was integrated to estimate microalgal growth-related nutrient removal based majorly on environmental and intrinsic factors. Limitations and prospects of future full-scale microalgae-based advanced municipal wastewater treatment were also suggested. The manuscript could offer much valuable information for future studies on microalgae-based advanced wastewater treatment and water reuse.

Controls on microalgal community structures in cryoconite holes upon high-Arctic glaciers, Svalbard

NASA Astrophysics Data System (ADS)

Vonnahme, T. R.; Devetter, M.; Žárský, J. D.; Šabacká, M.; Elster, J.

2016-02-01

Glaciers are known to harbor surprisingly complex ecosystems. On their surface, distinct cylindrical holes filled with meltwater and sediments are considered hot spots for microbial life. The present paper addresses possible biological interactions within the community of prokaryotic cyanobacteria and eukaryotic microalgae (microalgae) and relations to their potential grazers, such as tardigrades and rotifers, additional to their environmental controls. Svalbard glaciers with substantial allochthonous input of material from local sources reveal high microalgal densities. Small valley glaciers with high sediment coverages and high impact of birds show high biomasses and support a high biological diversity. Invertebrate grazer densities do not show any significant negative correlation with microalgal abundances but rather a positive correlation with eukaryotic microalgae. Shared environmental preferences and a positive effect of grazing are the proposed mechanisms to explain these correlations. Most microalgae found in this study form colonies (< 10 cells, or > 25 µm), which may protect them against invertebrate grazing. This finding rather indicates grazing as a positive control on eukaryotic microalgae by nutrient recycling. Density differences between the eukaryotic microalgae and prokaryotic cyanobacteria and their high distinction in redundancy (RDA) and principal component (PCA) analyses indicate that these two groups are in strong contrast. Eukaryotic microalgae occurred mainly in unstable cryoconite holes with high sediment loads, high N : P ratios, and a high impact of nutrient input by bird guano, as a proxy for nutrients. In these environments autochthonous nitrogen fixation appears to be negligible. Selective wind transport of Oscillatoriales via soil and dust particles is proposed to explain their dominance in cryoconites further away from the glacier margins. We propose that, for the studied glaciers, nutrient levels related to recycling of limiting nutrients are the main factor driving variation in the community structure of microalgae and grazers.

Greenhouse gas fluxes of a shallow lake in south-central North Dakota, USA

USGS Publications Warehouse

Tangen, Brian; Finocchiaro, Raymond; Gleason, Robert A.; Dahl, Charles F.

2016-01-01

Greenhouse gas (GHG) fluxes of aquatic ecosystems in the northern Great Plains of the U.S. represent a significant data gap. Consequently, a 3-year study was conducted in south-central North Dakota, USA, to provide an initial estimate of GHG fluxes from a large, shallow lake. Mean GHG fluxes were 0.02 g carbon dioxide (CO2) m−2 h−1, 0.0009 g methane (CH4) m−2 h−1, and 0.0005 mg nitrous oxide (N2O) m−2 h−1. Fluxes of CO2 and CH4 displayed temporal and spatial variability which is characteristic of aquatic ecosystems, while fluxes of N2O were consistently low throughout the study. Comparisons between results of this study and published values suggest that mean daily fluxes of CO2, CH4, and N2O fromLong Lakewere low, particularly when compared to the well-studied prairie pothole wetlands of the region. Similarly, cumulative seasonal CH4 fluxes, which ranged from 2.68–7.58 g CH4 m−2, were relatively low compared to other wetland systems of North America. The observed variability among aquatic ecosystems underscores the need for further research.

A Saponification Method for Chlorophyll Removal from Microalgae Biomass as Oil Feedstock

PubMed Central

Li, Tao; Xu, Jin; Wu, Hualian; Wang, Guanghua; Dai, Shikun; Fan, Jiewei; He, Hui; Xiang, Wenzhou

2016-01-01

Microalgae oil is an optimal feedstock for nutraceutical, pharmaceutical and biodiesel production, but its high levels of chlorophyll limit its large-scale application. To date, few effective approaches have been developed to remove chlorophyll from microalgae oil. The main purpose of this study was to present a preprocessing method of algae oil feedstock (Scenedesmus) to remove chlorophyll by saponification. The results showed that 96% of chlorophyll in biomass was removed. High quality orange transparent oil could be extracted from the chlorophyll reduced biomass. Specifically, the proportion of neutral lipids and saturation levels of fatty acids increased, and the pigments composition became carotenoids-based. The critical parameters of chlorophyll reduced biodiesel conformed to the standards of the USA, China and EU. Sodium copper chlorophyllin could be prepared from the bleaching effluent. The results presented herein offer a useful pathway to improve the quality of microalgae oil and reduce the cost of microalgae biodiesel. PMID:27618070

A Saponification Method for Chlorophyll Removal from Microalgae Biomass as Oil Feedstock.

PubMed

Li, Tao; Xu, Jin; Wu, Hualian; Wang, Guanghua; Dai, Shikun; Fan, Jiewei; He, Hui; Xiang, Wenzhou

2016-09-07

Microalgae oil is an optimal feedstock for nutraceutical, pharmaceutical and biodiesel production, but its high levels of chlorophyll limit its large-scale application. To date, few effective approaches have been developed to remove chlorophyll from microalgae oil. The main purpose of this study was to present a preprocessing method of algae oil feedstock (Scenedesmus) to remove chlorophyll by saponification. The results showed that 96% of chlorophyll in biomass was removed. High quality orange transparent oil could be extracted from the chlorophyll reduced biomass. Specifically, the proportion of neutral lipids and saturation levels of fatty acids increased, and the pigments composition became carotenoids-based. The critical parameters of chlorophyll reduced biodiesel conformed to the standards of the USA, China and EU. Sodium copper chlorophyllin could be prepared from the bleaching effluent. The results presented herein offer a useful pathway to improve the quality of microalgae oil and reduce the cost of microalgae biodiesel.

Climate conditions, and changes, affect microalgae communities… should we worry?

PubMed

Gimenez Papiol, Gemma

2018-03-01

Microalgae play a pivotal role in the regulation of Earth's climate and its cycles, but are also affected by climate change, mainly by changes in temperature, light, ocean acidification, water stratification, and precipitation-induced nutrient inputs. The changes and impacts on microalgae communities are difficult to study, predict, and manage, but there is no doubt that there will be changes. These changes will have impacts beyond microalgae communities, and many of them will be negative. Some actions are currently ongoing for the mitigation of some of the negative impacts, such as harmful algal blooms and water quality, but global efforts for reducing CO 2 emissions, temperature rises, and ocean acidification are paramount for reducing the impact of climate change on microalgae communities, and eventually, on human well-being. Integr Environ Assess Manag 2018;14:181-184. © 2018 SETAC. © 2018 SETAC.

A novel microalgal lipid extraction method using biodiesel (fatty acid methyl esters) as an extractant.

PubMed

Huang, Wen-Can; Park, Chan Woo; Kim, Jong-Duk

2017-02-01

Although microalgae are considered promising renewable sources of biodiesel, the high cost of the downstream process is a significant obstacle in large-scale biodiesel production. In this study, a novel approach for microalgal biodiesel production was developed by using the biodiesel as an extractant. First, wet microalgae with 70% water content were incubated with a mixture of biodiesel/methanol and penetration of the mixture through the cell membrane and swelling of the lipids contained in microalgae was confirmed. Significant increases of lipid droplets were observed by confocal microscopy. Second, the swelled lipid droplets in microalgae were squeezed out using mechanical stress across the cell membrane and washed with methanol. The lipid extraction efficiency reached 68%. This process does not require drying of microalgae or solvent recovery, which the most energy-intensive step in solvent-based biodiesel production. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization of cell disruption methods for efficient recovery of bioactive metabolites via NMR of three freshwater microalgae (chlorophyta).

PubMed

Ma, Nyuk Ling; Teh, Kit Yinn; Lam, Su Shiung; Kaben, Anne Marie; Cha, Thye San

2015-08-01

This study demonstrates the use of NMR techniques coupled with chemometric analysis as a high throughput data mining method to identify and examine the efficiency of different disruption techniques tested on microalgae (Chlorella variabilis, Scenedesmus regularis and Ankistrodesmus gracilis). The yield and chemical diversity from the disruptions together with the effects of pre-oven and pre-freeze drying prior to disruption techniques were discussed. HCl extraction showed the highest recovery of oil compounds from the disrupted microalgae (up to 90%). In contrast, NMR analysis showed the highest intensity of bioactive metabolites obtained for homogenized extracts pre-treated with freeze-drying, indicating that homogenizing is a more favorable approach to recover bioactive substances from the disrupted microalgae. The results show the potential of NMR as a useful metabolic fingerprinting tool for assessing compound diversity in complex microalgae extracts. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anaerobic digestion of microalgal biomass: Challenges, opportunities and research needs.

PubMed

Gonzalez-Fernandez, Cristina; Sialve, Bruno; Molinuevo-Salces, Beatriz

2015-12-01

Integration of anaerobic digestion (AD) with microalgae processes has become a key topic to support economic and environmental development of this resource. Compared with other substrates, microalgae can be produced close to the plant without the need for arable lands and be fully integrated within a biorefinery. As a limiting step, anaerobic hydrolysis appears to be one of the most challenging steps to reach a positive economic balance and to completely exploit the potential of microalgae for biogas and fertilizers production. This review covers recent investigations dealing with microalgae AD and highlights research opportunities and needs to support the development of this resource. Novel approaches to increase hydrolysis rate, the importance of the reactor design and the noteworthiness of the microbial anaerobic community are addressed. Finally, the integration of AD with microalgae processes and the potential of the carboxylate platform for chemicals and biofuels production are reviewed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cell disruption for microalgae biorefineries.

PubMed

Günerken, E; D'Hondt, E; Eppink, M H M; Garcia-Gonzalez, L; Elst, K; Wijffels, R H

2015-01-01

Microalgae are a potential source for various valuable chemicals for commercial applications ranging from nutraceuticals to fuels. Objective in a biorefinery is to utilize biomass ingredients efficiently similarly to petroleum refineries in which oil is fractionated in fuels and a variety of products with higher value. Downstream processes in microalgae biorefineries consist of different steps whereof cell disruption is the most crucial part. To maintain the functionality of algae biochemicals during cell disruption while obtaining high disruption yields is an important challenge. Despite this need, studies on mild disruption of microalgae cells are limited. This review article focuses on the evaluation of conventional and emerging cell disruption technologies, and a comparison thereof with respect to their potential for the future microalgae biorefineries. The discussed techniques are bead milling, high pressure homogenization, high speed homogenization, ultrasonication, microwave treatment, pulsed electric field treatment, non-mechanical cell disruption and some emerging technologies. Copyright © 2015 Elsevier Inc. All rights reserved.

Cultivation and energy efficient harvesting of microalgae using thermoreversible sol-gel transition

PubMed Central

Estime, Bendy; Ren, Dacheng; Sureshkumar, Radhakrishna

2017-01-01

Microalgae represent a promising source of renewable biomass for the production of biofuels and valuable chemicals. However, energy efficient cultivation and harvesting technologies are necessary to improve economic viability. A Tris-Acetate-Phosphate-Pluronic (TAPP) medium that undergoes a thermoreversible sol-gel transition is developed to efficiently culture and harvest microalgae without affecting the productivity as compared to that in traditional culture in a well-mixed suspension. After seeding microalgae in the TAPP medium in a solution phase at 15 °C, the temperature is increased by 7 °C to induce gelation. Within the gel, microalgae are observed to grow in large clusters rather than as isolated cells. The settling velocity of the microalgal clusters is approximately ten times larger than that of individual cells cultured in typical solution media. Such clusters are easily harvested gravimetrically by decreasing the temperature to bring the medium to a solution phase. PMID:28102313

Microalgae to biofuels: life cycle impacts of methane production of anaerobically digested lipid extracted algae.

PubMed

Quinn, Jason C; Hanif, Asma; Sharvelle, Sybil; Bradley, Thomas H

2014-11-01

This study presents experimental measurements of the biochemical methane production for whole and lipid extracted Nannochloropsis salina. Results show whole microalgae produced 430 cm(3)-CH4 g-volatile solids(-1) (g-VS) (σ=60), 3 times more methane than was produced by the LEA, 140 cm(3)-CH4 g-VS(-1) (σ=30). Results illustrate current anaerobic modeling efforts in microalgae to biofuel assessments are not reflecting the impact of lipid removal. On a systems level, the overestimation of methane production is shown to positively skew the environmental impact of the microalgae to biofuels process. Discussion focuses on a comparison results to those of previous anaerobic digestion studies and quantifies the corresponding change in greenhouse gas emissions of the microalgae to biofuels process based on results from this study. Copyright © 2014 Elsevier Ltd. All rights reserved.

Water use and its recycling in microalgae cultivation for biofuel application.

PubMed

Farooq, Wasif; Suh, William I; Park, Min S; Yang, Ji-Won

2015-05-01

Microalgal biofuels are not yet economically viable due to high material and energy costs associated with production process. Microalgae cultivation is a water-intensive process compared to other downstream processes for biodiesel production. Various studies found that the production of 1 L of microalgal biodiesel requires approximately 3000 L of water. Water recycling in microalgae cultivation is desirable not only to reduce the water demand, but it also improves the economic feasibility of algal biofuels as due to nutrients and energy savings. This review highlights recently published studies on microalgae water demand and water recycling in microalgae cultivation. Strategies to reduce water footprint for microalgal cultivation, advantages and disadvantages of water recycling, and approaches to mitigate the negative effects of water reuse within the context of water and energy saving are also discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Increased Growth of the Microalga Chlorella vulgaris when Coimmobilized and Cocultured in Alginate Beads with the Plant-Growth-Promoting Bacterium Azospirillum brasilense†

PubMed Central

Gonzalez, Luz E.; Bashan, Yoav

2000-01-01

Coimmobilization of the freshwater microalga Chlorella vulgaris and the plant-growth-promoting bacterium Azospirillum brasilense in small alginate beads resulted in a significantly increased growth of the microalga. Dry and fresh weight, total number of cells, size of the microalgal clusters (colonies) within the bead, number of microalgal cells per cluster, and the levels of microalgal pigments significantly increased. Light microscopy revealed that both microorganisms colonized the same cavities inside the beads, though the microalgae tended to concentrate in the more aerated periphery while the bacteria colonized the entire bead. The effect of indole-3-acetic acid addition to microalgal culture prior to immobilization of microorganisms in alginate beads partially imitated the effect of A. brasilense. We propose that coimmobilization of microalgae and plant-growth-promoting bacteria is an effective means of increasing microalgal populations within confined environments. PMID:10742237

Impulsive control of a continuous-culture and flocculation harvest chemostat model

NASA Astrophysics Data System (ADS)

Zhang, Tongqian; Ma, Wanbiao; Meng, Xinzhu

2017-12-01

In this paper, a new mathematical model describing the process of continuous culture and harvest of microalgaes is proposed. By inputting medium and flocculant at two different fixed moments periodically, continuous culture and harvest of microalgaes is implemented. The mathematical analysis is conducted and the whole dynamics of model is investigated by using theory of impulsive differential equations. We find that the model has a microalgaes-extinction periodic solution and it is globally asymptotically stable when some certain threshold value is less than the unit. And the model is permanent when some certain threshold value is larger than the unit. Then, according to the threshold, the control strategies of continuous culture and harvest of microalgaes are discussed. The results show that continuous culture and harvest of microalgaes can be archived by adjusting suitable input time, input amount of medium or flocculant. Finally, some numerical simulations are carried out to verify the control strategy.

The effects of phosphorus limitation on carbon metabolism in diatoms.

PubMed

Brembu, Tore; Mühlroth, Alice; Alipanah, Leila; Bones, Atle M

2017-09-05

Phosphorus is an essential element for life, serving as an integral component of nucleic acids, lipids and a diverse range of other metabolites. Concentrations of bioavailable phosphorus are low in many aquatic environments. Microalgae, including diatoms, apply physiological and molecular strategies such as phosphorus scavenging or recycling as well as adjusting cell growth in order to adapt to limiting phosphorus concentrations. Such strategies also involve adjustments of the carbon metabolism. Here, we review the effect of phosphorus limitation on carbon metabolism in diatoms. Two transcriptome studies are analysed in detail, supplemented by other transcriptome, proteome and metabolite data, to gain an overview of different pathways and their responses. Phosphorus, nitrogen and silicon limitation responses are compared, and similarities and differences discussed. We use the current knowledge to propose a suggestive model for the carbon flow in phosphorus-replete and phosphorus-limited diatom cells.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Authors.

The effects of phosphorus limitation on carbon metabolism in diatoms

PubMed Central

Alipanah, Leila

2017-01-01

Phosphorus is an essential element for life, serving as an integral component of nucleic acids, lipids and a diverse range of other metabolites. Concentrations of bioavailable phosphorus are low in many aquatic environments. Microalgae, including diatoms, apply physiological and molecular strategies such as phosphorus scavenging or recycling as well as adjusting cell growth in order to adapt to limiting phosphorus concentrations. Such strategies also involve adjustments of the carbon metabolism. Here, we review the effect of phosphorus limitation on carbon metabolism in diatoms. Two transcriptome studies are analysed in detail, supplemented by other transcriptome, proteome and metabolite data, to gain an overview of different pathways and their responses. Phosphorus, nitrogen and silicon limitation responses are compared, and similarities and differences discussed. We use the current knowledge to propose a suggestive model for the carbon flow in phosphorus-replete and phosphorus-limited diatom cells. This article is part of the themed issue ‘The peculiar carbon metabolism in diatoms’. PMID:28717016

Toxicity of the fluoroquinolone antibiotics enrofloxacin and ciprofloxacin to photoautotrophic aquatic organisms.

PubMed

Ebert, Ina; Bachmann, Jean; Kühnen, Ute; Küster, Anette; Kussatz, Carola; Maletzki, Dirk; Schlüter, Christoph

2011-12-01

The present study investigated the growth inhibition effect of the fluoroquinolone antibiotics enrofloxacin and ciprofloxacin on four photoautotrophic aquatic species: the freshwater microalga Desmodesmus subspicatus, the cyanobacterium Anabaena flos-aquae, the monocotyledonous macrophyte Lemna minor, and the dicotyledonous macrophyte Myriophyllum spicatum. Both antibiotics, which act by inhibiting the bacterial DNA gyrase, demonstrated high toxicity to A. flos-aquae and L. minor and moderate to slight toxicity to D. subspicatus and M. spicatum. The cyanobacterium was the most sensitive species with median effective concentration (EC50) values of 173 and 10.2 µg/L for enrofloxacin and ciprofloxacin, respectively. Lemna minor proved to be similarly sensitive, with EC50 values of 107 and 62.5 µg/L for enrofloxacin and ciprofloxacin, respectively. While enrofloxacin was more toxic to green algae, ciprofloxacin was more toxic to cyanobacteria. Calculated EC50s for D. subspicatus were 5,568 µg/L and >8,042 µg/L for enrofloxacin and ciprofloxacin, respectively. These data, as well as effect data from the literature, were compared with predicted and reported environmental concentrations. For two of the four species, a risk was identified at ciprofloxacin concentrations found in surface waters, sewage treatment plant influents and effluents, as well as in hospital effluents. For ciprofloxacin the results of the present study indicate a risk even at the predicted environmental concentration. In contrast, for enrofloxacin no risk was identified at predicted and measured concentrations. Copyright © 2011 SETAC.

Design and operation of an outdoor microalgae test facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weissman, J.C.; Tillett, D.M.; Goebel, R.P.

The objective of the project covered in this report is to establish and operate a facility in the American Southwest to test the concept of producing microalgae on a large scale. This microalgae would then be used as a feedstock for producing liquid fuels. The site chosen for this project was an existing water research station in Roswell, New Mexico; the climate and water resources are representative of those in the Southwest. For this project, researchers tested specific designs, modes of operation, and strains of microalgae; proposed and evaluated modifications to technological concepts; and assessed the progress toward meeting costmore » objectives.« less

Use of microalgae to recycle nutrients in aqueous phase derived from hydrothermal liquefaction process.

PubMed

Leng, Lijian; Li, Jun; Wen, Zhiyou; Zhou, Wenguang

2018-05-01

Hydrothermal liquefaction (HTL) of microalgae biomass generates an aqueous phase (AP) byproduct with limited energy value. Recycling the AP solution as a source of nutrients for microalgae cultivation provides an opportunity for a cost-effective production of HTL based biofuel and algal biomass feedstock for HTL, allowing a closed-loop biofuel production in microalgae HTL biofuel system. This paper aims to provide a comprehensive overview of characteristics of AP and its nutrients recycling for algae production. Inhibitory effects resulted from the toxic compounds in AP and alleviation strategies are discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Isolation and Evaluation of Oil-Producing Microalgae from Subtropical Coastal and Brackish Waters

PubMed Central

Lim, David K. Y.; Garg, Sourabh; Timmins, Matthew; Zhang, Eugene S. B.; Thomas-Hall, Skye R.; Schuhmann, Holger; Li, Yan; Schenk, Peer M.

2012-01-01

Microalgae have been widely reported as a promising source of biofuels, mainly based on their high areal productivity of biomass and lipids as triacylglycerides and the possibility for cultivation on non-arable land. The isolation and selection of suitable strains that are robust and display high growth and lipid accumulation rates is an important prerequisite for their successful cultivation as a bioenergy source, a process that can be compared to the initial selection and domestication of agricultural crops. We developed standard protocols for the isolation and cultivation for a range of marine and brackish microalgae. By comparing growth rates and lipid productivity, we assessed the potential of subtropical coastal and brackish microalgae for the production of biodiesel and other oil-based bioproducts. This study identified Nannochloropsis sp., Dunaniella salina and new isolates of Chlorella sp. and Tetraselmis sp. as suitable candidates for a multiple-product algae crop. We conclude that subtropical coastal microalgae display a variety of fatty acid profiles that offer a wide scope for several oil-based bioproducts, including biodiesel and omega-3 fatty acids. A biorefinery approach for microalgae would make economical production more feasible but challenges remain for efficient harvesting and extraction processes for some species. PMID:22792403

Mobility of nanosized cerium dioxide and polymeric capsules in quartz and loamy sands saturated with model and natural groundwaters.

PubMed

Petosa, Adamo Riccardo; Ohl, Carolin; Rajput, Faraz; Tufenkji, Nathalie

2013-10-01

The environmental and health risks posed by emerging engineered nanoparticles (ENPs) released into aquatic environments are largely dependent on their aggregation, transport, and deposition behavior. Herein, laboratory-scale columns were used to examine the mobility of polyacrylic acid (PAA)-coated cerium dioxide nanoparticles (nCeO2) and an analogous nanosized polymeric capsule (nCAP) in water saturated quartz sand or loamy sand. The influence of solution ionic strength (IS) and cation type (Na(+), Ca(2+), or Mg(2+)) on the transport potential of these ENPs was examined in both granular matrices and results were also compared to measurements obtained using a natural groundwater. ENP suspensions were characterized using dynamic light scattering and nanoparticle tracking analysis to establish aggregate size, and laser Doppler electrophoresis to determine ENP electrophoretic mobility. Regardless of IS, virtually all nCeO2 particles suspended in NaNO3 eluted from the quartz sand-packed columns. In contrast, heightened nCeO2 and nCAP particle retention and dynamic (time-dependent) transport behavior was observed with increasing concentrations of the divalent salts and in the presence of natural groundwater. Enhanced particle retention was also observed in loamy sand in comparison to the quartz sand, emphasizing the need to consider the nature of the aqueous matrix and granular medium in evaluating contamination risks associated with the release of ENPs in natural and engineered aquatic environments. Copyright © 2013 Elsevier Ltd. All rights reserved.

The role of silica nanoparticles on long-term room-temperature stabilization of water-in-oil emulsions containing microalgae.

PubMed

Fernández, L; Scher, H; VanderGheynst, J S

2015-12-01

Prior research has demonstrated that microalgae can be stored for extended periods of time at room temperature in water-in-oil (W/O) emulsions stabilized by surface modified silica nanoparticles. However, little research has been done to examine the impact of nanoparticle concentration on emulsion stability. Such information is important for large-scale production of emulsions for microalgae storage and delivery. Studies were done to examine the impact of silica nanoparticle concentration on emulsion stability and identify the lower limit for nanoparticle concentration. Emulsion physical stability was determined using internal phase droplet size measurements and biological stability was evaluated using cell density measurements. The results demonstrate that nanoparticle concentrations as low as 0·5wt% in the oil phase can be used without significant losses in emulsion stability and microalgae viability. Stabilization technologies are needed for long-term storage and application of microalgae in agricultural-scale systems. While prior work has demonstrated that water-in-oil emulsions containing silica nanoparticles offer a promising solution for long-term microalgae storage at room temperature, little research has been done to examine the impact of nanoparticle concentration on emulsion stability. Here, we show the effects of silica nanoparticle concentration on maintaining physical stability of emulsions and sustaining viable cells. The results enable informed decisions to be made regarding production of emulsions containing silica nanoparticles and associated impacts on stabilization of microalgae. © 2015 The Society for Applied Microbiology.

Microalgae-bacteria biofilms: a sustainable synergistic approach in remediation of acid mine drainage.

PubMed

Abinandan, Sudharsanam; Subashchandrabose, Suresh R; Venkateswarlu, Kadiyala; Megharaj, Mallavarapu

2018-02-01

Microalgae and bacteria offer a huge potential in delving interest to study and explore various mechanisms under extreme environments. Acid mine drainage (AMD) is one such environment which is extremely acidic containing copious amounts of heavy metals and poses a major threat to the ecosystem. Despite its extreme conditions, AMD is the habitat for several microbes and their activities. The use of various chemicals in prevention of AMD formation and conventional treatment in a larger scale is not feasible under different geological conditions. It implies that microbe-mediated approach is a viable and sustainable alternative technology for AMD remediation. Microalgae in biofilms play a pivotal role in such bioremediation as they maintain mutualism with heterotrophic bacteria. Synergistic approach of using microalgae-bacteria biofilms provides supportive metabolites from algal biomass for growth of bacteria and mediates remediation of AMD. However, by virtue of their physiology and capabilities of metal removal, non-acidophilic microalgae can be acclimated for use in AMD remediation. A combination of selective acidophilic and non-acidophilic microalgae together with bacteria, all in the form of biofilms, may be very effective for bioremediation of metal-contaminated waters. The present review critically examines the nature of mutualistic interactions established between microalgae and bacteria in biofilms and their role in removal of metals from AMDs, and consequent biomass production for the yield of biofuel. Integration of microalgal-bacterial consortia in fuel cells would be an attractive emerging approach of microbial biotechnology for AMD remediation.

Effect of gamma 60Co irradiation on the lipid content and fatty acid composition of Nannochloropsis sp. microalgae

NASA Astrophysics Data System (ADS)

Ermavitalini, Dini; Sari, Ika Puspita; Prasetyo, Endry Nugroho; Abdulgani, Nurlita; Saputro, Triono Bagus

2017-06-01

Nannochloropsissp. has been identified as a promising feed stock for biodiesel production in recent years. Nannochloropsis sp. have high lipid content between 31-68 % of dry biomass weight. Mutagenesis induced by Gamma 60Co irradiation can be utilized to alter Nannochloropsis sp. characteristic to get microalgae mutant strain that can produce a higher lipid content than the wild strain. The aim of this research was to know the effect of gamma 60Co irradiation to the biomass, lipid content and fatty acid compotition of Nannochloropsis sp. microalgae. In this research, irradiation was done in different doses there were 0, 2, 4, 6 and 10 Gray (Gy). Measuring microalgae biomass and lipid content were done in late exponential phase at the end of each treatment. Research design used is random complete with 95 % confident level for quantitative analysis based on biomass and lipid content. Fatty acid compotition was analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that gamma irradiated gave an effect on lipid content and fatty acid profile of Nannochloropsis sp. Tukey test showed total lipid content of control micoalgae (0 Gy) was significat different with 10 Gy irradiated microalgae, but no significant different with 2,4 and 6 Gy irradiated microalgae. The highest lipid content were found in 10 Gy irradiated microalgae equal to 62.65 %. Fatty acid profile of 10 Gy irradiated Nannochloropsis sp. had 9 fatty acids while control Nannochloropsis sp. had 6 fatty acids.

