Science.gov

Sample records for aerobic photosynthetic bacteria

  1. Functional Relationship Between Phytoplankton and Aerobic Anoxygenic Photosynthetic Bacteria: Modes of Coexistence

    NASA Astrophysics Data System (ADS)

    Kolber, Z. S.; Haffa, A.; Klimov, D.

    2006-12-01

    Aerobic Anoxygenic Photosynthetic Bacteria (AAPs) are ubiquitously distributed in the upper ocean. Although they contain bacteriochlorophyll a (BChla), the main absorption bands in the near UV (370 nm) and infrared (800-850 nm) make this pigment impractical in light harvesting below the first few meters of the water column. Instead, they utilize carotenoids as major light harvesting pigments. Since these carotenoids absorb in the 430-550 nm range, phytoplankton and AAPs utilize a similar portion of the available light spectrum. As AAPs cannot utilize water as the electron donor, they transfer electrons between a range of organic/inorganic electron donors and electron acceptors, thus significantly participating in the redox cycle in the upper ocean. We have measured the vertical distribution and photosynthetic properties of both phytoplankton and AAPs in a highly oligotrophic region 800 km SW of Monterey Bay (34N, 129W), and we have consistently observed the presence of a BChla maximum about 30 to 40 meters above the chlorophyll maximum, indicating that phytoplankton and AAPs occupy different ecological niches in the water column. However, the abundance of AAPs generally displayed a maximum at dawn and a minimum at the dusk, indicating a high level of mortality. This diel cycle was observed in 5 micron and 3 micron size fractions, indicating active grazing by small protists. Incubation experiments with natural, mixed population of AAPs and phytoplankton results in an unusually high accumulation of AAPs in DCMU-treated samples, indicating that pigmented protists do contribute significantly to AAP grazing in a tightly-controlled microbial loop. On the other hand, AAP incubations in pure cultures indicate that they biomineralize sulfur, thus affecting the sulfur cycle. All of these observations indicate that the role of AAPs in the upper ocean ecology is defined by their relationship with phototrophic and heterotrophic communities, rather than by their relative

  2. High abundances of aerobic anoxygenic photosynthetic bacteria in the South Pacific Ocean.

    PubMed

    Lami, Raphaël; Cottrell, Matthew T; Ras, Joséphine; Ulloa, Osvaldo; Obernosterer, Ingrid; Claustre, Hervé; Kirchman, David L; Lebaron, Philippe

    2007-07-01

    Little is known about the abundance, distribution, and ecology of aerobic anoxygenic phototrophic (AAP) bacteria, particularly in oligotrophic environments, which represent 60% of the ocean. We investigated the abundance of AAP bacteria across the South Pacific Ocean, including the center of the gyre, the most oligotrophic water body of the world ocean. AAP bacteria, Prochlorococcus, and total prokaryotic abundances, as well as bacteriochlorophyll a (BChl a) and divinyl-chlorophyll a concentrations, were measured at several depths in the photic zone along a gradient of oligotrophic conditions. The abundances of AAP bacteria and Prochlorococcus were high, together accounting for up to 58% of the total prokaryotic community. The abundance of AAP bacteria alone was up to 1.94 x 10(5) cells ml(-1) and as high as 24% of the overall community. These measurements were consistent with the high BChl a concentrations (up to 3.32 x 10(-3) microg liter(-1)) found at all stations. However, the BChl a content per AAP bacterial cell was low, suggesting that AAP bacteria are mostly heterotrophic organisms. Interestingly, the biovolume and therefore biomass of AAP bacteria was on average twofold higher than that of other prokaryotic cells. This study demonstrates that AAP bacteria can be abundant in various oligotrophic conditions, including the most oligotrophic regime of the world ocean, and can account for a large part of the bacterioplanktonic carbon stock.

  3. Isolation of aerobic anoxygenic photosynthetic bacteria from black smoker plume waters of the juan de fuca ridge in the pacific ocean.

    PubMed

    Yurkov, V; Beatty, J T

    1998-01-01

    A strain of the aerobic anoxygenic photosynthetic bacteria was isolated from a deep-ocean hydrothermal vent plume environment. The in vivo absorption spectra of cells indicate the presence of bacteriochlorophyll a incorporated into light-harvesting complex I and a reaction center. The general morphological and physiological characteristics of this new isolate are described.

  4. Isolation of Aerobic Anoxygenic Photosynthetic Bacteria from Black Smoker Plume Waters of the Juan de Fuca Ridge in the Pacific Ocean

    PubMed Central

    Yurkov, Vladimir; Beatty, J. Thomas

    1998-01-01

    A strain of the aerobic anoxygenic photosynthetic bacteria was isolated from a deep-ocean hydrothermal vent plume environment. The in vivo absorption spectra of cells indicate the presence of bacteriochlorophyll a incorporated into light-harvesting complex I and a reaction center. The general morphological and physiological characteristics of this new isolate are described. PMID:16349490

  5. Photosynthetic reaction centers in bacteria

    SciTech Connect

    Norris, J.R. Univ. of Chicago, IL ); Schiffer, M. )

    1990-07-30

    The photochemistry of photosynthesis begins in complexes called reaction centers. These have become model systems to study the fundamental process by which plants and bacteria convert and store solar energy as chemical free energy. In green plants, photosynthesis occurs in two systems, each of which contains a different reaction center, working in series. In one, known as photosystem 1, oxidized nicotinamide adenine dinucleotide phosphate (NADP[sup +]) is reduced to NADPH for use in a series of dark reactions called the Calvin cycle, named for Nobel Laureate Melvin Calvin, by which carbon dioxide is converted into useful fuels such as carbohydrates and sugars. In the other half of the photosynthetic machinery of green plants, called photosystem 2, water is oxidized to produce molecular oxygen. A different form of photosynthesis occurs in photosynthetic bacteria, which typically live at the bottom of ponds and feed on organic debris. Two main types of photosynthetic bacteria exist: purple and green. Neither type liberates oxygen from water. Instead, the bacteria feed on organic media or inorganic materials, such as sulfides, which are easier to reduce or oxidize than carbon dioxide or water. Perhaps in consequence, their photosynthetic machinery is simpler than that of green, oxygen-evolving plants and their primary photochemistry is better understood.

  6. Filamentous bacteria existence in aerobic granular reactors.

    PubMed

    Figueroa, M; Val del Río, A; Campos, J L; Méndez, R; Mosquera-Corral, A

    2015-05-01

    Filamentous bacteria are associated to biomass settling problems in wastewater treatment plants. In systems based on aerobic granular biomass they have been proposed to contribute to the initial biomass aggregation process. However, their development on mature aerobic granular systems has not been sufficiently studied. In the present research work, filamentous bacteria were studied for the first time after long-term operation (up to 300 days) of aerobic granular systems. Chloroflexi and Sphaerotilus natans have been observed in a reactor fed with synthetic wastewater. These filamentous bacteria could only come from the inoculated sludge. Thiothrix and Chloroflexi bacteria were observed in aerobic granular biomass treating wastewater from a fish canning industry. Meganema perideroedes was detected in a reactor treating wastewater from a plant processing marine products. As a conclusion, the source of filamentous bacteria in these mature aerobic granular systems fed with industrial effluents was the incoming wastewater.

  7. Hydrogen metabolism of photosynthetic bacteria and algae

    SciTech Connect

    Kumazawa, S.; Mitsui, A.

    1982-01-01

    The metabolism, metabolic pathways and biochemistry of hydrogen in photosynthetic bacteria and algae are reviewed. Detailed information on the occurrence and measurement of hydrogenase activity is presented. Hydrogen production rates for different species of algae and bacteria are presented. 173 references, 1 figure, 7 tables.

  8. Biology of Moderately Halophilic Aerobic Bacteria

    PubMed Central

    Ventosa, Antonio; Nieto, Joaquín J.; Oren, Aharon

    1998-01-01

    The moderately halophilic heterotrophic aerobic bacteria form a diverse group of microorganisms. The property of halophilism is widespread within the bacterial domain. Bacterial halophiles are abundant in environments such as salt lakes, saline soils, and salted food products. Most species keep their intracellular ionic concentrations at low levels while synthesizing or accumulating organic solutes to provide osmotic equilibrium of the cytoplasm with the surrounding medium. Complex mechanisms of adjustment of the intracellular environments and the properties of the cytoplasmic membrane enable rapid adaptation to changes in the salt concentration of the environment. Approaches to the study of genetic processes have recently been developed for several moderate halophiles, opening the way toward an understanding of haloadaptation at the molecular level. The new information obtained is also expected to contribute to the development of novel biotechnological uses for these organisms. PMID:9618450

  9. Culturing photosynthetic bacteria through surface plasmon resonance

    SciTech Connect

    Ooms, Matthew D.; Bajin, Lauren; Sinton, David

    2012-12-17

    In this work, cultivation of photosynthetic microbes in surface plasmon enhanced evanescent fields is demonstrated. Proliferation of Synechococcus elongatus was obtained on gold surfaces excited with surface plasmons. Excitation over three days resulted in 10 {mu}m thick biofilms with maximum cell volume density of 20% vol/vol (2% more total accumulation than control experiments with direct light). Collectively, these results indicate the ability to (1) excite surface-bound cells using plasmonic light fields, and (2) subsequently grow thick biofilms by coupling light from the surface. Plasmonic light delivery presents opportunities for high-density optofluidic photobioreactors for microalgal analysis and solar fuel production.

  10. Culturing photosynthetic bacteria through surface plasmon resonance

    NASA Astrophysics Data System (ADS)

    Ooms, Matthew D.; Bajin, Lauren; Sinton, David

    2012-12-01

    In this work, cultivation of photosynthetic microbes in surface plasmon enhanced evanescent fields is demonstrated. Proliferation of Synechococcus elongatus was obtained on gold surfaces excited with surface plasmons. Excitation over three days resulted in 10 μm thick biofilms with maximum cell volume density of 20% vol/vol (2% more total accumulation than control experiments with direct light). Collectively, these results indicate the ability to (1) excite surface-bound cells using plasmonic light fields, and (2) subsequently grow thick biofilms by coupling light from the surface. Plasmonic light delivery presents opportunities for high-density optofluidic photobioreactors for microalgal analysis and solar fuel production.

  11. Nitrogen fixation by photosynthetic bacteria in lowland rice culture.

    PubMed

    Habte, M; Alexander, M

    1980-02-01

    Propanil (3',4'-dichloropropionanilide) was a potent inhibitor of the nitrogenase activity of blue-green algae (cyanobacteria) in flooded soil, but the herbicide at comparable concentrations was not toxic to rice, protozoa, and nitrogen-fixing bacteria. Ethanol-amended flooded soils treated with propanil exhibited higher rates of nitrogenase activity than those not treated with the herbicide. The enhanced nitrogenase activity in propanil-treated soils was associated with a rise in the population of purple sulfur bacteria, especially of cells resembling Chromatium and Thiospirillum. By employing propanil and a means of excluding light from the floodwater to prevent the development of phototrophs during rice growth under lowland conditions, the relative activities of blue-green algae, photosynthetic bacteria, and the rhizosphere microflora were determined. The results suggest that the potential contribution of photosynthetic bacteria may be quite high. PMID:16345507

  12. Nitrogen Fixation by Photosynthetic Bacteria in Lowland Rice Culture

    PubMed Central

    Habte, M.; Alexander, M.

    1980-01-01

    Propanil (3′,4′-dichloropropionanilide) was a potent inhibitor of the nitrogenase activity of blue-green algae (cyanobacteria) in flooded soil, but the herbicide at comparable concentrations was not toxic to rice, protozoa, and nitrogen-fixing bacteria. Ethanol-amended flooded soils treated with propanil exhibited higher rates of nitrogenase activity than those not treated with the herbicide. The enhanced nitrogenase activity in propanil-treated soils was associated with a rise in the population of purple sulfur bacteria, especially of cells resembling Chromatium and Thiospirillum. By employing propanil and a means of excluding light from the floodwater to prevent the development of phototrophs during rice growth under lowland conditions, the relative activities of blue-green algae, photosynthetic bacteria, and the rhizosphere microflora were determined. The results suggest that the potential contribution of photosynthetic bacteria may be quite high. PMID:16345507

  13. The aerobic activity of metronidazole against anaerobic bacteria.

    PubMed

    Dione, Niokhor; Khelaifia, Saber; Lagier, Jean-Christophe; Raoult, Didier

    2015-05-01

    Recently, the aerobic growth of strictly anaerobic bacteria was demonstrated using antioxidants. Metronidazole is frequently used to treat infections caused by anaerobic bacteria; however, to date its antibacterial activity was only tested in anaerobic conditions. Here we aerobically tested using antioxidants the in vitro activities of metronidazole, gentamicin, doxycycline and imipenem against 10 common anaerobic and aerobic bacteria. In vitro susceptibility testing was performed by the disk diffusion method, and minimum inhibitory concentrations (MICs) were determined by Etest. Aerobic culture of the bacteria was performed at 37°C using Schaedler agar medium supplemented with 1mg/mL ascorbic acid and 0.1mg/mL glutathione; the pH was adjusted to 7.2 by 10M KOH. Growth of anaerobic bacteria cultured aerobically using antioxidants was inhibited by metronidazole after 72h of incubation at 37°C, with a mean inhibition diameter of 37.76mm and an MIC of 1μg/mL; however, strains remained non-sensitive to gentamicin. No growth inhibition of aerobic bacteria was observed after 24h of incubation at 37°C with metronidazole; however, inhibition was observed with doxycycline and imipenem used as controls. These results indicate that bacterial sensitivity to metronidazole is not related to the oxygen tension but is a result of the sensitivity of the micro-organism. In future, both culture and antibiotic susceptibility testing of strictly anaerobic bacteria will be performed in an aerobic atmosphere using antioxidants in clinical microbiology laboratories.

  14. Phylogenetically Diverse Aerobic Anoxygenic Phototrophic Bacteria Isolated from Epilithic Biofilms in Tama River, Japan

    PubMed Central

    Hirose, Setsuko; Matsuura, Katsumi; Haruta, Shin

    2016-01-01

    The diversity of aerobic anoxygenic phototrophic (AAP) bacteria in freshwater environments, particularly in rivers, has not been examined in as much detail as in ocean environments. In the present study, we investigated the phylogenetic and physiological diversities of AAP bacteria in biofilms that developed on submerged stones in a freshwater river using culture methods. The biofilms collected were homogenized and inoculated on solid media and incubated aerobically in the dark. Sixty-eight red-, pink-, yellow-, orange-, or brown-colored colonies were isolated, and, of these, 28 isolates contained the photosynthetic pigment, bacteriochlorophyll (BChl) a. Phylogenetic analyses based on 16S rRNA gene sequences showed that the isolates were classified into 14 groups in 8 operational taxonomic units (OTUs) and distributed in the orders Rhodospirillales, Rhodobacterales, and Sphingomonadales of Alphaproteobacteria and in Betaproteobacteria. Physiological analyses confirmed that none of the representative isolates from any of the groups grew under anaerobic phototrophic conditions. Seven isolates in 4 OTUs showed a 16S rRNA gene sequence identity of 98.0% or less with any established species, suggesting the presence of previously undescribed species of AAP bacteria. Six isolates in 2 other OTUs had the closest relatives, which have not been reported to be AAP bacteria. Physiological comparisons among the isolates revealed differences in preferences for nutrient concentrations, BChl contents, and light-harvesting proteins. These results suggest that diverse and previously unknown AAP bacteria inhabit river biofilms. PMID:27453124

  15. [Photosynthetic activity and components of the electron transport chain in the aerobic bacteriochlorophyll A-containing bacterium Roseinatronobacter thiooxidans].

    PubMed

    Stadnichuk, I N; Ianiushin, M F; Boĭchenko, V A; Lukashev, E P; Boldareva, E N; Solov'ev, A A; Gorlenko, V M

    2009-01-01

    Bioenergetics of the aerobic bacteriochlorophyll a-containing (BCl a) bacterium (ABC bacterium) Roseinatronobacter thiooxidans is a combination of photosynthesis, oxygen respiration, and oxidation of sulfur compounds under alkaliphilic conditions. The photosynthetic activity of Rna. thiooxidans cells was established by the photoinhibition of cell respiration and reversible photobleaching discoloration of the BCl a of reaction centers (RC), connected by the chain of electron transfer with cytochrome c551 oxidation. The species under study, like many purple bacteria and some of the known ABC bacteria, possesses a light-harvesting pigment-protein (LHI) complex with the average number of 30 molecules of antenna BCl a per one photosynthetic RC. Under microaerobic growth conditions, the cells contained bc1 complex and two terminal oxidases: cbb3-cytochrome oxidase and the alternative cytochrome oxidase of the a3 type. Besides, Rna. thiooxidans was shown to have several different soluble low- and high-potential cytochromes c, probably associated with the ability of utilizing sulfur compounds as additional electron donors.

  16. Counting Viruses and Bacteria in Photosynthetic Microbial Mats

    PubMed Central

    Staal, Marc; Middelboe, Mathias; Brussaard, Corina P. D.