Lethal and sublethal responses of native mussels (Unionidae: Lampsilis siliquoidea and L. higginsii) to elevated carbon dioxide

USGS Publications Warehouse

Waller, Diane L.; Bartsch, Michelle; Bartsch, Lynn; Jackson, Craig

2018-01-01

Levels of carbon dioxide (CO2) that have been proposed for aquatic invasive species (AIS) control [24 000 – 96 000 µatm partial pressure CO2 (PCO2); 1 atm = 101.325 kPa] were tested on juvenile mussels, the Fatmucket (Lampsilis siliquoidea) and the U.S. federally endangered Higgins Eye (L. higginsii). A suite of responses (survival, growth, behavior, and gene expression) were measured after 28-d exposure and 14-d postexposure to CO2. The 28-d LC20 (lethal concentration to 20%) was lower for L. higginsii (31 800 µatm PCO2, 95% confidence interval (CI) 15 000 – 42 800 µatm) than for L. siliquoidea (58 200 µatm PCO2, 95% CI 45 200 – 68 100 µatm). Treatment-related reductions occurred in all measures of growth and condition. Expression of chitin synthase, key for shell formation, was down-regulated at 28-d exposure. Carbon dioxide caused narcotization and unburial of mussels, behaviors that could increase mortality by predation and displacement. We conclude that survival and growth of juvenile mussels could be reduced by continuous exposure to elevated CO2, but recovery may be possible in shorter duration exposure.

Effects of zeolites on cultures of marine micro-algae: A brief review.

PubMed

Fachini, Adriano; Vasconcelos, Maria Teresa S D

2006-10-01

The cation-exchange capacity of zeolites is well known and has been increasingly explored in different fields with both economic and environmental successes. In aquatic medium with low salinity, zeolites have found multiple applications. However, a review of the literature on the applications of zeolites in salt waters found relatively few articles, including some recently published papers. The purpose of this review is to present the state-of-the-art on applications of using zeolites for amending the trace elemental contents of salt water as well as the implications of this property for promoting marine micro-algal growth. This paper deals with the following features: Sorption capacity of zeolites including 1. application of zeolites in saltwater, 2. the role of silicon and zeolites on cultures of micro-algae, and 3. the role of organically chelated trace metals. The following competing factors have been identified as effects of zeolites on algal growth in salt water: (i) ammonia decrease: growth inhibition reduced; (ii) macro-nutrients increase, mainly silicon: stimulation of silicon-dependent algae; (iii) trace metals increase (desorption from zeolites) or decrease (adsorption): inhibition or stimulation, depending on the nature of the element and its concentration; and, (iv) changes in the chelating organics exudation: inhibition or stimulation of growth, depending on the (a) nature of the complexed element; (b) bioavailability of the complex; and (c) concentration of the elements simultaneously present in inorganic forms. Zeolites have been capable of stimulating the growth of the silicon-demanding marine micro-algae, like diatoms, mainly because they can act as a silicon buffer in seawater. Zeolites can also influence the yield of non-silicon-demanding algae, because the changes they can cause (liberation and adsorption of trace elements) in the composition of the medium. Zeolites have been capable of stimulating the growth of the marine micro-algae. However, the extent of ion exchange between zeolite and seawater, which conditions the effects, will depend on several factors: (1) initial metal concentration in seawater; (2) levels of trace metals in the zeolites (contaminants); (3) characteristics of the zeolites in terms of both ion-exchange capacity and specific affinities for the different cations; (4) quantity of zeolite per litre of solution; (5) pH and (6) response of the organism in terms of liberation of organic ligands. Therefore, a previous investigation in each particular case is recommended, in order to select the zeolitic characteristics and concentrations that will maximize the algal yield. Stimulation of phytoplankton growth can be economically relevant since phytoplankton constitutes the basis of the marine food webs and is required in fish farming nurseries in the marine aquaculture industry. Zeolites are cheap, only small amounts (few milligrams per liter of culture) are required and the addition of some micro-nutrients may be omitted. Therefore, the inclusion of zeolites in algal cultures in aquaculture may have economic advantages.

Modifications of the metabolic pathways of lipid and triacylglycerol production in microalgae

PubMed Central

2011-01-01

Microalgae have presented themselves as a strong candidate to replace diminishing oil reserves as a source of lipids for biofuels. Here we describe successful modifications of terrestrial plant lipid content which increase overall lipid production or shift the balance of lipid production towards lipid varieties more useful for biofuel production. Our discussion ranges from the biosynthetic pathways and rate limiting steps of triacylglycerol formation to enzymes required for the formation of triacylglycerol containing exotic lipids. Secondarily, we discuss techniques for genetic engineering and modification of various microalgae which can be combined with insights gained from research in higher plants to aid in the creation of production strains of microalgae. PMID:22047615

Evaluation of available saline water resources in New Mexico for the production of microalgae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lansford, R.; Hernandez, J.; Enis, P.

Researchers evaluated saline water resources in New Mexico for their suitability as sites for large-scale microalgae production facilities. Production of microalgae could provide a renewable source of fuel, chemicals, and food. In addition, making use of the unused saline water resources would increase the economic activity in the state. After analyzing the 15 billion acre-ft of unused saline water resources in the state, scientists narrowed the locations down to six sites with the most potential. With further analysis, they chose the Tularosa Basin in southern New Mexico as the best-suited area for 100-hectare microalgae production facility. 34 refs., 38 figs.,more » 14 tabs.« less

Hydrodynamic study of an internal airlift reactor for microalgae culture.

PubMed

Rengel, Ana; Zoughaib, Assaad; Dron, Dominique; Clodic, Denis

2012-01-01

Internal airlift reactors are closed systems considered today for microalgae cultivation. Several works have studied their hydrodynamics but based on important solid concentrations, not with biomass concentrations usually found in microalgae cultures. In this study, an internal airlift reactor has been built and tested in order to clarify the hydrodynamics of this system, based on microalgae typical concentrations. A model is proposed taking into account the variation of air bubble velocity according to volumetric air flow rate injected into the system. A relationship between riser and downcomer gas holdups is established, which varied slightly with solids concentrations. The repartition of solids along the reactor resulted to be homogenous for the range of concentrations and volumetric air flow rate studied here. Liquid velocities increase with volumetric air flow rate, and they vary slightly when solids are added to the system. Finally, liquid circulation time found in each section of the reactor is in concordance with those employed in microalgae culture.

Attached cultivation technology of microalgae for efficient biomass feedstock production.

PubMed

Liu, Tianzhong; Wang, Junfeng; Hu, Qiang; Cheng, Pengfei; Ji, Bei; Liu, Jinli; Chen, Yu; Zhang, Wei; Chen, Xiaoling; Chen, Lin; Gao, Lili; Ji, Chunli; Wang, Hui

2013-01-01

The potential of microalgae biofuel has not been realized because of low productivity and high costs associated with the current cultivation systems. In this paper, an attached cultivation method was introduced, in which microalgae cells grew on the surface of vertical artificial supporting material to form algal film. Multiple of the algal films were assembled in an array fashion to dilute solar irradiation to facilitate high photosynthetic efficiency. Results showed that a broad range of microalgae species can grow with this attached method. A biomass productivity of 50-80 g m(-2) d(-1) was obtained outdoors for Scenedesmus obliquus, corresponding to the photosynthetic efficiency of 5.2-8.3% (total solar radiation). This attached method also offers lots of possible advantages over traditional open ponds, such as on water saving, harvesting, contamination controlling and scale-up. The attached cultivation represents a promising technology for economically viable production of microalgae biofuels. Copyright © 2012 Elsevier Ltd. All rights reserved.

Extremophilic micro-algae and their potential contribution in biotechnology.

PubMed

Varshney, Prachi; Mikulic, Paulina; Vonshak, Avigad; Beardall, John; Wangikar, Pramod P

2015-05-01

Micro-algae have potential as sustainable sources of energy and products and alternative mode of agriculture. However, their mass cultivation is challenging due to low survival under harsh outdoor conditions and competition from other, undesired, species. Extremophilic micro-algae have a role to play by virtue of their ability to grow under acidic or alkaline pH, high temperature, light, CO2 level and metal concentration. In this review, we provide several examples of potential biotechnological applications of extremophilic micro-algae and the ranges of tolerated extremes. We also discuss the adaptive mechanisms of tolerance to these extremes. Analysis of phylogenetic relationship of the reported extremophiles suggests certain groups of the Kingdom Protista to be more tolerant to extremophilic conditions than other taxa. While extremophilic microalgae are beginning to be explored, much needs to be done in terms of the physiology, molecular biology, metabolic engineering and outdoor cultivation trials before their true potential is realized. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microalgae biorefineries: The Brazilian scenario in perspective.

PubMed

Brasil, B S A F; Silva, F C P; Siqueira, F G

2017-10-25

Biorefineries have the potential to meet a significant part of the growing demand for energy, fuels, chemicals and materials worldwide. Indeed, the bio-based industry is expected to play a major role in energy security and climate change mitigation during the 21th century. Despite this, there are challenges related to resource consumption, processing optimization and waste minimization that still need to be overcome. In this context, microalgae appear as a promising non-edible feedstock with advantages over traditional land crops, such as high productivity, continuous harvesting throughout the year and minimal problems regarding land use. Importantly, both cultivation and microalgae processing can take place at the same site, which increases the possibilities for process integration and a reduction in logistic costs at biorefinery facilities. This review describes the actual scenario for microalgae biorefineries integration to the biofuels and petrochemical industries in Brazil, while highlighting the major challenges and recent advances in microalgae large-scale production. Copyright © 2016 Elsevier B.V. All rights reserved.

Co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatment.

PubMed

Olsson, Jesper; Feng, Xin Mei; Ascue, Johnny; Gentili, Francesco G; Shabiimam, M A; Nehrenheim, Emma; Thorin, Eva

2014-11-01

In this study two wet microalgae cultures and one dried microalgae culture were co-digested in different proportions with sewage sludge in mesophilic and thermophilic conditions. The aim was to evaluate if the co-digestion could lead to an increased efficiency of methane production compared to digestion of sewage sludge alone. The results showed that co-digestion with both wet and dried microalgae, in certain proportions, increased the biochemical methane potential (BMP) compared with digestion of sewage sludge alone in mesophilic conditions. The BMP was significantly higher than the calculated BMP in many of the mixtures. This synergetic effect was statistically significant in a mixture containing 63% (w/w VS based) undigested sewage sludge and 37% (w/w VS based) wet algae slurry, which produced 23% more methane than observed with undigested sewage sludge alone. The trend was that thermophilic co-digestion of microalgae and undigested sewage sludge did not give the same synergy. Copyright © 2014 Elsevier Ltd. All rights reserved.

Potential for heavy metal (copper and zinc) removal from contaminated marine sediments using microalgae and light emitting diodes

NASA Astrophysics Data System (ADS)

Kwon, Hyeong Kyu; Jeon, Jin Young; Oh, Seok Jin

2017-03-01

The effects of monochromatic (blue, yellow and red LED) and mixed wavelengths (fluorescent lamp) on the adsorption and absorption of Cu and Zn by Phaeodactylum tricornutum, Nitzschia sp., Skeletonema sp., and Chlorella vulgaris were investigated. In addition, we confirmed the potential of microalgae for phytoremediation of these heavy metals from contaminated marine sediment by using microcosm experiments that incorporated LEDs and semipermeable membrane (SPM) tube containing microalgae. Among the four microalgae, C. vulgaris grown under red LED exhibited the highest Cu and Zn removal with values of 17.5 × 10-15 g Cu/cell and 38.3 × 10-15 g Zn/cell, respectively. Thus, C. vulgaris could be a useful species for phytoremediation. In the microcosm experiments with SPM containing C. vulgaris, the highest Cu and Zn removal from sediment and interstitial water showed under red LED. Therefore, phytoremediation using LED and SPM tube containing microalgae could be utilized as an eco-friendly technique for remediating contaminated marine sediment.

High-value bioproducts from microalgae: strategies and progress.

PubMed

Liang, Ming-Hua; Zhu, Jianhua; Jiang, Jian-Guo

2018-04-20

Microalgae have been considered as alternative sustainable resources for high-value bioproducts such as lipids (especially triacylglycerides [TAGs]), polyunsaturated fatty acids (PUFAs), and carotenoids, due to their relatively high photosynthetic efficiency, no arable land requirement, and ease of scale-up. It is of great significance to exploit microalgae for the production of high-value bioproducts. How to improve the content or productivity of specific bioproducts has become one of the most urgent challenges. In this review, we will describe high-value bioproducts from microalgae and their biosynthetic pathways (mainly for lipids, PUFAs, and carotenoids). Recent progress and strategies for the enhanced production of bioproducts from microalgae are also described in detail, and these strategies take advantages of optimized cultivation conditions with abiotic stress, chemical stress (addition of metabolic precursors, phytohormones, chemical inhibitors, and chemicals inducing oxidative stress response), and molecular approaches such as metabolic engineering, transcriptional engineering, and gene disruption strategies (mainly RNAi, antisense RNA, miRNA-based knockdown, and CRISPR/Cas9).

Integration process of biodiesel production from filamentous oleaginous microalgae Tribonema minus.

PubMed

Wang, Hui; Gao, Lili; Chen, Lin; Guo, Fajin; Liu, Tianzhong

2013-08-01

Biodiesel production from microalgae has been receiving considerable attention. Past studies mainly relied on tiny sized single-cell oleaginous microalgal species, the biodiesel based on filamentous oleaginous microalgae was rarely reported. Thus, integrated process of biodiesel production from filamentous oleaginous microalgal strain Tribonema minus was studied in this work. The filamentous microalgae was cultivated for 21 days in 40 L glass panel, microalgae cells was harvested by DAF without any flocculants after the lipid content was 50.23%. After that, total lipid was extracted by subcritical ethanol from wet algal paste and 44.55% of crude lipid was triacylglycerols. Two-step catalytic conversion of pre-esterification and transesterification was adopted to convert the crude algal oil to biodiesel. The conversion rate of triacylglycerols reached 96.52% under the methanol to oil molar ratio of 12:1 during catalysis with 2% potassium hydroxide at 65°C for 30 min. The biodiesel product from T. minus conformed to Chinese National Standards. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quantification and characterisation of fatty acid methyl esters in microalgae: Comparison of pretreatment and purification methods.

PubMed

Lage, Sandra; Gentili, Francesco G

2018-06-01

A systematic qualitative and quantitative analysis of fatty acid methyl esters (FAMEs) is crucial for microalgae species selection for biodiesel production. The aim of this study is to identify the best method to assess microalgae FAMEs composition and content. A single-step method, was tested with and without purification steps-that is, separation of lipid classes by thin-layer chromatography (TLC) or solid-phase extraction (SPE). The efficiency of a direct transesterification method was also evaluated. Additionally, the yield of the FAMEs and the profiles of the microalgae samples with different pretreatments (boiled in isopropanol, freezing, oven-dried and freeze-dried) were compared. The application of a purification step after lipid extraction proved to be essential for an accurate FAMEs characterisation. The purification methods, which included TLC and SPE, provided superior results compared to not purifying the samples. Freeze-dried microalgae produced the lowest FAMEs yield. However, FAMEs profiles were generally equivalent among the pretreatments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Food availability on the shore: Linking epilithic and planktonic microalgae to the food ingested by two intertidal gastropods.

PubMed

Ding, Meng-Wen; Wang, Zhao-Kai; Dong, Yun-Wei

2018-05-01

Research on the interaction of primary producers and consumers is crucial for understanding trophic transfer in intertidal food webs. This study explores the association between epilithic and planktonic microalgae, and gut contents of two targeted intertidal gastropods, the periwinkle Echinolittorina radiata (splash zone) and the limpet Cellana toreuma (mid-intertidal zone). With the application of gut fluorescence technique and metabarcoding, this study investigates the quantity and composition of two different sources of microalgae (epilithic and planktonic) and the food ingested by the gastropods. The results suggest the following findings: 1) The planktonic microalgae have higher compositional similarity to the gut contents of grazing gastropods. 2) Increased gut pigment content in C. toreuma is observed with increasing abundance of epilithic and planktonic microalgae. However, there was no such pattern observed for E. radiata. This difference could be attributed to potentially divergent foraging behaviours of the two species that inhabit different shore heights. Copyright © 2018 Elsevier Ltd. All rights reserved.

A Verhulst model for microalgae Botryococcus sp. growth and nutrient removal in wastewater

NASA Astrophysics Data System (ADS)

Jamaian, Siti Suhana; Bakeri, Noorhadila Mohd; Sunar, Norshuhaila Mohamed; Gani, Paran

2017-08-01

Microalgae Botryococcus sp. is a colonial green alga found in lakes and reservoirs in Malaysia. Previous studies reported that the potential of Botryococcus sp. photosynthesis as a source of fuel. The Botryococcus sp. contains hydrocarbon up to 75% of dry weight, which can be converted into petrol, diesel or turbine fuel or other liquid or gaseous hydrocarbons. Recently, an experimental study was conducted on phycoremediation technology for wastewater using Botryococcus sp. The phycoremediation technology is useful to remove the excess of nutrients such as nitrogen, phosphorus and also have the ability to remove various pollutants from wastewater. This research implements the Verhulst model to estimate the nutrient removal by microalgae Botryococcus sp. from the wastewater. This model has been validated with the experiments of microalgae Botryococcus sp. grown in domestic and palm oil wastewater. The results suggested that microalgae Botryococcus sp. could be cultured in domestic and palm oil wastewater while nutrients are reduced from these wastewaters.

Cell-wall disruption and lipid/astaxanthin extraction from microalgae: Chlorella and Haematococcus.

PubMed

Kim, Dong-Yeon; Vijayan, Durairaj; Praveenkumar, Ramasamy; Han, Jong-In; Lee, Kyubock; Park, Ji-Yeon; Chang, Won-Seok; Lee, Jin-Suk; Oh, You-Kwan

2016-01-01

Recently, biofuels and nutraceuticals produced from microalgae have emerged as major interests, resulting in intensive research of the microalgal biorefinery process. In this paper, recent developments in cell-wall disruption and extraction methods are reviewed, focusing on lipid and astaxanthin production from the biotechnologically important microalgae Chlorella and Haematococcus, respectively. As a common, critical bottleneck for recovery of intracellular components such as lipid and astaxanthin from these microalgae, the composition and structure of rigid, thick cell-walls were analyzed. Various chemical, physical, physico-chemical, and biological methods applied for cell-wall breakage and lipid/astaxanthin extraction from Chlorella and Haematococcus are discussed in detail and compared based on efficiency, energy consumption, type and dosage of solvent, biomass concentration and status (wet/dried), toxicity, scalability, and synergistic combinations. This report could serve as a useful guide to the implementation of practical downstream processes for recovery of valuable products from microalgae including Chlorella and Haematococcus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Vibrating membrane filtration as improved technology for microalgae dewatering.

PubMed

Nurra, Claudia; Clavero, Ester; Salvadó, Joan; Torras, Carles

2014-04-01

The effect of shear-enhanced filtration by vibratory process in microalgae dewatering is presented in this paper. The aim of this research was to investigate the technical performance and improvement of vibrating membrane filtration compared with conventional tangential cross-flow filtration in microalgae concentration. An industrial-scale available commercial set-up was used. Several membrane materials as polyethersulfone, polyacrylonitrile, etc., and mean pore sizes (from 7000Da to 0.2μm) were tested and compared in both filtration set-ups. Experiments were carried-out with Nannochloropsis gaditana and Phaeodactylum tricornutum microalgae. It has been demonstrated that, even if the choice of the membrane depends on its cut-off, its material and the type of microalgae filtrated, dynamic filtration is always the best technology over a conventional one. If with conventional filtration permeability values were in the vicinity of 10L/h/m(2)/bar in steady state phase, with dynamic filtration these values increased to 30L/h/m(2)/bar or more. Copyright © 2014 Elsevier Ltd. All rights reserved.

Low-cost production of green microalga Botryococcus braunii biomass with high lipid content through mixotrophic and photoautotrophic cultivation.

PubMed

Yeesang, Chittra; Cheirsilp, Benjamas

2014-09-01

Botryococcus braunii is a microalga that is regarded as a potential source of renewable fuel because of its ability to produce large amounts of lipid that can be converted into biodiesel. Agro-industrial by-products and wastes are of great interest as cultivation medium for microorganisms because of their low cost, renewable nature, and abundance. In this study, two strategies for low-cost production of B. braunii biomass with high lipid content were performed: (i) the mixotrophic cultivation using molasses, a cheap by-product from the sugar cane plant as a carbon source, and (ii) the photoautotrophic cultivation using nitrate-rich wastewater supplemented with CO2 as a carbon source. The mixotrophic cultivation added with 15 g L(-1) molasses produced a high amount of biomass of 3.05 g L(-1) with a high lipid content of 36.9 %. The photoautotrophic cultivation in nitrate-rich wastewater supplemented with 2.0 % CO2 produced a biomass of 2.26 g L(-1) and a lipid content of 30.3 %. The benefits of this photoautotrophic cultivation are that this cultivation would help to reduce accumulation of atmospheric carbon dioxide and more than 90 % of the nitrate could be removed from the wastewater. When this cultivation was scaled up in a stirred tank photobioreactor and run with semi-continuous cultivation regime, the highest microalgal biomass of 5.16 g L(-1) with a comparable lipid content of 32.2 % was achieved. These two strategies could be promising ways for producing cheap lipid-rich microalgal biomass that can be used as biofuel feedstocks and animal feeds.

Carbon dioxide consumption of the microalga Scenedesmus obtusiusculus under transient inlet CO2 concentration variations.

PubMed

Cabello, Juan; Morales, Marcia; Revah, Sergio

2017-04-15

The extensive microalgae diversity offers considerable versatility for a wide range of biotechnological applications in environmental and production processes. Microalgal cultivation is based on CO 2 fixation via photosynthesis and, consequently, it is necessary to evaluate, in a short time and reliable way, the effect of the CO 2 gas concentration on the consumption rate and establish the tolerance range of different strains and the amount of inorganic carbon that can be incorporated into biomass in order to establish the potential for industrial scale application. Dynamic experiments allow calculating the short-term microalgal photosynthetic activity of strains in photobioreactors. In this paper, the effect of step-changes in CO 2 concentration fed to a 20L bubble column photobioreactor on the CO 2 consumption rate of Scenedesmus obtusiusculus was evaluated at different operation times. The highest apparent CO 2 consumption rate (336μmolm -2 s -1 and 5.6% of CO 2 ) was 6530mg CO2 g b -1 d -1 and it decreased to 222mg CO2 g b -1 d -1 when biomass concentration increased of 0.5 to 3.1g b L -1 and 5.6% of CO 2 was fed. For low CO 2 concentrations (<3.8%) the pH remained close to the optimal value (7.5 and 8). The CO 2 consumption rates show that S. obtusiusculus was not limited by CO 2 availability for concentrations above of 3.8%. The CO 2 mass balance showed that 90% of the C-CO 2 transferred was used for S. obtusiusculus growth. Copyright © 2017. Published by Elsevier B.V.

Photosynthesis as a Possible Source of Gas Bubbles in Shallow Sandy Coastal Sediments

DTIC Science & Technology

2011-09-30

bubbles can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen. OBJECTIVES The next...reflectivity. We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present. After...Graduate School of Oceanography / University of Rhode Island (GSO/URI) to identify the benthic microalgae in the samples. Following the untimely death of

Photosynthesis as a Possible Source of Gas Bubbles in Shallow Sandy Coastal Sediments

DTIC Science & Technology

2012-09-30

clearly demonstrates that gas bubbles can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen...We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present. Although benthic...Jan Rines (Graduate School of Oceanography / University of Rhode Island = GSO/URI) to identify the benthic microalgae in the samples. Following the

Identification of Microalgae by Laser Desorption/Ionization Mass Spectrometry Coupled with Multiple Nanomatrices.

PubMed

Peng, Lung-Hsiang; Unnikrishnan, Binesh; Shih, Chi-Yu; Hsiung, Tung-Ming; Chang, Jeng; Hsu, Pang-Hung; Chiu, Tai-Chia; Huang, Chih-Ching

2016-04-01

In this study, we demonstrate a simple method to identify microalgae by surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) using three different substrates: HgSe, HgTe, and HgTeSe nanostructures. The fragmentation/ionization processes of complex molecules in algae varied according to the heat absorption and transfer efficiency of the nanostructured matrices (NMs). Therefore, the mass spectra obtained for microalgae showed different patterns of m/z values for different NMs. The spectra contained both significant and nonsignificant peaks. Constructing a Venn diagram with the significant peaks obtained for algae when using HgSe, HgTe, and HgTeSe NMs in m/z ratio range 100-1000, a unique relationship among the three sets of values was obtained. This unique relationship of sets is different for each species of microalgae. Therefore, by observing the particular relationship of sets, we successfully identified different algae such as Isochrysis galbana, Emiliania huxleyi, Thalassiosira weissflogii, Nannochloris sp., Skeletonema cf. costatum, and Tetraselmis chui. This simple and cost-effective SALDI-MS analysis method coupled with multi-nanomaterials as substrates may be extended to identify other microalgae and microorganisms in real samples. Graphical Abstract Identification of microalgae by surface-assisted laser desorption/ionization mass spectrometry coupled with three different mercury-based nanosubstrates.

Study of Selecting on Light Source Used for Micro-algae Cultivation in Space

NASA Astrophysics Data System (ADS)

Ai, Weidang; Ai, Weidang; Guo, Shuang-Sheng; Gao, Feng; Tang, Yong-Kang; Qin, Li-Feng

To select suitable light source for micro-algae cultivation in future space station, the selected Spirulina plastensis(No.7) were cultured under different lightening qualities, including six light sources that were made up of different combinations of red and blue light-emitting diode(LED). The growth, photosynthetic efficiency and nutrition quality of the Spirulina, were analyzed. From the experiments, the red light may promote the cumulation of biomass of the Spirulina, and the cumulating rate was the highest under all red light source, but the syntheses of protein, phycobiliprotein, β-carotene, VE and other nutrients needs a certain portion of blue light; yet, the complete blue light condition is not favorable to the growth of Spirulina, and may bring pollution by chlorella and other kinds of micro-algae. It is concluded that the LEDs can be used as the light resource of micro-algae cultivation. The normal growth and development of microalgae need two light sources of both red and blue LEDs. The comprehensive analyses of the various factors that affect the growth of Spirulina, such as nutrition quality and photosynthetic activities, etc., showed that the combination of 80% red and 20% blue LED is the optimum one among those tested combinations. Key word: light-emitting diode; micro-algae; controlled ecological life support system (CELSS); space cultivation

A type 2 diacylglycerol acyltransferase accelerates the triacylglycerol biosynthesis in heterokont oleaginous microalga Nannochloropsis oceanica.

PubMed

Li, Da-Wei; Cen, Shi-Ying; Liu, Yu-Hong; Balamurugan, Srinivasan; Zheng, Xin-Yan; Alimujiang, Adili; Yang, Wei-Dong; Liu, Jie-Sheng; Li, Hong-Ye

2016-07-10

Oleaginous microalgae have received a considerable attention as potential biofuel feedstock. However, lack of industry-suitable strain with lipid rich biomass limits its commercial applications. Targeted engineering of lipogenic pathways represents a promising strategy to enhance the efficacy of microalgal oil production. In this study, a type 2 diacylglycerol acyltransferase (DGAT), a rate-limiting enzyme in triacylglycerol (TAG) biosynthesis, was identified and overexpressed in heterokont oleaginous microalga Nannochloropsis oceanica for the first time. Overexpression of DGAT2 in Nannochloropsis increased the relative transcript abundance by 3.48-fold in engineered microalgae cells. TAG biosynthesis was subsequently accelerated by DGAT2 overexpression and neutral lipid content was significantly elevated by 69% in engineered microalgae. The fatty acid profile determined by GC-MS revealed that fatty acid composition was altered in engineered microalgae. Saturated fatty acids and polyunsaturated fatty acids were found to be increased whereas monounsaturated fatty acids content decreased. Furthermore, DGAT2 overexpression did not show negative impact on algal growth parameters. The present investigation showed that the identified DGAT2 would be a potential candidate for enhancing TAG biosynthesis and might facilitate the development of promising oleaginous strains with industrial potential. Copyright © 2016 Elsevier B.V. All rights reserved.

Extracellular Metabolites from Industrial Microalgae and Their Biotechnological Potential

PubMed Central

Liu, Lu; Pohnert, Georg; Wei, Dong

2016-01-01

Industrial microalgae, as a big family of promising producers of renewable biomass feedstock, have been commercially exploited for functional food, living feed and feed additives, high-value chemicals in nutraceuticals, cosmeceuticals, and chemical reagents. Recently, microalgae have also been considered as a group that might play an important role in biofuel development and environmental protection. Almost all current products of industrial microalgae are derived from their biomass; however, large amounts of spent cell-free media are available from mass cultivation that is mostly unexploited. In this contribution we discuss that these media, which may contain a remarkable diversity of bioactive substances are worthy to be recovered for further use. Obviously, the extracellular metabolites from industrial microalgae have long been neglected in the development of production methods for valuable metabolites. With the advances in the last ten years, more and more structures and properties from extracellular metabolites have been identified, and the potential utilization over wide fields is attracting attention. Some of these extracellular metabolites can be potentially used as drugs, antioxidants, growth regulators or metal chelators. The purpose of this review is to provide an overview of the known extracellular metabolites from industrial microalgae which might be of commercial interest. The attention mainly focuses on the reports of extracellular bioactive metabolites and their potential application in biotechnology. PMID:27775594

Extracellular Metabolites from Industrial Microalgae and Their Biotechnological Potential.

PubMed

Liu, Lu; Pohnert, Georg; Wei, Dong

2016-10-20

Industrial microalgae, as a big family of promising producers of renewable biomass feedstock, have been commercially exploited for functional food, living feed and feed additives, high-value chemicals in nutraceuticals, cosmeceuticals, and chemical reagents. Recently, microalgae have also been considered as a group that might play an important role in biofuel development and environmental protection. Almost all current products of industrial microalgae are derived from their biomass; however, large amounts of spent cell-free media are available from mass cultivation that is mostly unexploited. In this contribution we discuss that these media, which may contain a remarkable diversity of bioactive substances are worthy to be recovered for further use. Obviously, the extracellular metabolites from industrial microalgae have long been neglected in the development of production methods for valuable metabolites. With the advances in the last ten years, more and more structures and properties from extracellular metabolites have been identified, and the potential utilization over wide fields is attracting attention. Some of these extracellular metabolites can be potentially used as drugs, antioxidants, growth regulators or metal chelators. The purpose of this review is to provide an overview of the known extracellular metabolites from industrial microalgae which might be of commercial interest. The attention mainly focuses on the reports of extracellular bioactive metabolites and their potential application in biotechnology.

A multilayer concentric filter device to diminish clogging for separation of particles and microalgae based on size.

PubMed

Chen, Chih-Chung; Chen, Yu-An; Liu, Yi-Ju; Yao, Da-Jeng

2014-04-21

Microalgae species have great economic importance; they are a source of medicines, health foods, animal feeds, industrial pigments, cosmetic additives and biodiesel. Specific microalgae species collected from the environment must be isolated for examination and further application, but their varied size and culture conditions make their isolation using conventional methods, such as filtration, streaking plate and flow cytometric sorting, labour-intensive and costly. A separation device based on size is one of the most rapid, simple and inexpensive methods to separate microalgae, but this approach encounters major disadvantages of clogging and multiple filtration steps when the size of microalgae varies over a wide range. In this work, we propose a multilayer concentric filter device with varied pore size and is driven by a centrifugation force. The device, which includes multiple filter layers, was employed to separate a heterogeneous population of microparticles into several subpopulations by filtration in one step. A cross-flow to attenuate prospective clogging was generated by altering the rate of rotation instantly through the relative motion between the fluid and the filter according to the structural design of the device. Mixed microparticles of varied size were tested to demonstrate that clogging was significantly suppressed due to a highly efficient separation. Microalgae in a heterogeneous population collected from an environmental soil collection were separated and enriched into four subpopulations according to size in a one step filtration process. A microalgae sample contaminated with bacteria and insect eggs was also tested to prove the decontamination capability of the device.

Wastewater nutrient removal in a mixed microalgae-bacteria culture: effect of light and temperature on the microalgae-bacteria competition.

PubMed

González-Camejo, J; Barat, R; Pachés, M; Murgui, M; Seco, A; Ferrer, J

2018-02-01

The aim of this study was to evaluate the effect of light intensity and temperature on nutrient removal and biomass productivity in a microalgae-bacteria culture and their effects on the microalgae-bacteria competition. Three experiments were carried out at constant temperature and various light intensities: 40, 85 and 125 µE m -2  s -1 . Other two experiments were carried out at variable temperatures: 23 ± 2°C and 28 ± 2°C at light intensity of 85 and 125 µE m -2  s -1 , respectively. The photobioreactor was fed by the effluent from an anaerobic membrane bioreactor. High nitrogen and phosphorus removal efficiencies (about 99%) were achieved under the following operating conditions: 85-125 µE m -2  s -1 and 22 ± 1°C. In the microalgae-bacteria culture studied, increasing light intensity favoured microalgae growth and limited the nitrification process. However, a non-graduated temperature increase (up to 32°C) under the light intensities studied caused the proliferation of nitrifying bacteria and the nitrite and nitrate accumulation. Hence, light intensity and temperature are key parameters in the control of the microalgae-bacteria competition. Biomass productivity significantly increased with light intensity, reaching 50.5 ± 9.6, 80.3 ± 6.5 and 94.3 ± 7.9 mgVSS L -1  d -1 for a light intensity of 40, 85 and 125 µE m -2  s -1 , respectively.

Effects of a docosahexaenoic acid-rich microalgae nutritional product on insulin sensitivity after prolonged dexamethasone treatment in healthy mature horses.

PubMed

Brennan, Kristen M; Graugnard, Daniel E; Spry, Malinda L; Brewster-Barnes, Tammy; Smith, Allison C; Schaeffer, Rachel E; Urschel, Kristine L

2015-10-01

To determine effects of a microalgae nutritional product on insulin sensitivity in horses. 8 healthy mature horses. PROCEDURES :Horses (n = 4/group) received a basal diet without (control diet) or with docosahexaenoic acid-rich microalgae meal (150 g/d) for 49 days (day 0 = first day of diet). On day 28, an isoglycemic hyperinsulinemic clamp procedure was performed. Horses then received dexamethasone (0.04 mg/kg/d) for 21 days. On day 49, the clamp procedure was repeated. After a 60-day washout, horses received the alternate diet, and procedures were repeated. Plasma fatty acid, glucose, and insulin concentrations and glucose and insulin dynamics during the clamp procedure were measured on days 28 and 49. Two estimates of insulin sensitivity (reciprocal of the square root of the insulin concentration and the modified insulin-to-glucose ratio for ponies) were calculated. Baseline glucose and insulin concentrations or measures of insulin sensitivity on day 28 did not differ between horses when fed the control diet or the basal diet plus microalgae meal. On day 49 (ie, after dexamethasone administration), the microalgae meal was associated with lower baseline insulin and glucose concentrations and an improved modified insulin-to-glucose ratio for ponies, compared with results for the control diet. Although the microalgae meal had no effect on clamp variables following dexamethasone treatment, it was associated with improved plasma glucose and insulin concentrations and insulin sensitivity estimates. A role for microalgae in the nutritional management of insulin-resistant horses warrants investigation.

Fluxes of carbon dioxide and methane from diverse aquatic environments in an agricultural landscape

NASA Astrophysics Data System (ADS)

Stanley, E. H.; Crawford, J. T.; Loken, L. C.; Casson, N. J.; Gubbins, N. J.; Oliver, S. K.

2014-12-01

The contribution of aquatic environments to landscape carbon cycling is particularly apparent in carbon- and water-rich regions. Such areas arguably represent an end member in terms of the relative significance of aquatic carbon cycling, while dry, carbon-poor zones are the likely opposing end member. Not surprisingly, most limnological attention has focused on these former regions, leaving open questions as to how aquatic systems in other locales influence larger-scale carbon dynamics. This includes human-dominated landscapes where agricultural and urban land uses can fundamentally alter carbon dynamics. Surveys of streams, ponds, and lakes in a southern Wisconsin landscape highlight three findings relevant to understanding the role of these aquatic systems in larger-scale carbon dynamics. First, streams and ponds had unexpectedly high summertime concentrations in and fluxes of CO2 and CH4. These values were approximately an order of magnitude greater than for less disturbed, forest and wetland-dominated landscapes in northern Wisconsin. Second, while mean C gas concentrations in lakes were lower than in streams and ponds, detailed spatial measurements demonstrate variability in surface water CO2 (43-1090 ppm pCO2) and CH4 (6-839 ppm pCH4) within a lake on a single day is similar to that observed among 25 streams included in our survey (260-6000 ppm pCO2; 50-600 ppm pCH4). This small-scale heterogeneity highlights a basic challenge for upscaling site-specific data collected at one or a few points to the whole lake and across lakes. Third, while agricultural and urban ecosystems are not necessarily carbon-rich environments, area-specific carbon storage in streams and ponds is substantial (up to 3000-5000 g C per m2). Further, carbon storage was strongly related to CH4 concentrations in streams, as C-rich sediments provided both an environment and substrate to fuel methanogenesis. The picture that emerges of C processing in aquatic environments throughout this human-dominated landscape is one of large C pools and fluxes and high spatial variability, suggesting that these land uses may be accelerating rates of aquatic C cycling and amplifying the role of these ecosystems in anthropogenic landscapes.

Physical and Biological Effects on Tide Flat Sediment Stability and Strength - Phase 2

DTIC Science & Technology

2011-09-30

forcings, such as insolation, rainfall, benthic microalgae and seagrass (Zostera japonica) abundance, these variations did not always result in...m2 in the winter to a high of >3000 shoots/m2 in late summer. (B) Is chlorophyll a content in mg/g dry sediment (a proxy for benthic microalgae ...Another area of insight regarding physical/biological interactions involves the impact of microphytobenthos (MPB) or benthic microalgae on the

Photosynthesis as a Possible Source of Gas Bubbles in Shallow Sandy Coastal Sediments

DTIC Science & Technology

2010-09-30

gas bubbles can be formed when photosynthesis by benthic microalgae causes pore water to become supersaturated with oxygen. OBJECTIVES The...acoustic reflectivity. We also collected sediment samples from the upper few mm of sand to identify the dominant taxa of benthic microalgae present... microalgae in the samples. Following the untimely death of Dr. D.V. Holliday, the remaining team members are sharing the responsibility of analyzing data and

Microalgae-microbial fuel cell: A mini review.

PubMed

Lee, Duu-Jong; Chang, Jo-Shu; Lai, Juin-Yih

2015-12-01

Microalgae-microbial fuel cells (mMFCs) are a device that can convert solar energy to electrical energy via biological pathways. This mini-review lists new research and development works on microalgae processes, microbial fuel cell (MFC) processes, and their combined version, mMFC. The substantial improvement and technological advancement are highlighted, with a discussion on the challenges and prospects for possible commercialization of mMFC technologies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nuclear transformation of eukaryotic microalgae: historical overview, achievements and problems.

PubMed

León, Rosa; Fernández, Emilio

2007-01-01

Transformation of microalgae is a first step in their use for biotechnological applications involving foreign protein production or molecular modifications of specific cell metabolic pathways. Since the first reliable achievements of nuclear transformation in Chlamydomonas, other eukaryotic microalgae have become transformed with molecular markers that allow a direct selection. Different methods--glass beads, electroporation, particle bombardment, or Agrobacterium--and constructions have been set up in several organisms and successfully used. However, some problems associated with efficiency, integration, or stability of the transgenes still persist and are analysed herein. Though the number of microalgae species successfully transformed is not very high, prospects for transformation of many more are good enough on the basis of what has been achieved so far.

Biofuels from microalgae.

PubMed

Li, Yanqun; Horsman, Mark; Wu, Nan; Lan, Christopher Q; Dubois-Calero, Nathalie

2008-01-01

Microalgae are a diverse group of prokaryotic and eukaryotic photosynthetic microorganisms that grow rapidly due to their simple structure. They can potentially be employed for the production of biofuels in an economically effective and environmentally sustainable manner. Microalgae have been investigated for the production of a number of different biofuels including biodiesel, bio-oil, bio-syngas, and bio-hydrogen. The production of these biofuels can be coupled with flue gas CO2 mitigation, wastewater treatment, and the production of high-value chemicals. Microalgal farming can also be carried out with seawater using marine microalgal species as the producers. Developments in microalgal cultivation and downstream processing (e.g., harvesting, drying, and thermochemical processing) are expected to further enhance the cost-effectiveness of the biofuel from microalgae strategy.

Cultivation Of Microalgae (Chlorella vulgaris) For Biodiesel Production

NASA Astrophysics Data System (ADS)

Blinová, Lenka; Bartošová, Alica; Gerulová, Kristína

2015-06-01

Production of biofuel from renewable sources is considered to be one of the most sustainable alternatives to petroleum sourced fuels. Biofuels are also viable means of environmental and economic sustainability. Biofuels are divided into four generations, depending on the type of biomass used for biofuels production. At present, microalgae are presented as an ideal third generation biofuel feedstock because of their rapid growth rate. They also do not compete with food or feed crops, and can be produced on non-arable land. Cultivation conditions (temperature, pH, light, nutrient quantity and quality, salinity, aerating) are the major factors that influence photosynthesis activity and behaviour of the microalgae growth rate. In this paper, we present an overview about the effect of cultivation conditions on microalgae growth.

The potentials and challenges of algae based biofuels: a review of the techno-economic, life cycle, and resource assessment modeling.

PubMed

Quinn, Jason C; Davis, Ryan

2015-05-01

Microalgae biofuel production has been extensively evaluated through resource, economic and life cycle assessments. Resource assessments consistently identify land as non-limiting and highlight the need to consider siting based on combined geographical constraints of land and other critical resources such as water and carbon dioxide. Economic assessments report a selling cost of fuel that ranges between $1.64 and over $30 gal(-1) consistent with large variability reported in the life cycle literature, -75 to 534 gCO2-eq MJ(-1). Large drivers behind such variability stem from differences in productivity assumptions, pathway technologies, and system boundaries. Productivity represents foundational units in these assessments with current assumed yields in various assessments varying by a factor of 60. A review of the literature in these areas highlights the need for harmonized assessments such that direct comparisons of alternative processing technologies can be made on the metrics of resource requirements, economic feasibility, and environmental impact. Copyright © 2014 Elsevier Ltd. All rights reserved.

De novo Biosynthesis of Biodiesel by Escherichia coli in Optimized Fed-Batch Cultivation

PubMed Central

Cai, Ke; Tan, Xiaoming; Lu, Xuefeng

2011-01-01

Biodiesel is a renewable alternative to petroleum diesel fuel that can contribute to carbon dioxide emission reduction and energy supply. Biodiesel is composed of fatty acid alkyl esters, including fatty acid methyl esters (FAMEs) and fatty acid ethyl esters (FAEEs), and is currently produced through the transesterification reaction of methanol (or ethanol) and triacylglycerols (TAGs). TAGs are mainly obtained from oilseed plants and microalgae. A sustainable supply of TAGs is a major bottleneck for current biodiesel production. Here we report the de novo biosynthesis of FAEEs from glucose, which can be derived from lignocellulosic biomass, in genetically engineered Escherichia coli by introduction of the ethanol-producing pathway from Zymomonas mobilis, genetic manipulation to increase the pool of fatty acyl-CoA, and heterologous expression of acyl-coenzyme A: diacylglycerol acyltransferase from Acinetobacter baylyi. An optimized fed-batch microbial fermentation of the modified E. coli strain yielded a titer of 922 mg L−1 FAEEs that consisted primarily of ethyl palmitate, -oleate, -myristate and -palmitoleate. PMID:21629774

Utilization of carbon dioxide in industrial flue gases for the cultivation of microalga Chlorella sp.

PubMed

Kao, Chien-Ya; Chen, Tsai-Yu; Chang, Yu-Bin; Chiu, Tzai-Wen; Lin, Hsiun-Yu; Chen, Chun-Da; Chang, Jo-Shu; Lin, Chih-Sheng

2014-08-01

The biomass and lipid productivity of Chlorella sp. MTF-15 cultivated using aeration with flue gases from a coke oven, hot stove or power plant in a steel plant of the China Steel Corporation in Taiwan were investigated. Using the flue gas from the coke oven, hot stove or power plant for cultivation, the microalgal strain obtained a maximum specific growth rate and lipid production of (0.827 d(-1), 0.688 g L(-1)), (0.762 d(-1), 0.961 g L(-1)), and (0.728 d(-1), 0.792 g L(-1)), respectively. This study demonstrated that Chlorella sp. MTF-15 could efficiently utilize the CO₂, NOX and SO₂ present in the different flue gases. The results also showed that the growth potential, lipid production and fatty acid composition of the microalgal strain were dependent on the composition of the flue gas and on the operating strategy deployed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effective cultivation of microalgae for biofuel production: a pilot-scale evaluation of a novel oleaginous microalga Graesiella sp. WBG-1.

PubMed

Wen, Xiaobin; Du, Kui; Wang, Zhongjie; Peng, Xinan; Luo, Liming; Tao, Huanping; Xu, Yan; Zhang, Dan; Geng, Yahong; Li, Yeguang

2016-01-01

Commercial production of microalgal biodiesel is not yet economically viable, largely because of low storage lipid yield in microalgae mass cultivation. Selection of lipid-rich microalgae, thus, becomes one of the key research topics for microalgal biodiesel production. However, the laboratory screening protocols alone cannot predict the ability of the strains to dominate and perform in outdoor ponds. Comprehensive assessment of microalgae species should be performed not only under the laboratory conditions, but also in the fields. Laboratory investigations using a bubbled column photobioreactor indicated the microalga Graesiella sp. WBG-1 to be the most productive species among the 63 Chlorophyta strains. In a 10 L reactor, mimicking the industrial circular pond, Graesiella sp. WBG-1 produced 12.03 g biomass m(-2) day(-1) and 5.44 g lipids (45.23 % DW) m(-2) day(-1) under 15 mol m(-2) day(-1) artificial light irradiations. The lipid content decreased to ~34 % DW when the microalga was cultured in 30 L tank PBR under natural solar irradiations, but the decline of lipid content with scaling up was the minimum among the tested strains. Based on these results, the microalga was further tested for its lipid production and culture competitiveness using a pilot-scale raceway pond (200 m(2) illuminated area, culture volume 40,000 L). Consequently, Graesiella sp. WBG-1 maintained a high lipid content (33.4 % DW), of which ~90 % was storage TAGs. Results from the outdoor experiments indicated the nice adaptability of the Graesiella sp. WBG-1 to strong and fluctuating natural solar irradiance and temperature, and also demonstrated several other features, such as large cell size (easy for harvest and resistant to swallow by protozoa) and tolerance to high culture pH (helpful to CO2 fixation). Graesiella sp. WBG-1 was a promising strain capable of accumulating large amount of storage lipid under nature solar irradiance and temperature. The high lipid content of 33.4 % DW was achieved for the first time in pilot-scale raceway pond. The results also provide evidence for the feasibility of using low-cost raceway pond for autotrophic cultivation of microalgae for biodiesel production.

Influence of aquatic training on the motor performance of patients with haemophilic arthropathy.

PubMed

Vallejo, L; Pardo, A; Gomis, M; Gallach, J E; Pérez, S; Querol, F

2010-01-01

Thirteen patients with haemophilia A took part in this study voluntarily. They underwent an aquatic training programme over a 9-week period (27 sessions; three sessions per week; 1 h per session). Their motor performance was assessed by the following cardio-respiratory and mechanical variables before and after the training programme: oxygen uptake (VO(2), mL min(-1)), relative oxygen uptake (rel VO(2), mL min(-1).kg(-1)), carbon dioxide (CO(2), mL min(-1)), respiratory quotient (R), heart rate (bpm) and the distance covered in 12 min (the Cooper test, m). Nine patients successfully completed the intervention and measurement protocols without bleeding or other adverse events. After the proposed training programme, significant differences between the pre-test and post-test were observed. Patients' aerobic capacity increased considerably, and their oxygen uptake improved by 51.51% (P < 0.05), while their relative oxygen uptake went up by 37.73% (P < 0.05). Their mechanical capacity also increased considerably (14.68%, P < 0.01). Our results suggest that 27 specially designed aquatic training sessions for our patients with haemophilia A had a positive effect on their motor performance and considerably improved their aerobic and mechanical capacity without causing adverse effects.

Microalgae as a raw material for biofuels production.

PubMed

Gouveia, Luisa; Oliveira, Ana Cristina

2009-02-01

Biofuels demand is unquestionable in order to reduce gaseous emissions (fossil CO(2), nitrogen and sulfur oxides) and their purported greenhouse, climatic changes and global warming effects, to face the frequent oil supply crises, as a way to help non-fossil fuel producer countries to reduce energy dependence, contributing to security of supply, promoting environmental sustainability and meeting the EU target of at least of 10% biofuels in the transport sector by 2020. Biodiesel is usually produced from oleaginous crops, such as rapeseed, soybean, sunflower and palm. However, the use of microalgae can be a suitable alternative feedstock for next generation biofuels because certain species contain high amounts of oil, which could be extracted, processed and refined into transportation fuels, using currently available technology; they have fast growth rate, permit the use of non-arable land and non-potable water, use far less water and do not displace food crops cultures; their production is not seasonal and they can be harvested daily. The screening of microalgae (Chlorella vulgaris, Spirulina maxima, Nannochloropsis sp., Neochloris oleabundans, Scenedesmus obliquus and Dunaliella tertiolecta) was done in order to choose the best one(s), in terms of quantity and quality as oil source for biofuel production. Neochloris oleabundans (fresh water microalga) and Nannochloropsis sp. (marine microalga) proved to be suitable as raw materials for biofuel production, due to their high oil content (29.0 and 28.7%, respectively). Both microalgae, when grown under nitrogen shortage, show a great increase (approximately 50%) in oil quantity. If the purpose is to produce biodiesel only from one species, Scenedesmus obliquus presents the most adequate fatty acid profile, namely in terms of linolenic and other polyunsaturated fatty acids. However, the microalgae Neochloris oleabundans, Nannochloropsis sp. and Dunaliella tertiolecta can also be used if associated with other microalgal oils and/or vegetable oils.

Toxic pressure of herbicides on microalgae in Dutch estuarine and coastal waters

NASA Astrophysics Data System (ADS)

Booij, Petra; Sjollema, Sascha B.; van der Geest, Harm G.; Leonards, Pim E. G.; Lamoree, Marja H.; de Voogt, W. Pim; Admiraal, Wim; Laane, Remi W. P. M.; Vethaak, A. Dick

2015-08-01

For several decades now, there has been an increase in the sources and types of chemicals in estuarine and coastal waters as a consequence of anthropogenic activities. This has led to considerable concern about the effects of these chemicals on the marine food chain. The fact is that estuarine and coastal waters are the most productive ecosystems with high primary production by microalgae. The toxic pressure of specific phytotoxic chemicals now poses a major threat to these ecosystems. In a previous study, six herbicides (atrazine, diuron, irgarol, isoproturon, terbutryn and terbutylazine) were identified as the main contaminants affecting photosynthesis in marine microalgae. The purpose of this study is to investigate the toxic pressure of these herbicides in the Dutch estuarine and coastal waters in relation to the effective photosystem II efficiency (ΦPSII) in microalgae. Temporal and spatial variations in the concentrations of these herbicides were analyzed based on monitoring data. Additionally, a field study was carried out in which chemical analysis of water was performed and also a toxicity assessment using the Pulse Amplitude Modulation (PAM) fluorometry assay that measures ΦPSII. The toxic pressure on ΦPSII in microalgae has decreased with 55-82% from 2003 to 2012, with the Western Scheldt estuary showing the highest toxic pressure. By combining toxicity data from the PAM assay with chemical analysis of herbicide concentrations, we have identified diuron and terbutylazine as the main contributors to the toxic pressure on microalgae. Although direct effects are not expected, the toxic pressure is close to the 10% effect level in the PAM assay. A compliance check with the current environmental legislation of the European Union revealed that the quality standards are not sufficient to protect marine microalgae.

Global evaluation of biofuel potential from microalgae

PubMed Central

Moody, Jeffrey W.; McGinty, Christopher M.; Quinn, Jason C.

2014-01-01

In the current literature, the life cycle, technoeconomic, and resource assessments of microalgae-based biofuel production systems have relied on growth models extrapolated from laboratory-scale data, leading to a large uncertainty in results. This type of simplistic growth modeling overestimates productivity potential and fails to incorporate biological effects, geographical location, or cultivation architecture. This study uses a large-scale, validated, outdoor photobioreactor microalgae growth model based on 21 reactor- and species-specific inputs to model the growth of Nannochloropsis. This model accurately accounts for biological effects such as nutrient uptake, respiration, and temperature and uses hourly historical meteorological data to determine the current global productivity potential. Global maps of the current near-term microalgae lipid and biomass productivity were generated based on the results of annual simulations at 4,388 global locations. Maximum annual average lipid yields between 24 and 27 m3·ha−1·y−1, corresponding to biomass yields of 13 to 15 g·m−2·d−1, are possible in Australia, Brazil, Colombia, Egypt, Ethiopia, India, Kenya, and Saudi Arabia. The microalgae lipid productivity results of this study were integrated with geography-specific fuel consumption and land availability data to perform a scalability assessment. Results highlight the promising potential of microalgae-based biofuels compared with traditional terrestrial feedstocks. When water, nutrients, and CO2 are not limiting, many regions can potentially meet significant fractions of their transportation fuel requirements through microalgae production, without land resource restriction. Discussion focuses on sensitivity of monthly variability in lipid production compared with annual average yields, effects of temperature on productivity, and a comparison of results with previous published modeling assumptions. PMID:24912176

Dietary administration of microalgae Navicula sp. affects immune status and gene expression of gilthead seabream (Sparus aurata).

PubMed

Reyes-Becerril, Martha; Guardiola, Francisco; Rojas, Maurilia; Ascencio-Valle, Felipe; Esteban, María Ángeles

2013-09-01

Effects of silage microalgae enriched with a probiotic and lyophilized microalgae were evaluated on main immune parameters and different gene expression of gilthead seabream (Sparus aurata L.). A total of 60 seabream were grouped into 3 treatment diets which were a control diet (commercial diet) without microalgae (C), commercial diet supplemented with silage microalgae Navicula sp. plus Lactobacillus sakei 5-4 (10(6) CFU g(-1)) (SM), and commercial diet supplemented with lyophilized microalgae (LM) for 4 weeks. Generally, the results showed a significant increase in the immune parameters, principally in leucocyte peroxidase, phagocytosis and complement activities in fish fed with SM diet compared to control group. About the gene expression in head-kidney, transcript levels (Interleukin-8, Interleukin-1β and β-defensin) were upregulated in fish fed with SM after 4 weeks of treatments. However, the gene expression was upregulated in intestine from fish fed with LM with significant difference in transferrin and cyclooxygenase 2 gene at 2 weeks, and in occludin, transferrin, interleukin-8 and interleukin-1β at 4 weeks. Finally, about the digestive enzymes, LM diet caused an upregulated of α-amylase and alkaline phosphatase genes at 2 weeks; however SM diet caused an upregulated trypsin gene at 4 weeks. SM diet a higher enhancing effect on gilthead seabream immune parameters than that observed when using LM. Furthermore, dietary administration of microalgae Navicula sp. provokes upregulation of several genes in the gut that correlates with slight inflammation. Further studies are needed to know if this diatom could be useful for administering as diet supplement for farmed fish. Copyright © 2013 Elsevier Ltd. All rights reserved.