    2015-01-01

    Viral abundances in benthic environments are the highest found in aquatic systems. Photosynthetic microbial mats represent benthic environments with high microbial activity and possibly high viral densities, yet viral abundances have not been examined in such systems. Existing extraction procedures typically used in benthic viral ecology were applied to the complex matrix of microbial mats but were found to inefficiently extract viruses. Here, we present a method for extraction and quantification of viruses from photosynthetic microbial mats using epifluorescence microscopy (EFM) and flow cytometry (FCM). A combination of EDTA addition, probe sonication, and enzyme treatment applied to a glutaraldehyde-fixed sample resulted in a substantially higher viral (5- to 33-fold) extraction efficiency and reduced background noise compared to previously published methods. Using this method, it was found that in general, intertidal photosynthetic microbial mats harbor very high viral abundances (2.8 × 1010 ± 0.3 × 1010 g−1) compared with benthic habitats (107 to 109 g−1). This procedure also showed 4.5- and 4-fold-increased efficacies of extraction of viruses and bacteria, respectively, from intertidal sediments, allowing a single method to be used for the microbial mat and underlying sediment. PMID:25595761

  17. Aerobic Denitrifying Bacteria That Produce Low Levels of Nitrous Oxide

    PubMed Central

    Takaya, Naoki; Catalan-Sakairi, Maria Antonina B.; Sakaguchi, Yasushi; Kato, Isao; Zhou, Zhemin; Shoun, Hirofumi

    2003-01-01

    Most denitrifiers produce nitrous oxide (N2O) instead of dinitrogen (N2) under aerobic conditions. We isolated and characterized novel aerobic denitrifiers that produce low levels of N2O under aerobic conditions. We monitored the denitrification activities of two of the isolates, strains TR2 and K50, in batch and continuous cultures. Both strains reduced nitrate (NO3−) to N2 at rates of 0.9 and 0.03 μmol min−1 unit of optical density at 540 nm−1 at dissolved oxygen (O2) (DO) concentrations of 39 and 38 μmol liter−1, respectively. At the same DO level, the typical denitrifier Pseudomonas stutzeri and the previously described aerobic denitrifier Paracoccus denitrificans did not produce N2 but evolved more than 10-fold more N2O than strains TR2 and K50 evolved. The isolates denitrified NO3− with concomitant consumption of O2. These results indicated that strains TR2 and K50 are aerobic denitrifiers. These two isolates were taxonomically placed in the β subclass of the class Proteobacteria and were identified as P. stutzeri TR2 and Pseudomonas sp. strain K50. These strains should be useful for future investigations of the mechanisms of denitrifying bacteria that regulate N2O emission, the single-stage process for nitrogen removal, and microbial N2O emission into the ecosystem. PMID:12788710

  18. Polyhydroxyalkanoates production by a mixed photosynthetic consortium of bacteria and algae.

    PubMed

    Fradinho, J C; Domingos, J M B; Carvalho, G; Oehmen, A; Reis, M A M

    2013-03-01

    For the first time, a mixed photosynthetic culture (MPC) consisting of a consortium of bacteria and algae was investigated for its capacity to accumulate polyhydroxyalkanoates (PHA). The culture was subjected to a feast and famine regime in an illuminated environment without supplying oxygen or any other electron acceptor. The MPC accumulated PHA during the feast phase and consumed it in the famine phase, where the PHA consumption was made possible due to oxygen production by algae. The internal cycling of carbohydrates was also observed, which was likely linked to bacterial glycogen being used as an additional source of energy for acetate uptake during the feast phase, and restored in the famine phase via PHA degradation. The MPC reached a PHA content of 20%, with a PHA storage yield per acetate similar to aerobic systems, opening up the possibility of a new sunlight-driven PHA production process without the need for aeration.

  19. Growth of nitrite-oxidizing bacteria by aerobic hydrogen oxidation.

    PubMed

    Koch, Hanna; Galushko, Alexander; Albertsen, Mads; Schintlmeister, Arno; Gruber-Dorninger, Christiane; Lücker, Sebastian; Pelletier, Eric; Le Paslier, Denis; Spieck, Eva; Richter, Andreas; Nielsen, Per H; Wagner, Michael; Daims, Holger

    2014-08-29

    The bacterial oxidation of nitrite to nitrate is a key process of the biogeochemical nitrogen cycle. Nitrite-oxidizing bacteria are considered a highly specialized functional group, which depends on the supply of nitrite from other microorganisms and whose distribution strictly correlates with nitrification in the environment and in wastewater treatment plants. On the basis of genomics, physiological experiments, and single-cell analyses, we show that Nitrospira moscoviensis, which represents a widely distributed lineage of nitrite-oxidizing bacteria, has the genetic inventory to utilize hydrogen (H2) as an alternative energy source for aerobic respiration and grows on H2 without nitrite. CO2 fixation occurred with H2 as the sole electron donor. Our results demonstrate a chemolithoautotrophic lifestyle of nitrite-oxidizing bacteria outside the nitrogen cycle, suggesting greater ecological flexibility than previously assumed.

  20. Aerobic sulfur-oxidizing bacteria: Environmental selection and diversification

    NASA Technical Reports Server (NTRS)

    Caldwell, D.

    1985-01-01

    Sulfur-oxidizing bacteria oxidize reduced inorganic compounds to sulfuric acid. Lithotrophic sulfur oxidizer use the energy obtained from oxidation for microbial growth. Heterotrophic sulfur oxidizers obtain energy from the oxidation of organic compounds. In sulfur-oxidizing mixotrophs energy are derived either from the oxidation of inorganic or organic compounds. Sulfur-oxidizing bacteria are usually located within the sulfide/oxygen interfaces of springs, sediments, soil microenvironments, and the hypolimnion. Colonization of the interface is necessary since sulfide auto-oxidizes and because both oxygen and sulfide are needed for growth. The environmental stresses associated with the colonization of these interfaces resulted in the evolution of morphologically diverse and unique aerobic sulfur oxidizers.

  1. Synergistic Effect of Photosynthetic Bacteria and Isolated Bacteria in Their Antifungal Activities against Root Rot Fungi.

    PubMed

    Wei, Hongyi; Okunishi, Suguru; Yoshikawa, Takeshi; Kamei, Yuto; Dawwoda, Mahmoud A O; Santander-DE Leon, Sheila Mae S; Nuñal, Sharon Nonato; Maeda, Hiroto

    2016-01-01

    Antifungal bacteria (AB) in root rot fungus (RRF)-contaminated sweet potato farms were isolated, and seven strains were initially chosen as antagonistic candidates. An antagonistic test by using the mycelial disk placement method revealed that one AB strain by itself could inhibit the RRF growth. This AB strain was identified as Bacillus polyfermenticus based on phylogeny of 16S ribosomal RNA genes. Two AB strains (Bacillus aerophilus) displayed high levels of antifungal activity when paired with photosynthetic bacterial strain A (a purple nonsulfur photosynthetic bacterium Rhodopseudomonas faecalis). The results suggest the possible use of the isolates as agents for the biological control of the RRF infection of agricultural products in fields of cultivation. PMID:27667522

  2. Aerobic salivary bacteria in wild and captive Komodo dragons.

    PubMed

    Montgomery, Joel M; Gillespie, Don; Sastrawan, Putra; Fredeking, Terry M; Stewart, George L

    2002-07-01

    During the months of November 1996, August 1997, and March 1998, saliva and plasma samples were collected for isolation of aerobic bacteria from 26 wild and 13 captive Komodo dragons (Varanus komodoensis). Twenty-eight Gram-negative and 29 Gram-positive species of bacteria were isolated from the saliva of the 39 Komodo dragons. A greater number of wild than captive dragons were positive for both Gram-negative and Gram-positive bacteria. The average number of bacterial species within the saliva of wild dragons was 46% greater than for captive dragons. While Escherichia coli was the most common bacterium isolated from the saliva of wild dragons, this species was not present in captive dragons. The most common bacteria isolated from the saliva of captive dragons were Staphylococcus capitis and Staphylococcus capitis and Staphylococcus caseolyticus, neither of which were found in wild dragons. High mortality was seen among mice injected with saliva from wild dragons and the only bacterium isolated from the blood of dying mice was Pasteurella multocida. A competitive inhibition enzyme-linked immunosorbent assay revealed the presence of anti-Pasteurella antibody in the plasma of Komodo dragons. Four species of bacteria isolated from dragon saliva showed resistance to one or more of 16 antimicrobics tested. The wide variety of bacteria demonstrated in the saliva of the Komodo dragon in this study, at least one species of which was highly lethal in mice and 54 species of which are known pathogens, support the observation that wounds inflicted by this animal are often associated with sepsis and subsequent bacteremia in prey animals.

  3. Aerobic salivary bacteria in wild and captive Komodo dragons.

    PubMed

    Montgomery, Joel M; Gillespie, Don; Sastrawan, Putra; Fredeking, Terry M; Stewart, George L

    2002-07-01

    During the months of November 1996, August 1997, and March 1998, saliva and plasma samples were collected for isolation of aerobic bacteria from 26 wild and 13 captive Komodo dragons (Varanus komodoensis). Twenty-eight Gram-negative and 29 Gram-positive species of bacteria were isolated from the saliva of the 39 Komodo dragons. A greater number of wild than captive dragons were positive for both Gram-negative and Gram-positive bacteria. The average number of bacterial species within the saliva of wild dragons was 46% greater than for captive dragons. While Escherichia coli was the most common bacterium isolated from the saliva of wild dragons, this species was not present in captive dragons. The most common bacteria isolated from the saliva of captive dragons were Staphylococcus capitis and Staphylococcus capitis and Staphylococcus caseolyticus, neither of which were found in wild dragons. High mortality was seen among mice injected with saliva from wild dragons and the only bacterium isolated from the blood of dying mice was Pasteurella multocida. A competitive inhibition enzyme-linked immunosorbent assay revealed the presence of anti-Pasteurella antibody in the plasma of Komodo dragons. Four species of bacteria isolated from dragon saliva showed resistance to one or more of 16 antimicrobics tested. The wide variety of bacteria demonstrated in the saliva of the Komodo dragon in this study, at least one species of which was highly lethal in mice and 54 species of which are known pathogens, support the observation that wounds inflicted by this animal are often associated with sepsis and subsequent bacteremia in prey animals. PMID:12238371

  4. Synthesis of High-Molecular-Weight Polyhydroxyalkanoates by Marine Photosynthetic Purple Bacteria.

    PubMed

    Higuchi-Takeuchi, Mieko; Morisaki, Kumiko; Toyooka, Kiminori; Numata, Keiji

    2016-01-01

    Polyhydroxyalkanoate (PHA) is a biopolyester/bioplastic that is produced by a variety of microorganisms to store carbon and increase reducing redox potential. Photosynthetic bacteria convert carbon dioxide into organic compounds using light energy and are known to accumulate PHA. We analyzed PHAs synthesized by 3 purple sulfur bacteria and 9 purple non-sulfur bacteria strains. These 12 purple bacteria were cultured in nitrogen-limited medium containing acetate and/or sodium bicarbonate as carbon sources. PHA production in the purple sulfur bacteria was induced by nitrogen-limited conditions. Purple non-sulfur bacteria accumulated PHA even under normal growth conditions, and PHA production in 3 strains was enhanced by nitrogen-limited conditions. Gel permeation chromatography analysis revealed that 5 photosynthetic purple bacteria synthesized high-molecular-weight PHAs, which are useful for industrial applications. Quantitative reverse transcription polymerase chain reaction analysis revealed that mRNA levels of phaC and PhaZ genes were low under nitrogen-limited conditions, resulting in production of high-molecular-weight PHAs. We conclude that all 12 tested strains are able to synthesize PHA to some degree, and we identify 5 photosynthetic purple bacteria that accumulate high-molecular-weight PHA molecules. Furthermore, the photosynthetic purple bacteria synthesized PHA when they were cultured in seawater supplemented with acetate. The photosynthetic purple bacteria strains characterized in this study should be useful as host microorganisms for large-scale PHA production utilizing abundant marine resources and carbon dioxide.

  5. Synthesis of High-Molecular-Weight Polyhydroxyalkanoates by Marine Photosynthetic Purple Bacteria

    PubMed Central

    Higuchi-Takeuchi, Mieko; Morisaki, Kumiko; Toyooka, Kiminori; Numata, Keiji

    2016-01-01

    Polyhydroxyalkanoate (PHA) is a biopolyester/bioplastic that is produced by a variety of microorganisms to store carbon and increase reducing redox potential. Photosynthetic bacteria convert carbon dioxide into organic compounds using light energy and are known to accumulate PHA. We analyzed PHAs synthesized by 3 purple sulfur bacteria and 9 purple non-sulfur bacteria strains. These 12 purple bacteria were cultured in nitrogen-limited medium containing acetate and/or sodium bicarbonate as carbon sources. PHA production in the purple sulfur bacteria was induced by nitrogen-limited conditions. Purple non-sulfur bacteria accumulated PHA even under normal growth conditions, and PHA production in 3 strains was enhanced by nitrogen-limited conditions. Gel permeation chromatography analysis revealed that 5 photosynthetic purple bacteria synthesized high-molecular-weight PHAs, which are useful for industrial applications. Quantitative reverse transcription polymerase chain reaction analysis revealed that mRNA levels of phaC and PhaZ genes were low under nitrogen-limited conditions, resulting in production of high-molecular-weight PHAs. We conclude that all 12 tested strains are able to synthesize PHA to some degree, and we identify 5 photosynthetic purple bacteria that accumulate high-molecular-weight PHA molecules. Furthermore, the photosynthetic purple bacteria synthesized PHA when they were cultured in seawater supplemented with acetate. The photosynthetic purple bacteria strains characterized in this study should be useful as host microorganisms for large-scale PHA production utilizing abundant marine resources and carbon dioxide. PMID:27513570

  6. Synthesis of High-Molecular-Weight Polyhydroxyalkanoates by Marine Photosynthetic Purple Bacteria.

    PubMed

    Higuchi-Takeuchi, Mieko; Morisaki, Kumiko; Toyooka, Kiminori; Numata, Keiji

    2016-01-01

    Polyhydroxyalkanoate (PHA) is a biopolyester/bioplastic that is produced by a variety of microorganisms to store carbon and increase reducing redox potential. Photosynthetic bacteria convert carbon dioxide into organic compounds using light energy and are known to accumulate PHA. We analyzed PHAs synthesized by 3 purple sulfur bacteria and 9 purple non-sulfur bacteria strains. These 12 purple bacteria were cultured in nitrogen-limited medium containing acetate and/or sodium bicarbonate as carbon sources. PHA production in the purple sulfur bacteria was induced by nitrogen-limited conditions. Purple non-sulfur bacteria accumulated PHA even under normal growth conditions, and PHA production in 3 strains was enhanced by nitrogen-limited conditions. Gel permeation chromatography analysis revealed that 5 photosynthetic purple bacteria synthesized high-molecular-weight PHAs, which are useful for industrial applications. Quantitative reverse transcription polymerase chain reaction analysis revealed that mRNA levels of phaC and PhaZ genes were low under nitrogen-limited conditions, resulting in production of high-molecular-weight PHAs. We conclude that all 12 tested strains are able to synthesize PHA to some degree, and we identify 5 photosynthetic purple bacteria that accumulate high-molecular-weight PHA molecules. Furthermore, the photosynthetic purple bacteria synthesized PHA when they were cultured in seawater supplemented with acetate. The photosynthetic purple bacteria strains characterized in this study should be useful as host microorganisms for large-scale PHA production utilizing abundant marine resources and carbon dioxide. PMID:27513570

  7. Aerobic and anaerobic oxidation of hydrogen by acidophilic bacteria.

    PubMed

    Hedrich, Sabrina; Johnson, D Barrie

    2013-12-01

    While many prokaryotic species are known to use hydrogen as an electron donor to support their growth, this trait has only previously been reported for two acidophilic bacteria, Hydrogenobaculum acidophilum (in the presence of reduced sulfur) and Acidithiobacillus (At.) ferrooxidans. To test the hypothesis that hydrogen may be utilized more widely by acidophilic bacteria, 38 strains of acidophilic bacteria, including representatives of 20 designated and four proposed species, were screened for their abilities to grow via the dissimilatory oxidation of hydrogen. Growth was demonstrated in several species of acidophiles that also use other inorganic electron donors (ferrous iron and sulfur) but in none of the obligately heterotrophic species tested. Strains of At. ferrooxidans, At. ferridurans and At. caldus, grew chemolithotrophically on hydrogen, though those of At. thiooxidans and At. ferrivorans did not. Growth was also observed with Sulfobacillus acidophilus, Sb. benefaciens and Sb. thermosulfidooxidans, though not with other iron-oxidizing Firmicutes. Similarly, Acidimicrobium ferrooxidans grew on hydrogen, closely related acidophilic actinobacteria did not. Growth yields of At. ferrooxidans and At. ferridurans grown aerobically on hydrogen (c. 10(10)  cells mL(-1) ) were far greater than typically obtained using other electron donors. Several species also grew anaerobically by coupling hydrogen oxidation to the reduction of ferric iron.

  8. Engineered photosynthetic bacteria, method of manufacture of biofuels

    DOEpatents

    Laible, Philip D.; Snyder, Seth W.

    2016-09-13

    The invention provides for a novel type of biofuel; a method for cleaving anchors from photosynthetic organisms; and a method for producing biofuels using photosynthetic organisms, the method comprising identifying photosynthesis co-factors and their anchors in the organisms; modifying the organisms to increase production of the anchors; accumulating biomass of the organisms in growth media; and harvesting the anchors.

  9. Photosynthetic reaction center of green sulfur bacteria studied by EPR

    SciTech Connect

    Nitschke, W.; Rutherford, A.W. ); Fieler, U. )

    1990-04-24

    Membrane preparations of two species of the green sulfur bacteria Chlorobium have been studied be EPR. Three signals were detected which were attributed to iron-sulfur centers acting as electron acceptors in the photosynthetic reaction center. (1) A signal from a center designated F{sub B}, was photoinduced at 4K. (2) A similar signal, F{sub A}, was photoinduced in addition to the F{sub B} signal upon a short period of illumination at 200 K. (3) Further illumination at 200 K resulted in the appearance of a broad feature at g=1.78. This is attributed to the g{sub x} component of an iron-sulfur center designated F{sub X}. The designations of these signals as F{sub B}, F{sub A}, and F{sub X} are based on their spectroscopic similarities to signals in photosystem I (PS I). The orientation dependence of these EPR signals in ordered Chlorobium membrane multilayers is remarkably similar to that of their PS I homologues. A magnetic interaction between the reduced forms of F{sub B} and F{sub A} occurs, which is also very similar to that seen in PS I. The triplet state of P{sub 840}, the primary electron donor, could be photoinduced at 4 K in samples which had been preincubated with sodium dithionite and methyl viologen and then preilluminated at 200 K. The preillumination reduces the iron-sulfur centers while the preincubation is thought to result in the inactivation of an earlier electron acceptor. Orientation studies of the triplet signal in ordered multilayers indicate that the bacteriochlorophylls which act as the primary electron donor in Chlorobium are arranged with a structural geometry almost identical with that of the special pair in purple bacteria. The Chlorobium reaction center appears to be similar in some respects to both PS I and to the purple bacterial reaction center. This is discussed with regard to the evolution of the different types of reaction centers from a common ancestor.

  10. Vertical distribution and characterization of aerobic phototrophic bacteria at the Juan de Fuca Ridge in the Pacific Ocean.

    PubMed

    Rathgeber, Christopher; Lince, Michael T; Alric, Jean; Lang, Andrew S; Humphrey, Elaine; Blankenship, Robert E; Verméglio, André; Plumley, F Gerald; Van Dover, Cindy L; Beatty, J Thomas; Yurkov, Vladimir

    2008-09-01

    The vertical distribution of culturable anoxygenic phototrophic bacteria was investigated at five sites at or near the Juan de Fuca Ridge in the Pacific Ocean. Twelve similar strains of obligately aerobic phototrophic bacteria were isolated in pure culture, from depths ranging from 500 to 2,379 m below the surface. These strains appear morphologically, physiologically, biochemically, and phylogenetically similar to Citromicrobium bathyomarinum strain JF-1, a bacterium previously isolated from hydrothermal vent plume waters. Only one aerobic phototrophic strain was isolated from surface waters. This strain is morphologically and physiologically distinct from the strains isolated at deeper sampling locations, and phylogenetic analysis indicates that it is most closely related to the genus Erythrobacter. Phototrophs were cultivated from three water casts taken above vents but not from two casts taken away from active vent sites. No culturable anaerobic anoxygenic phototrophs were detected. The photosynthetic apparatus was investigated in strain JF-1 and contains light-harvesting I and reaction center complexes, which are functional under aerobic conditions.

  11. Evaluation of the petrifilm aerobic count plate for enumeration of aerobic marine bacteria from seawater and Caulerpa lentillifera.

    PubMed

    Kudaka, Jun; Horii, Toru; Tamanaha, Koji; Itokazu, Kiyomasa; Nakamura, Masaji; Taira, Katsuya; Nidaira, Minoru; Okano, Sho; Kitahara, Akio

    2010-08-01

    The enumeration and evaluation of the activity of marine bacteria are important in the food industry. However, detection of marine bacteria in seawater or seafood has not been easy. The Petrifilm aerobic count plate (ACP) is a ready-to-use alternative to the traditional enumeration media used for bacteria associated with food. The purpose of this study was to evaluate the usefulness of a simple detection and enumeration method utilizing the Petrifilm ACP for enumeration of aerobic marine bacteria from seawater and an edible seaweed, Caulerpa lentillifera. The efficiency of enumeration of total aerobic marine bacteria on Petrifilm ACP was compared with that using the spread plate method on marine agar with 80 seawater and 64 C. lentillifera samples. With sterile seawater as the diluent, a close correlation was observed between the method utilizing Petrifilm ACP and that utilizing the conventional marine agar (r=0.98 for seawater and 0.91 for C. lentillifera). The Petrifilm ACP method was simpler and less time-consuming than the conventional method. These results indicate that Petrifilm ACP is a suitable alternative to conventional marine agar for enumeration of marine microorganisms in seawater and C. lentillifera samples.

  12. Growth and photosynthetic efficiency promotion of sugar beet (Beta vulgaris L.) by endophytic bacteria.

    PubMed

    Shi, Yingwu; Lou, Kai; Li, Chun

    2010-07-01

    Very little is known about the physiological interactions between plants and endophytic bacteria. We investigated the impact of three endophytic bacteria, Bacillus pumilus 2-1, Chryseobacterium indologene 2-2, and Acinetobacter johnsonii 3-1, on the photosynthetic capacity and growth of sugar beet. Endophyte-free plants were obtained first and infected with the bacteria. Measurements of total chlorophyll content revealed very significant differences between endophyte-free beet plants and some infected by endophytic bacteria. The maximum photochemical yield (Fv/Fm) was used to determine any photosynthetic effect on plants caused by biotic or abiotic factors. After 30 days of growth, there was significantly higher Fv/Fm for endophyte-infected than endophyte-free plants. The light response curves of beet showed that photosynthetic capacity was significantly increased in endophyte-infected plants. Photosynthesis of endophyte-free plants was saturated at 1,300 micromol m(-2) s(-1), whereas endophyte-infected plants were not saturated at the irradiance used. The effect seemed to be due to promotion of electron transport in the thylakoid membranes. Promotion of photosynthetic capacity in sugar beet was due to increased chlorophyll content, leading to a consequent increased carbohydrate synthesis. It is possible that the increased maximum yield of photosynthesis in sugar beet was promoted by phytohormones and produced by the bacteria.

  13. Effect of different nitroheterocyclic compounds on aerobic, microaerophilic, and anaerobic bacteria.

    PubMed Central

    Hof, H; Ströder, J; Buisson, J P; Royer, R

    1986-01-01

    The antibacterial activities of different nitroheterocyclic compounds were assessed by an agar dilution method against aerobic, microaerophilic, and anaerobic bacteria. Nitronaphthofurans inhibited the multiplication of aerobic bacteria at low concentrations (MIC for 50% of strains tested [MIC50], 1 mg/liter). Under anaerobic growth conditions the MICs were found to be even lower. The rough, DNA repair-deficient mutants of Salmonella typhimurium were more susceptible, whereas nitroreductase-deficient strains were resistant. Microaerophilic campylobacter isolates could be divided into two groups, one of which was as susceptible as aerobic bacteria (MIC50, 1 mg/liter) and the other of which was more highly susceptible (MIC50, 0.015 mg/liter). All anaerobic bacteria tested were susceptible to nitronaphthofurans (MIC50, 0.125 mg/liter). Nitrothiazole exerted antibacterial activities similar to those of the nitronaphthofurans. Metronidazole, a nitroimidazole derivative, and nitrofurans were definitely less active. Nitrobenzofurans showed relatively high MICs. PMID:3800344

  14. Rapid redox signal transmission by "Cable Bacteria" beneath a photosynthetic biofilm.

    PubMed

    Malkin, S Y; Meysman, F J R

    2015-02-01

    Recently, long filamentous bacteria, belonging to the family Desulfobulbaceae, were shown to induce electrical currents over long distances in the surface layer of marine sediments. These "cable bacteria" are capable of harvesting electrons from free sulfide in deeper sediment horizons and transferring these electrons along their longitudinal axes to oxygen present near the sediment-water interface. In the present work, we investigated the relationship between cable bacteria and a photosynthetic algal biofilm. In a first experiment, we investigated sediment that hosted both cable bacteria and a photosynthetic biofilm and tested the effect of an imposed diel light-dark cycle by continuously monitoring sulfide at depth. Changes in photosynthesis at the sediment surface had an immediate and repeatable effect on sulfide concentrations at depth, indicating that cable bacteria can rapidly transmit a geochemical effect to centimeters of depth in response to changing conditions at the sediment surface. We also observed a secondary response of the free sulfide at depth manifest on the time scale of hours, suggesting that cable bacteria adjust to a moving oxygen front with a regulatory or a behavioral response, such as motility. Finally, we show that on the time scale of days, the presence of an oxygenic biofilm results in a deeper and more acidic suboxic zone, indicating that a greater oxygen supply can enable cable bacteria to harvest a greater quantity of electrons from marine sediments. Rapid acclimation strategies and highly efficient electron harvesting are likely key advantages of cable bacteria, enabling their success in high sulfide generating coastal sediments.

  15. Phylogenetic diversity and activity of aerobic heterotrophic bacteria from a hypersaline oil-polluted microbial mat.

    PubMed

    Abed, Raeid M M; Zein, Burhanuddin; Al-Thukair, Assad; de Beer, Dirk

    2007-06-01

    The diversity and function of aerobic heterotrophic bacteria (AHB) in cyanobacterial mats have been largely overlooked. We used culture-dependent and molecular techniques to explore the species diversity, degradative capacities and functional guilds of AHB in the photic layer (2mm) of an oil-polluted microbial mat from Saudi Arabia. Enrichment isolation was carried out at different salinities (5% and 12%) and temperatures (28 and 45 degrees C) and on various substrates (acetate, glycolate, Spirulina extract and crude oils). Counts of most probable number showed a numerical abundance of AHB in the range of 1.15-8.13x10(6) cellsg(-1) and suggested the presence of halotolerant and thermotolerant populations. Most of the 16S rRNA sequences of the obtained clones and isolates were phylogenetically affiliated to the groups Gammaproteobacteria, Bacteriodetes and Alphaproteobacteria. Groups like Deltaproteobacteria, Verrucomicrobia, Planctomycetes, Spirochaetes, Acidobacteria and Deinococcus-Thermus were only detected by cloning. The strains isolated on acetate and glycolate belonged to the genera Marinobacter, Halomonas, Roseobacter and Rhodobacter whereas the strains enriched on crude oil belonged to Marinobacter and Alcanivorax. Members of the Bacteriodetes group were only enriched on Spirulina extract indicating their specialization in the degradation of cyanobacterial dead cells. The substrate spectra of representative strains showed the ability of all AHB to metabolize cyanobacterial photosynthetic and fermentation products. However, the unique in situ conditions of the mat apparently favored the enrichment of versatile strains that grew on both the cyanobacterial exudates and the hydrocarbons. We conclude that AHB in cyanobacterial mats represent a diverse community that plays an important role in carbon-cycling within microbial mats. PMID:17056222

  16. Photosynthetic bacteria production from food processing wastewater in sequencing batch and membrane photo-bioreactors.

    PubMed

    Chitapornpan, S; Chiemchaisri, C; Chiemchaisri, W; Honda, R; Yamamoto, K

    2012-01-01

    Application of photosynthetic process could be highly efficient and surpass anaerobic treatment in releasing less greenhouse gas and odor while the biomass produced can be utilized. The combination of photosynthetic process with membrane separation is possibly effective for water reclamation and biomass production. In this study, cultivation of mixed culture photosynthetic bacteria from food processing wastewater was investigated in a sequencing batch reactor (SBR) and a membrane bioreactor (MBR) supplied with infrared light. Both photo-bioreactors were operated at a hydraulic retention time (HRT) of 10 days. Higher MLSS concentration achieved in the MBR through complete retention of biomass resulted in a slightly improved performance. When the system was operated with MLSS controlled by occasional sludge withdrawal, total biomass production of MBR and SBR photo-bioreactor was almost equal. However, 64.5% of total biomass production was washed out with the effluent in SBR system. Consequently, the higher biomass could be recovered for utilization in MBR. PMID:22258682

  17. Forster energy transfer in chlorosomes of green photosynthetic bacteria

    NASA Technical Reports Server (NTRS)

    Causgrove, T. P.; Brune, D. C.; Blankenship, R. E.

    1992-01-01

    Energy transfer properties of whole cells and chlorosome antenna complexes isolated from the green sulfur bacteria Chlorobium limicola (containing bacteriochlorophyll c), Chlorobium vibrioforme (containing bacteriochlorophyll d) and Pelodictyon phaeoclathratiforme (containing bacteriochlorophyll e) were measured. The spectral overlap of the major chlorosome pigment (bacteriochlorophyll c, d or, e) with the bacteriochlorophyll a B795 chlorosome baseplate pigment is greatest for bacteriochlorophyll c and smallest for bacteriochlorophyll e. The absorbance and fluorescence spectra of isolated chlorosomes were measured, fitted to gaussian curves and the overlap factors with B795 calculated. Energy transfer times from the bacteriochlorophyll c, d or e to B795 were measured in whole cells and the results interpreted in terms of the Forster theory of energy transfer.

  18. Comparison of dry medium culture plates for mesophilic aerobic bacteria in milk, ice cream, ham, and codfish fillet products.

    PubMed

    Park, Junghyun; Kim, Myunghee

    2013-12-01

    This study was performed to compare the performance of Sanita-Kun dry medium culture plate with those of traditional culture medium and Petrifilm dry medium culture plate for the enumeration of the mesophilic aerobic bacteria in milk, ice cream, ham, and codfish fillet. Mesophilic aerobic bacteria were comparatively evaluated in milk, ice cream, ham, and codfish fillet using Sanita-Kun aerobic count (SAC), Petrifilm aerobic count (PAC), and traditional plate count agar (PCA) media. According to the results, all methods showed high correlations of 0.989~1.000 and no significant differences were observed for enumerating the mesophilic aerobic bacteria in the tested food products. SAC method was easier to perform and count colonies efficiently as compared to the PCA and PAC methods. Therefore, we concluded that the SAC method offers an acceptable alternative to the PCA and PAC methods for counting the mesophilic aerobic bacteria in milk, ice cream, ham, and codfish fillet products. PMID:24551829

  19. Comparison of dry medium culture plates for mesophilic aerobic bacteria in milk, ice cream, ham, and codfish fillet products.

    PubMed

    Park, Junghyun; Kim, Myunghee

    2013-12-01

    This study was performed to compare the performance of Sanita-Kun dry medium culture plate with those of traditional culture medium and Petrifilm dry medium culture plate for the enumeration of the mesophilic aerobic bacteria in milk, ice cream, ham, and codfish fillet. Mesophilic aerobic bacteria were comparatively evaluated in milk, ice cream, ham, and codfish fillet using Sanita-Kun aerobic count (SAC), Petrifilm aerobic count (PAC), and traditional plate count agar (PCA) media. According to the results, all methods showed high correlations of 0.989~1.000 and no significant differences were observed for enumerating the mesophilic aerobic bacteria in the tested food products. SAC method was easier to perform and count colonies efficiently as compared to the PCA and PAC methods. Therefore, we concluded that the SAC method offers an acceptable alternative to the PCA and PAC methods for counting the mesophilic aerobic bacteria in milk, ice cream, ham, and codfish fillet products.

  20. Structure, Function and Reconstitution of Antenna Complexes of Green Photosynthetic Bacteria

    SciTech Connect

    Blankenship, Robert E.

    2005-06-10

    Most chlorophyll-type pigments in a photosynthetic organism function as an antenna, absorbing light and transferring excitations to a photochemical reaction center where energy storage takes place by a series of chemical reactions. The green photosynthetic bacteria are characterized by large antenna complexes known as chlorosomes, in which pigment-pigment interactions are of dominant importance. The overall objective of this project is to determine the mechanisms of excitation transfer and regulation of this unique antenna system, including how it is integrated into the rest of the photosynthetic energy transduction apparatus. Techniques that are being used in this research include biochemical analysis, spectroscopy, microscopy, X-ray structural studies, and reconstitution from purified components. Our recent results indicate that the chlorosome baseplate structure, which is the membrane attachment site for the chlorosome to the membrane, is a unique pigment-protein that contains large amounts of carotenoids and small amounts of bacteriochlorophyll a. Reconstitution of directed energy transfer in chlorosomes will be carried out using purified baseplates and oligomeric pigments. The integral membrane B808-866 antenna complex from Chloroflexus aurantiacus and the Fenna-Matthews-Olson protein-reaction center complex from green sulfur bacteria will be characterized by spectroscopic and structural techniques.

  1. Aerobic biodegradation of propylene glycol by soil bacteria.

    PubMed

    Toscano, Giuseppe; Cavalca, Lucia; Letizia Colarieti, M; Scelza, Rosalia; Scotti, Riccardo; Rao, Maria A; Andreoni, Vincenza; Ciccazzo, Sonia; Greco, Guido

    2013-09-01

    Propylene glycol (PG) is a main component of aircraft deicing fluids and its extensive use in Northern airports is a source of soil and groundwater contamination. Bacterial consortia able to grow on PG as sole carbon and energy source were selected from soil samples taken along the runways of Oslo Airport Gardermoen site (Norway). DGGE analysis of enrichment cultures showed that PG-degrading populations were mainly composed by Pseudomonas species, although Bacteroidetes were found, as well. Nineteen bacterial strains, able to grow on PG as sole carbon and energy source, were isolated and identified as different Pseudomonas species. Maximum specific growth rate of mixed cultures in the absence of nutrient limitation was 0.014 h(-1) at 4 °C. Substrate C:N:P molar ratios calculated on the basis of measured growth yields are in good agreement with the suggested values for biostimulation reported in literature. Therefore, the addition of nutrients is suggested as a suitable technique to sustain PG aerobic degradation at the maximum rate by autochthonous microorganisms of unsaturated soil profile.

  2. Leucine incorporation by aerobic anoxygenic phototrophic bacteria in the Delaware estuary

    PubMed Central

    Stegman, Monica R; Cottrell, Matthew T; Kirchman, David L

    2014-01-01

    Aerobic anoxygenic phototrophic (AAP) bacteria are well known to be abundant in estuaries, coastal regions and in the open ocean, but little is known about their activity in any aquatic ecosystem. To explore the activity of AAP bacteria in the Delaware estuary and coastal waters, single-cell 3H-leucine incorporation by these bacteria was examined with a new approach that combines infrared epifluorescence microscopy and microautoradiography. The approach was used on samples from the Delaware coast from August through December and on transects through the Delaware estuary in August and November 2011. The percent of active AAP bacteria was up to twofold higher than the percentage of active cells in the rest of the bacterial community in the estuary. Likewise, the silver grain area around active AAP bacteria in microautoradiography preparations was larger than the area around cells in the rest of the bacterial community, indicating higher rates of leucine consumption by AAP bacteria. The cell size of AAP bacteria was 50% bigger than the size of other bacteria, about the same difference on average as measured for activity. The abundance of AAP bacteria was negatively correlated and their activity positively correlated with light availability in the water column, although light did not affect 3H-leucine incorporation in light–dark experiments. Our results suggest that AAP bacteria are bigger and more active than other bacteria, and likely contribute more to organic carbon fluxes than indicated by their abundance. PMID:24824666

  3. Structure, Function, and Regulation of Antenna Complexes of Green Photosynthetic Bacteria

    SciTech Connect

    Robert E. Blankenship

    2001-04-27

    This project is concerned with the structure and function of the chlorosome antennas found in green photosynthetic bacteria. Chlorosomes are ellipsoidal structures attached to the cytoplasmic side of the inner cell membrane. These antenna complexes provide a very large absorption cross section for light capture. Evidence is overwhelming that the chlorosome represents a very different type of antenna from that found in any other photosynthetic system yet studied. It is now clear that chlorosomes do not contain traditional pigment-proteins, in which the pigments bind to specific sites on proteins. Instead, the chlorosome pigments are organized in vivo into pigment oligomers in which direct pigment-pigment interactions are of dominant importance. Our group has used a multidisciplinary approach to investigate this unique system, including model systems, ultrafast spectroscopy, molecular biology, protein chemistry and X-ray crystallography.

  4. [The phylogenetic diversity of aerobic organotrophic bacteria from the Dagan high-temperature oil field].