Analysis of life cycle assessment of food/energy/waste systems and development and analysis of microalgae cultivation/wastewater treatment inclusive system

NASA Astrophysics Data System (ADS)

Armstrong, Kristina Ochsner

Across the world, crises in food, energy, land and water resources, as well as waste and greenhouse gas accumulation are inspiring research into the interactions among these environmental pressures. In the food/energy/waste problem set, most of the research is focused on describing the antagonistic relationships between food, energy and waste; these relationships are often analyzed with life cycle assessment (LCA). These analyses often include reporting of metrics of environmental performance with few functional units, often focusing on energy use, productivity and environmental impact while neglecting water use, food nutrition and safety. Additionally, they are often attributional studies with small scope which report location-specific parameters only. This thesis puts forth a series of recommendations to amend the current practice of LCA to combat these limitations and then utilizes these suggestions to analyze a synergistic food/waste/energy system. As an example analysis, this thesis describes the effect of combining wastewater treatment and microalgae cultivation on the productivity and scalability of the synergistic system. To ameliorate the high nutrient and water demands of microalgae cultivation, many studies suggest that microalgae be cultivated in wastewater so as to achieve large scale and low environmental costs. While cultivation studies have found this to be true, none explore the viability of the substitution in terms of productivity and scale-up. The results of this study suggest that while the integrated system may be suitable for low-intensity microalgae cultivation, for freshwater microalgae species or wastewater treatment it is not suitable for high intensity salt water microalgae cultivation. This study shows that the integration could result in reduced lipid content, high wastewater requirements, no greenhouse gas emissions benefit and only a small energy benefit.

Lipid production of microalga Chlorella sorokiniana CY1 is improved by light source arrangement, bioreactor operation mode and deep-sea water supplements.

PubMed

Chen, Chun-Yen; Chang, Hsin-Yueh

2016-03-01

Microalgae-based biodiesel has been recognized as a sustainable and promising alternative to fossil diesel. High lipid productivity of microalgae is required for economic production of biodiesel from microalgae. This study was undertaken to enhance the growth and oil accumulation of an indigenous microalga Chlorella sorokiniana CY1 by applying engineering strategies using deep-sea water as the medium. First, the microalga was cultivated using LED as the immersed light source, and the results showed that the immersed LED could effectively enhance the oil/lipid content and final microalgal biomass concentration to 53.8% and 2.5 g/l, respectively. Next, the semi-batch photobioreactor operation with deep-sea water was shown to improve lipid content and microalgal growth over those from using batch and continuous cultures under similar operating conditions. The optimal replacement ratio was 50%, resulting in an oil/lipid content and final biomass concentration of 61.5% and 2.8 g/l, respectively. A long-term semi-batch culture utilizing 50%-replaced medium was carried out for four runs. The final biomass concentration and lipid productivity were 2.5 g/L and 112.2 mg/L/d, respectively. The fatty acid composition of the microalgal lipids was predominant by palmitic acid, stearic acid, oleic acid and linoleic acid, and this lipid quality is suitable for biodiesel production. This demonstrates that optimizing light source arrangement, bioreactor operation and deep-sea water supplements could effectively promote the lipid production of C. sorokiniana CY1 for the applications in microalgae-based biodiesel industry. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effects of different levels of Chlorella microalgae on blood biochemical parameters and trace mineral concentrations of laying hens reared under heat stress condition

NASA Astrophysics Data System (ADS)

Moradi kor, Nasroallah; Akbari, Mohsen; Olfati, Ali

2016-05-01

This study was conducted to investigate the effect of different supplementation levels of Chlorella microalgae on serum metabolites and the plasma content of minerals in laying hens reared under heat stress condition (27.5-36.7 °C, variable). A total number of 378 (40 weeks of age, with mean body weight of 1390 ± 120 g) were randomly allocated to six treatments with seven replicates. The birds were randomly assigned to 6 treatments (C, T1, T2, T3, T4, and T5) with 7 replicate cages of 9 birds. C. microalgae at the rates of 100, 200, 300, 400, and 500 ppm with water were offered to groups T1, T2, T3, T4, and T5, respectively, while group C served as a control. At 71 days of trial, blood samples (14 samples per treatment) were taken for measuring serum metabolites and at 72 days for plasma mineral analysis. The results of this experiment showed that the supplementation of 200-500 ppm C. microalgae decreased the serum content of cholesterol, triglycerides, and LDL ( P < 0.05) whereas HDL content increased ( P < 0.05) in the hens supplemented with C. microalgae (300 or 400 and 500 ppm). C. microalgae at rates of 300-500 ppm caused a marked ( P < 0.05) increase in the plasma content of manganese or iodine and selenium but other minerals were not statistically different among treatments. Overall, from the results of the present experiment, it can be concluded that supplementation of C. microalgae at high rates was beneficial on blood parameters of laying hens reared under heat stress.

Simplified, rapid, and inexpensive estimation of water primary productivity based on chlorophyll fluorescence parameter Fo.

PubMed

Chen, Hui; Zhou, Wei; Chen, Weixian; Xie, Wei; Jiang, Liping; Liang, Qinlang; Huang, Mingjun; Wu, Zongwen; Wang, Qiang

2017-04-01

Primary productivity in water environment relies on the photosynthetic production of microalgae. Chlorophyll fluorescence is widely used to detect the growth status and photosynthetic efficiency of microalgae. In this study, a method was established to determine the Chl a content, cell density of microalgae, and water primary productivity by measuring chlorophyll fluorescence parameter Fo. A significant linear relationship between chlorophyll fluorescence parameter Fo and Chl a content of microalgae, as well as between Fo and cell density, was observed under pure-culture conditions. Furthermore, water samples collected from natural aquaculture ponds were used to validate the correlation between Fo and water primary productivity, which is closely related to Chl a content in water. Thus, for a given pure culture of microalgae or phytoplankton (mainly microalgae) in aquaculture ponds or other natural ponds for which the relationship between the Fo value and Chl a content or cell density could be established, Chl a content or cell density could be determined by measuring the Fo value, thereby making it possible to calculate the water primary productivity. It is believed that this method can provide a convenient way of efficiently estimating the primary productivity in natural aquaculture ponds and bringing economic value in limnetic ecology assessment, as well as in algal bloom monitoring. Copyright © 2017 Elsevier GmbH. All rights reserved.

Paper-based device for separation and cultivation of single microalga.

PubMed

Chen, Chih-Chung; Liu, Yi-Ju; Yao, Da-Jeng

2015-12-01

Single-cell separation is among the most useful techniques in biochemical research, diagnosis and various industrial applications. Microalgae species have great economic importance as industrial raw materials. Microalgae species collected from environment are typically a mixed and heterogeneous population of species that must be isolated and purified for examination and further application. Conventional methods, such as serial dilution and a streaking-plate method, are intensive of labor and inefficient. We developed a paper-based device for separation and cultivation of single microalga. The fabrication was simply conducted with a common laser printer and required only a few minutes without lithographic instruments and clean-room. The driving force of the paper device was simple capillarity without a complicated pump connection that is part of most devices for microfluidics. The open-structure design of the paper device makes it operable with a common laboratory micropipette for sample transfer and manipulation with a naked eye or adaptable to a robotic system with functionality of high-throughput retrieval and analysis. The efficiency of isolating a single cell from mixed microalgae species is seven times as great as with a conventional method involving serial dilution. The paper device can serve also as an incubator for microalgae growth on simply rinsing the paper with a growth medium. Many applications such as highly expressed cell selection and various single-cell analysis would be applicable. Copyright © 2015 Elsevier B.V. All rights reserved.

Expression of the heterologous Dunaliella tertiolecta fatty acyl-ACP thioesterase leads to increased lipid production in Chlamydomonas reinhardtii.

PubMed

Tan, Kenneth Wei Min; Lee, Yuan Kun

2017-04-10

Biofuel production from genetically-engineered microalgae is currently among the most widely studied strategies in generating renewable energy. However, microalgae currently suffer from low oil yields which limit the commercial feasibility of industrial-scale production. A major bottleneck in cost-efficient biofuel production from microalgae is the dilemma between biomass productivity and lipid accumulation. When grown under stressful culture conditions such as nitrogen depletion, microalgae accumulate large amounts of neutral lipids, but it comes at the expense of growth which negatively impacts overall lipid productivity. Overexpression of acyl-ACP thioesterases (TE) had been successful in increasing the production of fatty acids (FA) in prokaryotes such as E. coli and cyanobacteria, but has not been effectively tested in microalgae. In this study, we introduced a TE from D. tertiolecta (DtTE) into C. reinhardtii to investigate its effects on FA production without compromising growth. The results indicate that C. reinhardtii transformants were able to produce 63 and 94% more neutral lipids than the wild-type, which translates to an approximately 56% improvement in total lipids, without compromising growth. These findings demonstrate the cross-species functionality of TE, and provide a platform for further studies into using TE as a strategy to increase biofuel production from microalgae. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct biodiesel production from wet microalgae biomass of Chlorella pyrenoidosa through in situ transesterification.

PubMed

Cao, Hechun; Zhang, Zhiling; Wu, Xuwen; Miao, Xiaoling

2013-01-01

A one-step process was applied to directly converting wet oil-bearing microalgae biomass of Chlorella pyrenoidosa containing about 90% of water into biodiesel. In order to investigate the effects of water content on biodiesel production, distilled water was added to dried microalgae biomass to form wet biomass used to produce biodiesel. The results showed that at lower temperature of 90°C, water had a negative effect on biodiesel production. The biodiesel yield decreased from 91.4% to 10.3% as water content increased from 0% to 90%. Higher temperature could compensate the negative effect. When temperature reached 150°C, there was no negative effect, and biodiesel yield was over 100%. Based on the above research, wet microalgae biomass was directly applied to biodiesel production, and the optimal conditions were investigated. Under the optimal conditions of 100 mg dry weight equivalent wet microalgae biomass, 4 mL methanol, 8 mL n-hexane, 0.5 M H2SO4, 120°C, and 180 min reaction time, the biodiesel yield reached as high as 92.5% and the FAME content was 93.2%. The results suggested that biodiesel could be effectively produced directly from wet microalgae biomass and this effort may offer the benefits of energy requirements for biodiesel production.

Improving carbohydrate production of Chlorella sorokiniana NIES-2168 through semi-continuous process coupled with mixotrophic cultivation.

PubMed

Wang, Yue; Chiu, Sheng-Yi; Ho, Shih-Hsin; Liu, Zhuo; Hasunuma, Tomohisa; Chang, Ting-Ting; Chang, Kuan-Fu; Chang, Jo-Shu; Ren, Nan-Qi; Kondo, Akihiko

2016-08-01

Biofuels from microalgae is now a hot issue of great potential. However, achieving high starch productivity with photoautotrophic microalgae is still challenging. A feasible approach to enhance the growth and target product of microalgae is to conduct mixotrophic cultivation. The appropriate acetate addition combined with CO2 supply as dual carbon sources (i.e., mixotrophic cultivation) could enhance the cell growth of some microalgae species, but the effect of acetate-mediated mixotrophic culture mode on carbohydrate accumulation in microalgae remains unclear. Moreover, there is still lack of the information concerning how to increase the productivity of carbohydrates from microalgae under acetate-amended mixotrophic cultivation and how to optimize the engineering strategies to achieve the goal. This study was undertaken to develop an optimal acetate-contained mixotrophic cultivation system coupled with effective operation strategies to markedly improve the carbohydrate productivity of Chlorella sorokiniana NIES-2168. The optimal carbohydrate productivity of 695 mg/L/d was obtained, which is the highest value ever reported. The monosaccharide in the accumulated carbohydrates is mainly glucose (i.e., 85-90%), which is very suitable for bio-alcohols fermentation. Hence, by applying the optimal process developed in this study, C. sorokiniana NIES-2168 has a high potential to serve as a feedstock for subsequent biofuels conversion. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent Developments on Genetic Engineering of Microalgae for Biofuels and Bio-Based Chemicals.

PubMed

Ng, I-Son; Tan, Shih-I; Kao, Pei-Hsun; Chang, Yu-Kaung; Chang, Jo-Shu

2017-10-01

Microalgae serve as a promising source for the production of biofuels and bio-based chemicals. They are superior to terrestrial plants as feedstock in many aspects and their biomass is naturally rich in lipids, carbohydrates, proteins, pigments, and other valuable compounds. Due to the relatively slow growth rate and high cultivation cost of microalgae, to screen efficient and robust microalgal strains as well as genetic modifications of the available strains for further improvement are of urgent demand in the development of microalgae-based biorefinery. In genetic engineering of microalgae, transformation and selection methods are the key steps to accomplish the target gene modification. However, determination of the preferable type and dosage of antibiotics used for transformant selection is usually time-consuming and microalgal-strain-dependent. Therefore, more powerful and efficient techniques should be developed to meet this need. In this review, the conventional and emerging genome-editing tools (e.g., CRISPR-Cas9, TALEN, and ZFN) used in editing the genomes of nuclear, mitochondria, and chloroplast of microalgae are thoroughly surveyed. Although all the techniques mentioned above demonstrate their abilities to perform gene editing and desired phenotype screening, there still need to overcome higher production cost and lower biomass productivity, to achieve efficient production of the desired products in microalgal biorefineries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct Biodiesel Production from Wet Microalgae Biomass of Chlorella pyrenoidosa through In Situ Transesterification

PubMed Central

Cao, Hechun; Zhang, Zhiling; Wu, Xuwen; Miao, Xiaoling

2013-01-01

A one-step process was applied to directly converting wet oil-bearing microalgae biomass of Chlorella pyrenoidosa containing about 90% of water into biodiesel. In order to investigate the effects of water content on biodiesel production, distilled water was added to dried microalgae biomass to form wet biomass used to produce biodiesel. The results showed that at lower temperature of 90°C, water had a negative effect on biodiesel production. The biodiesel yield decreased from 91.4% to 10.3% as water content increased from 0% to 90%. Higher temperature could compensate the negative effect. When temperature reached 150°C, there was no negative effect, and biodiesel yield was over 100%. Based on the above research, wet microalgae biomass was directly applied to biodiesel production, and the optimal conditions were investigated. Under the optimal conditions of 100 mg dry weight equivalent wet microalgae biomass, 4 mL methanol, 8 mL n-hexane, 0.5 M H2SO4, 120°C, and 180 min reaction time, the biodiesel yield reached as high as 92.5% and the FAME content was 93.2%. The results suggested that biodiesel could be effectively produced directly from wet microalgae biomass and this effort may offer the benefits of energy requirements for biodiesel production. PMID:24195081

Nutrient and media recycling in heterotrophic microalgae cultures.

PubMed

Lowrey, Joshua; Armenta, Roberto E; Brooks, Marianne S

2016-02-01

In order for microalgae-based processes to reach commercial production for biofuels and high-value products such as omega-3 fatty acids, it is necessary that economic feasibility be demonstrated at the industrial scale. Therefore, process optimization is critical to ensure that the maximum yield can be achieved from the most efficient use of resources. This is particularly true for processes involving heterotrophic microalgae, which have not been studied as extensively as phototrophic microalgae. An area that has received significant conceptual praise, but little experimental validation, is that of nutrient recycling, where the waste materials from prior cultures and post-lipid extraction are reused for secondary fermentations. While the concept is very simple and could result in significant economic and environmental benefits, there are some underlying challenges that must be overcome before adoption of nutrient recycling is viable at commercial scale. Even more, adapting nutrient recycling for optimized heterotrophic cultures presents some added challenges that must be identified and addressed that have been largely unexplored to date. These challenges center on carbon and nitrogen recycling and the implications of using waste materials in conjunction with virgin nutrients for secondary cultures. The aim of this review is to provide a foundation for further understanding of nutrient recycling for microalgae cultivation. As such, we outline the current state of technology and practical challenges associated with nutrient recycling for heterotrophic microalgae on an industrial scale and give recommendations for future work.

CO2 , NOx and SOx removal from flue gas via microalgae cultivation: a critical review.

PubMed

Yen, Hong-Wei; Ho, Shih-Hsin; Chen, Chun-Yen; Chang, Jo-Shu

2015-06-01

Flue gas refers to the gas emitting from the combustion processes, and it contains CO2 , NOx , SOx and other potentially hazardous compounds. Due to the increasing concerns of CO2 emissions and environmental pollution, the cleaning process of flue gas has attracted much attention. Using microalgae to clean up flue gas via photosynthesis is considered a promising CO2 mitigation process for flue gas. However, the impurities in the flue gas may inhibit microalgal growth, leading to a lower microalgae-based CO2 fixation rate. The inhibition effects of SOx that contribute to the low pH could be alleviated by maintaining a stable pH level, while NOx can be utilized as a nitrogen source to promote microalgae growth when it dissolves and is oxidized in the culture medium. The yielded microalgal biomass from fixing flue gas CO2 and utilizing NOx and SOx as nutrients would become suitable feedstock to produce biofuels and bio-based chemicals. In addition to the removal of SOx , NOx and CO2 , using microalgae to remove heavy metals from flue gas is also quite attractive. In conclusion, the use of microalgae for simultaneous removal of CO2 , SOx and NOx from flue gas is an environmentally benign process and represents an ideal platform for CO2 reutilization. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhanced accumulation of starch and total carbohydrates in alginate-immobilized Chlorella spp. induced by Azospirillum brasilense: I. Autotrophic conditions.

PubMed

Choix, Francisco J; de-Bashan, Luz E; Bashan, Yoav

2012-10-10

The effect of the microalgae-growth promoting bacterium Azospirillum brasilense on accumulation of total carbohydrates and starch in two species of Chlorella (Chlorella vulgaris and Chlorella sorokiniana), when the bacterium and each microalga were jointly immobilized in alginate beads was studied under autotrophic conditions for 144 h in synthetic medium. The interaction of the bacterium with the microalgae enhanced accumulation of total carbohydrate and starch. Cells of Chlorella accumulated the highest amounts of carbohydrate after incubation for 24h. Yet, this did not coincide with the highest affinity and volumetric productivity measured in these cultures. However, after incubation for 72 h, mainly in jointly immobilized treatments of both microalgae species, the cultures reached their highest total carbohydrate content (mainly as starch) and also the highest affinity and volumetric productivity. These results demonstrate the potential of A. brasilense to affect carbohydrates and starch accumulation in Chlorella spp. when both microorganisms are co-cultured, which can be an important tool for applications of microalgae. Copyright © 2012. Published by Elsevier Inc.

Production of long chain omega-3 fatty acids and carotenoids in tropical areas by a new heat-tolerant microalga Tetraselmis sp. DS3.

PubMed

Tsai, Hsin-Pei; Chuang, Lu-Te; Chen, Ching-Nen Nathan

2016-02-01

Demand for long chain ω-3 fatty acids from non-fish source for vegetarians has increased recently. Marine microalgae are the primary producers of EPA/DHA and promising alternatives for fish oil. Tropical areas have abundant sunlight throughout the year for microalgal cultivation but this practice can be hindered by high temperature. Discovery of heat-tolerant marine microalgae that can synthesize EPA/DHA will solve these problems. A new species of microalga was isolated from a high temperature lagoon and identified as Tetraselmis sp. DS3. These cells could grow at 40 °C, the highest temperature for marine microalgal growth ever reported. Its ω-3 fatty acids and EPA accounted for 33 and 10% of total lipids, respectively, grown in nitrogen-depleted conditions. These cells also accumulated more than 5% β-carotene and 0.48% lutein in biomass. This new microalga can be cultivated for long chain ω-3 fatty acids and lutein production in the tropical areas. Copyright © 2015 Elsevier Ltd. All rights reserved.

Microalgae Nutraceuticals.

PubMed

Nicoletti, Marcello

2016-08-22

Among the new entries in the food supplements sector, an important place must be assigned to nutraceuticals containing microalgae, nowadays accounting for a large and rapidly expanding market. The marketed products are mainly based on three production strains, i.e., Spirulina and Chlorella, followed at a distance by Klamath. It is a composite situation, since two of them are cyanobacteria and the second one is eukaryotic. The reality is that each presents similarities in shape and appearance concerning the marketed form and several utilizations, and peculiarities that need special attention and adequate studies. First, general information is reported about the current scientific knowledge on each microalga, in particular the nutritional value and properties in prevention and wellbeing. Second, original studies are presented concerning the quality control of marketed products. Quality control is a key argument in nutraceuticals validation. Microalgae are particular organisms that need specific approaches to confirm identity and validate properties. The proposed control of quality is based on microscopic analysis of the morphologic characteristics. The final parts of this paper are dedicated to the need for specificity in uses and claims and to considerations about the future of microalgae in food supplements.

Utilization of industrial dairy waste as microalgae cultivation medium : a potential study for sustainable energy resources

NASA Astrophysics Data System (ADS)

Nurmayani, S.; Sugiarti, Y.; Putra, R. H.

2016-04-01

Microalgae is one of biodiesel resources and call as third generation biofuel. Biodiesel is one alternative energy that being developed. So study about resource of biodiesel need a development, for the example is development the basic material such as microalgae. In this paper we explain the potential use of dairy waste from industry as a cultivation medium of microalgae for biodiesel production. Dairy waste from dairy industry contains 34.98% protein, 4.42% lactose, 9.77% fiber, 11.04% fat, 2.33% calcium, 1.05% phosfor, and 0.4 % magnesium, meaning that the dairy waste from dairy industry has a relatively high nutrient content and complete from a source of carbon, nitrogen and phosphorus as macro nutrients. The method in this paper is literature review to resulting a new conclusion about the potency of waste water from dairy industry as microalgae cultivation medium. Based on the study, the dairy waste from dairy industry has potency to be used as cultivation medium of Botryococcus braunii in the production of biodiesel, replacing the conventional cultivation medium.

Lipid catabolism in microalgae.

PubMed

Kong, Fantao; Romero, Ismael Torres; Warakanont, Jaruswan; Li-Beisson, Yonghua

2018-06-01

Lipid degradation processes are important in microalgae because survival and growth of microalgal cells under fluctuating environmental conditions require permanent remodeling or turnover of membrane lipids as well as rapid mobilization of storage lipids. Lipid catabolism comprises two major spatially and temporarily separated steps, namely lipolysis, which releases fatty acids and head groups and is catalyzed by lipases at membranes or lipid droplets, and degradation of fatty acids to acetyl-CoA, which occurs in peroxisomes through the β-oxidation pathway in green microalgae, and can sometimes occur in mitochondria in some other algal species. Here we review the current knowledge on the enzymes and regulatory proteins involved in lipolysis and peroxisomal β-oxidation and highlight gaps in our understanding of lipid degradation pathways in microalgae. Metabolic use of acetyl-CoA products via glyoxylate cycle and gluconeogenesis is also reviewed. We then present the implication of various cellular processes such as vesicle trafficking, cell cycle and autophagy on lipid turnover. Finally, physiological roles and the manipulation of lipid catabolism for biotechnological applications in microalgae are discussed. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Ozone Application for Tofu Waste Water Treatment and Its Utilisation for Growth Medium of Microalgae Spirulina sp

NASA Astrophysics Data System (ADS)

Hadiyanto, Hadiyanto

2018-02-01

Tofu industries produce waste water containing high organic contents and suspendid solid which is harmful if directly discharged to the environment. This waste can lead to disruption of water quality and lowering the environmental carrying capacity of waters around the tofu industries. Besides, the tofu waste water still contains high nitrogen contents which can be used for microalgae growth. This study was aimed to reduce the pollution load (chemical oxygen demand-COD) of tofue wastewater by using ozone treatments and to utilize nutrients in treated tofu waste water as medium growth of microalgae. The result showed that the reduction of COD by implementation of ozone treatment followed first order kinetic. Under variation of waste concentrations between 10-40%, the degradation rate constant was in the range of 0.00237-0.0149 min-1. The microalgae was able to grow in the tofue waste medium by the growth rate constants of 0.15-0.29 day-1. This study concluded that tofu waste was highly potent for microalgae growth.

Pretreated animal and human waste as a substantial nutrient source for cultivation of microalgae for biodiesel production.

PubMed

Kumar, Vinod; Kumar, Akshay; Nanda, Manisha

2018-05-25

The use of human and animal wastes for fertilization of aquaculture ponds has been practiced for thousands of years. In the present work, we have used the excreta (human urine, poultry waste, cow dung, and urine) as a nutrient source for the cultivation of Chlorella singularis, Micractinium pusillum, and Chlorella sorokiniana strains of microalgae. Different solid wastes were treated with 60 mM H 2 SO 4 for the extraction of nutrients. After treatment, the supernatant of different solid wastes and liquid waste were diluted 5, 10, 15, and 20% to be used as a media for the cultivation of microalgae. Chlorella sorokiniana was able to grow in all concentration of excreta media. The maximum growth rate 140 ± 3.1 mg/L/day and lipid production (45.5 ± 2.3 mg/L/day) was obtained in 20% poultry. Among the different excreta media used for cultivation of microalgae, poultry media displayed the best results and thus, should be used for large scale cultivation of microalgae.

Contribution of benthic microalgae to the temporal variation in phytoplankton assemblages in a macrotidal system.

PubMed

Hernández Fariñas, Tania; Ribeiro, Lourenço; Soudant, Dominique; Belin, Catherine; Bacher, Cédric; Lampert, Luis; Barillé, Laurent

2017-10-01

Suspended marine benthic microalgae in the water column reflect the close relationship between the benthic and pelagic components of coastal ecosystems. In this study, a 12-year phytoplankton time-series was used to investigate the contribution of benthic microalgae to the pelagic system at a site along the French-Atlantic coast. Furthermore, all taxa identified were allocated into different growth forms in order to study their seasonal patterns. The highest contribution of benthic microalgae was observed during the winter period, reaching up to 60% of the carbon biomass in the water column. The haptobenthic growth form showed the highest contribution in terms of biomass, dominant in the fall-winter period when the turbidity and the river flow were high. The epipelic growth form did not follow any seasonal pattern. The epiphytic diatom Licmophora was most commonly found during summer. As benthic microalgae were found in the water column throughout the year, the temporal variation detected in the structure of pelagic assemblages in a macrotidal ecosystem was partly derived from the differentiated contribution of several benthic growth forms. © 2017 Phycological Society of America.

Microalgae Nutraceuticals

PubMed Central

Nicoletti, Marcello

2016-01-01

Among the new entries in the food supplements sector, an important place must be assigned to nutraceuticals containing microalgae, nowadays accounting for a large and rapidly expanding market. The marketed products are mainly based on three production strains, i.e., Spirulina and Chlorella, followed at a distance by Klamath. It is a composite situation, since two of them are cyanobacteria and the second one is eukaryotic. The reality is that each presents similarities in shape and appearance concerning the marketed form and several utilizations, and peculiarities that need special attention and adequate studies. First, general information is reported about the current scientific knowledge on each microalga, in particular the nutritional value and properties in prevention and wellbeing. Second, original studies are presented concerning the quality control of marketed products. Quality control is a key argument in nutraceuticals validation. Microalgae are particular organisms that need specific approaches to confirm identity and validate properties. The proposed control of quality is based on microscopic analysis of the morphologic characteristics. The final parts of this paper are dedicated to the need for specificity in uses and claims and to considerations about the future of microalgae in food supplements. PMID:28231149

Sustainable production of toxin free marine microalgae biomass as fish feed in large scale open system in the Qatari desert.

PubMed

Das, Probir; Thaher, Mahmoud Ibrahim; Hakim, Mohammed Abdul Quadir Mohd Abdul; Al-Jabri, Hareb Mohammed S J

2015-09-01

Mass cultivation of microalgae biomass for feed should be cost effective and toxin free. Evaporation loss in Qatar can be as high as 2 cm/d. Hence, production of marine microalgae biomass in Qatar would also require mitigating water loss as there was only very limited groundwater reserve. To address these issues, a combination of four growth conditions were applied to a 25,000 L raceway pond: locally isolated microalgae strain was selected which could grow in elevated salinity; strain that did not require silica and vitamins; volume of the culture would increase over time keeping denser inoculum in the beginning, and evaporation water loss would be balanced by adding seawater only. A local saline tolerant Nannochloropsis sp. was selected which did not require silica and vitamins. When the above conditions were combined in the pond, average areal biomass productivities reached 20.37 g/m(2)/d, and the culture was not contaminated by any toxic microalgae. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characteristics and kinetics study of simultaneous pyrolysis of microalgae Chlorella vulgaris, wood and polypropylene through TGA.