    PubMed

    Nazina, T N; Sokolova, D Sh; Shestakova, N M; Grigor'ian, A A; Mikhaĭlova, E M; Babich, T L; Lysenko, A M; Turova, T P; Poltaraus, A B; Feng, Tsin'syan; Ni, Fangtian; Beliaev, S S

    2005-01-01

    The distribution and species diversity of aerobic organotrophic bacteria in the Dagan high-temperature oil field (China), which is exploited via flooding, have been studied. Twenty-two strains of the most characteristic thermophilic and mesophilic aerobic organotrophic bacteria have been isolated from the oil stratum. It has been found that, in a laboratory, the mesophilic and thermophilic isolates grow in the temperature, pH, and salinity ranges characteristic of the injection well near-bottom zones or of the oil stratum, respectively, and assimilate a wide range of hydrocarbons, fatty acids, lower alcohols, and crude oil, thus exhibiting adaptation to the environment. Using comparative phylogenetic 16S rRNA analysis, the taxonomic affiliation of the isolates has been established. The aerobic microbial community includes gram-positive bacteria with a high and low G+C content of DNA, and gamma and beta subclasses of Proteobacteria. The thermophilic bacteria belong to the genera Geobacillus and Thermoactinomyces, and the mesophilic strains belong to the genera Bacillus, Micrococcus, Cellulomonas, Pseudomonas, and Acinetobacter. The microbial community of the oil stratum is dominated by known species of the genus Geobacillus (G. subterraneus, G. stearothermophilus, and G. thermoglucosidasius) and a novel species "Geobacillus jurassicus." A number of novel thermophilic oil-oxidizing bacilli have been isolated.

  5. [The phylogenetic diversity of aerobic organotrophic bacteria from the Dagan high-temperature oil field].

    PubMed

    Nazina, T N; Sokolova, D Sh; Shestakova, N M; Grigor'ian, A A; Mikhaĭlova, E M; Babich, T L; Lysenko, A M; Turova, T P; Poltaraus, A B; Feng, Tsin'syan; Ni, Fangtian; Beliaev, S S

    2005-01-01

    The distribution and species diversity of aerobic organotrophic bacteria in the Dagan high-temperature oil field (China), which is exploited via flooding, have been studied. Twenty-two strains of the most characteristic thermophilic and mesophilic aerobic organotrophic bacteria have been isolated from the oil stratum. It has been found that, in a laboratory, the mesophilic and thermophilic isolates grow in the temperature, pH, and salinity ranges characteristic of the injection well near-bottom zones or of the oil stratum, respectively, and assimilate a wide range of hydrocarbons, fatty acids, lower alcohols, and crude oil, thus exhibiting adaptation to the environment. Using comparative phylogenetic 16S rRNA analysis, the taxonomic affiliation of the isolates has been established. The aerobic microbial community includes gram-positive bacteria with a high and low G+C content of DNA, and gamma and beta subclasses of Proteobacteria. The thermophilic bacteria belong to the genera Geobacillus and Thermoactinomyces, and the mesophilic strains belong to the genera Bacillus, Micrococcus, Cellulomonas, Pseudomonas, and Acinetobacter. The microbial community of the oil stratum is dominated by known species of the genus Geobacillus (G. subterraneus, G. stearothermophilus, and G. thermoglucosidasius) and a novel species "Geobacillus jurassicus." A number of novel thermophilic oil-oxidizing bacilli have been isolated. PMID:16119855

  6. Rhodopseudomonas acidophila strain 10050 contains photosynthetic LH2 antenna complexes that are not enriched with phosphatidylglycerol, and the phospholipids have a fatty acyl composition that is unusual for purple non-sulfur bacteria.

    PubMed

    Russell, Nicholas J; Coleman, Julie K; Howard, Tina D; Johnston, Evelyn; Cogdell, Richard J

    2002-12-01

    The phospholipid composition of Rhodopseudomonas acidophila strain 10050 grown aerobically or anaerobically in the light was determined. The major phospholipids present in the aerobic cells were phosphatidylethanolamine (PE; 54%), phosphatidylglycerol (PG; 24%) and cardiolipin (diphosphatidylglycerol, DPG) (14%), together with phosphatidylcholine (PC; 5%). On moving the cells to anaerobic photosynthetic growth in the light PE remained the major phospholipid (37-49%), but there was a major change in the proportion of PC, which increased to 31-33%, and corresponding reductions in the contents of PG to 11-16% and DPG to 4-5%. The fatty acid composition of the phospholipids was unusual, compared with other purple non-sulfur photosynthetic bacteria, in that it contained 16:0 (29%), 17:1 (20%) and 19:1 (9%) plus several mainly unsaturated 2-OH fatty acids (9% total) as major components, when grown aerobically in the dark. In contrast when grown photosynthetically under anaerobic conditions there was <2% 17:1 or 19:1 present, while the amounts of 16:1 and 18:1 increased, and 16:0 decreased. The phospholipid composition of the purified light-harvesting complex 2 (LH2) complex was PE (43%), PC (42%) and DPG (15%). Unexpectedly, there was no PG associated with the purified LH2. These findings contrast with previous studies on several other photosynthetic bacteria, which had shown an increase in PG upon photosynthetic growth [Biochem. J. 181 (1979) 339]. The prior hypothesis that phosphatidylglycerol has some specific role to play in the function of light-harvesting complexes cannot be true for Rps. acidophila. It is suggested that specific integral membrane proteins may strongly influence the phospholipid content of the host membranes into which they are inserted.

  7. Molecular Regulation of Photosynthetic Carbon Dioxide Fixation in Nonsulfur Purple Bacteria

    SciTech Connect

    Tabita, Fred Robert

    2015-12-01

    The overall objective of this project is to determine the mechanism by which a transcriptional activator protein affects CO2 fixation (cbb) gene expression in nonsulfur purple photosynthetic bacteria, with special emphasis to Rhodobacter sphaeroides and with comparison to Rhodopseudomonas palustris. These studies culminated in several publications which indicated that additional regulators interact with the master regulator CbbR in both R. sphaeroides and R. palustris. In addition, the interactive control of the carbon and nitrogen assimilatory pathways was studied and unique regulatory signals were discovered.

  8. Aerobic anoxygenic phototrophic bacteria in the Mid-Atlantic Bight and the North Pacific Gyre.

    PubMed

    Cottrell, Matthew T; Mannino, Antonio; Kirchman, David L

    2006-01-01

    The abundance of aerobic anoxygenic phototrophic (AAP) bacteria, cyanobacteria, and heterotrophs was examined in the Mid-Atlantic Bight and the central North Pacific Gyre using infrared fluorescence microscopy coupled with image analysis and flow cytometry. AAP bacteria comprised 5% to 16% of total prokaryotes in the Atlantic Ocean but only 5% or less in the Pacific Ocean. In the Atlantic, AAP bacterial abundance was as much as 2-fold higher than that of Prochlorococcus spp. and 10-fold higher than that of Synechococcus spp. In contrast, Prochlorococcus spp. outnumbered AAP bacteria 5- to 50-fold in the Pacific. In both oceans, subsurface abundance maxima occurred within the photic zone, and AAP bacteria were least abundant below the 1% light depth. The abundance of AAP bacteria rivaled some groups of strictly heterotrophic bacteria and was often higher than the abundance of known AAP bacterial genera (Erythrobacter and Roseobacter spp.). Concentrations of bacteriochlorophyll a (BChl a) were low ( approximately 1%) compared to those of chlorophyll a in the North Atlantic. Although the BChl a content of AAP bacteria per cell was typically 20- to 250-fold lower than the divinyl-chlorophyll a content of Prochlorococcus, the pigment content of AAP bacteria approached that of Prochlorococcus in shelf break water. Our results suggest that AAP bacteria can be quite abundant in some oceanic regimes and that their distribution in the water column is consistent with phototrophy.

  9. Aerobic Anoxygenic Phototrophic Bacteria in the Mid-Atlantic Bight and the North Pacific Gyre. Revised

    NASA Technical Reports Server (NTRS)

    Cottrell, Matthew T.; Mannino, Antonio; Kirchman, David L.

    2005-01-01

    The abundance of aerobic anoxygenic phototrophic (AM) bacteria, cyanobacteria and heterotrophs was examined in the Mid-Atlantic Bight and the central North Pacific gyre using infrared fluorescence microscopy coupled with image analysis and flow cytometry. AAP bacteria comprised 5% to 16% of total prokaryotes in the Atlantic but only 5% or less in the Pacific. In the Atlantic, AAP bacterial abundance was as much as 2-fold higher than Prochlorococcus and 10-folder higher than Synechococcus. In contrast, Prochlorococcus outnumbered AAP bacteria 5- to 50-fold in the Pacific. In both oceans, subsurface abundance maxima occurred within the photic zone, and AAP bacteria were least abundant below the 1% light depth. Concentrations of bacteriochlorophyll a (BChl a) were low (approx.1%) compared to chlorophyll a. Although the BChl a content of AAP bacteria per cell was typically 20- to 250-fold lower than the divinyl-chlorophyll a content of Prochlorococcus, in shelf break water the pigment content of AAP bacteria approached that of Prochlorococcus. The abundance of AAP bacteria rivaled some groups of strictly heterotrophic bacteria and was often higher than the abundance of known AAP genera (Erythrobacter and Roseobacter spp.). The distribution of AAP bacteria in the water column, which was similar in the Atlantic and the Pacific, was consistent with phototrophy.

  10. Can pulsed xenon ultraviolet light systems disinfect aerobic bacteria in the absence of manual disinfection?

    PubMed

    Jinadatha, Chetan; Villamaria, Frank C; Ganachari-Mallappa, Nagaraja; Brown, Donna S; Liao, I-Chia; Stock, Eileen M; Copeland, Laurel A; Zeber, John E

    2015-04-01

    Whereas pulsed xenon-based ultraviolet light no-touch disinfection systems are being increasingly used for room disinfection after patient discharge with manual cleaning, their effectiveness in the absence of manual disinfection has not been previously evaluated. Our study indicates that pulsed xenon-based ultraviolet light systems effectively reduce aerobic bacteria in the absence of manual disinfection. These data are important for hospitals planning to adopt this technology as adjunct to routine manual disinfection.

  11. A Screening Method for the Isolation of Polyhydroxyalkanoate-Producing Purple Non-sulfur Photosynthetic Bacteria from Natural Seawater

    PubMed Central

    Higuchi-Takeuchi, Mieko; Morisaki, Kumiko; Numata, Keiji

    2016-01-01

    Polyhydroxyalkanoates (PHAs) are a family of biopolyesters accumulated by a variety of microorganisms as carbon and energy storage under starvation conditions. We focused on marine purple non-sulfur photosynthetic bacteria as host microorganisms for PHA production and developed a method for their isolation from natural seawater. To identify novel PHA-producing marine purple non-sulfur photosynthetic bacteria, natural seawaters were cultured in nutrient-rich medium for purple non-sulfur photosynthetic bacteria, and twelve pink- or red-pigmented colonies were picked up. Gas chromatography mass spectrometry analysis revealed that four isolates synthesized PHA at levels ranging from 0.5 to 24.4 wt% of cell dry weight. The 16S ribosomal RNA sequence analysis revealed that one isolate (HM2) showed 100% identity to marine purple non-sulfur photosynthetic bacteria. In conclusion, we have demonstrated in this study that PHA-producing marine purple non-sulfur photosynthetic bacteria can be isolated from natural seawater under nutrient-rich conditions. PMID:27708640

  12. C-type cytochromes in the photosynthetic electron transfer pathways in green sulfur bacteria and heliobacteria.

    PubMed

    Azai, Chihiro; Tsukatani, Yusuke; Itoh, Shigeru; Oh-oka, Hirozo

    2010-06-01

    Green sulfur bacteria and heliobacteria are strictly anaerobic phototrophs that have homodimeric type 1 reaction center complexes. Within these complexes, highly reducing substances are produced through an initial charge separation followed by electron transfer reactions driven by light energy absorption. In order to attain efficient energy conversion, it is important for the photooxidized reaction center to be rapidly rereduced. Green sulfur bacteria utilize reduced inorganic sulfur compounds (sulfide, thiosulfate, and/or sulfur) as electron sources for their anoxygenic photosynthetic growth. Membrane-bound and soluble cytochromes c play essential roles in the supply of electrons from sulfur oxidation pathways to the P840 reaction center. In the case of gram-positive heliobacteria, the photooxidized P800 reaction center is rereduced by cytochrome c-553 (PetJ) whose N-terminal cysteine residue is modified with fatty acid chains anchored to the cytoplasmic membrane. PMID:20091230

  13. Relevance of the photosynthetic reaction center from purple bacteria to the structure of photosystem II

    SciTech Connect

    Michel, H.; Deisenhofer, J.

    1988-01-12

    Photosynthetic organisms are able to oxidize organic or inorganic compounds upon the absorption of light, and they use the extracted electron for the fixation of carbon dioxide. The most important oxidation product is oxygen due to the splitting of water. In eukaryotes these processes occur in photosystem II of chloroplasts. Among prokaryotes photosynthetic oxygen evolution is restricted to cyanobacteria and prochloron-type organisms. How water is split in the oxygen-evolving complex of photosystem II belongs to the most important question to be answered. The primary charge separation occurs in the reaction center of photosystem II. This reaction center is a complex consisting of peripheral and integral membrane proteins, several chlorophyll A molecules, two pheophytin A molecules, two and three plastoquinone molecules, and one non-heme iron atom. The location of the photosystem II reaction center is still a matter of debate. Nakatani et al. (l984) concluded from fluorescence measurements that a protein of apparent molecular weight 47,000 (CP47) is the apoprotein of the photosystem II reaction center. A different view emerged from work with the photosynthetic reaction centers from the purple bacteria. The amino acid sequence of the M subunit of the reaction center from Phodopseudomonas (Rps.) sphaeroides has sequence homologies with the D1 protein from spinach. A substantial amount of structural information can be obtained with the reaction center from Rhodopseudomonas viridis, which can be crystallized. Here the authors discuss the structure of the photosynthetic reaction center from the purple bacterium Rps. viridis and describe the role of those amino acids that are conserved between the bacterial and photosystem II reaction center.

  14. Nutrient conversions by photosynthetic bacteria in a concentrated animal feeding operation lagoon system.

    PubMed

    Sund, J L; Evenson, C J; Strevett, K A; Nairn, R W; Athay, D; Trawinski, E

    2001-01-01

    A diurnal examination was conducted to determine the effect of photosynthetic bacteria on nutrient conversions in a two-stage concentrated animal feeding operation (CAFO) lagoon system in west-central Oklahoma. Changes in nutrients, microbial populations, and physical parameters were examined at three depths (0, 1.5, and 3.0 m) every 3 h over a 36-h period. The south lagoon (SL) was anaerobic (dissolved oxygen [DO] = 0.09 +/- 0.12 mg/L) while the north lagoon (NL) was facultative (DO ranged from 4.0-0.1 mg/L over 36-h period). Negative sulfide-sulfate (-0.85) and bacteriochlorophyll a (bchl a)-sulfate (-0.83) correlations, as well as positive bchl a-sulfide (0.87) and light intensity (I)-bchl a (0.89) correlations revealed that the SL was dominated by sulfur conversions driven by the photosynthetic purple sulfur bacteria (PSB). The correlation data was supported by diurnal trends for sulfate, sulfide, and bchl a. Both nitrogen and sulfur conversions played a role in the NL; however, nitrogen conversions appeared to dominate this system because of the activity of cyanobacteria. This was shown by positive chlorophyll a (chl a)-I (0.91) and chl a-nitrate (0.98) correlations and the negative correlation between ammonium and nitrite (-0.88). Correlation data was further supported by diurnal trends observed for chl a, DO, and ammonium. For both lagoons, the dominant photosynthetic microbial species determined which nutrient conversion processes were most important. PMID:11285928

  15. Binary Interactions of Antagonistic Bacteria with Candida albicans Under Aerobic and Anaerobic Conditions.

    PubMed

    Benadé, Eliska; Stone, Wendy; Mouton, Marnel; Postma, Ferdinand; Wilsenach, Jac; Botha, Alfred

    2016-04-01

    We used both aerobic and anaerobic liquid co-cultures, prepared with Luria Bertani broth, to study the effect of bacteria on the survival of Candida albicans in the external environment, away from an animal host. The bacteria were represented by Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Clostridium, Enterobacter, Klebsiella pneumoniae, Kluyvera ascorbata and Serratia marcescens. Under aerobic conditions, the yeast's growth was inhibited in the presence of bacterial growth; however, under anaerobic conditions, yeast and bacterial growth in co-cultures was similar to that observed for pure cultures. Subsequent assays revealed that the majority of bacterial strains aerobically produced extracellular hydrolytic enzymes capable of yeast cell wall hydrolysis, including chitinases and mannan-degrading enzymes. In contrast, except for the A. hydrophila strain, these enzymes were not detected in anaerobic bacterial cultures, nor was the antimicrobial compound prodigiosin found in anaerobic cultures of S. marcescens. When we suspended C. albicans cells in crude extracellular enzyme preparations from K. pneumoniae and S. marcescens, we detected no negative effect on yeast viability. However, we found that these preparations enhance the toxicity of prodigiosin towards the yeast, especially in combination with mannan-degrading enzymes. Analyses of the chitin and mannan content of yeast cell walls revealed that less chitin was produced under anaerobic than aerobic conditions; however, the levels of mannan, known for its low permeability, remained the same. The latter phenomenon, as well as reduced production of the bacterial enzymes and prodigiosin, may contribute to anaerobic growth and survival of C. albicans in the presence of bacteria.