PubMed

Azizi, Kolsoom; Keshavarz Moraveji, Mostafa; Abedini Najafabadi, Hamed

2017-11-01

Thermal decomposition behavior and kinetics of microalgae Chlorella vulgaris, wood and polypropylene were investigated using thermogravimetric analysis (TGA). Experiments were carried out at heating rates of 10, 20 and 40°C/min from ambient temperature to 600°C. The results show that pyrolysis process of C. vulgaris and wood can be divided into three stages while pyrolysis of polypropylene occurs almost totally in one step. It is shown that wood can delay the pyrolysis of microalgae while microalgae can accelerate the pyrolysis of wood. The existence of polymer during the pyrolysis of microalgae or wood will lead to two divided groups of peaks in DTG curve of mixtures. The results showed that interaction is inhibitive rather than synergistic during the decomposition process of materials. Kinetics of process is studied by the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The average E values obtained from FWO and KAS methods were 131.228 and 142.678kJ/mol, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adhesion of Chlamydomonas microalgae to surfaces is switchable by light

NASA Astrophysics Data System (ADS)

Kreis, Christian Titus; Le Blay, Marine; Linne, Christine; Makowski, Marcin Michal; Bäumchen, Oliver

2018-01-01

Microalgae are photoactive microbes that live in liquid-infused environments, such as soil, temporary pools and rocks, where they encounter and colonize a plethora of surfaces. Their photoactivity manifests itself in a variety of processes, including light-directed motility (phototaxis), the growth of microalgal populations, and their photosynthetic machinery. Although microbial responses to light have been widely recognized, any influence of light on cell-surface interactions remains elusive. Here, we reveal that the unspecific adhesion of microalgae to surfaces can be reversibly switched on and off by light. Using a micropipette force spectroscopy technique, we measured in vivo single-cell adhesion forces and show that the microalga's flagella provide light-switchable adhesive contacts with the surface. This light-induced adhesion to surfaces is an active and completely reversible process that occurs on a timescale of seconds. Our results suggest that light-switchable adhesiveness is a natural functionality of microalgae to regulate the transition between the planktonic and the surface-associated state, which yields an adhesive adaptation to optimize the photosynthetic efficiency in conjunction with phototaxis.

Kinetic characteristics and modeling of microalgae Chlorella vulgaris growth and CO2 biofixation considering the coupled effects of light intensity and dissolved inorganic carbon.

PubMed

Chang, Hai-Xing; Huang, Yun; Fu, Qian; Liao, Qiang; Zhu, Xun

2016-04-01

Understanding and optimizing the microalgae growth process is an essential prerequisite for effective CO2 capture using microalgae in photobioreactors. In this study, the kinetic characteristics of microalgae Chlorella vulgaris growth in response to light intensity and dissolved inorganic carbon (DIC) concentration were investigated. The greatest values of maximum biomass concentration (Xmax) and maximum specific growth rate (μmax) were obtained as 2.303 g L(-1) and 0.078 h(-1), respectively, at a light intensity of 120 μmol m(-2) s(-1) and DIC concentration of 17 mM. Based on the results, mathematical models describing the coupled effects of light intensity and DIC concentration on microalgae growth and CO2 biofixation are proposed. The models are able to predict the temporal evolution of C. vulgaris growth and CO2 biofixation rates from lag to stationary phases. Verification experiments confirmed that the model predictions agreed well with the experimental results. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of Selenite on Unicellular Green Microalga Chlorella pyrenoidosa: Bioaccumulation of Selenium, Enhancement of Photosynthetic Pigments, and Amino Acid Production.

PubMed

Zhong, Yu; Cheng, Jay J

2017-12-20

Microalgae were studied as function bioaccumulators of selenium (Se) for food and feed supplement. To investigate the bioaccumulation of Se and its effects on the unicellular green alga Chlorella pyrenoidosa, the algal growth curve, fluorescence parameters, antioxidant enzyme activity, and fatty acid and amino acid profiles were examined. We found that Se at low concentrations (≤40 mg L -1 ) positively promoted algal growth and inhibited lipid peroxidation and intracellular reactive oxygen species. The antioxidative effect was associated with an increase in the levels of glutathione peroxidase, catalase, linolenic acid, and photosynthetic pigments. Meanwhile, a significant increase in amino acid and organic Se content was also detected in the microalgae. In contrast, we found opposite effects in C. pyrenoidosa exposed to >60 mg L -1 Se. The antioxidation and toxicity appeared to be correlated with the bioaccumulation of excess Se. These results provide a better understanding of the effect of Se on green microalgae, which may help in the development of new technological applications for the production of Se-enriched biomass from microalgae.

Enhancement of Biomass and Lipid Productivities of Water Surface-Floating Microalgae by Chemical Mutagenesis

PubMed Central

Nojima, Daisuke; Ishizuka, Yuki; Muto, Masaki; Ujiro, Asuka; Kodama, Fumito; Yoshino, Tomoko; Maeda, Yoshiaki; Matsunaga, Tadashi; Tanaka, Tsuyoshi

2017-01-01

Water surface-floating microalgae have great potential for biofuel applications due to the ease of the harvesting process, which is one of the most problematic steps in conventional microalgal biofuel production. We have collected promising water surface-floating microalgae and characterized their capacity for biomass and lipid production. In this study, we performed chemical mutagenesis of two water surface-floating microalgae to elevate productivity. Floating microalgal strains AVFF007 and FFG039 (tentatively identified as Botryosphaerella sp. and Chlorococcum sp., respectively) were exposed to ethyl methane sulfonate (EMS) or 1-methyl-3-nitro-1-nitrosoguanidine (MNNG), and pale green mutants (PMs) were obtained. The most promising FFG039 PM formed robust biofilms on the surface of the culture medium, similar to those formed by wild type strains, and it exhibited 1.7-fold and 1.9-fold higher biomass and lipid productivities than those of the wild type. This study indicates that the chemical mutation strategy improves the lipid productivity of water surface-floating microalgae without inhibiting biofilm formation and floating ability. PMID:28555001

Enhancement of Biomass and Lipid Productivities of Water Surface-Floating Microalgae by Chemical Mutagenesis.

PubMed

Nojima, Daisuke; Ishizuka, Yuki; Muto, Masaki; Ujiro, Asuka; Kodama, Fumito; Yoshino, Tomoko; Maeda, Yoshiaki; Matsunaga, Tadashi; Tanaka, Tsuyoshi

2017-05-27

Water surface-floating microalgae have great potential for biofuel applications due to the ease of the harvesting process, which is one of the most problematic steps in conventional microalgal biofuel production. We have collected promising water surface-floating microalgae and characterized their capacity for biomass and lipid production. In this study, we performed chemical mutagenesis of two water surface-floating microalgae to elevate productivity. Floating microalgal strains AVFF007 and FFG039 (tentatively identified as Botryosphaerella sp. and Chlorococcum sp., respectively) were exposed to ethyl methane sulfonate (EMS) or 1-methyl-3-nitro-1-nitrosoguanidine (MNNG), and pale green mutants (PMs) were obtained. The most promising FFG039 PM formed robust biofilms on the surface of the culture medium, similar to those formed by wild type strains, and it exhibited 1.7-fold and 1.9-fold higher biomass and lipid productivities than those of the wild type. This study indicates that the chemical mutation strategy improves the lipid productivity of water surface-floating microalgae without inhibiting biofilm formation and floating ability.

Anaerobic digestion of cattail by rumen cultures.

PubMed

Hu, Zhen-Hu; Yu, Han-Qing

2006-01-01

The anaerobic digestion of aquatic plants could serve the dual roles for producing renewable energy and reducing waste. In this study, the anaerobic digestion of cattail (Typha latifolia linn), a lignocellulosic aquatic plant, by rumen microorganisms in batch cultures was investigated. At a substrate level of 12.4 g/l volatile solids (VS) and pH 6.7, maximum VS conversion of 66% was achieved within an incubation time of 125 h. However, a decrease in pH from 6.7 to 5.8 resulted in a marked reduction in VS conversion. The total volatile fatty acids (VFAs) yield was about 0.56 g/g VS digested. Acetate and propionate were the major aqueous fermentation products, while butyrate, i-butyrate and valerate were also formed in smaller quantities. Biogas that was produced was composed of carbon dioxide, methane and hydrogen. A modified Gompertz equation was developed to describe substrate consumption and product formation. The hydrolysis of insoluble components was the rate-limiting step in the anaerobic digestion of cattail.

Enzymatic versus nonenzymatic mechanisms for Fe(III) reduction in aquatic sediments

USGS Publications Warehouse

Lovley, D.R.; Phillips, E.J.P.; Lonergan, D.J.

1991-01-01

The potential for nonenzymatic reduction of Fe(III) either by organic compounds or by the development of a low redox potential during microbial metabolism was compared with direct, enzymatic Fe(III) reduction by Fe(III)-reducing microorganisms. At circumneutral pH, very few organic compounds nonenzymatically reduced Fe(III). In contrast, in the presence of the appropriate Fe(IH)-reducing microorganisms, most of the organic compounds examined could be completely oxidized to carbon dioxide with the reduction of Fe(III). Even for those organic compounds that could nonenzymatically reduce Fe(III), microbial Fe(III) reduction was much more extensive. The development of a low redox potential during microbial fermentation did not result in nonenzymatic Fe(III) reduction. Model organic compounds were readily oxidized in Fe(III)-reducing aquifer sediments, but not in sterilized sediments. These results suggest that microorganisms enzymatically catalyze most of the Fe(III) reduction in the Fe(III) reduction zone of aquatic sediments and aquifers.

Feasibility of remote sensing benthic microalgae

NASA Technical Reports Server (NTRS)

Zingmark, R. G.

1979-01-01

Results of data analyses from multispectral scanning data are presented. The data was collected in July 1977 for concentration of chlorophyll in benthic microalgae (mainly diatoms) on an estuary mudflat.

Multi-Product Microalgae Biorefineries: From Concept Towards Reality.

PubMed

't Lam, G P; Vermuë, M H; Eppink, M H M; Wijffels, R H; van den Berg, C

2018-02-01

Although microalgae are a promising biobased feedstock, industrial scale production is still far off. To enhance the economic viability of large-scale microalgae processes, all biomass components need to be valorized, requiring a multi-product biorefinery. However, this concept is still too expensive. Typically, downstream processing of industrial biotechnological bulk products accounts for 20-40% of the total production costs, while for a microalgae multi-product biorefinery the costs are substantially higher (50-60%). These costs are high due to the lack of appropriate and mild technologies to access the different product fractions such as proteins, carbohydrates, and lipids. To reduce the costs, simplified processes need to be developed for the main unit operations including harvesting, cell disruption, extraction, and possibly fractionation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Carotenoids in Microalgae.

PubMed

Henríquez, Vitalia; Escobar, Carolina; Galarza, Janeth; Gimpel, Javier

Carotenoids are a class of isoprenoids synthesized by all photosynthetic organisms as well as by some non-photosynthetic bacteria and fungi with broad applications in food, feed and cosmetics, and also in the nutraceutical and pharmaceutical industries. Microalgae represent an important source of high-value products, which include carotenoids, among others. Carotenoids play key roles in light harvesting and energy transfer during photosynthesis and in the protection of the photosynthetic apparatus against photooxidative damage. Carotenoids are generally divided into carotenes and xanthophyls, but accumulation in microalgae can also be classified as primary (essential for survival) and secondary (by exposure to specific stimuli).In this chapter, we outline the high value carotenoids produced by commercially important microalgae, their production pathways, the improved production rates that can be achieved by genetic engineering as well as their biotechnological applications.

Multilateral approach on enhancing economic viability of lipid production from microalgae: A review.

PubMed

Shin, Ye Sol; Choi, Hong Il; Choi, Jin Won; Lee, Jeong Seop; Sung, Young Joon; Sim, Sang Jun

2018-06-01

Microalgae have been rising as a feedstock for biofuel in response to the energy crisis. Due to a high lipid content, composed of fatty acids favorable for the biodiesel production, microalgae are still being investigated as an alternative to biodiesel. Environmental factors and process conditions can alternate the quality and the quantity of lipid produced by microalgae, which can be critical for the overall production of biodiesel. To maximize both the lipid content and the biomass productivity, it is necessary to start with robust algal strains and optimal physio-chemical properties of the culture environment in combination with a novel culture system. These accumulative approaches for cost reduction can take algal process one step closer in achieving the economic feasibility. Copyright © 2018 Elsevier Ltd. All rights reserved.

Environmental concentrations of pharmaceuticals directly affect phytoplankton and effects propagate through trophic interactions.

PubMed

Grzesiuk, Malgorzata; Spijkerman, Elly; Lachmann, Sabrina C; Wacker, Alexander

2018-07-30

Pharmaceuticals are found in freshwater ecosystems where even low concentrations in the range of ng L -1 may affect aquatic organisms. In the current study, we investigated the effects of chronic exposure to three pharmaceuticals on two microalgae, a potential modulation of the effects by additional inorganic phosphorus (P i ) limitation, and a potential propagation of the pharmaceuticals' effect across a trophic interaction. The latter considers that pharmaceuticals are bioaccumulated by algae, potentially metabolized into more (or less) toxic derivates and consequently consumed by zooplankton. We cultured Acutodesmus obliquus and Nannochloropsis limnetica in P i -replete and P i -limited medium contaminated with one of three commonly human used pharmaceuticals: fluoxetine, ibuprofen, and propranolol. Secondly, we tested to what extent first level consumers (Daphnia magna) were affected when fed with pharmaceutical-grown algae. Chronic exposure, covering 30 generations, led to (i) decreased cell numbers of A. obliquus in the presence of fluoxetine (under P i -replete conditions) (ii) increased carotenoid to chlorophyll ratios in N. limnetica (under P i -limited conditions), and (iii) increased photosynthetic yields in A. obliquus (in both P i -conditions). In addition, ibuprofen affected both algae and their consumer: Feeding ibuprofen-contaminated algae to P i -stressed D. magna improved their survival. We demonstrate, that even very low concentrations of pharmaceuticals present in freshwater ecosystems can significantly affect aquatic organisms when chronically exposed. Our study indicates that pharmaceutical effects can cross trophic levels and travel up the food chain. Copyright © 2018 Elsevier Inc. All rights reserved.

[Growth inhibition of the four species of red tide microalgae by extracts from Enteromorpha prolifera extracted with the five solvents].

PubMed

Sun, Ying-Ying; Liu, Xiao-Xiao; Wang, Chang-Hai

2010-06-01

To study the effects of extracts of Enteromorpha prolifera on the growth of the four species of red tide microalgae (Amphidinium hoefleri, Karenia mikimitoi, Alexandrium tamarense and Skeletonema costatum), the extracts were extracted with five solvents (methanol, acetone, ethyl acetate, chloroform and petroleum ether), respectively. Based on the observation of algal morphology and the measurement of algal density, cell size and the contents of physiological indicators (chlorophyll, protein and polysaccharide), the results showed methanol extracts of E. prolifera had the strongest action. The inhibitory effects of A. hoefleri, K. mikimitoi, A. tamarense and S. costatum by the methanol extracts were 54.0%, 48.1%, 44.0% and 37.5% in day 10, respectively. The extracts of E. prolifera extracted with methanol, acetone and ethyl acetate caused cavities, pieces and pigment reduction in cells, and those with chloroform and petroleum ether caused goffers on cells. The extracts of E. prolifera extracted with all the five solvents decreased athletic ability of the cells, among which those extracted with ethyl acetate, chloroform and petroleum ether decreased cell size of test microalgae. The further investigation found that the methanol extracts significantly decreased contents of chlorophyll, protein and polysaccharide in the cells of those microalgae. The inhibitory effect of chlorophyll, protein and polysaccharide contents of four species of microalgae by the methanol extracts was about 51%. On the basis of the above experiments, dry powder of E. prolifera were extracts with methanol, and extracts were obtained. The methanol extracts were partitioned to petroleum ether phase, ethyl acetate phase, n-butanol phase and distilled water phase by liquid-liquid fractionation, and those with petroleum ether and ethyl acetate significantly inhibited the growth of all test microalgae, and the inhibitory effect of four species of microalgae by those two extracts was above 25% in day 10. Our researches expressed that antialgal substances in E. prolifera extracted with methanol were obtained. And two fractions (petroleum ether phase and ethyl acetate phase) that inhibited the growth of all test microalgae were obtained when the methanol extracts was fractionated by liquid-liquid fractionation.

Toxic effects of the interaction of titanium dioxide nanoparticles with chemicals or physical factors

PubMed Central

Liu, Kui; Lin, Xialu; Zhao, Jinshun

2013-01-01

Due to their chemical stability and nonallergic, nonirritant, and ultraviolet protective properties, titanium dioxide (TiO2) nanoparticles (NPs) have been widely used in industries such as electronics, optics, and material sciences, as well as architecture, medicine, and pharmacology. However, increasing concerns have been raised in regards to its ecotoxicity and toxicity on the aquatic environment as well as to humans. Although insights have been gained into the effects of TiO2 NPs on susceptible biological systems, there is still much ground to be covered, particularly in respect of our knowledge of the effects of the interaction of TiO2 NPs with other chemicals or physical factors. Studies suggest that interactions of TiO2 NPs with other chemicals or physical factors may result in an increase in toxicity or adverse effects. This review highlights recent progress in the study of the interactive effects of TiO2 NPs with other chemicals or physical factors. PMID:23901269

New challenges in microalgae biotechnology.

PubMed

Valverde, Federico; Romero-Campero, Francisco J; León, Rosa; Guerrero, Miguel G; Serrano, Aurelio

2016-08-01

Photosynthetic protists, also called microalgae, have been systematically studied for more than a century. However, only recently broad biotechnological applications have fostered a novel wave of research on their potentialities as sustainable resources of renewable energy as well as valuable industrial and agro-food products. At the recent VII European Congress of Protistology held in Seville, three outstanding examples of different research strategies on microalgae with biotechnological implications were presented, which suggested that integrative approaches will produce very significant advances in this field in the next future. In any case, intense research and the application of systems biology and genetic engineering techniques are absolutely essential to reach the full potential of microalgae as cell-factories of bio-based products and, therefore, could contribute significantly to solve the problems of biosustainability and energy shortage. Copyright © 2016 Elsevier GmbH. All rights reserved.

Flashing light in microalgae biotechnology.

PubMed

Abu-Ghosh, Said; Fixler, Dror; Dubinsky, Zvy; Iluz, David

2016-03-01

Flashing light can enhance photosynthesis and improve the quality and quantity of microalgal biomass, as it can increase the products of interest by magnitudes. Therefore, the integration of flashing light effect into microalgal cultivation systems should be considered. However, microalgae require a balanced mix of the light/dark cycle for higher growth rates, and respond to light intensity differently according to the pigments acquired or lost during the growth. This review highlights recently published results on flashing light effect on microalgae and its applications in biotechnology, as well as the recently developed bioreactors designed to fulfill this effect. It also discusses how this knowledge can be applied in selecting the optimal light frequencies and intensities with specific technical properties for increasing biomass production and/or the yield of the chemicals of interest by microalgae belonging to different genera. Copyright © 2015 Elsevier Ltd. All rights reserved.

Maximizing the productivity of the microalgae Scenedesmus AMDD cultivated in a continuous photobioreactor using an online flow rate control.

PubMed

McGinn, Patrick J; MacQuarrie, Scott P; Choi, Jerome; Tartakovsky, Boris

2017-01-01

In this study, production of the microalga Scenedesmus AMDD in a 300 L continuous flow photobioreactor was maximized using an online flow (dilution rate) control algorithm. To enable online control, biomass concentration was estimated in real time by measuring chlorophyll-related culture fluorescence. A simple microalgae growth model was developed and used to solve the optimization problem aimed at maximizing the photobioreactor productivity. When optimally controlled, Scenedesmus AMDD culture demonstrated an average volumetric biomass productivity of 0.11 g L -1  d -1 over a 25 day cultivation period, equivalent to a 70 % performance improvement compared to the same photobioreactor operated as a turbidostat. The proposed approach for optimizing photobioreactor flow can be adapted to a broad range of microalgae cultivation systems.

Microalga propels along vorticity direction in a shear flow

NASA Astrophysics Data System (ADS)

Chengala, Anwar; Hondzo, Miki; Sheng, Jian

2013-05-01

Using high-speed digital holographic microscopy and microfluidics, we discover that, when encountering fluid flow shear above a threshold, unicellular green alga Dunaliella primolecta migrates unambiguously in the cross-stream direction that is normal to the plane of shear and coincides with the local fluid flow vorticity. The flow shear drives motile microalgae to collectively migrate in a thin two-dimensional horizontal plane and consequently alters the spatial distribution of microalgal cells within a given suspension. This shear-induced algal migration differs substantially from periodic rotational motion of passive ellipsoids, known as Jeffery orbits, as well as gyrotaxis by bottom-heavy swimming microalgae in a shear flow due to the subtle interplay between torques generated by gravity and viscous shear. Our findings could facilitate mechanistic solutions for modeling planktonic thin layers and sustainable cultivation of microalgae for human nutrition and bioenergy feedstock.

Geoengineering, marine microalgae, and climate stabilization in the 21st century

NASA Astrophysics Data System (ADS)

Greene, Charles H.; Huntley, Mark E.; Archibald, Ian; Gerber, Léda N.; Sills, Deborah L.; Granados, Joe; Beal, Colin M.; Walsh, Michael J.

2017-03-01

Society has set ambitious targets for stabilizing mean global temperature. To attain these targets, it will have to reduce CO2 emissions to near zero by mid-century and subsequently remove CO2 from the atmosphere during the latter half of the century. There is a recognized need to develop technologies for CO2 removal; however, attempts to develop direct air-capture systems have faced both energetic and financial constraints. Recently, BioEnergy with Carbon Capture and Storage (BECCS) has emerged as a leading candidate for removing CO2 from the atmosphere. However, BECCS can have negative consequences on land, nutrient, and water use as well as biodiversity and food production. Here, we describe an alternative approach based on the large-scale industrial production of marine microalgae. When cultivated with proper attention to power, carbon, and nutrient sources, microalgae can be processed to produce a variety of biopetroleum products, including carbon-neutral biofuels for the transportation sector and long-lived, potentially carbon-negative construction materials for the built environment. In addition to these direct roles in mitigating and potentially reversing the effects of fossil CO2 emissions, microalgae can also play an important indirect role. As microalgae exhibit much higher primary production rates than terrestrial plants, they require much less land area to produce an equivalent amount of bioenergy and/or food. On a global scale, the avoided emissions resulting from displacement of conventional agriculture may exceed the benefits of microalgae biofuels in achieving the climate stabilization goals.

Identification of optimum fatty acid extraction methods for two different microalgae Phaeodactylum tricornutum and Haematococcus pluvialis for food and biodiesel applications.

PubMed

Otero, Paz; Saha, Sushanta Kumar; Gushin, Joanne Mc; Moane, Siobhan; Barron, John; Murray, Patrick

2017-07-01

Microalgae have the potential to synthesize and accumulate lipids which contain high value fatty acids intended for nutrition and biodiesel applications. Nevertheless, lipid extraction methods for microalgae cells are not well established and there is not a standard analytical methodology to extract fatty acids from lipid-producing microalgae. In this paper, current lipid extraction procedures employing organic solvents (chloroform/methanol, 2:1 and 1:2, v/v), sodium hypochlorite solution (NaClO), acid-catalysed hot-water extraction and the saponification process [2.5 M KOH/methanol (1:4, v/v)] have been evaluated with two species of microalgae with different types of cell walls. One is a marine diatom, Phaeodactylum tricornutum, and the other a freshwater green microalga, Haematococcus pluvialis. Lipids from all types of extracts were estimated gravimetrically and their fatty acids were quantified by a HPLC equipped with Q-TOF mass spectrometer. Results indicated significant differences both in lipids yield and fatty acids composition. The chloroform and methanol mixture was the most effective extraction solvent for the unsaturated fatty acids such as DPA (C22:05), DHA, (C22:06), EPA (C20:05) and ARA (C20:04). While acid treatments improved the saturated fatty acids (SFAs) yield, especially the short chain SFA, lauric acid (C12:0), whose amount was 64% higher in P. tricornutum and 156% higher in H. pluvialis compared to organic solvent extractions. Graphical abstract ᅟ.

Membrane Proteomic Insights into the Physiology and Taxonomy of an Oleaginous Green Microalga1

PubMed Central

Vera-Estrella, Rosario

2017-01-01

Ettlia oleoabundans is a nonsequenced oleaginous green microalga. Despite the significant biotechnological interest in producing value-added compounds from the acyl lipids of this microalga, a basic understanding of the physiology and biochemistry of oleaginous microalgae is lacking, especially under nitrogen deprivation conditions known to trigger lipid accumulation. Using an RNA sequencing-based proteomics approach together with manual annotation, we are able to provide, to our knowledge, the first membrane proteome of an oleaginous microalga. This approach allowed the identification of novel proteins in E. oleoabundans, including two photoprotection-related proteins, Photosystem II Subunit S and Maintenance of Photosystem II under High Light1, which were considered exclusive to higher photosynthetic organisms, as well as Retinitis Pigmentosa Type 2-Clathrin Light Chain, a membrane protein with a novel domain architecture. Free-flow zonal electrophoresis of microalgal membranes coupled to liquid chromatography-tandem mass spectrometry proved to be a useful technique for determining the intracellular location of proteins of interest. Carbon-flow compartmentalization in E. oleoabundans was modeled using this information. Molecular phylogenetic analyses of protein markers and 18S ribosomal DNA support the reclassification of E. oleoabundans within the trebouxiophycean microalgae, rather than with the Chlorophyceae class, in which it is currently classified, indicating that it may not be closely related to the model green alga Chlamydomonas reinhardtii. A detailed survey of biological processes taking place in the membranes of nitrogen-deprived E. oleoabundans, including lipid metabolism, provides insights into the basic biology of this nonmodel organism. PMID:27837088

Microplastic interactions with freshwater microalgae: Hetero-aggregation and changes in plastic density appear strongly dependent on polymer type.

PubMed

Lagarde, Fabienne; Olivier, Ophélie; Zanella, Marie; Daniel, Philippe; Hiard, Sophie; Caruso, Aurore

2016-08-01

In this study, the interactions between microplastics, chosen among the most widely used in industry such as polypropylene (PP) and high-density polyethylene (HDPE), and a model freshwater microalgae, Chlamydomas reinhardtii, were investigated. It was shown that the presence of high concentrations of microplastics with size >400 μm did not directly impact the growth of microalgae in the first days of contact and that the expression of three genes involved in the stress response was not modified after 78 days. In parallel, a similar colonization was observed for the two polymers. However, after 20 days of contact, in the case of PP only, hetero-aggregates constituted of microalgae, microplastics and exopolysaccharides were formed. An estimation of the hetero-aggregates composition was approximately 50% of PP fragments and 50% of microalgae, which led to a final density close to 1.2. Such hetero-aggregates appear as an important pathway for the vertical transport of PP microplastics from the water surface to sediment. Moreover, after more than 70 days of contact with microplastics, the microalgae genes involved in the sugar biosynthesis pathways were strongly over-expressed compared to control conditions. The levels of over-expression were higher in the case of HDPE than in PP condition. This work presents the first evidence that depending on their chemical nature, microplastics will follow different fates in the environment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Uptake and biotransformation of 2,2‧,4,4‧-tetrabromodiphenyl ether (BDE-47) in four marine microalgae species

NASA Astrophysics Data System (ADS)

Po, Beverly H. K.; Ho, Ka-Lok; Lam, Michael H. W.; Giesy, John P.; Chiu, Jill M. Y.