  16. Binary Interactions of Antagonistic Bacteria with Candida albicans Under Aerobic and Anaerobic Conditions.

    PubMed

    Benadé, Eliska; Stone, Wendy; Mouton, Marnel; Postma, Ferdinand; Wilsenach, Jac; Botha, Alfred

    2016-04-01

    We used both aerobic and anaerobic liquid co-cultures, prepared with Luria Bertani broth, to study the effect of bacteria on the survival of Candida albicans in the external environment, away from an animal host. The bacteria were represented by Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Clostridium, Enterobacter, Klebsiella pneumoniae, Kluyvera ascorbata and Serratia marcescens. Under aerobic conditions, the yeast's growth was inhibited in the presence of bacterial growth; however, under anaerobic conditions, yeast and bacterial growth in co-cultures was similar to that observed for pure cultures. Subsequent assays revealed that the majority of bacterial strains aerobically produced extracellular hydrolytic enzymes capable of yeast cell wall hydrolysis, including chitinases and mannan-degrading enzymes. In contrast, except for the A. hydrophila strain, these enzymes were not detected in anaerobic bacterial cultures, nor was the antimicrobial compound prodigiosin found in anaerobic cultures of S. marcescens. When we suspended C. albicans cells in crude extracellular enzyme preparations from K. pneumoniae and S. marcescens, we detected no negative effect on yeast viability. However, we found that these preparations enhance the toxicity of prodigiosin towards the yeast, especially in combination with mannan-degrading enzymes. Analyses of the chitin and mannan content of yeast cell walls revealed that less chitin was produced under anaerobic than aerobic conditions; however, the levels of mannan, known for its low permeability, remained the same. The latter phenomenon, as well as reduced production of the bacterial enzymes and prodigiosin, may contribute to anaerobic growth and survival of C. albicans in the presence of bacteria. PMID:26566932

  17. Role of phosphate solubilizing bacteria on rock phosphate solubility and growth of aerobic rice.

    PubMed

    Panhwar, Q A; Radziah, O; Zaharah, A R; Sariah, M; Razi, I Mohd

    2011-09-01

    Use of phosphate-solubilizing bacteria (PSB) as inoculants has concurrently increased phosphorous uptake in plants and improved yields in several crop species. The ability of PSB to improve growth of aerobic rice (Oryza sativa L.) through enhanced phosphorus (P) uptake from Christmas island rock phosphate (RP) was studied in glasshouse experiments. Two isolated PSB strains; Bacillus spp. PSB9 and PSB16, were evaluated with RP treatments at 0, 30 and 60 kg ha(-1). Surface sterilized seeds of aerobic rice were planted in plastic pots containing 3 kg soil and the effect of treatments incorporated at planting were observed over 60 days of growth. The isolated PSB strains (PSB9 and PSB16) solubilized significantly high amounts of P (20.05-24.08 mg kg(-1)) compared to non-inoculated (19-23.10 mg kg(-1)) treatments. Significantly higher P solubilization (24.08 mg kg(-1)) and plant P uptake (5.31 mg plant(-1)) was observed with the PSB16 strain at the highest P level of 60 kg ha(-1). The higher amounts of soluble P in the soil solution increased P uptake in plants and resulted in higher plant biomass (21.48 g plant(-1)). PSB strains also increased plant height (80 cm) and improved root morphology in aerobic rice. The results showed that inoculation of aerobic rice with PSB improved phosphate solubilizing activity of incorporated RP.

  18. Metabolic Engineering and Modeling of Metabolic Pathways to Improve Hydrogen Production by Photosynthetic Bacteria

    SciTech Connect

    Jiao, Y.; Navid, A.

    2014-12-19

    Rising energy demands and the imperative to reduce carbon dioxide (CO2) emissions are driving research on biofuels development. Hydrogen gas (H2) is one of the most promising biofuels and is seen as a future energy carrier by virtue of the fact that 1) it is renewable, 2) does not evolve the “greenhouse gas” CO2 in combustion, 3) liberates large amounts of energy per unit weight in combustion (having about 3 times the energy content of gasoline), and 4) is easily converted to electricity by fuel cells. Among the various bioenergy strategies, environmental groups and others say that the concept of the direct manufacture of alternative fuels, such as H2, by photosynthetic organisms is the only biofuel alternative without significant negative criticism [1]. Biological H2 production by photosynthetic microorganisms requires the use of a simple solar reactor such as a transparent closed box, with low energy requirements, and is considered as an attractive system to develop as a biocatalyst for H2 production [2]. Various purple bacteria including Rhodopseudomonas palustris, can utilize organic substrates as electron donors to produce H2 at the expense of solar energy. Because of the elimination of energy cost used for H2O oxidation and the prevention of the production of O2 that inhibits the H2-producing enzymes, the efficiency of light energy conversion to H2 by anoxygenic photosynthetic bacteria is in principle much higher than that by green algae or cyanobacteria, and is regarded as one of the most promising cultures for biological H2 production [3]. Here implemented a simple and relatively straightforward strategy for hydrogen production by photosynthetic microorganisms using sunlight, sulfur- or iron-based inorganic substrates, and CO2 as the feedstock. Carefully selected microorganisms with bioengineered beneficial

  19. Aerobic transformation of cadmium through metal sulfide biosynthesis in photosynthetic microorganisms

    PubMed Central

    2013-01-01

    Background Cadmium is a non-essential metal that is toxic because of its interference with essential metals such as iron, calcium and zinc causing numerous detrimental metabolic and cellular effects. The amount of this metal in the environment has increased dramatically since the advent of the industrial age as a result of mining activities, the use of fertilizers and sewage sludge in farming, and discharges from manufacturing activities. The metal bioremediation utility of phototrophic microbes has been demonstrated through their ability to detoxify Hg(II) into HgS under aerobic conditions. Metal sulfides are generally very insoluble and therefore, biologically unavailable. Results When Cd(II) was exposed to cells it was bioconverted into CdS by the green alga Chlamydomonas reinhardtii, the red alga Cyanidioschyzon merolae, and the cyanobacterium, Synechoccocus leopoliensis. Supplementation of the two eukaryotic algae with extra sulfate, but not sulfite or cysteine, increased their cadmium tolerances as well as their abilities to produce CdS, indicating an involvement of sulfate assimilation in the detoxification process. However, the combined activities of extracted serine acetyl-transferase (SAT) and O-acetylserine(thiol)lyase (OASTL) used to monitor sulfate assimilation, was not significantly elevated during cell treatments that favored sulfide biosynthesis. It is possible that the prolonged incubation of the experiments occurring over two days could have compensated for the low rates of sulfate assimilation. This was also the case for S. leopoliensis where sulfite and cysteine as well as sulfate supplementation enhanced CdS synthesis. In general, conditions that increased cadmium sulfide production also resulted in elevated cysteine desulfhydrase activities, strongly suggesting that cysteine is the direct source of sulfur for CdS synthesis. Conclusions Cadmium(II) tolerance and CdS formation were significantly enhanced by sulfate supplementation, thus

  20. Space agriculture for habitation on Mars with hyper-thermophilic aerobic composting bacteria

    NASA Astrophysics Data System (ADS)

    Kanazawa, S.; Ishikawa, Y.; Tomita-Yokotani, K.; Hashimoto, H.; Kitaya, Y.; Yamashita, M.; Nagatomo, M.; Oshima, T.; Wada, H.; Space Agriculture Task Force, J.

    Manned Mars exploration requires recycle of materials to support human life A conceptual design is developed for space agriculture which is driven by the biologically regenerative function Hyper-thermophilic aerobic composting bacterial ecology is the core of materials recycling system to process human metabolic waste and inedible biomass and convert them to fertilizer for plants cultivation A photosynthetic reaction of plants will be driven by solar energy Water will be recycled by cultivation of plants and passing it through plant bodies Sub-surface water and atmospheric carbon dioxide are the natural resource available on Mars and these resources will be converted to oxygen and foods We envision that the agricultural system will be scaled up by importing materials from Martian environment Excess oxygen will be obtained from growing trees for structural and other components Minor elements including N P K and other traces will be introduced as fertilizers or nutrients into the agricultural materials circulation Nitrogen will be collected from Martian atmosphere We will assess biological fixation of nitrogen using micro-organisms responsible in Earth biosphere Hyper-thermophilic aerobic bacterial ecology is effective to convert waste materials into useful forms to plants This microbial technology has been well established on ground for processing sewage and waste materials For instance the hyper-thermophilic bacterial system is applied to a composting machine in a size of a trash box in home kitchen Since such a home electronics

  1. Aerobic Mercury-resistant bacteria alter Mercury speciation and retention in the Tagus Estuary (Portugal).

    PubMed

    Figueiredo, Neusa L; Canário, João; O'Driscoll, Nelson J; Duarte, Aida; Carvalho, Cristina

    2016-02-01

    Aerobic mercury-resistant bacteria were isolated from the sediments of two highly mercury-polluted areas of the Tagus Estuary (Barreiro and Cala do Norte) and one natural reserve area (Alcochete) in order to test their capacity to transform mercury. Bacterial species were identified using 16S rRNA amplification and sequencing techniques and the results indicate the prevalence of Bacillus sp. Resistance patterns to mercurial compounds were established by the determination of minimal inhibitory concentrations. Representative Hg-resistant bacteria were further tested for transformation pathways (reduction, volatilization and methylation) in cultures containing mercury chloride. Bacterial Hg-methylation was carried out by Vibrio fluvialis, Bacillus megaterium and Serratia marcescens that transformed 2-8% of total mercury into methylmercury in 48h. In addition, most of the HgR bacterial isolates showed Hg(2+)-reduction andHg(0)-volatilization resulting 6-50% mercury loss from the culture media. In summary, the results obtained under controlled laboratory conditions indicate that aerobic Hg-resistant bacteria from the Tagus Estuary significantly affect both the methylation and reduction of mercury and may have a dual face by providing a pathway for pollution dispersion while forming methylmercury, which is highly toxic for living organisms.

  2. The effect of bacteria, enzymes and inulin on fermentation and aerobic stability of corn silage

    PubMed Central

    Peymanfar, S; Kermanshahi, RK

    2012-01-01

    Background and Objectives Ensiling is a conservation method for forage crops. It is based on the fact that anaerobe lactic acid bacteria (LAB) convert watersoluble carbohydrates into organic acids. Therefore, pH decreases and the forage is preserved. The aim of this study was to isolate special kinds of lactic acid bacteria from silage and to study the effect of bacteria, inulin and enzymes as silage additives on the fermentation and aerobic stability of the silage. Materials and Methods The heterofermentative LAB were isolated from corn silages in Broujerd, Iran and biochemically characterized. Acid tolerance was studied by exposure to acidic PBS and growth in bile salt was measured by the spectrophotometric method. Results The results of molecular analysis using 16SrDNA sequences showed that the isolates belonged to Lactobacillus and Enterococcus genera. To enhance stability in acidic environment and against bile salts, microencapsulation with Alginate and Chitosan was used. The Lactobacillus plantarum strains were used as control. The inoculants (1 × 107 cfu/g) alone or in combination with inulin or in combination with enzymes were added to chopped forages and ensiled in 1.5-L anaerobic jars. Conclusion Combination of the isolates Lactobacillus and Enterococcus with inulin and enzymes can improve the aerobic stability of corn silage. PMID:23205249

  3. 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. PMID:26266755

  4. 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.

  5. Structure, Function and Reconstitution of Antenna Complexes from Green Photosynthetic Bacteria

    SciTech Connect

    Robert E. Blankenship

    2005-08-10

    This project is concerned with the structure and function of the chlorosome antennas found in green photosynthetic bacteria. Chlorosomes are ellipsoidal structures attached to the cytoplasmic side of the inner cell membrane. These antenna complexes provide a very large absorption cross section for light capture. Evidence is overwhelming that the chlorosome represents a very different type of antenna from that found in any other photosynthetic system yet studied. It is now clear that chlorosomes do not contain traditional pigment-proteins, in which the pigments bind to specific sites on proteins. Instead, the chlorosome pigments are organized in vivo into pigment oligomers in which direct pigment-pigment interactions are of dominant importance. Our group has used a multidisciplinary approach to investigate this unique system, as well as the complexes that they directly interact with. Our work has included using model systems, numerous types of both steady-state and ultrafast spectroscopy, molecular biology, protein chemistry and X-ray crystallography. Details of our recent results using these approaches are given below and in the references. Numbers cited in the sections refer to DOE-sponsored publications that are listed below. Only publications dated 2001-2004 or later are included in this report. In addition to the primary literature reports, a comprehensive review of this area of research has been written as well as a commentary.

  6. Phylogenetic and Kinetic Diversity of Aerobic Vinyl Chloride-Assimilating Bacteria from Contaminated Sites

    PubMed Central

    Coleman, Nicholas V.; Mattes, Timothy E.; Gossett, James M.; Spain, Jim C.

    2002-01-01

    Aerobic bacteria that grow on vinyl chloride (VC) have been isolated previously, but their diversity and distribution are largely unknown. It is also unclear whether such bacteria contribute to the natural attenuation of VC at chlorinated-ethene-contaminated sites. We detected aerobic VC biodegradation in 23 of 37 microcosms and enrichments inoculated with samples from various sites. Twelve different bacteria (11 Mycobacterium strains and 1 Nocardioides strain) capable of growth on VC as the sole carbon source were isolated, and 5 representative strains were examined further. All the isolates grew on ethene in addition to VC and contained VC-inducible ethene monooxygenase activity. The Mycobacterium strains (JS60, JS61, JS616, and JS617) all had similar growth yields (5.4 to 6.6 g of protein/mol), maximum specific growth rates (0.17 to 0.23 day−1), and maximum specific substrate utilization rates (9 to 16 nmol/min/mg of protein) with VC. The Nocardioides strain (JS614) had a higher growth yield (10.3 g of protein/mol), growth rate (0.71 day−1), and substrate utilization rate (43 nmol/min/mg of protein) with VC but was much more sensitive to VC starvation. Half-velocity constant (Ks) values for VC were between 0.5 and 3.2 μM, while Ks values for oxygen ranged from 0.03 to 0.3 mg/liter. Our results indicate that aerobic VC-degrading microorganisms (predominantly Mycobacterium strains) are widely distributed at sites contaminated with chlorinated solvents and are likely to be responsible for the natural attenuation of VC. PMID:12450841

  7. Biomass and carotenoid production in photosynthetic bacteria wastewater treatment: effects of light intensity.

    PubMed

    Zhou, Qin; Zhang, Panyue; Zhang, Guangming

    2014-11-01

    This study investigated the feasibility of using photosynthetic bacteria (PSB) to produce biomass and carotenoid while treating wastewater. The effects of light intensity on the biomass, carotenoid and bacteriochlorophyll accumulation in together with pollutant removal were studied. Results showed that it was feasible to use PSB to treat wastewater as well as to produce biomass or carotenoid. 2000 lux was an optimal intensity for biomass production and COD removal, and the corresponding values were 2645 mg/L and 94.7%. 8000 lux was an optimal light intensity for carotenoid production (1.455 mg/L). Mechanism analysis displayed that the greater the bacteriochlorophyll and carotenoid were secreted, the lower the light conversion efficiency turned out to be. The highest light conversion efficiency was achieved at 500 lux; the ATP production, biomass production, and COD removal were the highest at 2000 lux, but the bacteriochlorophyll and carotenoid content were the lowest at 2000 lux. PMID:25218205

  8. Energy transfer and relaxation dynamics in light-harvesting antenna complexes of photosynthetic bacteria

    SciTech Connect

    Kuehn, O.; Sundstroem, V.

    1997-04-24

    The dissipative dynamics of excitons in the outer antenna system of photosynthetic bacteria is investigated using an equation of motion approach. The coupling to environmental degrees of freedom is treated employing Redfield relaxation theory. It is shown that within the secular approximation the concept of essential excitonic states provides a convenient means for reducing the number of coupled differential equations to be solved. Further we derive the appropriate quenching matrix that accounts for the flow of excitation energy between weakly interacting pigment pools. Numerical simulations are presented to emphasize the influence of the various relaxation and dephasing mechanisms as well as the excitonic band structure on the energy transfer. 44 refs., 9 figs., 1 tab.

  9. Biomass and pigments production in photosynthetic bacteria wastewater treatment: effects of light sources.

    PubMed

    Zhou, Qin; Zhang, Panyue; Zhang, Guangming

    2015-03-01

    This study is aimed at enhancing biomass and pigments production together with pollution removal in photosynthetic bacteria (PSB) wastewater treatment via different light sources. Red, yellow, blue, white LED and incandescent lamp were used. Results showed different light sources had great effects on the PSB. PSB had the highest biomass production, COD removal and biomass yield with red LED. The corresponding biomass, COD removal and biomass yield reached 2580 mg/L, 88.6% and 0.49 mg-biomass/mg-COD-removal, respectively. The hydraulic retention time of wastewater treatment could be shortened to 72 h with red LED. Mechanism analysis showed higher ATP was produced with red LED than others. Light sources could significantly affect the pigments production. The pigments productions were greatly higher with LED than incandescent lamp. Yellow LED had the highest pigments production while red LED produced the highest carotenoid/bacteriochlorophyll ratio. Considering both efficiency and energy cost, red LED was the optimal light source.

  10. Biomass and carotenoid production in photosynthetic bacteria wastewater treatment: effects of light intensity.

    PubMed

    Zhou, Qin; Zhang, Panyue; Zhang, Guangming

    2014-11-01

    This study investigated the feasibility of using photosynthetic bacteria (PSB) to produce biomass and carotenoid while treating wastewater. The effects of light intensity on the biomass, carotenoid and bacteriochlorophyll accumulation in together with pollutant removal were studied. Results showed that it was feasible to use PSB to treat wastewater as well as to produce biomass or carotenoid. 2000 lux was an optimal intensity for biomass production and COD removal, and the corresponding values were 2645 mg/L and 94.7%. 8000 lux was an optimal light intensity for carotenoid production (1.455 mg/L). Mechanism analysis displayed that the greater the bacteriochlorophyll and carotenoid were secreted, the lower the light conversion efficiency turned out to be. The highest light conversion efficiency was achieved at 500 lux; the ATP production, biomass production, and COD removal were the highest at 2000 lux, but the bacteriochlorophyll and carotenoid content were the lowest at 2000 lux.

  11. Evaluation of the 3M™ Petrifilm™ Rapid Aerobic Count Plate for the Enumeration of Aerobic Bacteria: Collaborative Study, First Action 2015.13.

    PubMed

    Bird, Patrick; Flannery, Jonathan; Crowley, Erin; Agin, James; Goins, David; Jechorek, Robert

    2016-05-01

    The 3M™ Petrifilm™ Rapid Aerobic Count (RAC) Plate is a sample-ready culture medium system containing dual-sensor indicator technology for the rapid quantification of aerobic bacteria in food products. The 3M Petrifilm RAC Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA BAM) Chapter 3 (Aerobic Plate Count) for the enumeration of aerobic bacteria in raw easy-peel shrimp and the Standard Methods for the Examination of Dairy Products (SMEDP) Chapter 6 (Standard Plate Count Method) for the enumeration of aerobic bacteria in pasteurized skim milk and instant nonfat dry milk (instant NFDM). The 3M Petrifilm RAC Plate was evaluated using a paired study design in a multilaboratory collaborative study following current AOAC validation guidelines. Three target contamination levels (low, 10-100 CFU/g; medium, 100-1000 CFU/g; and high 1000-10 000 CFU/g) were evaluated for naturally occurring aerobic microflora for each matrix. For raw easy-peel shrimp, duplicate 3M Petrifilm RAC Plates were enumerated after 24 ± 2 h incubation at both 32 and 35°C. Pasteurized skim milk 3M Petrifilm RAC Plates were enumerated after 24 ± 2 h incubation at 32°C, and instant NFDM 3M Petrifilm RAC Plates were enumerated after 48 ± 3 h incubation at 32°C. No statistical difference was observed between 3M Petrifilm RAC Plate and FDA BAM or SMEDP reference methods for each contamination level.

  12. Evaluation of the 3M™ Petrifilm™ Rapid Aerobic Count Plate for the Enumeration of Aerobic Bacteria: Collaborative Study, First Action 2015.13.

    PubMed

    Bird, Patrick; Flannery, Jonathan; Crowley, Erin; Agin, James; Goins, David; Jechorek, Robert

    2016-05-01

    The 3M™ Petrifilm™ Rapid Aerobic Count (RAC) Plate is a sample-ready culture medium system containing dual-sensor indicator technology for the rapid quantification of aerobic bacteria in food products. The 3M Petrifilm RAC Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA BAM) Chapter 3 (Aerobic Plate Count) for the enumeration of aerobic bacteria in raw easy-peel shrimp and the Standard Methods for the Examination of Dairy Products (SMEDP) Chapter 6 (Standard Plate Count Method) for the enumeration of aerobic bacteria in pasteurized skim milk and instant nonfat dry milk (instant NFDM). The 3M Petrifilm RAC Plate was evaluated using a paired study design in a multilaboratory collaborative study following current AOAC validation guidelines. Three target contamination levels (low, 10-100 CFU/g; medium, 100-1000 CFU/g; and high 1000-10 000 CFU/g) were evaluated for naturally occurring aerobic microflora for each matrix. For raw easy-peel shrimp, duplicate 3M Petrifilm RAC Plates were enumerated after 24 ± 2 h incubation at both 32 and 35°C. Pasteurized skim milk 3M Petrifilm RAC Plates were enumerated after 24 ± 2 h incubation at 32°C, and instant NFDM 3M Petrifilm RAC Plates were enumerated after 48 ± 3 h incubation at 32°C. No statistical difference was observed between 3M Petrifilm RAC Plate and FDA BAM or SMEDP reference methods for each contamination level. PMID:27297837

  13. Population of aerobic heterotrophic nitrogen-fixing bacteria associated with wetland and dryland rice

    SciTech Connect

    Barraquio, W.L.; De Guzman, M.R.; Barrion, M.; Watanahe, I.

    1982-01-01

    Nitrogen-fixing activity and populations of nitrogen-fixing bacteria associated with two varieties of rice grown in dryland and wetland conditions were measured at various growth stages during the dry season. Acetylene reduction activities were measured both in the field and for the hydroponically grown rice, which was transferred from the field to water culture 1 day before assay. The activities measured by both methods were higher in wetland than in dryland rice. The population of nitrogen-fixing heterotrophic bacteria associated with rhizosphere soil, root, and basal shoots was determined by the most probable number method with semisolid glucose-yeast extract and semisolid malate-yeast extract media. The number of nitrogen-fixing bacteria was higher in wetland conditions than in dryland conditions. The difference between two conditions was most pronounced in the population associated with the basal shoot. The glucose medium gave higher counts than did the malate medium. Colonies were picked from tryptic soy agar plates, and their nitrogen-fixing activity was tested on a semisolid glucose-yeast extract medium. The incidence of nitrogen-fixing bacteria among aerobic heterotrophic bacteria in association with rhizosphere soil, root, and basal shoots was much lower in dryland rice than in wetland rice. (Refs. 11).

  14. Role of ammonia-oxidizing bacteria in micropollutant removal from wastewater with aerobic granular sludge.

    PubMed

    Margot, Jonas; Lochmatter, Samuel; Barry, D A; Holliger, Christof

    2016-01-01

    Nitrifying wastewater treatment plants (WWTPs) are more efficient than non-nitrifying WWTPs to remove several micropollutants such as pharmaceuticals and pesticides. This may be related to the activity of nitrifying organisms, such as ammonia-oxidizing bacteria (AOBs), which could possibly co-metabolically oxidize micropollutants with their ammonia monooxygenase (AMO). The role of AOBs in micropollutant removal was investigated with aerobic granular sludge (AGS), a promising technology for municipal WWTPs. Two identical laboratory-scale AGS sequencing batch reactors (AGS-SBRs) were operated with or without nitrification (inhibition of AMOs) to assess their potential for micropollutant removal. Of the 36 micropollutants studied at 1 μg l(-1) in synthetic wastewater, nine were over 80% removed, but 17 were eliminated by less than 20%. Five substances (bisphenol A, naproxen, irgarol, terbutryn and iohexol) were removed better in the reactor with nitrification, probably due to co-oxidation catalysed by AMOs. However, for the removal of all other micropollutants, AOBs did not seem to play a significant role. Many compounds were better removed in aerobic condition, suggesting that aerobic heterotrophic organisms were involved in the degradation. As the AGS-SBRs did not favour the growth of such organisms, their potential for micropollutant removal appeared to be lower than that of conventional nitrifying WWTPs. PMID:26877039

  15. Aerobic biodegradation of dichloroethenes by indigenous bacteria isolated from contaminated sites in Africa.

    PubMed

    Olaniran, Ademola O; Pillay, Dorsamy; Pillay, Balakrishna

    2008-08-01

    The widespread use of tetrachloroethene (PCE) and trichloroethene (TCE) as dry cleaning solvents and degreasing agents for military and industrial applications has resulted in significant environmental contamination worldwide. Anaerobic biotransformation of PCE and TCE through reductive dechlorination frequently lead to the accumulation of dichloroethenes (DCEs), thus limiting the use of reductive dechlorination for the biotransformation of the compounds. In this study, seven bacteria indigenous to contaminated sites in Africa were characterized for DCE degradation under aerobic conditions. The specific growth rate constants of the bacterial isolates ranged between 0.346-0.552 d(-1) and 0.461-0.667 d(-1) in cis-DCE and trans-DCE, respectively. Gas chromatographic analysis revealed that up to 75% of the compounds were degraded within seven days with the degradation rate constants ranging between 0.167 and 0.198 d(-1). The two compounds were also observed to be significantly degraded, simultaneously, rather than sequentially, when present as a mixture. Phylogenetic analysis of the 16S rRNA gene sequences of the bacterial isolates revealed their identity as well as their relation to other environmentally-important bacteria. The observed biodegradation of DCEs may contribute to PCE and TCE removal at the aerobic fringe of groundwater plumes undergoing reductive dechlorination in contaminated sites. PMID:18635246

  16. Bacteriuria screening and antimicrobial susceptibility testing of aerobic bacteria by an electrochemical method.

    PubMed

    Strassburger, J; Tiller, F W

    1984-04-01

    A method is described for detecting significant bacteriuria and determination of minimal inhibition concentrations (MIC's) of aerobically growing bacteria by using electrochemical electrodes to measure changes of oxygen tensions in liquid nutrient media resulting from bacterial growth. Urine specimens (n = 577) were screened electrochemically, parallel investigations were performed by standard culture methods and by photometrical measurements. All the specimens showing significant bacteriuria in standard culture were selected within 3.5 h by the electrochemical technique. An oxygen index OI was introduced which quantitatively reflects changes in oxygen tension of nutrient media during growth. OI shows good agreement with extinction and light scattering indices, respectively. On the basis of OI as a parameter of inhibited and uninhibited growth a correlation between OI and MIC's of aerobically growing bacteria was found. The electrochemical method provides an useful aid for rapid, preliminary antimicrobial susceptibility testing and definite bacteriuria screening. The application of this method in bacteriological urine diagnostics significantly reduces laboratory work and costs, and can be recommended for the screening of urine specimens to exclude negative specimens from further processing.

  17. Aerobic biodegradation of dichloroethenes by indigenous bacteria isolated from contaminated sites in Africa.

    PubMed

    Olaniran, Ademola O; Pillay, Dorsamy; Pillay, Balakrishna

    2008-08-01

    The widespread use of tetrachloroethene (PCE) and trichloroethene (TCE) as dry cleaning solvents and degreasing agents for military and industrial applications has resulted in significant environmental contamination worldwide. Anaerobic biotransformation of PCE and TCE through reductive dechlorination frequently lead to the accumulation of dichloroethenes (DCEs), thus limiting the use of reductive dechlorination for the biotransformation of the compounds. In this study, seven bacteria indigenous to contaminated sites in Africa were characterized for DCE degradation under aerobic conditions. The specific growth rate constants of the bacterial isolates ranged between 0.346-0.552 d(-1) and 0.461-0.667 d(-1) in cis-DCE and trans-DCE, respectively. Gas chromatographic analysis revealed that up to 75% of the compounds were degraded within seven days with the degradation rate constants ranging between 0.167 and 0.198 d(-1). The two compounds were also observed to be significantly degraded, simultaneously, rather than sequentially, when present as a mixture. Phylogenetic analysis of the 16S rRNA gene sequences of the bacterial isolates revealed their identity as well as their relation to other environmentally-important bacteria. The observed biodegradation of DCEs may contribute to PCE and TCE removal at the aerobic fringe of groundwater plumes undergoing reductive dechlorination in contaminated sites.

  18. Abundance and genetic diversity of aerobic anoxygenic phototrophic bacteria of coastal regions of the pacific ocean.

    PubMed

    Ritchie, Anna E; Johnson, Zackary I

    2012-04-01

    Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophic microbes that are found in a broad range of aquatic environments. Although potentially significant to the microbial ecology and biogeochemistry of marine ecosystems, their abundance and genetic diversity and the environmental variables that regulate these properties are poorly understood. Using samples along nearshore/offshore transects from five disparate islands in the Pacific Ocean (Oahu, Molokai, Futuna, Aniwa, and Lord Howe) and off California, we show that AAP bacteria, as quantified by the pufM gene biomarker, are most abundant near shore and in areas with high chlorophyll or Synechococcus abundance. These AAP bacterial populations are genetically diverse, with most members belonging to the alpha- or gammaproteobacterial groups and with subclades that are associated with specific environmental variables. The genetic diversity of AAP bacteria is structured along the nearshore/offshore transects in relation to environmental variables, and uncultured pufM gene libraries suggest that nearshore communities are distinct from those offshore. AAP bacterial communities are also genetically distinct between islands, such that the stations that are most distantly separated are the most genetically distinct. Together, these results demonstrate that environmental variables regulate both the abundance and diversity of AAP bacteria but that endemism may also be a contributing factor in structuring these communities.

  19. Purple Sulfur Bacteria Control the Growth of Aerobic Heterotrophic Bacterioplankton in a Meromictic Salt Lake

    PubMed Central

    Overmann, J.; Beatty, J. T.; Hall, K. J.

    1996-01-01

    In meromictic Mahoney Lake, British Columbia, Canada, the heterotrophic bacterial production in the mixolimnion exceeded concomitant primary production by a factor of 7. Bacterial growth rates were correlated neither to primary production nor to the amount of chlorophyll a. Both results indicate an uncoupling of bacteria and phytoplankton. In the chemocline of the lake, an extremely dense population of the purple sulfur bacterium Amoebobacter purpureus is present year round. We investigated whether anoxygenic phototrophs are significant for the growth of aerobic bacterioplankton in the overlaying water. Bacterial growth rates in the mixolimnion were limited by inorganic phosphorus or nitrogen most of the time, and the biomass of heterotrophic bacteria did not increase until, in autumn, 86% of the cells of A. purpureus appeared in the mixolimnion because of their reduced buoyant density. The increase in heterotrophic bacterial biomass, soluble phosphorus concentrations below the detection limit, and an extraordinarily high activity of alkaline phosphatase in the mixolimnion indicate a rapid liberation of organically bound phosphorus from A. purpureus cells accompanied by a simultaneous incorporation into heterotrophic bacterioplankton. High concentrations of allochthonously derived dissolved organic carbon (mean, 60 mg of C(middot)liter(sup-1)) were measured in the lake water. In Mahoney Lake, liberation of phosphorus from upwelling purple sulfur bacteria and degradation of allochthonous dissolved organic carbon as an additional carbon source render heterotrophic bacterial production largely independent of the photosynthesis of phytoplankton. A recycling of inorganic nutrients via phototrophic bacteria also appears to be relevant in other lakes with anoxic bottom waters. PMID:16535399

  20. Effects of oxidants and reductants on the efficiency of excitation transfer in green photosynthetic bacteria.

    PubMed

    Wang, J; Brune, D C; Blankenship, R E

    1990-02-22

    The efficiency of energy transfer in chlorosome antennas in the green sulfur bacteria Chlorobium vibrioforme and Chlorobium limicola was found to be highly sensitive to the redox potential of the suspension. Energy transfer efficiencies were measured by comparing the absorption spectrum of the bacteriochlorophyll c or d pigments in the chlorosome to the excitation spectrum for fluorescence arising from the chlorosome baseplate and membrane-bound antenna complexes. The efficiency of energy transfer approaches 100% at low redox potentials induced by addition of sodium dithionite or other strong reductants, and is lowered to 10-20% under aerobic conditions or after addition of a variety of membrane-permeable oxidizing agents. The redox effect on energy transfer is observed in whole cells, isolated membranes and purified chlorosomes, indicating that the modulation of energy transfer efficiency arises within the antenna complexes and is not directly mediated by the redox state of the reaction center. It is proposed that chlorosomes contain a component that acts as a highly quenching center in its oxidized state, but is an inefficient quencher when reduced by endogenous or exogenous reductants. This effect may be a control mechanism that prevents cellular damage resulting from reaction of oxygen with reduced low-potential electron acceptors found in the green sulfur bacteria. The redox modulation effect is not observed in the green gliding bacterium Chloroflexus aurantiacus, which contains chlorosomes but does not contain low-potential electron acceptors.

  1. Effects of oxidants and reductants on the efficiency of excitation transfer in green photosynthetic bacteria

    NASA Technical Reports Server (NTRS)

    Wang, J.; Brune, D. C.; Blankenship, R. E.

    1990-01-01

    The efficiency of energy transfer in chlorosome antennas in the green sulfur bacteria Chlorobium vibrioforme and Chlorobium limicola was found to be highly sensitive to the redox potential of the suspension. Energy transfer efficiencies were measured by comparing the absorption spectrum of the bacteriochlorophyll c or d pigments in the chlorosome to the excitation spectrum for fluorescence arising from the chlorosome baseplate and membrane-bound antenna complexes. The efficiency of energy transfer approaches 100% at low redox potentials induced by addition of sodium dithionite or other strong reductants, and is lowered to 10-20% under aerobic conditions or after addition of a variety of membrane-permeable oxidizing agents. The redox effect on energy transfer is observed in whole cells, isolated membranes and purified chlorosomes, indicating that the modulation of energy transfer efficiency arises within the antenna complexes and is not directly mediated by the redox state of the reaction center. It is proposed that chlorosomes contain a component that acts as a highly quenching center in its oxidized state, but is an inefficient quencher when reduced by endogenous or exogenous reductants. This effect may be a control mechanism that prevents cellular damage resulting from reaction of oxygen with reduced low-potential electron acceptors found in the green sulfur bacteria. The redox modulation effect is not observed in the green gliding bacterium Chloroflexus aurantiacus, which contains chlorosomes but does not contain low-potential electron acceptors.

  2. [Bioaugmentation for shortcut nitrification in SBR treating for sewage containing sea water by nitrification-aerobic denitrification bacteria].

    PubMed

    Qu, Yang; Zhang, Pei-Yu; Yu, De-Shuang; Guo, Sha-Sha; Yang, Rui-Xia

    2010-10-01

    The feasibility of heterotrophic nitrification-aerobic denitrification bacteria applied in shortcut nitrification system was studied. Four heterotrophic nitrification-aerobic denitrification strains mixed with halotolerant activated sludge was added into SBR in order to test their bioaugmentation ability for shortcut nitrification system, which was treating for sewage containing sea water, and the difference between bioaugmentation system and original system was compared. The results showed that the maximum accumulation of NO2(-) -N in bioaugmentation system was 34.92% lower than that in original system, and the time of maximum accumulation of NO2(-) -N was 2 hours earlier than that in original system. The TN and COD was continuously decreasing in the later phase of nitrification in bioaugmentation system, and finally the removal rate of TN and COD were 15.24% and 5.39% higher than that in original system respectively, as well as the removal rate of NH4(+) -N and the nitrosation rate were 6.85% and 14.47% higher than that in original system. And the pH was 0.46 higher than that in original system, whereas the ORP was 25.84 mV lower. It was considered that the function of heterotrophic nitrification-aerobic denitrification bacteria should strengthen the performance of bioaugmentation system. When the seawater content raised to 70%, the stability of bioaugmentation system was better than that in original system, and the current that transforming shortcut nitrification to complete nitrification was restrained by heterotrophic nitrification-aerobic denitrification bacteria effectively. The number of heterotrophic nitrification-aerobic denitrification bacteria was changed when bioaugmentation system and original system ran in different phase and the bacteria had a great loss with the discharge of activated sludge. These results may provide a theoretical reference about the feasibility that the heterotrophic nitrification-aerobic denitrification bacteria applied in

  3. In vitro susceptibility tests for cationic peptides: comparison of broth microdilution methods for bacteria that grow aerobically.