2017-03-01

Hydroxylated- and methoxylated- polybrominated diphenyl ethers (OH-PBDEs and MeO-PBDEs) are more toxic than PBDEs and occur widely in the marine environment, and yet their origins remain controversial. In this study, four species of microalgae (Isochrysis galbana, Prorocentrum minimum, Skeletonema grethae and Thalassiosira pseudonana) were exposed to BDE-47, which is synthetic and is the predominant congener of PBDEs in the environment. By chemical analysis after incubation of 2 to 6 days, the efficiency of uptake of BDE-47 and, more importantly, the potential of undergoing biotransformation to form OH-PBDEs and MeO-PBDEs by the microalgae were investigated. Growth rates of these axenic microalgae were not affected upon exposure to environmentally relevant concentrations (0.2-20 μg BDE-47 L-1), and accumulation ranged from 0.772 ± 0.092 μg BDE-47 g-1 lipid to 215 ± 54 μg BDE-47 g-1 lipid within 2 days. Debromination of BDE-47 and formation of BDE-28 occurred in all microalgae species (0.01 to 0.87%), but biotransformation to OH-PBDEs was only found in I. galbana upon exposure to extremely high concentration. The results of this study showed that biotransformation of microalgae species is unlikely an explanation for the OH-PBDEs and MeO-PBDEs found in the marine environment.

Anaerobes into heavy metal: Dissimilatory metal reduction in anoxic environments

USGS Publications Warehouse

Lovley, D.R.

1993-01-01

Within the last decade, a novel form of microbial metabolism of major environmental significance has been elucidated. In this process, known as dissimilatory metal reduction, specialized microorganisms, living in anoxic aquatic sediments and ground water, oxidize organic compounds to carbon dioxide with metals serving as the oxidant. Recent studies have demonstrated that this metabolism explains a number of important geochemical phenomena in ancient and modern sedimentary environments, affecting not only the cycling of metals but also the fate of organic matter. Furthermore, this metabolism may have practical application in remediation of environments contaminated with toxic metals and/or organics.

Metabolic Engineering of Microalgal Based Biofuel Production: Prospects and Challenges.

PubMed

Banerjee, Chiranjib; Dubey, Kashyap K; Shukla, Pratyoosh

2016-01-01

The current scenario in renewable energy is focused on development of alternate and sustainable energy sources, amongst which microalgae stands as one of the promising feedstock for biofuel production. It is well known that microalgae generate much larger amounts of biofuels in a shorter time than other sources based on plant seeds. However, the greatest challenge in a transition to algae-based biofuel production is the various other complications involved in microalgal cultivation, its harvesting, concentration, drying and lipid extraction. Several green microalgae accumulate lipids, especially triacylglycerols (TAGs), which are main precursors in the production of lipid. The various aspects on metabolic pathway analysis of an oleaginous microalgae i.e., Chlamydomonas reinhardtii have elucidated some novel metabolically important genes and this enhances the lipid production in this microalgae. Adding to it, various other aspects in metabolic engineering using OptFlux and effectual bioprocess design also gives an interactive snapshot of enhancing lipid production which ultimately improvises the oil yield. This article reviews the current status of microalgal based technologies for biofuel production, bioreactor process design, flux analysis and it also provides various strategies to increase lipids accumulation via metabolic engineering.

Advanced treatment of residual nitrogen from biologically treated coke effluent by a microalga-mediated process using volatile fatty acids (VFAs) under stepwise mixotrophic conditions.

PubMed

Ryu, Byung-Gon; Kim, Woong; Heo, Sung-Woon; Kim, Donghyun; Choi, Gang-Guk; Yang, Ji-Won

2015-09-01

This work describes the development of a microalga-mediated process for simultaneous removal of residual ammonium nitrogen (NH4(+)-N) and production of lipids from biologically treated coke effluent. Four species of green algae were tested using a sequential mixotrophic process. In the first phase-CO2-supplied mixotrophic condition-all microalgae assimilated NH4(+)-N with no evident inhibition. In second phase-volatile fatty acids (VFAs)-supplied mixotrophic condition-removal rates of NH4(+)-N and biomass significantly increased. Among the microalgae used, Arctic Chlorella sp. ArM0029B had the highest rate of NH4(+)-N removal (0.97 mg/L/h) and fatty acid production (24.9 mg/L/d) which were 3.6- and 2.1-fold higher than those observed under the CO2-supplied mixotrophic condition. Redundancy analysis (RDA) indicated that acetate and butyrate were decisive factors for increasing NH4(+)-N removal and fatty acid production. These results demonstrate that microalgae can be used in a sequential process for treatment of residual nitrogen after initial treatment of activated sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antitumor activity of Chlorella sorokiniana and Scenedesmus sp. microalgae native of Nuevo León State, México.

PubMed

Reyna-Martinez, Raul; Gomez-Flores, Ricardo; López-Chuken, Ulrico; Quintanilla-Licea, Ramiro; Caballero-Hernandez, Diana; Rodríguez-Padilla, Cristina; Beltrán-Rocha, Julio Cesar; Tamez-Guerra, Patricia

2018-01-01

Cancer cases result in 13% of all deaths worldwide. Unwanted side effects in patients under conventional treatments have led to the search for beneficial alternative therapies. Microalgae synthesize compounds with known in vitro and in vivo biological activity against different tumor cell lines. Therefore, native microalgae from the State of Nuevo Leon, Mexico may become a potential source of antitumor agents. The aim of the present study was to evaluate the in vitro cytotoxic effect of Nuevo Leon regional Chlorella sorokiniana (Chlorellales: Chlorellaceae) and Scenedesmus sp. (Chlorococcales: Scenedesmaceae). Native microalgae crude organic extracts cytotoxicity against murine L5178Y-R lymphoma cell line and normal lymphocyte proliferation were evaluated using the MTT reduction colorimetric assay. Cell death pathway was analyzed by acridine orange and ethidium bromide staining, DNA degradation in 2% agarose gel electrophoresis and caspases activity. Results indicated significant ( p  < 0.05) 61.89% ± 3.26% and 74.77% ± 1.84% tumor cytotoxicity by C. sorokiniana and Scenedesmus sp. methanol extracts, respectively, at 500 µg/mL, by the mechanism of apoptosis. This study contributes to Mexican microalgae biodiversity knowledge and their potential as antitumor agent sources.

Microalgae and wastewater treatment

PubMed Central

Abdel-Raouf, N.; Al-Homaidan, A.A.; Ibraheem, I.B.M.

2012-01-01

Organic and inorganic substances which were released into the environment as a result of domestic, agricultural and industrial water activities lead to organic and inorganic pollution. The normal primary and secondary treatment processes of these wastewaters have been introduced in a growing number of places, in order to eliminate the easily settled materials and to oxidize the organic material present in wastewater. The final result is a clear, apparently clean effluent which is discharged into natural water bodies. This secondary effluent is, however, loaded with inorganic nitrogen and phosphorus and causes eutrophication and more long-term problems because of refractory organics and heavy metals that are discharged. Microalgae culture offers an interesting step for wastewater treatments, because they provide a tertiary biotreatment coupled with the production of potentially valuable biomass, which can be used for several purposes. Microalgae cultures offer an elegant solution to tertiary and quandary treatments due to the ability of microalgae to use inorganic nitrogen and phosphorus for their growth. And also, for their capacity to remove heavy metals, as well as some toxic organic compounds, therefore, it does not lead to secondary pollution. In the current review we will highlight on the role of micro-algae in the treatment of wastewater. PMID:24936135

Biodiesel production from wet microalgae feedstock using sequential wet extraction/transesterification and direct transesterification processes.

PubMed

Chen, Ching-Lung; Huang, Chien-Chang; Ho, Kao-Chia; Hsiao, Ping-Xuan; Wu, Meng-Shan; Chang, Jo-Shu

2015-10-01

Although producing biodiesel from microalgae seems promising, there is still a lack of technology for the quick and cost-effective conversion of biodiesel from wet microalgae. This study was aimed to develop a novel microalgal biodiesel producing method, consisting of an open system of microwave disruption, partial dewatering (via combination of methanol treatment and low-speed centrifugation), oil extraction, and transesterification without the pre-removal of the co-solvent, using Chlamydomonas sp. JSC4 with 68.7 wt% water content as the feedstock. Direct transesterification with the disrupted wet microalgae was also conducted. The biomass content of the wet microalgae increased to 56.6 and 60.5 wt%, respectively, after microwave disruption and partial dewatering. About 96.2% oil recovery was achieved under the conditions of: extraction temperature, 45°C; hexane/methanol ratio, 3:1; extraction time, 80 min. Transesterification of the extracted oil reached 97.2% conversion within 15 min at 45°C and 6:1 solvent/methanol ratio with simultaneous Chlorophyll removal during the process. Nearly 100% biodiesel conversion was also obtained while conducting direct transesterification of the disrupted oil-bearing microalgal biomass. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effective flocculation of Chlorella vulgaris using chitosan with zeta potential measurement

NASA Astrophysics Data System (ADS)

Low, Y. J.; Lau, S. W.

2017-06-01

Microalgae are considered as one promising source of third-generation biofuels due to their fast growth rates, potentially higher yield rates and wide ranges of growth conditions. However, the extremely low biomass concentration in microalgae cultures presents a great challenge to the harvesting of microalgae because a large volume of water needs to be removed to obtain dry microalgal cells for the subsequent oil extraction process. In this study, the fresh water microalgae Chlorella vulgaris (C. vulgaris) was effectively harvested using both low molecular weight (MW) and high MW chitosan flocculants. The flocculation efficiency was evaluated by physical appearance, supernatant absorbance, zeta potential and solids content after centrifugal dewatering. High flocculation efficiency of 98.0-99.0% was achieved at the optimal dosage of 30-40 mg/g with formation of large microalgae flocs. This study suggests that the polymer bridging mechanism was governing the flocculation behaviour of C. vulgaris using high MW chitosan. Besides, charge patch neutralisation mechanism prevailed at low MW chitosan where lower dosage was sufficient to reach near-zero zeta potential compared with the high MW chitosan. The amount of chitosan polymer present in the culture may also affect the mechanism of flocculation.

Toxic effects of microplastic on marine microalgae Skeletonema costatum: Interactions between microplastic and algae.

PubMed

Zhang, Cai; Chen, Xiaohua; Wang, Jiangtao; Tan, Liju

2017-01-01

To investigate toxic effects of microplastic on marine microalgae Skeletonema costatum, both algal growth inhibition test and non-contact shading test were carried out, and algal photosynthesis parameters were also determined. The SEM images were used to observe interactions between microplastic and algae. It was found that microplastic (mPVC, average diameter 1 μm) had obvious inhibition on growth of microalgae and the maximum growth inhibition ratio (IR) reached up to 39.7% after 96 h exposure. However, plastic debris (bPVC, average diameter 1 mm) had no effects on growth of microalgae. High concentration (50 mg/L) mPVC also had negative effects on algal photosynthesis since both chlorophyll content and photosynthetic efficiency (ΦPSⅡ) decreased under mPVC treatments. Shading effect was not one reason for toxicity of microplastic on algae in this study. Compared with non-contact shading effect, interactions between microplastic and microalage such as adsorption and aggregation were more reasonable explanations for toxic effects of microplastic on marine microalgae. The SEM images provided a more direct and reasonable method to observe the behaviors of microplastic. Copyright © 2016 Elsevier Ltd. All rights reserved.

Establishment of stable synthetic mutualism without co-evolution between microalgae and bacteria demonstrated by mutual transfer of metabolites (NanoSIMS isotopic imaging) and persistent physical association (Fluorescent in situ hybridization)

DOE PAGES

de-Bashan, Luz E.; Mayali, Xavier; Bebout, Brad M.; ...

2016-03-03

The demonstration of a mutualistic interaction requires evidence of benefits for both partners as well as stability of the association over multiple generations. A synthetic mutualism between the freshwater microalga Chlorella sorokiniana and the soil-derived plant growth-promoting bacterium (PGPB) Azospirillum brasilense was created when both microorganisms were co-immobilized in alginate beads. Using stable isotope enrichment experiments followed by high-resolution secondary ion mass spectrometry (SIMS) imaging of single cells, we demonstrated transfer of carbon and nitrogen compounds between the two partners. Further, using fluorescent in situ hybridization (FISH), mechanical disruption and scanning electron microscopy, we demonstrated the stability of their physicalmore » association for a period of 10 days after the aggregated cells were released from the beads. The bacteria significantly enhanced the growth of the microalgae while the microalgae supported growth of the bacteria in a medium where it could not otherwise grow. In conclusion, we propose that this microalga-bacterium association is a true synthetic mutualism independent of co-evolution. (155 words).« less

A Review on the Assessment of Stress Conditions for Simultaneous Production of Microalgal Lipids and Carotenoids

PubMed Central

Minhas, Amritpreet K.; Hodgson, Peter; Barrow, Colin J.; Adholeya, Alok

2016-01-01

Microalgal species are potential resource of both biofuels and high-value metabolites, and their production is growth dependent. Growth parameters can be screened for the selection of novel microalgal species that produce molecules of interest. In this context our review confirms that, autotrophic and heterotrophic organisms have demonstrated a dual potential, namely the ability to produce lipids as well as value-added products (particularly carotenoids) under influence of various physico-chemical stresses on microalgae. Some species of microalgae can synthesize, besides some pigments, very-long-chain polyunsaturated fatty acids (VL-PUFA,>20C) such as docosahexaenoic acid and eicosapentaenoic acid, those have significant applications in food and health. Producing value-added by-products in addition to biofuels, fatty acid methyl esters (FAME), and lipids has the potential to improve microalgae-based biorefineries by employing either the autotrophic or the heterotrophic mode, which could be an offshoot of biotechnology. The review considers the potential of microalgae to produce a range of products and indicates future directions for developing suitable criteria for choosing novel isolates through bioprospecting large gene pool of microalga obtained from various habitats and climatic conditions. PMID:27199903

Antitumor activity of Chlorella sorokiniana and Scenedesmus sp. microalgae native of Nuevo León State, México

PubMed Central

Beltrán-Rocha, Julio Cesar

2018-01-01

Cancer cases result in 13% of all deaths worldwide. Unwanted side effects in patients under conventional treatments have led to the search for beneficial alternative therapies. Microalgae synthesize compounds with known in vitro and in vivo biological activity against different tumor cell lines. Therefore, native microalgae from the State of Nuevo Leon, Mexico may become a potential source of antitumor agents. The aim of the present study was to evaluate the in vitro cytotoxic effect of Nuevo Leon regional Chlorella sorokiniana (Chlorellales: Chlorellaceae) and Scenedesmus sp. (Chlorococcales: Scenedesmaceae). Native microalgae crude organic extracts cytotoxicity against murine L5178Y-R lymphoma cell line and normal lymphocyte proliferation were evaluated using the MTT reduction colorimetric assay. Cell death pathway was analyzed by acridine orange and ethidium bromide staining, DNA degradation in 2% agarose gel electrophoresis and caspases activity. Results indicated significant (p < 0.05) 61.89% ± 3.26% and 74.77% ± 1.84% tumor cytotoxicity by C. sorokiniana and Scenedesmus sp. methanol extracts, respectively, at 500 µg/mL, by the mechanism of apoptosis. This study contributes to Mexican microalgae biodiversity knowledge and their potential as antitumor agent sources. PMID:29441241

Polishing of POME by Chlorella sp. in suspended and immobilized system

NASA Astrophysics Data System (ADS)

Lahin, F. A.; Sarbatly, R.; Suali, E.

2016-06-01

The effect of using suspended and immobilized growth of Chlorella sp. to treat POME was studied. Cotton and nylon ropes were used as the immobilization material in a rotating microalgae biofilm reactor. The result showed that POME treated in suspended growth system was able to remove 81.9% and 55.5% of the total nitrogen (TN) and total phosphorus (TP) respectively. Whereas the immobilized system showed lower removal of 77.22% and 53.02% for TN and TP. Lower performance of immobilized microalgae is due to the limited light penetration and supply of CO2 inside the immobilization materials. The rotating microalgae biofilm reactor was able to reduce the biochemical oxygen demand (BOD) to 90 mg/L and chemical oxygen demand (COD) to 720 mg/L. Higher BOD and COD reading were obtained in suspended growth due to the presence of small number of microalgae cell in the samples. This study shows that suspended growth system is able to remove higher percentages of nitrogen and phosphorus. However, an efficient separation method such as membrane filtration is required to harvest the cultivated microalgae cell to avoid organic matter release into water bodies.

Acute toxicity assessment of perfluorinated carboxylic acids towards the Baltic microalgae.

PubMed

Latała, Adam; Nędzi, Marcin; Stepnowski, Piotr

2009-09-01

The presence of high-energy carbon-fluorine bonds in perfluoro compounds lends them great stability and causes them to be environmentally persistent. Relatively little is known about the acute toxicity of perfluorinated carboxylic acids (PFCAs) to ecotoxicological markers such as aquatic plants and animals. This study tested the toxicity of these compounds to the green alga Chlorella vulgaris, the diatom Skeletonema marinoi and the blue-green alga Geitlerinema amphibium, which are species representative of the algal flora of the Baltic Sea. The EC(50) values obtained range from 0.28 mM to 12.84 mM. A distinct relationship between hydrophobicity and toxicity is demonstrated. For every extra perfluoromethylene group in the alkyl chain, the toxicity increases twofold. LogEC(50) values are very well correlated linearly with both the number of carbon atoms in the perfluoroalkyl chain and the partition coefficients. The results also indicate that there are clear differences between the responses of particular taxonomic groups of algae: blue-green algae and diatoms are far more sensitive to PFCAs than green algae, probably because of differences in cell wall structure.

Chemical and ecotoxicological analyses of sediments and elutriates of contaminated rivers due to e-waste recycling activities using a diverse battery of bioassays.

PubMed

Wang, F; Leung, A O W; Wu, S C; Yang, M S; Wong, M H

2009-07-01

A multi-trophic, multi-exposure phase assessment approach was applied to characterize the toxicity of sediments collected from two rivers in Guiyu, China, an e-waste recycling centre. Elutriate toxicity tests (bacterium Vibrio fischeri and microalga Selenastrum capricornutum) and whole sediment toxicity test (crustacean Heterocypris incongruens) showed that most sediments exhibited acute toxicity, due to elevated heavy metals and PAHs levels, and low pH caused by uncontrolled acid discharge. The survival rates of crustaceans were negatively (p < 0.05) correlated with total PAHs in sediments (411-1755 mg kg(-1)); EC50s of V. fischeri on the elutriates were significantly correlated with elutriate pH (p < 0.01). Significant (p < 0.05) correlations between the induction of hepatic metallothionein in tilapia (Oreochromis mossambicus) and metal concentrations (Cu, Zn, Pb) in sediments were also observed, when fish were fed with diets containing sediment. The results showed that uncontrolled e-waste recycling activities may bring adverse effects to local aquatic ecosystem.

Rheological Analysis of Live and Dead Microalgae Suspensions

NASA Astrophysics Data System (ADS)

Song, Young Seok; Kang, Chul; Jeong, Jiwon; Kim, Kyu-Oh; Lim, Eunju

2018-04-01

We investigate the rheological properties of microalgae suspensions that are currently being used in various applications. Two kinds of microalgae, chlorella and Synechococcus, were used for preparation of the suspensions, and their rheological characteristics were analyzed experimentally. In order to evaluate the viability of algae, we performed live and dead tests using trypan blue staining assays. Morphological analyses for the algae were conducted using a scanning electron microscope (SEM) and an optical microscope (OP). We examined the viscoelastic behavior of the live and the dead algae suspensions by performing dynamic oscillatory shear tests.

Algae and their biodegradation effects on building materials in the Ostrava industrial agglomeration

NASA Astrophysics Data System (ADS)

Vojtková, H.

2017-10-01

Microorganisms cause changes in the building stone, which reduce its usable life and reliability. Microalgae make important parts of the biodegradation consortia of microorganisms on the surface of building materials. Via their metabolites, microalgae affect the stability of mineral components and thus lead to the material destruction. The aim of the paper was to identify aerophytic microalgae on the surface of engineering structures in the Ostrava agglomeration, and to describe the basic interactions between such microorganisms and the building materials, which may lead to the destruction of the materials.

Microalgae for economic applications: advantages and perspectives for bioethanol

DOE PAGES

Simas-Rodrigues, Cíntia; Villela, Helena D. M.; Martins, Aline P.; ...

2015-04-04

Renewable energy has attracted significant interest in recent years as a result of sustainability, environmental impact, and socio-economic considerations. Given existing technological knowledge and based on projections relating to biofuels derived from microalgae, microalgal feedstock is considered to be one of the most important renewable energy sources potentially available for industrial production. Finally and therefore, this paper examines microalgal bioethanol technology, which converts biomass from microalgae to fuel, the chemical processes involved, and possible ways of increasing the bioethanol yield, such as abiotic factors and genetic manipulation of fermenting organisms.

Lipids rich in ω-3 polyunsaturated fatty acids from microalgae.

PubMed

Santos-Sánchez, N F; Valadez-Blanco, R; Hernández-Carlos, B; Torres-Ariño, A; Guadarrama-Mendoza, P C; Salas-Coronado, R

2016-10-01

Despite microalgae recently receiving enormous attention as a potential source of biodiesel, their use is still not feasible as an alternative to fossil fuels. Recently, interest in microalgae has focused on the production of bioactive compounds such as polyunsaturated fatty acids (PUFA), which provide microalgae a high added value. Several considerations need to be assessed for optimizing PUFA production from microalgae. Firstly, a microalgae species that produces high PUFA concentrations should be selected, such as Nannochloropsis gaditana, Isochrysis galbana, Phaeodactylum tricornutum, and Crypthecodinium cohnii, with marine species gaining more attention than do freshwater species. Closed cultivation processes, e.g., photobioreactors, are the most appropriate since temperature, pH, and nutrients can be controlled. An airlift column with LEDs or optical fibers to distribute photons into the culture media can be used at small scale to produce inoculum, while tubular and flat panels are used at commercial scale. Depending on the microalgae, a temperature range from 15 to 28 °C and a pH from 7 to 8 can be employed. Relevant conditions for PUFA production are medium light irradiances (50-300 μmol photons m(-2) s(-1)), air enriched with (0-1 % (v/v) CO2, as well as nitrogen and phosphorous limitation. For research purposes, the most appropriate medium for PUFA production is Bold's Basal, whereas mixotrophic cultivation using sucrose or glucose as the carbon source has been reported for industrial processes. For cell harvesting, the use of tangential flow membrane filtration or disk stack centrifugation is advisable at commercial scale. Current researches on PUFA extraction have focused on the use of organic solvents assisted with ultrasound or microwaves, supercritical fluids, and electroporation or are enzyme assisted. Commercial-scale extraction involves mainly physical methods such as bead mills and expeller presses. All these factors should be taken into account when choosing a PUFA production system, as discussed in this review.

Hyperspectral imaging of microalgae using two-photon excitation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sinclair, Michael B.; Melgaard, David Kennett; Reichardt, Thomas A.

2010-10-01

A considerable amount research is being conducted on microalgae, since microalgae are becoming a promising source of renewable energy. Most of this research is centered on lipid production in microalgae because microalgae produce triacylglycerol which is ideal for biodiesel fuels. Although we are interested in research to increase lipid production in algae, we are also interested in research to sustain healthy algal cultures in large scale biomass production farms or facilities. The early detection of fluctuations in algal health, productivity, and invasive predators must be developed to ensure that algae are an efficient and cost-effective source of biofuel. Therefore wemore » are developing technologies to monitor the health of algae using spectroscopic measurements in the field. To do this, we have proposed to spectroscopically monitor large algal cultivations using LIDAR (Light Detection And Ranging) remote sensing technology. Before we can deploy this type of technology, we must first characterize the spectral bio-signatures that are related to algal health. Recently, we have adapted our confocal hyperspectral imaging microscope at Sandia to have two-photon excitation capabilities using a chameleon tunable laser. We are using this microscope to understand the spectroscopic signatures necessary to characterize microalgae at the cellular level prior to using these signatures to classify the health of bulk samples, with the eventual goal of using of LIDAR to monitor large scale ponds and raceways. By imaging algal cultures using a tunable laser to excite at several different wavelengths we will be able to select the optimal excitation/emission wavelengths needed to characterize algal cultures. To analyze the hyperspectral images generated from this two-photon microscope, we are using Multivariate Curve Resolution (MCR) algorithms to extract the spectral signatures and their associated relative intensities from the data. For this presentation, I will show our two-photon hyperspectral imaging results on a variety of microalgae species and show how these results can be used to characterize algal ponds and raceways.« less

Improvement of lipid yield from microalgae Spirulina platensis using ultrasound assisted osmotic shock extraction method

NASA Astrophysics Data System (ADS)

Adetya, NP; Hadiyanto, H.

2018-01-01

Microalgae Spirulina sp. has been identified as potential source of natural food supplement and food colorant. The high water content of microalgae (70-90%) causes an obstacle in biomass dehydration which requires large amounts of energy, eventually damaging the lipid in the microalgae. Therefore, the lipid must be extracted by using a suitable method which complies to wet biomass conditions. One of the methods is applying osmotic shock. This study was aimed to investigate the influence of osmotic agent (NaCl) concentration (10-30%) and extraction time (20-50 min) on yield of lipid and also to determine the optimal conditions in the extraction process through response surface methodology. The extraction was conducted at a temperature of 40°C under ultrasound frequency of 40 kHz. The result showed that the optimum yield lipid obtained was 6.39% in 16.98% NaCl concentration for 36 minutes 10 seconds.

Thermogravimetric study on pyrolysis kinetics of Chlorella pyrenoidosa and bloom-forming cyanobacteria.

PubMed

Hu, Mian; Chen, Zhihua; Guo, Dabin; Liu, Cuixia; Xiao, Bo; Hu, Zhiquan; Liu, Shiming

2015-02-01

The pyrolysis process of two microalgae, Chlorella pyrenoidosa (CP) and bloom-forming cyanobacteria (CB) was examined by thermo-gravimetry to investigate their thermal decomposition behavior under non-isothermal conditions. It has found that the pyrolysis of both microalgae consists of three stages and stage II is the major mass reduction stage with mass loss of 70.69% for CP and 64.43% for CB, respectively. The pyrolysis kinetics of both microalgae was further studied using single-step global model (SSGM) and distributed activation energy model (DAEM). The mean apparent activation energy of CP and CB in SSGM was calculated as 143.71 and 173.46 kJ/mol, respectively. However, SSGM was not suitable for modeling pyrolysis kinetic of both microalgae due to the mechanism change during conversion. The DAEM with 200 first-order reactions showed an excellent fit between simulated data and experimental results. Copyright © 2014 Elsevier Ltd. All rights reserved.

A novel method to harvest Chlorella sp. by co-flocculation/air flotation.

PubMed

Zhang, Haiyang; Lin, Zhe; Tan, Daoyong; Liu, Chunhua; Kuang, Yali; Li, Zhu

2017-01-01

To develop a more effective dissolved air flotation process for harvesting microalgae biomass, a co-flocculation/air flotation (CAF) system was developed that uses an ejector followed by a helix tube flocculation reactor (HTFR) as a co-flocculation device to harvest Chlorella sp. 64.01. The optimal size distribution of micro-bubbles and an air release efficiency of 96 % were obtained when the flow ratio of inlet fluid (raw water) to motive fluid (saturated water) of the ejector was 0.14. With a reaction time of 24 s in the HTFR, microalgae cells and micro-bubbles were well flocculated, and these aerated flocs caused a fast rising velocity (96 m/h) and high harvesting efficiency (94 %). In a CAF process, micro-bubbles can be encapsulated into microalgae flocs, which makes aerated flocs more stable. CAF is an effective approach to harvesting microalgae.

Autotrophic and heterotrophic microalgae and cyanobacteria cultivation for food and feed: life cycle assessment.