    PubMed

    Giacometti, A; Cirioni, O; Barchiesi, F; Del Prete, M S; Fortuna, M; Caselli, F; Scalise, G

    2000-06-01

    The in vitro susceptibilities of 90 clinical isolates of gram-positive and gram-negative aerobic bacteria to six cationic peptides, buforin II, cecropin P1, indolicidin, magainin II, nisin, and ranalexin, were evaluated by two broth microdilution methods. The first method was performed according to the procedures outlined by the National Committee for Clinical Laboratory Standards for bacteria that grow aerobically, while the second was performed according to the procedures recently proposed by the R. E. W. Hancock laboratory for testing antimicrobial peptides. Overall, the first method produced MICs two- and fourfold higher than the second method. PMID:10817731

  4. The hydrological context determines the beta-diversity of aerobic anoxygenic phototrophic bacteria in European Arctic seas but does not favor endemism

    PubMed Central

    Lehours, Anne-Catherine; Jeanthon, Christian

    2015-01-01

    Despite an increasing number of studies over the last 15 years, aerobic anoxygenic photoheterotrophic (AAP) bacteria remain a puzzling functional group in terms of physiology, metabolism, and ecology. To contribute to a better knowledge of their environmental distribution, the present study aims at analyzing their diversity and structure at the boundary between the Norwegian, Greenland, and Barents Seas. The polymorphism of a marker gene encoding a sub-unit of the photosynthetic apparatus (pufM gene) was analyzed and attempted to be related to environmental parameters. The Atlantic or Arctic origin of water masses had a strong impact on the AAP bacterial community structure whose populations mostly belonged to the Alpha- and Gammaproteobacteria. A majority (>60%) of pufM sequences were affiliated to the Gammaproteobacteria reasserting that this class often represents the major component of the AAP bacterial community in oceanic regions. Two alphaproteobacterial groups dominate locally suggesting that they can constitute key players in this marine system transiently. We found that temperature is a major determinant of alpha diversity of AAP bacteria in this marine biome with specific clades emerging locally according to the partitioning of water masses. Whereas we expected specific AAP bacterial populations in this peculiar and newly explored ecosystem, most pufM sequences were highly related to sequences retrieved elsewhere. This observation highlights that the studied area does not favor AAP bacteria endemism but also opens new questions about the truthfulness of biogeographical patterns and on the extent of AAP bacterial diversity. PMID:26191046

  5. Studies on Hydrogen Production by Photosynthetic Bacteria after Anaerobic Fermentation of Starch by a Hyperthermophile, Pyrococcus furiosus

    NASA Astrophysics Data System (ADS)

    Sugitate, Toshihiro; Fukatsu, Makoto; Ishimi, Katsuhiro; Kohno, Hideki; Wakayama, Tatsuki; Nakamura, Yoshihiro; Miyake, Jun; Asada, Yasuo

    In order to establish the sequential hydrogen production from waste starch using a hyperthermophile, Pyrococcus furiosus, and a photosynthetic bacterium, basic studies were done. P. furiosus produced hydrogen and acetate by anaerobic fermentation at 90°C. A photosynthetic bacterium, Rhodobacter sphaeroides RV, was able to produce hydrogen from acetate under anaerobic and light conditions at 30°C. However, Rb. sphaeroides RV was not able to produce hydrogen from acetate in the presence of sodium chloride that was essential for the growth and hydrogen production of P. furiosus although it produced hydrogen from lactate at a reduced rate with 1% sodium chloride. A newly isolated strain, CST-8, from natural environment was, however, able to produce hydrogen from acetate, especially with 3 mM L-alanine and in the presence of 1% sodium chloride. The sequential hydrogen production with P. furiosus and salt-tolerant photosynthetic bacteria could be probable at least in the laboratory experiment scale.

  6. Ammonium-oxidizing bacteria facilitate aerobic degradation of sulfanilic acid in activated sludge.

    PubMed

    Chen, Gang; Ginige, Maneesha P; Kaksonen, Anna H; Cheng, Ka Yu

    2014-01-01

    Sulfanilic acid (SA) is a toxic sulfonated aromatic amine commonly found in anaerobically treated azo dye contaminated effluents. Aerobic acclimatization of SA-degrading mixed microbial culture could lead to co-enrichment of ammonium-oxidizing bacteria (AOB) because of the concomitant release of ammonium from SA oxidation. To what extent the co-enriched AOB would affect SA oxidation at various ammonium concentrations was unclear. Here, a series of batch kinetic experiments were conducted to evaluate the effect of AOB on aerobic SA degradation in an acclimatized activated sludge culture capable of oxidizing SA and ammonium simultaneously. To account for the effect of AOB on SA degradation, allylthiourea was used to inhibit AOB activity in the culture. The results indicated that specific SA degradation rate of the mixed culture was negatively correlated with the initial ammonium concentration (0-93 mM, R²= 0.99). The presence of AOB accelerated SA degradation by reducing the inhibitory effect of ammonium (≥ 10 mM). The Haldane substrate inhibition model was used to correlate substrate concentration (SA and ammonium) and oxygen uptake rate. This study revealed, for the first time, that AOB could facilitate SA degradation at high concentration of ammonium (≥ 10 mM) in an enriched activated sludge culture.

  7. Diversity and phylogeny of the ectoine biosynthesis genes in aerobic, moderately halophilic methylotrophic bacteria.

    PubMed

    Reshetnikov, Alexander S; Khmelenina, Valentina N; Mustakhimov, Ildar I; Kalyuzhnaya, Marina; Lidstrom, Mary; Trotsenko, Yuri A

    2011-11-01

    The genes of ectoine biosynthesis pathway were identified in six species of aerobic, slightly halophilic bacteria utilizing methane, methanol or methylamine. Two types of ectoine gene cluster organization were revealed in the methylotrophs. The gene cluster ectABC coding for diaminobutyric acid (DABA) acetyltransferase (EctA), DABA aminotransferase (EctB) and ectoine synthase (EctC) was found in methanotrophs Methylobacter marinus 7C and Methylomicrobium kenyense AMO1(T). In methanotroph Methylomicrobium alcaliphilum ML1, methanol-utilizers Methylophaga thalassica 33146(T) , Methylophaga alcalica M8 and methylamine-utilizer Methylarcula marina h1(T), the genes forming the ectABC-ask operon are preceded by ectR, encoding a putative transcriptional regulatory protein EctR. Phylogenetic relationships of the Ect proteins do not correlate with phylogenetic affiliation of the strains, thus implying that the ability of methylotrophs to produce ectoine is most likely the result of a horizontal transfer event.

  8. Effect of Azospirillum brasilense and Burkholderia unamae Bacteria on Maize Photosynthetic Activity Evaluated Using the Photoacoustic Technique

    NASA Astrophysics Data System (ADS)

    Gordillo-Delgado, F.; Marín, E.; Calderón, A.

    2016-09-01

    In this work, the photosynthetic process of maize plants ( Zea mays), which were grown using seeds inoculated with plant growth promoting bacteria Azospirillum brasilense and Burkholderia unamae, was monitored. Photothermal and photobaric signals obtained by a time-resolved photoacoustic measurement configuration were used for measuring the oxygen evolution rate in situ. A frequency-resolved configuration of the method was utilized to determine the oxygen diffusion coefficient and the thermal diffusivity of the maize leaves. The latter parameters, which can be used as indicators of the photosynthetic activity of maize, are found to vary according to the plant-microbe interaction. Treatment with plant growth promoting bacteria induced a decrease in the oxygen diffusion coefficient of about 20 %.

  9. Antimicrobial Resistance and Resistance Genes in Aerobic Bacteria Isolated from Pork at Slaughter.

    PubMed

    Li, Lili; Heidemann Olsen, Rikke; Ye, Lei; Yan, He; Nie, Qing; Meng, Hecheng; Shi, Lei

    2016-04-01

    The aim of this study was to investigate the phenotypic and genotypic antimicrobial resistance, integrons, and transferability of resistance markers in 243 aerobic bacteria recovered from pork at slaughter in the People's Republic of China. The organisms belonged to 22 genera of gram-negative bacteria (92.2%) and gram-positive bacteria (7.8%). High levels of resistance were detected to tetracycline, trimethoprim-sulfamethoxazole, and ampicillin (36.2 to 54.3%), and lower levels were detected to nitrofurantoin, cefotaxime, gentamicin, ciprofloxacin, and chloramphenicol (7.8 to 29.2%). Across species, genes conferring antimicrobial resistance were observed with the following frequencies: blaTEM, 40.7%; blaCMY-2, 15.2%; blaCTX-M, 11.5%; sul2, 27.2%; sul1, 14.4%; tet(A), 5.4%; tet(L), 5.4%; tet(M), 5.0%; tet(E), 3.7%; tet(C), 3.3%; tet(S), 2.5%; and tet(K), 0.8%. Various antimicrobial resistance genes were found in new carriers: blaTEM in Lactococcus garvieae, Myroides odoratimimus, Aeromonas hydrophila, Staphylococcus sciuri, Raoultella terrigena, Macrococcus caseolyticus, Acinetobacter ursingii, Sphingobacterium sp., and Oceanobacillus sp.; blaCMY-2 in Lactococcus lactis, Klebsiella oxytoca, Serratia marcescens, Acinetobacter baumannii, and Myroides phaeus; tet(L) in M. caseolyticus; sul1 in Vibrio cincinnatiensis; sul2 in Acinetobacter bereziniae, Acinetobacter johnsonii, and V. cincinnatiensis; and the class 1 integron and gene cassette aadA2 in V. cincinnatiensis. Approximately 6.6% of isolates contained class 1 integrons, and one isolate harbored class 2 integrons. Plasmid associated intI1 and androgen receptor- encoding genes were transferred into Escherichia coli J53 and E. coli DH5α by conjugation and transformation experiments, respectively. Our study highlights the importance of aerobic bacteria from pork as reservoirs for antimicrobial resistance genes and mobile genetic elements that can readily be transferred intra- and interspecies. PMID:27052863

  10. A photosynthetic-plasmonic-voltaic cell: Excitation of photosynthetic bacteria and current collection through a plasmonic substrate

    SciTech Connect

    Samsonoff, Nathan; Ooms, Matthew D.; Sinton, David

    2014-01-27

    Excitation of photosynthetic biofilms using surface-confined evanescent light fields enables energy dense photobioreactors, while electrode-adhered biofilms can provide electricity directly. Here, we demonstrate concurrent light delivery and electron transport through a plasmonically excited metal film. Biofilms of cyanobacterium Synechococcus bacillaris on 50-nm gold films are excited via the Kretschmann configuration at λ = 670 nm. Cells show light/dark response to plasmonic excitation and grow denser biofilms, closer to the electrode surface, as compared to the direct irradiated case. Directly irradiated biofilms produced average electrical powers of 5.7 μW/m{sup 2} and plasmonically excited biofilms produced average electrical powers of 5.8 μW/m{sup 2}, with individual biofilms producing as much as 12 μW/m{sup 2}.

  11. Hybridization of cloned Rhodopseudomonas capsulata photosynthesis genes with DNA from other photosynthetic bacteria.

    PubMed Central

    Beatty, J T; Cohen, S N

    1983-01-01

    The homology of Rhodopseudomonas capsulata DNA segments carrying photosynthesis genes with sequences present in total DNA from certain other photosynthetic and non-photosynthetic bacterial species was determined by hybridization. R. capsulata DNA fragments that carry loci for production of peptide components of the photosynthetic reaction center and light-harvesting I antenna complex were found to hybridize to DNA from some photosynthetic species. However, fragments that carry carotenoid or bacteriochlorophyll biosynthesis genes showed either weak or undetectable heterospecific hybridization under the conditions employed. Images PMID:6406432

  12. An initial investigation into the ecology of culturable aerobic postmortem bacteria.

    PubMed

    Chun, Lauren P; Miguel, Marcus J; Junkins, Emily N; Forbes, Shari L; Carter, David O

    2015-12-01

    Postmortem microorganisms are increasingly recognized for their potential to serve as physical evidence. Yet, we still understand little about the ecology of postmortem microbes, particularly those associated with the skin and larval masses. We conducted an experiment to characterize microbiological and chemical properties of decomposing swine (Sus scrofa domesticus) carcasses on the island of Oahu, Hawaii, USA, during June 2013. Bacteria were collected from the head, limb, and larval mass during the initial 145h of decomposition. We also measured the pH, temperature, and oxidation-reduction potential of larval masses in situ. Bacteria were cultured aerobically on Standard Nutrient Agar at 22°C and identified using protein or genetic signals. Carcass decomposition followed a typical sigmoidal pattern and associated bacterial communities differed by sampling location and time since death, although all communities were dominated by phyla Actinobacteria, Firmicutes, and Proteobacteria. Larval masses were reducing environments (~-200mV) of neutral pH (6.5-7.5) and high temperature (35°C-40°C). We recommend that culturable postmortem and larval mass microbiology and chemistry be investigated in more detail, as it has potential to complement culture-independent studies and serve as a rapid estimate of PMI. PMID:26654073

  13. Acetic acid production from food wastes using yeast and acetic acid bacteria micro-aerobic fermentation.

    PubMed

    Li, Yang; He, Dongwei; Niu, Dongjie; Zhao, Youcai

    2015-05-01

    In this study, yeast and acetic acid bacteria strains were adopted to enhance the ethanol-type fermentation resulting to a volatile fatty acids yield of 30.22 g/L, and improve acetic acid production to 25.88 g/L, with food wastes as substrate. In contrast, only 12.81 g/L acetic acid can be obtained in the absence of strains. The parameters such as pH, oxidation reduction potential and volatile fatty acids were tested and the microbial diversity of different strains and activity of hydrolytic ferment were investigated to reveal the mechanism. The optimum pH and oxidation reduction potential for the acetic acid production were determined to be at 3.0-3.5 and -500 mV, respectively. Yeast can convert organic matters into ethanol, which is used by acetic acid bacteria to convert the organic wastes into acetic acid. The acetic acid thus obtained from food wastes micro-aerobic fermentation liquid could be extracted by distillation to get high-pure acetic acid.

  14. Membrane development in purple photosynthetic bacteria in response to alterations in light intensity and oxygen tension.

    PubMed

    Niederman, Robert A

    2013-10-01

    Studies on membrane development in purple bacteria during adaptation to alterations in light intensity and oxygen tension are reviewed. Anoxygenic phototrophic such as the purple α-proteobacterium Rhodobacter sphaeroides have served as simple, dynamic, and experimentally accessible model organisms for studies of the photosynthetic apparatus. A major landmark in photosynthesis research, which dramatically illustrates this point, was provided by the determination of the X-ray structure of the reaction center (RC) in Blastochloris viridis (Deisenhofer and Michel, EMBO J 8:2149-2170, 1989), once it was realized that this represented the general structure for the photosystem II RC present in all oxygenic phototrophs. This seminal advance, together with a considerable body of subsequent research on the light-harvesting (LH) and electron transfer components of the photosynthetic apparatus has provided a firm basis for the current understanding of how phototrophs acclimate to alterations in light intensity and quality. Oxygenic phototrophs adapt to these changes by extensive thylakoid membrane remodeling, which results in a dramatic supramolecular reordering to assure that an appropriate flow of quinone redox species occurs within the membrane bilayer for efficient and rapid electron transfer. Despite the high level of photosynthetic unit organization in Rba. sphaeroides as observed by atomic force microscopy (AFM), fluorescence induction/relaxation measurements have demonstrated that the addition of the peripheral LH2 antenna complex in cells adapting to low-intensity illumination results in a slowing of the rate of electron transfer turnover by the RC of up to an order of magnitude. This is ascribed to constraints in quinone redox species diffusion between the RC and cytochrome bc1 complexes arising from the increased packing density as the intracytoplasmic membrane (ICM) bilayer becomes crowded with LH2 rings. In addition to downshifts in light intensity as a paradigm

  15. Environmental detection of octahaem cytochrome c hydroxylamine/hydrazine oxidoreductase genes of aerobic and anaerobic ammonium-oxidizing bacteria.

    PubMed

    Schmid, Markus C; Hooper, Alan B; Klotz, Martin G; Woebken, Dagmar; Lam, Phyllis; Kuypers, Marcel M M; Pommerening-Roeser, Andreas; Op den Camp, Huub J M; Jetten, Mike S M

    2008-11-01

    Bacterial aerobic ammonium oxidation and anaerobic ammonium oxidation (anammox) are important processes in the global nitrogen cycle. Key enzymes in both processes are the octahaem cytochrome c (OCC) proteins, hydroxylamine oxidoreductase (HAO) of aerobic ammonium-oxidizing bacteria (AOB), which catalyses the oxidation of hydroxylamine to nitrite, and hydrazine oxidoreductase (HZO) of anammox bacteria, which converts hydrazine to N(2). While the genomes of AOB encode up to three nearly identical copies of hao operons, genome analysis of Candidatus'Kuenenia stuttgartiensis' showed eight highly divergent octahaem protein coding regions as possible candidates for the HZO. Based on their phylogenetic relationship and biochemical characteristics, the sequences of these eight gene products grouped in three clusters. Degenerate primers were designed on the basis of available gene sequences with the aim to detect hao and hzo genes in various ecosystems. The hao primer pairs amplified gene fragments from 738 to 1172 bp and the hzo primer pairs amplified gene fragments from 289 to 876 bp in length, when tested on genomic DNA isolated from a variety of AOB and anammox bacteria. A selection of these primer pairs was also used successfully to amplify and analyse the hao and hzo genes in community DNA isolated from different ecosystems harbouring both AOB and anammox bacteria. We propose that OCC protein-encoding genes are suitable targets for molecular ecological studies on both aerobic and anaerobic ammonium-oxidizing bacteria.