PubMed

Smetana, Sergiy; Sandmann, Michael; Rohn, Sascha; Pleissner, Daniel; Heinz, Volker

2017-12-01

The lack of protein sources in Europe could be reduced with onsite production of microalgae with autotrophic and heterotrophic systems, owing the confirmation of economic and environmental benefits. This study aimed at the life cycle assessment (LCA) of microalgae and cyanobacteria cultivation (Chlorella vulgaris and Arthrospira platensis) in autotrophic and heterotrophic conditions on a pilot industrial scale (in model conditions of Berlin, Germany) with further biomass processing for food and feed products. The comparison of analysis results with traditional benchmarks (protein concentrates) indicated higher environmental impact of microalgae protein powders. However high-moisture extrusion of heterotrophic cultivated C. vulgaris resulted in more environmentally sustainable product than pork and beef. Further optimization of production with Chlorella pyrenoidosa on hydrolyzed food waste could reduce environmental impact in 4.5 times and create one of the most sustainable sources of proteins. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of Organic Solvents on Microalgae Growth, Metabolism and Industrial Bioproduct Extraction: A Review.

PubMed

Miazek, Krystian; Kratky, Lukas; Sulc, Radek; Jirout, Tomas; Aguedo, Mario; Richel, Aurore; Goffin, Dorothee

2017-07-04

In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), as a result of exposure to organic solvents, are summarized. Applications of organic solvents as a carbon source for microalgal growth and production of target molecules are discussed. Possible implementation of various industrial effluents containing organic solvents into microalgal cultivation media, is evaluated. The effect of organic solvents on extraction of target compounds from microalgae is also considered. Techniques for lipid and carotenoid extraction from viable microalgal biomass (milking methods) and dead microalgal biomass (classical methods) are depicted. Moreover, the economic survey of lipid and carotenoid extraction from microalgae biomass, by means of different techniques and solvents, is conducted.

Biosequestration of atmospheric CO2 and flue gas-containing CO2 by microalgae.

PubMed

Cheah, Wai Yan; Show, Pau Loke; Chang, Jo-Shu; Ling, Tau Chuan; Juan, Joon Ching

2015-05-01

The unceasing rise of greenhouse gas emission has led to global warming and climate change. Global concern on this phenomenon has put forward the microalgal-based CO2 sequestration aiming to sequester carbon back to the biosphere, ultimately reducing greenhouse effects. Microalgae have recently gained enormous attention worldwide, to be the valuable feedstock for renewable energy production, due to their high growth rates, high lipid productivities and the ability to sequester carbon. The photosynthetic process of microalgae uses atmospheric CO2 and CO2 from flue gases, to synthesize nutrients for their growth. In this review article, we will primarily discuss the efficiency of CO2 biosequestration by microalgae species, factors influencing microalgal biomass productions, microalgal cultivation systems, the potential and limitations of using flue gas for microalgal cultivation as well as the bio-refinery approach of microalgal biomass. Copyright © 2014 Elsevier Ltd. All rights reserved.

Carotenoids from Marine Microalgae: A Valuable Natural Source for the Prevention of Chronic Diseases.

PubMed

Raposo, Maria Filomena de Jesus; de Morais, Alcina Maria Miranda Bernardo; de Morais, Rui Manuel Santos Costa

2015-08-14

Epidemiological studies have shown a relation between antioxidants and the prevention of several chronic diseases. Microalgae are a potential novel source of bioactive molecules, including a wide range of different carotenoids that can be used as nutraceuticals, food supplements and novel food products. The objective of this review is (i) to update the research that has been carried out on the most known carotenoids produced by marine microalgae, including reporting on their high potentialities to produce other less known important compounds; (ii) to compile the work that has been done in order to establish some relationship between carotenoids and oxidative protection and treatment; (iii) to summarize the association of oxidative stress and the various reactive species including free radicals with several human diseases; and (iv) to provide evidence of the potential of carotenoids from marine microalgae to be used as therapeutics to treat or prevent these oxidative stress-related diseases.

Heterotrophic cultivation of microalgae for pigment production: A review.

PubMed

Hu, Jianjun; Nagarajan, Dillirani; Zhang, Quanguo; Chang, Jo-Shu; Lee, Duu-Jong

Pigments (mainly carotenoids) are important nutraceuticals known for their potent anti-oxidant activities and have been used extensively as high end health supplements. Microalgae are the most promising sources of natural carotenoids and are devoid of the toxic effects associated with synthetic derivatives. Compared to photoautotrophic cultivation, heterotrophic cultivation of microalgae in well-controlled bioreactors for pigments production has attracted much attention for commercial applications due to overcoming the difficulties associated with the supply of CO 2 and light, as well as avoiding the contamination problems and land requirements in open autotrophic culture systems. In this review, the heterotrophic metabolic potential of microalgae and their uses in pigment production are comprehensively described. Strategies to enhance pigment production under heterotrophic conditions are critically discussed and the challenges faced in heterotrophic pigment production with possible alternative solutions are presented. Copyright © 2017 Elsevier Inc. All rights reserved.

Thermogravimetric analysis of the gasification of microalgae Chlorella vulgaris.

PubMed

Figueira, Camila Emilia; Moreira, Paulo Firmino; Giudici, Reinaldo

2015-12-01

The gasification of microalgae Chlorella vulgaris under an atmosphere of argon and water vapor was investigated by thermogravimetric analysis. The data were interpreted by using conventional isoconversional methods and also by the independent parallel reaction (IPR) model, in which the degradation is considered to happen individually to each pseudo-component of biomass (lipid, carbohydrate and protein). The IPR model allows obtaining the kinetic parameters of the degradation reaction of each component. Three main stages were observed during the gasification process and the differential thermogravimetric curve was satisfactorily fitted by the IPR model considering three pseudocomponents. The comparison of the activation energy values obtained by the methods and those found in the literature for other microalgae was satisfactory. Quantification of reaction products was performed using online gas chromatography. The major products detected were H2, CO and CH4, indicating the potential for producing fuel gas and syngas from microalgae. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bioactivity and Applications of Sulphated Polysaccharides from Marine Microalgae

PubMed Central

de Jesus Raposo, Maria Filomena; de Morais, Rui Manuel Santos Costa; de Morais, Alcina Maria Miranda Bernardo

2013-01-01

Marine microalgae have been used for a long time as food for humans, such as Arthrospira (formerly, Spirulina), and for animals in aquaculture. The biomass of these microalgae and the compounds they produce have been shown to possess several biological applications with numerous health benefits. The present review puts up-to-date the research on the biological activities and applications of polysaccharides, active biocompounds synthesized by marine unicellular algae, which are, most of the times, released into the surrounding medium (exo- or extracellular polysaccharides, EPS). It goes through the most studied activities of sulphated polysaccharides (sPS) or their derivatives, but also highlights lesser known applications as hypolipidaemic or hypoglycaemic, or as biolubricant agents and drag-reducers. Therefore, the great potentials of sPS from marine microalgae to be used as nutraceuticals, therapeutic agents, cosmetics, or in other areas, such as engineering, are approached in this review. PMID:23344113

Engineering fatty acid biosynthesis in microalgae for sustainable biodiesel.

PubMed

Blatti, Jillian L; Michaud, Jennifer; Burkart, Michael D

2013-06-01

Microalgae are a promising feedstock for biodiesel and other liquid fuels due to their fast growth rate, high lipid yields, and ability to grow in a broad range of environments. However, many microalgae achieve maximal lipid yields only under stress conditions hindering growth and providing compositions not ideal for biofuel applications. Metabolic engineering of algal fatty acid biosynthesis promises to create strains capable of economically producing fungible and sustainable biofuels. The algal fatty acid biosynthetic pathway has been deduced by homology to bacterial and plant systems, and much of our understanding is gleaned from basic studies in these systems. However, successful engineering of lipid metabolism in algae will necessitate a thorough characterization of the algal fatty acid synthase (FAS) including protein-protein interactions and regulation. This review describes recent efforts to engineer fatty acid biosynthesis toward optimizing microalgae as a biodiesel feedstock. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ultrasonic assisted biodiesel production of microalgae by direct transesterification

NASA Astrophysics Data System (ADS)

Kalsum, Ummu; Mahfud, Mahfud; Roesyadi, Achmad

2017-03-01

Microalgae are considered as the third generation source of biofuel and an excellent candidate for biofuel production to replace the fossil energy. The use of ultrasonic in producing biodiesel by direct transesterification of Nannochloropsis occulata using KOH as catalyst and methanol as a solvent was investigated. The following condition were determined as an optimum by experimental evaluates:: 1: 15 microalga to methanol (molar ratio); 3% catalyst concentration at temperature 40°C after 30 minute of ultrasonication. The highest yield of biodiesel produced was 30.3%. The main components of methyl ester from Nannochloropsis occulata were palmitic (C16 :0),, oleic (C18:1), stearic (C18;0), arahidic (C20:0) and myristic (C14:0). This stated that the application of ultrasounic for direct transesterificaiton of microalgae effectively reduced the reaction time compared to the reported values of conventional heating systems.

Carotenoids from Marine Microalgae: A Valuable Natural Source for the Prevention of Chronic Diseases

PubMed Central

Raposo, Maria Filomena de Jesus; de Morais, Alcina Maria Miranda Bernardo; de Morais, Rui Manuel Santos Costa

2015-01-01

Epidemiological studies have shown a relation between antioxidants and the prevention of several chronic diseases. Microalgae are a potential novel source of bioactive molecules, including a wide range of different carotenoids that can be used as nutraceuticals, food supplements and novel food products. The objective of this review is (i) to update the research that has been carried out on the most known carotenoids produced by marine microalgae, including reporting on their high potentialities to produce other less known important compounds; (ii) to compile the work that has been done in order to establish some relationship between carotenoids and oxidative protection and treatment; (iii) to summarize the association of oxidative stress and the various reactive species including free radicals with several human diseases; and (iv) to provide evidence of the potential of carotenoids from marine microalgae to be used as therapeutics to treat or prevent these oxidative stress-related diseases. PMID:26287216

Effect of Organic Solvents on Microalgae Growth, Metabolism and Industrial Bioproduct Extraction: A Review

PubMed Central

Miazek, Krystian; Sulc, Radek; Jirout, Tomas; Aguedo, Mario; Goffin, Dorothee

2017-01-01

In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), as a result of exposure to organic solvents, are summarized. Applications of organic solvents as a carbon source for microalgal growth and production of target molecules are discussed. Possible implementation of various industrial effluents containing organic solvents into microalgal cultivation media, is evaluated. The effect of organic solvents on extraction of target compounds from microalgae is also considered. Techniques for lipid and carotenoid extraction from viable microalgal biomass (milking methods) and dead microalgal biomass (classical methods) are depicted. Moreover, the economic survey of lipid and carotenoid extraction from microalgae biomass, by means of different techniques and solvents, is conducted. PMID:28677659

Use of orange peel extract for mixotrophic cultivation of Chlorella vulgaris: increased production of biomass and FAMEs.

PubMed

Park, Won-Kun; Moon, Myounghoon; Kwak, Min-Su; Jeon, Seungjib; Choi, Gang-Guk; Yang, Ji-Won; Lee, Bongsoo

2014-11-01

Mass cultivation of microalgae is necessary to achieve economically feasible production of microalgal biodiesel, but the high cost of nutrients is a major limitation. In this study, orange peel extract (OPE) was used as an inorganic and organic nutrient source for the cultivation of Chlorella vulgaris OW-01. Chemical composition analysis of the OPE indicated that it contains sufficient nutrients for mixotrophic cultivation of C. vulgaris OW-01. Analysis of biomass and FAME production showed that microalgae grown in OPE medium produced 3.4-times more biomass and 4.5-times more fatty acid methyl esters (FAMEs) than cells cultured in glucose-supplemented BG 11 medium (BG-G). These results suggest that growth of microalgae in an OPE-supplemented medium increases lipid production and that OPE has potential for use in the mass cultivation of microalgae. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of growth phase on the surface properties of three oleaginous microalgae (Botryococcus sp. FACGB-762, Chlorella sp. XJ-445 and Desmodesmus bijugatus XJ-231)

PubMed Central

Xia, Ling; Huang, Rong; Li, Yinta

2017-01-01

The effects of growth phase on the lipid content and surface properties of oleaginous microalgae Botryococcus sp. FACGB-762, Chlorella sp. XJ-445 and Desmodesmus bijugatus XJ-231 were investigated in this study. The results showed that throughout the growth phases, the lipid content of microalgae increased. The surface properties like particle size, the degree of hydrophobicity, and the total concentration of functional groups increased while net surface zeta potential decreased. The results suggested that the growth stage had significant influence not only on the lipid content but also on the surface characteristics. Moreover, the lipid content was significantly positively related to the concentration of hydroxyl functional groups in spite of algal strains or growth phases. These results provided a basis for further studies on the refinery process using oleaginous microalgae for biofuel production. PMID:29045481

Geoengineering, marine microalgae, and climate stabilization in the 21st century

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greene, Charles H.; Huntley, Mark E.; Archibald, Ian

Society has set ambitious targets for stabilizing mean global temperature. To attain these targets, it will have to reduce CO 2 emissions to near zero by mid-century and subsequently remove CO 2 from the atmosphere during the latter half of the century. There is a recognized need to develop technologies for CO 2 removal; however, attempts to develop direct air-capture systems have faced both energetic and financial constraints. Recently, BioEnergy with Carbon Capture and Storage (BECCS) has emerged as a leading candidate for removing CO 2 from the atmosphere. But, BECCS can have negative consequences on land, nutrient, and watermore » use as well as biodiversity and food production. Here, we describe an alternative approach based on the large-scale industrial production of marine microalgae. When cultivated with proper attention to power, carbon, and nutrient sources, microalgae can be processed to produce a variety of biopetroleum products, including carbon-neutral biofuels for the transportation sector and long-lived, potentially carbon-negative construction materials for the built environment. In addition to these direct roles in mitigating and potentially reversing the effects of fossil CO 2 emissions, microalgae can also play an important indirect role. Furthermore, as microalgae exhibit much higher primary production rates than terrestrial plants, they require much less land area to produce an equivalent amount of bioenergy and/or food. On a global scale, the avoided emissions resulting from displacement of conventional agriculture may exceed the benefits of microalgae biofuels in achieving the climate stabilization goals.« less

De Novo Transcriptomic Analysis of an Oleaginous Microalga: Pathway Description and Gene Discovery for Production of Next-Generation Biofuels

PubMed Central

Wan, LingLin; Han, Juan; Sang, Min; Li, AiFen; Wu, Hong; Yin, ShunJi; Zhang, ChengWu

2012-01-01

Background Eustigmatos cf. polyphem is a yellow-green unicellular soil microalga belonging to the eustimatophyte with high biomass and considerable production of triacylglycerols (TAGs) for biofuels, which is thus referred to as an oleaginous microalga. The paucity of microalgae genome sequences, however, limits development of gene-based biofuel feedstock optimization studies. Here we describe the sequencing and de novo transcriptome assembly for a non-model microalgae species, E. cf. polyphem, and identify pathways and genes of importance related to biofuel production. Results We performed the de novo assembly of E. cf. polyphem transcriptome using Illumina paired-end sequencing technology. In a single run, we produced 29,199,432 sequencing reads corresponding to 2.33 Gb total nucleotides. These reads were assembled into 75,632 unigenes with a mean size of 503 bp and an N50 of 663 bp, ranging from 100 bp to >3,000 bp. Assembled unigenes were subjected to BLAST similarity searches and annotated with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) orthology identifiers. These analyses identified the majority of carbohydrate, fatty acids, TAG and carotenoids biosynthesis and catabolism pathways in E. cf. polyphem. Conclusions Our data provides the construction of metabolic pathways involved in the biosynthesis and catabolism of carbohydrate, fatty acids, TAG and carotenoids in E. cf. polyphem and provides a foundation for the molecular genetics and functional genomics required to direct metabolic engineering efforts that seek to enhance the quantity and character of microalgae-based biofuel feedstock. PMID:22536352

Techno-economical evaluation of protein extraction for microalgae biorefinery

NASA Astrophysics Data System (ADS)

Sari, Y. W.; Sanders, J. P. M.; Bruins, M. E.

2016-01-01

Due to scarcity of fossil feedstocks, there is an increasing demand for biobased fuels. Microalgae are considered as promising biobased feedstocks. However, microalgae based fuels are not yet produced at large scale at present. Applying biorefinery, not only for oil, but also for other components, such as carbohydrates and protein, may lead to the sustainable and economical microalgae-based fuels. This paper discusses two relatively mild conditions for microalgal protein extraction, based on alkali and enzymes. Green microalgae (Chlorella fusca) with and without prior lipid removal were used as feedstocks. Under mild conditions, more protein could be extracted using proteases, with the highest yields for microalgae meal (without lipids). The data on protein extraction yields were used to calculate the costs for producing 1 ton of microalgal protein. The processing cost for the alkaline method was € 2448 /ton protein. Enzymatic method performed better from an economic point of view with € 1367 /ton protein on processing costs. However, this is still far from industrially feasible. For both extraction methods, biomass cost per ton of produced product were high. A higher protein extraction yield can partially solve this problem, lowering processing cost to €620 and 1180 /ton protein product, using alkali and enzyme, respectively. Although alkaline method has lower processing cost, optimization appears to be better achievable using enzymes. If the enzymatic method can be optimized by lowering the amount of alkali added, leading to processing cost of € 633/ton protein product. Higher revenue can be generated when the residue after protein extraction can be sold as fuel, or better as a highly digestible feed for cattle.

Membrane Proteomic Insights into the Physiology and Taxonomy of an Oleaginous Green Microalga.

PubMed

Garibay-Hernández, Adriana; Barkla, Bronwyn J; Vera-Estrella, Rosario; Martinez, Alfredo; Pantoja, Omar

2017-01-01

Ettlia oleoabundans is a nonsequenced oleaginous green microalga. Despite the significant biotechnological interest in producing value-added compounds from the acyl lipids of this microalga, a basic understanding of the physiology and biochemistry of oleaginous microalgae is lacking, especially under nitrogen deprivation conditions known to trigger lipid accumulation. Using an RNA sequencing-based proteomics approach together with manual annotation, we are able to provide, to our knowledge, the first membrane proteome of an oleaginous microalga. This approach allowed the identification of novel proteins in E. oleoabundans, including two photoprotection-related proteins, Photosystem II Subunit S and Maintenance of Photosystem II under High Light1, which were considered exclusive to higher photosynthetic organisms, as well as Retinitis Pigmentosa Type 2-Clathrin Light Chain, a membrane protein with a novel domain architecture. Free-flow zonal electrophoresis of microalgal membranes coupled to liquid chromatography-tandem mass spectrometry proved to be a useful technique for determining the intracellular location of proteins of interest. Carbon-flow compartmentalization in E. oleoabundans was modeled using this information. Molecular phylogenetic analyses of protein markers and 18S ribosomal DNA support the reclassification of E. oleoabundans within the trebouxiophycean microalgae, rather than with the Chlorophyceae class, in which it is currently classified, indicating that it may not be closely related to the model green alga Chlamydomonas reinhardtii A detailed survey of biological processes taking place in the membranes of nitrogen-deprived E. oleoabundans, including lipid metabolism, provides insights into the basic biology of this nonmodel organism. © 2017 American Society of Plant Biologists. All Rights Reserved.

Geoengineering, marine microalgae, and climate stabilization in the 21st century

DOE PAGES

Greene, Charles H.; Huntley, Mark E.; Archibald, Ian; ...

2017-03-21

Society has set ambitious targets for stabilizing mean global temperature. To attain these targets, it will have to reduce CO 2 emissions to near zero by mid-century and subsequently remove CO 2 from the atmosphere during the latter half of the century. There is a recognized need to develop technologies for CO 2 removal; however, attempts to develop direct air-capture systems have faced both energetic and financial constraints. Recently, BioEnergy with Carbon Capture and Storage (BECCS) has emerged as a leading candidate for removing CO 2 from the atmosphere. But, BECCS can have negative consequences on land, nutrient, and watermore » use as well as biodiversity and food production. Here, we describe an alternative approach based on the large-scale industrial production of marine microalgae. When cultivated with proper attention to power, carbon, and nutrient sources, microalgae can be processed to produce a variety of biopetroleum products, including carbon-neutral biofuels for the transportation sector and long-lived, potentially carbon-negative construction materials for the built environment. In addition to these direct roles in mitigating and potentially reversing the effects of fossil CO 2 emissions, microalgae can also play an important indirect role. Furthermore, as microalgae exhibit much higher primary production rates than terrestrial plants, they require much less land area to produce an equivalent amount of bioenergy and/or food. On a global scale, the avoided emissions resulting from displacement of conventional agriculture may exceed the benefits of microalgae biofuels in achieving the climate stabilization goals.« less

Effect of microalgae storage conditions on methane yields.

PubMed

Barreiro-Vescovo, Santiago; de Godos, Ignacio; Tomás-Pejó, Elia; Ballesteros, Mercedes; González-Fernández, Cristina

2018-05-01

During the last decade, a lot of research has been focused on identifying the methane yields achievable when using microalgae biomass (fresh and pretreated) as a substrate in anaerobic digestion. Encountered differences are frequently attributed to the different microalgae strains (cell walls and macromolecular profiles) or the different metabolic activities of anaerobic sludge used as inoculum. Nevertheless, under the hypothesis that the state of microalgae upon biomass storage may also play a significant role, this study was designed to evaluate the effect of biomass processing and storage on methane yields and hydrolysis kinetics in batch mode assays. Slight changes in the macromolecular profile distribution of the different tested biomass were observed. Regardless of the time that the biomass was stored, results revealed that frozen biomass doubled the hydrolysis constant and enhanced methane yield by 1.56-fold compared to fresh microalgae biomass (82.4 mL CH 4  g COD in -1 ). Similar enhancement was obtained with the freeze-dried biomass, and slightly lower values were obtained (1.34-fold) for the biomass kept at 4 °C longer than a week. Likewise, the semi-continuously operated reactor fed with microalgae biomass stored for 28 days at 4 °C did not show any effect in terms of methane production, although nitrogen mineralization was higher than expected. Remarkably, the initial stage of the biomass should be carefully considered for comparison purposes with the available literature on batch mode assays. This study highlights the importance of considering how the biomass is stored before the anaerobic digestion process to avoid misleading conclusions.

Design of a Nutrient Reclamation System for the Cultivation of Microalgae for Biofuel Production and Other Industrial Applications

NASA Astrophysics Data System (ADS)

Sandefur, Heather Nicole

Microalgal biomass has been identified as a promising feedstock for a number of industrial applications, including the synthesis of new pharmaceutical and biofuel products. However, there are several economic limitations associated with the scale up of existing algal production processes. Critical economic studies of algae-based industrial processes highlight the high cost of supplying essential nutrients to microalgae cultures. With microalgae cells having relatively high nitrogen contents (4 to 8%), the N fertilizer cost in industrial-scale production is significant. In addition, the disposal of the large volumes of cell residuals that are generated during product extraction stages can pose other economic challenges. While waste streams can provide a concentrated source of nutrients, concerns about the presence of biological contaminants and the expense of heat treatment pose challenges to processes that use wastewater as a nutrient source in microalgae cultures. The goal of this study was to evaluate the potential application of ultrafiltration technology to aid in the utilization of agricultural wastewater in the cultivation of a high-value microalgae strain. An ultrafiltration system was used to remove inorganic solids and biological contaminants from wastewater taken from a swine farm in Savoy, Arkansas. The permeate from the system was then used as the nutrient source for the cultivation of the marine microalgae Porphyridium cruentum. During the ultrafiltration system operation, little membrane fouling was observed, and permeate fluxes remained relatively constant during both short-term and long-term tests. The complete rejection of E. coli and coliforms from the wastewater was also observed, in addition to a 75% reduction in total solids, including inorganic materials. The processed permeate was shown to have very high concentrations of total nitrogen (695.6 mg L-1) and total phosphorus (69.1 mg L-1 ). In addition, the growth of P. cruentum was analyzed in a medium containing swine waste permeate, and was compared to P. cruentum growth in a control medium. A higher biomass productivity, lipid productivity, and lipid content were observed in the microalgae cultivated in the swine waste medium compared to that of the control medium. These results suggest that, through the use of ultrafiltration technology as an alternative to traditional heat treatment, agricultural wastewaters could be effectively utilized as a nutrient source for microalgae cultivation.

In situ Transesterification of Microalgal Oil to Produce Algal Biodiesel

DOT National Transportation Integrated Search

2012-06-01

This research was to process whole microalgae cells for biodiesel production without first extracting lipids. The ultimate : goal is develop a novel process for algal biodiesel production directly from microalgae cells in a single step, i.e., in situ...

Discrimination of Pigments of Microalgae, Bacteria and Yeasts Using Lightweight Handheld Raman Spectrometers: Prospects for Astrobiology

NASA Astrophysics Data System (ADS)

Jehlicka, J.; Osterrothova, K.; Nedbalova, L.; Gunde-Cimerman, N.; Oren, A.

2014-06-01

Handheld Raman instrumentation with 532 nm lasers can be used to distinguish carotenoids of autotrophic microalgae, purple sulfur bacteria, halophilic Archaea and pigmented yeasts. Pigments are proposed as biomarkers for astrobiology of Mars.

Terpenes as green solvents for extraction of oil from microalgae.

PubMed

Dejoye Tanzi, Celine; Abert Vian, Maryline; Ginies, Christian; Elmaataoui, Mohamed; Chemat, Farid

2012-07-09

Herein is described a green and original alternative procedure for the extraction of oil from microalgae. Extractions were carried out using terpenes obtained from renewable feedstocks as alternative solvents instead of hazardous petroleum solvents such as n-hexane. The described method is achieved in two steps using Soxhlet extraction followed by the elimination of the solvent from the medium using Clevenger distillation in the second step. Oils extracted from microalgae were compared in terms of qualitative and quantitative determination. No significant difference was obtained between each extract, allowing us to conclude that the proposed method is green, clean and efficient.

Environmental quality assessment using microalgae structures adjacent fish faming at Setoko Island, Batam City, Kepulaun Riau Province

NASA Astrophysics Data System (ADS)

Hariyati, Riche; Putro, Sapto

2018-05-01

Along with the increasing challenges that come with the demand for national and international fisheries’ products and the potential emergence of various environmental concerns, various efforts have been made to increase production capacity through extensification and intensification programs. This study aimed to assess the environmental quality and the level of disturbance in the floating net cage aquaculture area based on the microalgae community structure. The research was conducted from August to October 2017 at the water ecosystem used for aquaculture at Setoko Island, Batam City, Kepulauan Riau Province. Purposive random sampling was used by determining 3 sampling stations with three replicates. Data was analyzed using saprobic, Shanon-Wiener (H’) diversity, abundance and domination indices. The result showed that 13 genus microalgae (bawal fish fish farming), 9 genus (fish farming kakap) and 11 genus of microalgae (kerapu fish farming ) consisting of Chlorophyta, Chyanophyta Chrysophyta and Dinophyta were recorded. The value of H’ index at the farming area ranged from 0.73 to 1.5. Microalgae abundance was dominated by Phacus sp, Coscinodiscus sp, Climacosphenia sp and Spirogyra sp. Based on the saprobic index, the farm area has an index value of 1.92, thus it can be refferred to as the oligo/β-meso-saprobic phase, indicating light disturbance by organic enrichment.

Ingestion of Brachionus plicatilis under different microalgae conditions

NASA Astrophysics Data System (ADS)

Zhou, Wenli; Tang, Xuexi; Qiao, Xiuting; Wang, You; Wang, Renjun; Feng, Lei

2009-09-01

The effects of four microalgae, Chlorella vulgaris, Platymonas helgolandicavar, Isochrysis galbana, and Nitzschia closterium on the grazing and filtering rates of the marine rotifer, Brachionus plicatilis, were evaluated under laboratory conditions. The grazing rates in separate cultures of the four microalga were as follows: C. vulgaris > P. helgolandicavar > I. galbana > N. closterium. However, the filtering rates occurred in the following order: P. helgolandicavar > N. closterium > C. vulgaris > I. galbana. A mixed diets experiment revealed that P. helgolandicavar was the preferred diet of B. plicatilis. In addition, the grazing rate of B. plicatilis increased gradually as the density of the microalgae increased, until concentrations of 2.5×106 cells mL-1 for C. vulgaris and 1.5×106 cells mL-1 for I. galbana were obtained. Furthermore, the filtering rate increased slightly when the density of the microalgae was low, after which it declined as the microalgal density increased. The grazing rates of B. plicatilis were as follows during the different growth phases: stationary phase > exponential phase > lag phase > decline phase. Additionally, the filtering rates during the growth phases were: exponential phase > lag phase > stationary phase > decline phase. The results of this study provide foundational information that can be used to explore the optimal culture conditions for rotifers and to promote the development of aquaculture.

Hydrocarbon productivities in different Botryococcus strains: comparative methods in product quantification.

PubMed

Eroglu, Ela; Okada, Shigeru; Melis, Anastasios

2011-08-01

Six different strains of the green microalgae Botryococcus belonging to the A-race or B-race, accumulating alkadiene or botryococcene hydrocarbons, respectively, were compared for biomass and hydrocarbon productivities. Biomass productivity was assessed gravimetrically upon strain growth in the laboratory under defined conditions. Hydrocarbon productivities were measured by three different and independent experimental approaches, including density equilibrium of the intact cells and micro-colonies, spectrophotometric analysis of hydrocarbon extracts, and gravimetric quantitation of eluted hydrocarbons. All three hydrocarbon-quantitation methods yielded similar results for each of the strains examined. The B-race microalgae Botryococcus braunii var. Showa and Kawaguchi-1 constitutively accumulated botryococcene hydrocarbons equivalent to 30% and 20%, respectively, of their overall biomass. The A-race microalgae Botryococcus braunii, varieties Yamanaka, UTEX 2441 and UTEX LB572 constitutively accumulated alkadiene hydrocarbons ranging from 14% to 13% and 10% of their overall biomass, respectively. Botryococcus sudeticus (UTEX 2629), a morphologically different green microalga, had the lowest hydrocarbon accumulation, equal to about 3% of its overall biomass. Results validate the density equilibrium and spectrophotometric analysis methods in the quantitation of botryococcene-type hydrocarbons. These analytical advances will serve in the screening and selection of B. braunii and of other microalgae in efforts to identify those having a high hydrocarbon content for use in commercial applications.

Recent Developments on the Production of Transportation Fuels via Catalytic Conversion of Microalgae: Experiments and Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Fan; Wang, Ping; Duan, Yuhua

2012-08-02

Due to continuing high demand, depletion of non-renewable resources and increasing concerns about climate change, the use of fossil fuel-derived transportation fuels faces relentless challenges both from a world markets and an environmental perspective. The production of renewable transportation fuel from microalgae continues to attract much attention because of its potential for fast growth rates, high oil content, ability to grow in unconventional scenarios, and inherent carbon neutrality. Moreover, the use of microalgae would minimize “food versus fuel” concerns associated with several biomass strategies, as microalgae do not compete with food crops in the food chain. This paper reviews themore » progress of recent research on the production of transportation fuels via homogeneous and heterogeneous catalytic conversions of microalgae. This review also describes the development of tools that may allow for a more fundamental understanding of catalyst selection and conversion processes using computational modelling. The catalytic conversion reaction pathways that have been investigated are fully discussed based on both experimental and theoretical approaches. Finally, this work makes several projections for the potential of various thermocatalytic pathways to produce alternative transportation fuels from algae, and identifies key areas where the authors feel that computational modelling should be directed to elucidate key information to optimize the process.« less

Multi-Wavelength Based Optical Density Sensor for Autonomous Monitoring of Microalgae

PubMed Central

Jia, Fei; Kacira, Murat; Ogden, Kimberly L.

2015-01-01

A multi-wavelength based optical density sensor unit was designed, developed, and evaluated to monitor microalgae growth in real time. The system consisted of five main components including: (1) laser diode modules as light sources; (2) photodiodes as detectors; (3) driver circuit; (4) flow cell; and (5) sensor housing temperature controller. The sensor unit was designed to be integrated into any microalgae culture system for both real time and non-real time optical density measurements and algae growth monitoring applications. It was shown that the sensor unit was capable of monitoring the dynamics and physiological changes of the microalgae culture in real-time. Algae biomass concentration was accurately estimated with optical density measurements at 650, 685 and 780 nm wavelengths used by the sensor unit. The sensor unit was able to monitor cell concentration as high as 1.05 g·L−1 (1.51 × 108 cells·mL−1) during the culture growth without any sample preparation for the measurements. Since high cell concentrations do not need to be diluted using the sensor unit, the system has the potential to be used in industrial microalgae cultivation systems for real time monitoring and control applications that can lead to improved resource use efficiency. PMID:26364640

Systems and economic analysis of microalgae ponds for conversion of CO{sub 2} to biomass. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benemann, J.R.; Oswald, W.J.

There is growing evidence that global warming could become a major global environmental threat during the 21st century. The precautionary principle commands preventive action, at both national and international levels, to minimize this potential threat. Many near-term, relatively inexpensive, mitigation options are available. In addition, long-term research is required to evaluate and develop advanced, possibly more expensive, countermeasures, in the eventuality that they may be required. The utilization of power plant CO{sub 2} and its recycling into fossil fuel substitutes by microalgae cultures could be one such long-term technology. Microalgae production is an expanding industry in the U.S., with threemore » commercial systems (of approximately 10 hectare each) producing nutriceuticals, specifically beta-carotene, extracted from Dunaliella, and Spirulina biomass. Microalgae are also used in wastewater treatment. Currently production costs are high, about $10,000/ton of algal biomass, almost two orders of magnitude higher than acceptable for greenhouse gas mitigation. This report reviews the current state-of-the-art, including algal cultivation and harvesting-processing, and outlines a technique for achieving very high productivities. Costs of CO{sub 2} mitigation with microalgae production of oils ({open_quotes}biodiesel{close_quotes}) are estimated and future R&D needs outlined.« less

Genetic engineering of the Calvin cycle toward enhanced photosynthetic CO2 fixation in microalgae.

PubMed

Yang, Bo; Liu, Jin; Ma, Xiaonian; Guo, Bingbing; Liu, Bin; Wu, Tao; Jiang, Yue; Chen, Feng

2017-01-01

Photosynthetic microalgae are emerging as potential biomass feedstock for sustainable production of biofuels and value-added bioproducts. CO 2 biomitigation through these organisms is considered as an eco-friendly and promising alternative to the existing carbon sequestration methods. Nonetheless, the inherent relatively low photosynthetic capacity of microalgae has hampered the practical use of this strategy for CO 2 biomitigation applications. Here, we demonstrate the feasibility of improving photosynthetic capacity by the genetic manipulation of the Calvin cycle in the typical green microalga Chlorella vulgaris . Firstly, we fused a plastid transit peptide to upstream of the enhanced green fluorescent protein (EGFP) and confirmed its expression in the chloroplast of C. vulgaris . Then we introduced the cyanobacterial fructose 1,6-bisphosphate aldolase, guided by the plastid transit peptide, into C. vulgaris chloroplast, leading to enhanced photosynthetic capacity (~ 1.2-fold) and cell growth. Molecular and physiochemical analyses suggested a possible role for aldolase overexpression in promoting the regeneration of ribulose 1,5-bisphosphate in the Calvin cycle and energy transfer in photosystems. Our work represents a proof-of-concept effort to enhance photosynthetic capacity by the engineering of the Calvin cycle in green microalgae. Our work also provides insights into targeted genetic engineering toward algal trait improvement for CO 2 biomitigation uses.

Neutral lipid accumulation at elevated temperature in conditional mutants of two microalgae species.

PubMed

Yao, Shuo; Brandt, Anders; Egsgaard, Helge; Gjermansen, Claes

2012-12-01

Triacylglycerols, an energy storage compound in microalgae, are known to be accumulated after nitrogen starvation of microalgae cells. Microalgae could be of importance for future biodiesel production due to their fast growth rate and high oil content. In collections of temperature sensitive mutants of Chlamydomonas reinhardtii and Chlorella vulgaris, nine out of fourty-one mutants in C. reinhardtii and eleven out of fifty-three mutants in C. vulgaris contained increased amounts of neutral lipids, predominantly as triacylglycerols. Upon temperature induced cell-cycle arrest, these mutants showed enlarged cellular volume compared with the wild type. The C. reinhardtii mutants were analyzed further and one type of mutants displayed a shift in lipid composition from polar membrane lipids to neutral lipids after a temperature up-shift, while the second type of mutants accumulated more total lipid per cell, predominantly as neutral lipids as compared with the wild type. Three C. reinhardtii mutants were analyzed further and found to be arrested after DNA synthesis but prior to cell division in the cell cycle. These mutants will be useful in order to further understand neutral lipid accumulation in microalgae and suggest possibilities for biodiesel production by specific induction of lipid accumulation in miroalgal cultures by cell-cycle inhibition. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

An informatics-based analysis of developments to date and prospects for the application of microalgae in the biological sequestration of industrial flue gas.

PubMed

Zhu, Xi; Rong, Junfeng; Chen, Hui; He, Chenliu; Hu, Wensheng; Wang, Qiang

2016-03-01

The excessive emission of flue gas contributes to air pollution, abnormal climate change, global warming, and sea level rises associated with glacial melting. With the ability to utilize NOx as a nitrogen source and to convert solar energy into chemical energy via CO2 fixation, microalgae can potentially reduce air pollution and relax global warming, while also enhancing biomass and biofuel production as well as the production of high-value-added products. This informatics-based review analyzes the trends in the related literature and in patent activity to draw conclusions and to offer a prospective view on the developments of microalgae for industrial flue gas biosequestration. It is revealed that in recent years, microalgal research for industrial flue gas biosequestration has started to attract increasing attention and has now developed into a hot research topic, although it is still at a relatively early stage, and needs more financial and policy support in order to better understand microalgae and to develop an economically viable process. In comparison with onsite microalgal CO2 capture, microalgae-based biological DeNOx appears to be a more realistic and attractive alternative that could be applied to NOx treatment.

Continuous culture methodology for the screening of microalgae for oil.

PubMed

Del Río, Esperanza; Armendáriz, Ana; García-Gómez, Elena; García-González, Mercedes; Guerrero, Miguel G

2015-02-10

A basic criterion in the selection of microalgae suitable as source of oil for biodiesel should be their actual capacity to produce lipids or, more properly, the fatty acid yield. Performance assessment of 10 preselected microalgae under both batch and continuous culture points to the latter approach as the most adequate for evaluating fatty acid productivity. Differences were patent in continuous culture among strains that otherwise had analogous oil accumulation potential under batch culture. Some promising strains under batch culture (like Muriella aurantiaca and Monoraphidium braunii) exhibited, however, values for actual fatty acid productivity lower than 40 mgL(-1)d(-1) in continuous regime. The analysis performed in photochemostat under continuous culture regime revealed the great potential of Chlorococcum olefaciens, Pseudokirchneriella subcapitata and Scenedesmus almeriensis as oil producing microalgae. Fatty acid productivity levels over 90 mgL(-1)d(-1) were recorded for the latter strains under moderate nitrogen limitation, conditions which led to an enrichment in saturated and monounsaturated fatty acids, a more suitable profile as raw material for biodiesel. The continuous culture methodology employed represents a sound procedure for screening microalgae for biofuel production, providing a reliable evaluation of their fatty acid production capacity, under conditions close to those of outdoor production systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Performance of a sand filter in removal of micro-algae from seawater in aquaculture production systems.

PubMed

Sabiri, N E; Castaing, J B; Massé, A; Jaouen, P

2012-01-01

In this study, a sand filter was used to remove micro-algae from seawater feeding aquaculture ponds. A lab-scale sand filter was used to filter 30,000 cells/mL of Heterocapsa triquetra suspension, a non-toxic micro-alga that has morphological and dimensional (15-20 microm) similarities with Alexandrium sp., one of the smallest toxic micro-algae in seawater. Removal efficiency and capture mechanisms for a fixed superficial velocity (3.5 m/h) were evaluated in relation to size distribution and mean diameter of the sand. Various sands (average diameter ranging between 200 microm and 600 microm) were characterized and used as porous media. The structural parameters of the fixed beds were evaluated for each medium using experimental measurements of pressure drop as a function of superficial velocity over a range of Reynolds numbers covering Darcy's regime and the inertial regime. For a filtration cycle of six hours, the best efficiency (E = 90%) was obtained with the following sand characteristics: sieved sand with a range of grain diameter of 100 and 300 microm and a mean grain diameter equal to 256 microm. Results obtained show the influence of the size distribution of sand on the quality of retention of the micro-algae studied.

Targeted delivery of fluorogenic peptide aptamers into live microalgae by femtosecond laser photoporation at single-cell resolution.

PubMed

Maeno, Takanori; Uzawa, Takanori; Kono, Izumi; Okano, Kazunori; Iino, Takanori; Fukita, Keisuke; Oshikawa, Yuki; Ogawa, Taro; Iwata, Osamu; Ito, Takuro; Suzuki, Kengo; Goda, Keisuke; Hosokawa, Yoichiroh

2018-05-29

Microalgae-based metabolic engineering has been proven effective for producing valuable substances such as food supplements, pharmaceutical drugs, biodegradable plastics, and biofuels in the past decade. The ability to accurately visualize and quantify intracellular metabolites in live microalgae is essential for efficient metabolic engineering, but remains a major challenge due to the lack of characterization methods. Here we demonstrate it by synthesizing fluorogenic peptide aptamers with specific binding affinity to a target metabolite and delivering them into live microalgae by femtosecond laser photoporation at single-cell resolution. As a proof-of-principle demonstration of our method, we use it to characterize Euglena gracilis, a photosynthetic unicellular motile microalgal species, which is capable of producing paramylon (a carbohydrate granule similar to starch). Specifically, we synthesize a peptide aptamer containing a paramylon-binding fluorescent probe, 7-nitrobenzofurazan, and introduce it into E. gracilis cells one-by-one by suppressing their mobility with mannitol and transiently perforating them with femtosecond laser pulses at 800 nm for photoporation. To demonstrate the method's practical utility in metabolic engineering, we perform spatially and temporally resolved fluorescence microscopy of single live photoporated E. gracilis cells under different culture conditions. Our method holds great promise for highly efficient microalgae-based metabolic engineering.

Strains of toxic and harmful microalgae, from waste water, marine, brackish and fresh water.

PubMed

Rodríguez-Palacio, M C; Crisóstomo-Vázquez, L; Alvarez-Hernández, S; Lozano-Ramírez, C

2012-01-01

Some microalgae are economically important in Mexico and the world because they can be potentially toxic. Algal explosive population growths are named harmful algal blooms and are frequently recorded in Mexico. The authors set up potentially toxic microalgae cultures from the Gulf of Mexico (Garrapatas tideland, Barberena river, Carpintero lagoon in Tamaulipas State; Chalchoapan and Catemaco lakes in Veracruz State), from the Mexican Pacific Ocean, Guerrero, Colima and Michoacán States, and from interior water bodies such as Vicente Aguirre dam, Chapultepec lake and several waste water treatment plants. This research is about the diversity and abundance of phytoplankton in relation a specific site because of harmful algal bloom events. Microalgae cultures are useful in order to solve taxonomic problems, to know life cycles, molecular studies, for the study of toxic species, and the isolation of useful metabolites. The cultures for this research are clonal, non-axenic, semi-continuous, 12:12 light/dark photoperiod, 20 ± 1 °C temperature and 90.5 µmol m(-2)s(-1) illumination. Four different culture media were used. This collection is open to the worldwide scientific community as a source of organisms in controlled conditions that can be used as a useful tool for microalgae research work.

The potential of freshwater macroalgae as a biofuels feedstock and the influence of nutrient availability on freshwater macroalgal biomass production

NASA Astrophysics Data System (ADS)

Yun, Jin-Ho

Extensive efforts have been made to evaluate the potential of microalgae as a biofuel feedstock during the past 4-5 decades. However, filamentous freshwater macroalgae have numerous characteristics that favor their potential use as an alternative algal feedstock for biofuels production. Freshwater macroalgae exhibit high rates of areal productivity, and their tendency to form dense floating mats on the water surface imply significant reductions in harvesting and dewater costs compared to microalgae. In Chapter 1, I reviewed the published literature on the elemental composition and energy content of five genera of freshwater macroalgae. This review suggested that freshwater macroalgae compare favorably with traditional bio-based energy sources, including terrestrial residues, wood, and coal. In addition, I performed a semi-continuous culture experiment using the common Chlorophyte genus Oedogonium to investigate whether nutrient availability can influence its higher heating value (HHV), productivity, and proximate analysis. The experimental study suggested that the most nutrient-limited growth conditions resulted in a significant increase in the HHV of the Oedogonium biomass (14.4 MJ/kg to 16.1 MJ/kg). Although there was no significant difference in productivity between the treatments, the average dry weight productivity of Oedogonium (3.37 g/m2/day) was found to be much higher than is achievable with common terrestrial plant crops. Although filamentous freshwater macroalgae, therefore, have significant potential as a renewable source of bioenergy, the ultimate success of freshwater macroalgae as a biofuel feedstock will depend upon the ability to produce biomass at the commercial-scale in a cost-effective and sustainable manner. Aquatic ecology can play an important role to achieve the scale-up of algal crop production by informing the supply rates of nutrients to the cultivation systems, and by helping to create adaptive production systems that are resilient to environmental change. In Chapter 2, I performed a review and an analysis of data from the published literature on the large-cultivation of freshwater macroalgae. This study revealed that the large-scale cultivation of freshwater macroalgae is feasible at relatively low cost using currently available technologies such as the Algal Turf Scrubber system (ATS). In addition, graphical analyses of published data obtained from ATS systems of varying sizes in operation worldwide revealed that both macroalgal biomass productivity and nutrient removal rates are hyperbolically related to the areal loading rates of both total nitrogen and total phosphorus. An assessment of the limited existing literature on carbon dioxide amendments suggested that the effectiveness and need for CO2 supplementation of macroalgal production systems like the ATS has not yet been conclusively demonstrated. Overall, this thesis demonstrates that filamentous freshwater macroalgae have great potential as a feedstock for both liquid and solid fuels, especially if nutrient-rich wastewater can be used as the supply of water and mineral nutrients. In addition, this thesis highlights the importance of studying the algal cultivation conditions that influence trade-offs between nutrient loading, biomass productivity, and biomass energy content. In particular, the hyperbolic relationship between algal biomass productivity and the areal loading rates of both total nitrogen and total phosphorus should provide critical insight when considering the production costs of macroalgal biomass at the commercial-scale.

Nanoscale wide-band semiconductors for photocatalytic remediation of aquatic pollution.

PubMed

Sarkar, Biplab; Daware, Akshay Vishnu; Gupta, Priya; Krishnani, Kishore Kumar; Baruah, Sunandan; Bhattacharjee, Surajit

2017-11-01

Water pollution is a serious challenge to the public health. Among different forms of aquatic pollutants, chemical and biological agents create paramount threat to water quality when the safety standards are surpassed. There are many conventional remediatory strategies that are practiced such as resin-based exchanger and activated charcoal/carbon andreverse osmosis. Newer technologies using plants, microorganisms, genetic engineering, and enzyme-based approaches are also proposed for aquatic pollution management. However, the conventional technologies have shown impending inadequacies. On the other hand, new bio-based techniques have failed to exhibit reproducibility, wide specificity, and fidelity in field conditions. Hence, to solve these shortcomings, nanotechnology ushered a ray of hope by applying nanoscale zinc oxide (ZnO), titanium dioxide (TiO 2 ), and tungsten oxide (WO 3 ) particles for the remediation of water pollution. These nanophotocatalysts are active, cost-effective, quicker in action, and can be implemented at a larger scale. These nanoparticles are climate-independent, assist in complete mineralization of pollutants, and can act non-specifically against chemically and biologically based aquatic pollutants. Photocatalysis for environmental remediation depends on the availability of solar light. The mechanism of photocatalysis involves the formation of electron-hole pairs upon light irradiations at intensities higher than their band gap energies. In the present review, different methods of synthesis of nanoscale ZnO, TiO 2 , and WO 3 as well as their structural characterizations have been discussed. Photodegradation of organic pollutants through mentioned nanoparticles has been reviewed with recent advancements. Enhancing the efficacy of photocatalysis through doping of TiO 2 and ZnO nanoparticles with non-metals, metals, and metal ions has also been documented in this report.

Urgent and Compelling Need for Coastal and Inland Aquatic Ecosystem Research Using Space-Based Sensors

NASA Astrophysics Data System (ADS)

Otis, D. B.; Muller-Karger, F. E.; Hestir, E.; Turpie, K. R.; Roberts, D. A.; Frouin, R.; Goodman, J.; Schaeffer, B. A.; Franz, B. A.; Humm, D. C.

2016-12-01

Coastal and inland waters and associated aquatic habitats, including wetlands, mangroves, submerged grasses, and coral reefs, are some of the most productive and diverse ecosystems on the planet. They provide services critical to human health, safety, and prosperity. Yet, they are highly vulnerable to changes in climate and other anthropogenic pressures. With a global population of over seven billion people and climbing, and a warming atmosphere driven by carbon dioxide now in excess of 400 ppb, these services are at risk of rapidly diminishing globally. We know little about how these ecosystems function. We need to characterize short-term changes in the functional biodiversity and biogeochemical cycles of these coastal and wetland ecosystems, from canopy to benthos, and trace these changes to their underlying environmental influences. This requires an observation-based approach that covers coastal and inland aquatic ecosystems in a repeated, synoptic manner. Space-borne sensing systems can provide this capability, supported by coordinated in situ calibration and product validation activities. The design requires high temporal resolution (weekly or better), medium spatial resolution (30 m pixels at nadir to complement Landsat-class sensors), and highly sensitive, ocean-color radiometric quality, high resolution spectroscopy with Visible and Short-Wave IR bands (order of 10 nm or better) to assess both atmospheric correction parameters and land vegetation composition. The strategy needs to include sunglint avoidance schemes, and methods to maximize signal to noise ratios and temporal coverage of aquatic areas. We describe such a system, and urge the U.S. to implement such an observing strategy in the short-term and sustain it for the benefit of humankind.

ASI: Dunaliella Marine Microalgae to Drop-In Replacement Liquid Transportation Fuel

USDA-ARS?s Scientific Manuscript database

Microalgae are a promising biofuels feedstock, theoretically yielding concentrations of triacylglycerides (TAGs) per unit area far higher than traditional feedstocks due to their rapid growth. Dunaliella is particularly advantageous as a feedstock because it is currently commercially mass cultured,...

Performance and emission analysis of single cylinder SI engine using bioethanol-gasoline blend produced from Salvinia Molesta

NASA Astrophysics Data System (ADS)

Gupta, Priyank; Protim Das, Partha; Mubarak, M.; Shaija, A.

2018-01-01

Rapid depletion of world’s crude oil reserve, rising global energy demand and concerns about greenhouse gases emission have led to the high-level interest in biofuels. The biofuel, bioethanol is found as an alternative fuel for SI engines as it has similar properties those of gasoline. Higher areal productivity with fast growth rate of microalgae and aquatic weeds makes them promising alternative feedstocks for bioethanol production. In this study, bioethanol produced from S.molesta (aquatic weed) using combined pre-treatment and hydrolysis followed by fermentation with yeast was used to make bioethanol-gasoline blend. The quantity of bioethanol produced from S.molesta was 99.12% pure. The physical properties such as density and heating value of bioethanol were 792.2 kg/m3 and 26.12 MJ/kg, respectively. In this work, the effects of bioethanol-gasoline (E5) fuel blends on the performance and combustion characteristics of a spark ignition (SI) engine were investigated. In the experiments, a single-cylinder, four-stroke SI engine was used. The tests were performed using electric dynamometer while running the engine at the speed (3200 rpm), and seven different load (0, 0.5, 1, 1.5, 2, 2.5 and 3 kW). The results obtained from the use of bioethanol-gasoline fuel blends were compared to those of gasoline fuel. The test results showed an increase of 0.3% in brake thermal efficiency for E5. From the emission analysis, reduced emissions of 39 ppm unburned hydrocarbon, 1.55% carbon monoxide and 2% smoke opacity, respectively was observed with E5 at full load. An increase in CO2 by 0.17% and NOx by 86.7 ppm was observed for E5 at full load.

Cultivation of newly isolated microalgae Coelastrum sp. in wastewater for simultaneous CO2 fixation, lipid production and wastewater treatment.

PubMed

Mousavi, Shokouh; Najafpour, Ghasem D; Mohammadi, Maedeh; Seifi, Mohammad Hasan

2018-04-01

Cultivation of microalgae in wastewater is a promising and cost-effective approach for both CO 2 biofixation and wastewater remediation. In this study, a new strain of Coelastrum sp. was isolated from cattle manure leachate. The isolated microalgae were then cultivated in wastewater. Effects of different sCOD concentrations (600, 750, 900, 1050 mg L -1 ) and light intensities (1000, 2300, 4600, 6900 and 10000 Lux) on biomass production, CO 2 consumption rate and nutrient removal from wastewater were investigated. The results showed that maximum cell growth and CO 2 consumption rate were 2.71 g L -1 and 53.12 mg L -1 day -1 , respectively, which were obtained in the wastewater with 750 mg L -1 sCOD and under the light intensity of 6900 Lux. The microalgae were able to completely consume all CO 2 after incubation period of 4 days. The highest sCOD, total Kjeldahl nitrogen (TKN), nitrate and total phosphorous (TP) removal at such conditions were 53.45, 91.18, 87.51 and 100%, respectively. The lipid content of microalgal biomass was also measured under different light intensities; maximum amount of lipid was determined to be 50.77% under illumination of 2300 Lux. Finally, the CO 2 consumption rate and biomass productivity of microalgae in semi-batch culture with continuous gas flow (CO 2 6%:N 2 94%) were investigated. The rate of CO 2 consumption and biomass productivity were 0.528 and 0.281 g L -1 day -1 , respectively. The TKN, nitrate, TP and sCOD removal rate of microalgae were 83.51, 80.91, 100, 41.4%, respectively.

Sesquiterpenoids with antialgal activity against the common red tide microalgae from marine macroalga Porphyra yezoensis.

PubMed

Sun, Ying-Ying; Xing, Jing-Zeng; Zhang, Jian-Shuo; Zhou, Wen-Jing; Pu, Yin-Fang

2018-03-01

Previous studies showed that methanol extracts from Porphyra yezoensis significantly inhibited Karenia mikimitoi and Skeletonema costatum. Five sesquiterpenoids (1-5) were successfully isolated from this marine macroalga through a combination of silica gel column chromatography and repeated preparative thin-layer chromatography in this paper. Their structure was identified as gossonorol (1), 7,10-epoxy-ar-bisabol-11-ol (2), cyclonerodiol (3), cadinol, (4) and 4-cadinen-1-ol (5) on the basis of spectroscopic data. These sesquiterpenoids were isolated from Porphyra yezoensis for the first time, and cyclonerodiol (3) and cadinol (4) isolated from marine macroalgae for the first time. Further, a quantitative relationship between the inhibition of algal growth and the concentration of each antialgal sesquiterpenoid (gossonorol, 7,10-epoxy-ar-bisabol-11-ol and cyclonerodiol) was determined and important parameters, e.g., EC 50-96h for future practical HAB control are to be obtained. Results showed that three sesquiterpenoids (1-3) had selective antialgal activity against the growth of red tide microalgae (Amphidinium carterae, Heterosigma akashiwo, Karenia mikimitoi, Phaeocystis globosa, Prorocentrum donghaiense, and Skeletonema costatum). More than two test red tide microalgae were significantly inhibited by these three sesquiterpenoids (1-3). Their antialgal activity against red tide microalgae has not been previously reported. Furthermore, EC 50-96h of gossonorol (1) and 7,10-epoxy-ar-bisabol-11-ol (2) for specific test red microalgae were not only significantly less than 10 μg/mL, but also were smaller than/or very close to those of potassium dichromate. Gossonorol (1) and 7,10-epoxy-ar-bisabol-11-ol (2) possessed good application potential than potassium dichromate as a characteristic antialgal agent against the specific harmful red tide microalgae (Heterosigma akashiwo, Phaeocystis globosa, and Prorocentrum donghaiense) (or Heterosigma akashiwo and Karenia mikimitoi).