  16. Development and dynamics of the photosynthetic apparatus in purple phototrophic bacteria.

    PubMed

    Niederman, Robert A

    2016-03-01

    The purple bacterium Rhodobacter sphaeroides provides a useful model system for studies of the assembly and dynamics of bacterial photosynthetic membranes. For the nascent developing membrane, proteomic analyses showed an ~2-fold enrichment in general membrane assembly factors, compared to chromatophores. When the protonophore carbonyl-cyanide m-chlorophenyl-hydrazone (CCCP) was added to an ICM inducing culture, an ~2-fold elevation in spectral counts vs. the control was seen for the SecA translocation ATPase, the preprotein translocase SecY, SecD and SecF insertion components, and chaperonins DnaJ and DnaK, which act early in the assembly process. It is suggested that these factors accumulated with their nascent polypeptides, as putative assembly intermediates in a functionally arrested state. Since in Synechocystis PCC 6803, a link has been established between Chl delivery involving the high-light HilD protein and the SecY/YidC-requiring cotranslational insertion of nascent polypeptides, such a connection between BChl biosynthesis and insertion and folding of nascent Rba. sphaeroides BChl binding proteins is likely to also occur. AFM imaging studies of the formation of the reaction center (RC)-light harvesting 1 (LH1) complex suggested a cooperative assembly mechanism in which, following the association between the RC template and the initial LH1 unit, addition of successive LH1 units to the RC drives the assembly process to completion. Alterations in membrane dynamics as the developing membrane becomes filled with LH2-rings were assessed by fluorescence induction/relaxation kinetics, which showed a slowing in RC electron transfer rate thought to mainly reflect alterations in donor side electron transfer. This was attributed to an increased distance for electron flow in cytochrome c2 between the RC and cytochrome bc1 complexes, as suggested in the current structural models. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic

  17. Skin Anti-Aging Activities of Bacteriochlorophyll a from Photosynthetic Bacteria, Rhodobacter sphaeroides.

    PubMed

    Kim, Nam Young; Yim, Tae Bin; Lee, Hyeon Yong

    2015-10-01

    In this work, the anti-aging skin effects of bacteriochlorophyll a isolated from Rhodobacter sphaeroides are first reported, with notably low cytotoxicity in the range of 1% to 14% in adding 0.00078 (% (w/w)) of the extracts, compared with the normal growth of both human dermal fibroblast and keratinocyte cells without any treatment as a control. The highest production of procollagen from human fibroblast cells (CCD-986sk) was observed as 221.7 ng/ml with 0.001 (% (w/w)) of bacteriochlorophyll a, whereas 150 and 200 ng/ml of procollagen production resulted from addition of 0.001 (% (w/w)) of the photosynthetic bacteria. The bacteriochlorophylla- induced TNF-α production increased to 63.8%, which was lower secretion from HaCaT cells than that from addition of 0.00005 (% (w/w)) of bacteriochlorophyll a. Additionally, bacteriochlorophyll a upregulated the expression of genes related to skin anti-aging (i.e., keratin 10, involucrin, transglutaminase-1, and MMPs), by up to 4-15 times those of the control. However, crude extracts from R. sphaeroides did not enhance the expression level of these genes. Bacteriochlorophyll a showed higher antioxidant activity of 63.8% in DPPH free radical scavenging than those of water, ethanol, and 70% ethanol extracts (14.0%, 57.2%, and 12.6%, respectively). It was also shown that the high antioxidant activity could be attributed to the skin anti-aging effect of bacteriochlorophyll a, although R. sphaeroides itself would not exhibit significant anti-aging activities.

  18. Plutonium Oxidation State Distribution under Aerobic and Anaerobic Subsurface Conditions for Metal-Reducing Bacteria

    NASA Astrophysics Data System (ADS)

    Reed, D. T.; Swanson, J.; Khaing, H.; Deo, R.; Rittmann, B.

    2009-12-01

    The fate and potential mobility of plutonium in the subsurface is receiving increased attention as the DOE looks to cleanup the many legacy nuclear waste sites and associated subsurface contamination. Plutonium is the near-surface contaminant of concern at several DOE sites and continues to be the contaminant of concern for the permanent disposal of nuclear waste. The mobility of plutonium is highly dependent on its redox distribution at its contamination source and along its potential migration pathways. This redox distribution is often controlled, especially in the near-surface where organic/inorganic contaminants often coexist, by the direct and indirect effects of microbial activity. The redox distribution of plutonium in the presence of facultative metal reducing bacteria (specifically Shewanella and Geobacter species) was established in a concurrent experimental and modeling study under aerobic and anaerobic conditions. Pu(VI), although relatively soluble under oxidizing conditions at near-neutral pH, does not persist under a wide range of the oxic and anoxic conditions investigated in microbiologically active systems. Pu(V) complexes, which exhibit high chemical toxicity towards microorganisms, are relatively stable under oxic conditions but are reduced by metal reducing bacteria under anaerobic conditions. These facultative metal-reducing bacteria led to the rapid reduction of higher valent plutonium to form Pu(III/IV) species depending on nature of the starting plutonium species and chelating agents present in solution. Redox cycling of these lower oxidation states is likely a critical step in the formation of pseudo colloids that may lead to long-range subsurface transport. The CCBATCH biogeochemical model is used to explain the redox mechanisms and final speciation of the plutonium oxidation state distributions observed. These results for microbiologically active systems are interpreted in the context of their importance in defining the overall migration

  19. Diversity and Habitat Preferences of Cultivated and Uncultivated Aerobic Methanotrophic Bacteria Evaluated Based on pmoA as Molecular Marker

    PubMed Central

    Knief, Claudia

    2015-01-01

    Methane-oxidizing bacteria are characterized by their capability to grow on methane as sole source of carbon and energy. Cultivation-dependent and -independent methods have revealed that this functional guild of bacteria comprises a substantial diversity of organisms. In particular the use of cultivation-independent methods targeting a subunit of the particulate methane monooxygenase (pmoA) as functional marker for the detection of aerobic methanotrophs has resulted in thousands of sequences representing “unknown methanotrophic bacteria.” This limits data interpretation due to restricted information about these uncultured methanotrophs. A few groups of uncultivated methanotrophs are assumed to play important roles in methane oxidation in specific habitats, while the biology behind other sequence clusters remains still largely unknown. The discovery of evolutionary related monooxygenases in non-methanotrophic bacteria and of pmoA paralogs in methanotrophs requires that sequence clusters of uncultivated organisms have to be interpreted with care. This review article describes the present diversity of cultivated and uncultivated aerobic methanotrophic bacteria based on pmoA gene sequence diversity. It summarizes current knowledge about cultivated and major clusters of uncultivated methanotrophic bacteria and evaluates habitat specificity of these bacteria at different levels of taxonomic resolution. Habitat specificity exists for diverse lineages and at different taxonomic levels. Methanotrophic genera such as Methylocystis and Methylocaldum are identified as generalists, but they harbor habitat specific methanotrophs at species level. This finding implies that future studies should consider these diverging preferences at different taxonomic levels when analyzing methanotrophic communities. PMID:26696968

  20. Space agriculture for habitation on Mars with hyper-thermophilic aerobic composting bacteria

    NASA Astrophysics Data System (ADS)

    Space Agriculture Task Force; Ishikawa, Y.; Tomita-Yokotani, K.; Hashimoto, H.; Kitaya, Y.; Yamashita, M.; Nagatomo, M.; Oshima, T.; Wada, H.

    Manned Mars exploration, especially for extended periods of time, will require recycle of materials to support human life. Here, a conceptual design is developed for a Martian agricultural system driven by biologically regenerative functions. One of the core biotechnologies function is the use of hyper-thermophilic aerobic composting bacterial ecology. These thermophilic bacteria can play an important role in increasing the effectiveness of the processing of human metabolic waste and inedible biomass and of converting them to fertilizer for the cultivation of plants. This microbial technology has been already well established for the purpose of processing sewage and waste materials for small local communities in Japan. One of the characteristics of the technology is that the metabolic heat release that occurs during bacterial fermentation raises the processing temperature sufficiently high at 80 100 °C to support hyper-thermophilic bacteria. Such a hyper-thermophilic system is found to have great capability of decomposing wastes including even their normally recalcitrant components, in a reasonably short period of time and of providing a better quality of fertilizer as an end-product. High quality compost has been shown to be a key element in creating a healthy regenerative food production system. In ground-based studies, the soil microbial ecology after the addition of high quality compost was shown to improve plant growth and promote a healthy symbiosis of arbuscular mycorrhizal fungi. Another advantage of such high processing temperature is the ability to sterilize the pathogenic organisms through the fermentation process and thus to secure the hygienic safety of the system. Plant cultivation is one of the other major systems. It should fully utilize solar energy received on the Martian surface for supplying energy for photosynthesis. Subsurface water and atmospheric carbon dioxide mined on Mars should be also used in the plant cultivation system. Oxygen and

  1. Isolation of Optically Targeted Single Bacteria by Application of Fluidic Force Microscopy to Aerobic Anoxygenic Phototrophs from the Phyllosphere

    PubMed Central

    Stiefel, Philipp; Zambelli, Tomaso

    2013-01-01

    In their natural environment, bacteria often behave differently than they do under laboratory conditions. To gain insight into the physiology of bacteria in situ, dedicated approaches are required to monitor their adaptations and specific behaviors under environmental conditions. Optical microscopy is crucial for the observation of fundamental characteristics of bacteria, such as cell shape, size, and marker gene expression. Here, fluidic force microscopy (FluidFM) was exploited to isolate optically selected bacteria for subsequent identification and characterization. In this study, bacteriochlorophyll-producing bacteria, which can be visualized due to their characteristic fluorescence in the infrared range, were isolated from leaf washes. Bacterial communities from the phyllosphere were investigated because they harbor genes indicative of aerobic anoxygenic photosynthesis. Our data show that different species of Methylobacterium express their photosystem in planta, and they show a distinct pattern of bacteriochlorophyll production under laboratory conditions that is dependent on supplied carbon sources. PMID:23770907

  2. Organic carbon recovery and photosynthetic bacteria population in an anaerobic membrane photo-bioreactor treating food processing wastewater.

    PubMed

    Chitapornpan, S; Chiemchaisri, C; Chiemchaisri, W; Honda, R; Yamamoto, K

    2013-08-01

    Purple non-sulfur bacteria (PNSB) were cultivated by food industry wastewater in the anaerobic membrane photo-bioreactor. Organic removal and biomass production and characteristics were accomplished via an explicit examination of the long term performance of the photo-bioreactor fed with real wastewater. With the support of infra-red light transmitting filter, PNSB could survive and maintain in the system even under the continual fluctuations of influent wastewater characteristics. The average BOD and COD removal efficiencies were found at the moderate range of 51% and 58%, respectively. Observed photosynthetic biomass yield was 0.6g dried solid/g BOD with crude protein content of 0.41 g/g dried solid. Denaturing gradient gel electrophoretic analysis (DGGE) and 16S rDNA sequencing revealed the presence of Rhodopseudomonas palustris and significant changes in the photosynthetic bacterial community within the system. PMID:23489563

  3. Organic carbon recovery and photosynthetic bacteria population in an anaerobic membrane photo-bioreactor treating food processing wastewater.

    PubMed

    Chitapornpan, S; Chiemchaisri, C; Chiemchaisri, W; Honda, R; Yamamoto, K

    2013-08-01

    Purple non-sulfur bacteria (PNSB) were cultivated by food industry wastewater in the anaerobic membrane photo-bioreactor. Organic removal and biomass production and characteristics were accomplished via an explicit examination of the long term performance of the photo-bioreactor fed with real wastewater. With the support of infra-red light transmitting filter, PNSB could survive and maintain in the system even under the continual fluctuations of influent wastewater characteristics. The average BOD and COD removal efficiencies were found at the moderate range of 51% and 58%, respectively. Observed photosynthetic biomass yield was 0.6g dried solid/g BOD with crude protein content of 0.41 g/g dried solid. Denaturing gradient gel electrophoretic analysis (DGGE) and 16S rDNA sequencing revealed the presence of Rhodopseudomonas palustris and significant changes in the photosynthetic bacterial community within the system.

  4. Organic Osmolytes in Aerobic Bacteria from Mono Lake, an Alkaline, Moderately Hypersaline Environment

    PubMed Central

    Ciulla, R. A.; Diaz, M. R.; Taylor, B. F.; Roberts, M. F.

    1997-01-01

    The identity and concentrations of intracellular organic solutes were determined by nuclear magnetic resonance spectroscopy for two strains of aerobic, gram-negative bacteria isolated from Mono Lake, Calif., an alkaline, moderately hypersaline lake. Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) was the major endogenous solute in both organisms. Concentrations of ectoine varied with external NaCl levels in strain ML-D but not in strain ML-G, where the level was high but invariant from 1.5 to 3.0 M NaCl. Hydroxyectoine also occurred in strain ML-D, especially at elevated NaCl concentrations (2.5 and 3.0 M), but at levels lower than those of ectoine. Exogenous organic solutes that might occur in Mono Lake were examined for their effects on the de novo synthesis of ectoine. Dimethylsulfoniopropionate (DMSP) (0.1 or 1 mM) did not significantly lower ectoine levels in either isolate, and only strain ML-G showed any capacity for DMSP accumulation. With nitrogen limitation, however, DMSP (0.1 mM) substituted for ectoine in strain ML-G and became the main organic solute. Glycine betaine (GB) was more effective than DMSP in affecting ectoine levels, principally in strain ML-D. Strain ML-D accumulated GB to 50 or 67% of its organic solute pool at 2.5 M NaCl, at an external level of 0.1 or 1 mM GB, respectively. Strain ML-D also accumulated arsenobetaine. The methylated zwitterionic compounds, probably metabolic products of phytoplankton (DMSP and GB) or brine shrimps (arsenobetaine) in Mono Lake, may function as osmolytes for indigenous bacteria when present at high concentrations or under conditions of nitrogen limitation or salt stress. PMID:16535487

  5. Diversity of aerobic methanotrophic bacteria in a permafrost active layer soil of the Lena Delta, Siberia.

    PubMed

    Liebner, Susanne; Rublack, Katja; Stuehrmann, Torben; Wagner, Dirk

    2009-01-01

    With this study, we present first data on the diversity of aerobic methanotrophic bacteria (MOB) in an Arctic permafrost active layer soil of the Lena Delta, Siberia. Applying denaturing gradient gel electrophoresis and cloning of 16S ribosomal ribonucleic acid (rRNA) and pmoA gene fragments of active layer samples, we found a general restriction of the methanotrophic diversity to sequences closely related to the genera Methylobacter and Methylosarcina, both type I MOB. In contrast, we revealed a distinct species-level diversity. Based on phylogenetic analysis of the 16S rRNA gene, two new clusters of MOB specific for the permafrost active layer soil of this study were found. In total, 8 out of 13 operational taxonomic units detected belong to these clusters. Members of these clusters were closely related to Methylobacter psychrophilus and Methylobacter tundripaludum, both isolated from Arctic environments. A dominance of MOB closely related to M. psychrophilus and M. tundripaludum was confirmed by an additional pmoA gene analysis. We used diversity indices such as the Shannon diversity index or the Chao1 richness estimator in order to compare the MOB community near the surface and near the permafrost table. We determined a similar diversity of the MOB community in both depths and suggest that it is not influenced by the extreme physical and geochemical gradients in the active layer. PMID:18592300

  6. Halotolerant aerobic heterotrophic bacteria from the Great Salt Plains of Oklahoma.

    PubMed

    Caton, T M; Witte, L R; Ngyuen, H D; Buchheim, J A; Buchheim, M A; Schneegurt, M A

    2004-11-01

    The Salt Plains National Wildlife Refuge (SPNWR) near Cherokee, Oklahoma, contains a barren salt flat where Permian brine rises to the surface and evaporates under dry conditions to leave a crust of white salt. Rainfall events dissolve the salt crust and create ephemeral streams and ponds. The rapidly changing salinity and high surface temperatures, salinity, and UV exposure make this an extreme environment. The Salt Plains Microbial Observatory (SPMO) examined the soil microbial community of this habitat using classic enrichment and isolation techniques and phylogenetic rDNA studies. Rich growth media have been emphasized that differ in total salt concentration and composition. Aerobic heterotrophic enrichments were performed under a variety of conditions. Heterotrophic enrichments and dilution plates have generated 105 bacterial isolates, representing 46 phylotypes. The bacterial isolates have been characterized phenotypically and subjected to rDNA sequencing and phylogenetic analyses. Fast-growing isolates obtained from enrichments with 10% salt are predominantly from the gamma subgroup of the Proteobacteria and from the low GC Gram-positive cluster. Several different areas on the salt flats have yielded a variety of isolates from the Gram-negative genera Halomonas, Idiomarina, Salinivibrio, and Bacteroidetes. Gram-positive bacteria are well represented in the culture collection including members of the Bacillus, Salibacillus, Oceanobacillus, and Halobacillus. PMID:15696379

  7. Cultivation of aerobic chemoorganotrophic proteobacteria and gram-positive bacteria from a hot spring microbial mat.

    PubMed Central

    Nold, S C; Kopczynski, E D; Ward, D M

    1996-01-01

    The diversity of aerobic chemoorganotrophic bacteria inhabiting the Octopus Spring cyanobacterial mat community (Yellowstone National Park) was examined by using serial-dilution enrichment culture and a variety of enrichment conditions to cultivate the numerically significant microbial populations. The most abundant bacterial populations cultivated from dilutions to extinction were obtained from enrichment flasks which contained 9.0 x 10(2) primary producer (Synechococcus spp.) cells in the inoculum. Two isolates exhibited 16S rRNA nucleotide sequences typical of beta-proteobacteria. One of these isolates contained a 16S rRNA sequence identical to a sequence type previously observed in the mat by molecular retrieval techniques. Both are distantly related to a new sequence directly retrieved from the mat and contributed by a beta-proteobacterial community member. Phenotypically diverse gram-positive isolates genetically similar to Bacillus flavothermus were obtained from a variety of dilutions and enrichment types. These isolates exhibited identical 16S rRNA nucleotide sequences through a variable region of the molecule. Of the three unique sequences observed, only one had been previously retrieved from the mat, illustrating both the inability of the cultivation methods to describe the composition of a microbial community and the limitations of the ability of molecular retrieval techniques to describe populations which may be less abundant in microbial communities. PMID:8899976

  8. Effects of exogenous aerobic bacteria on methane production and biodegradation of municipal solid waste in bioreactors.

    PubMed

    Ge, Sai; Liu, Lei; Xue, Qiang; Yuan, Zhiming

    2016-09-01

    Landfill is the most common and efficient ways of municipal solid waste (MSW) disposal and the landfill biogas, mostly methane, is currently utilized to generate electricity and heat. The aim of this work is to study the effects and the role of exogenous aerobic bacteria mixture (EABM) on methane production and biodegradation of MSW in bioreactors. The results showed that the addition of EABM could effectively enhance hydrolysis and acidogenesis processes of MSW degradation, resulting in 63.95% reduction of volatile solid (VS), the highest methane production rate (89.83Lkg(-1) organic matter) ever recorded and a threefold increase in accumulative methane production (362.9L) than the control (127.1L). In addition, it is demonstrated that white-rot fungi (WRF) might further promote the methane production through highly decomposing lignin, but the lower pH value in leachate and longer acidogenesis duration may cause methane production reduced. The data demonstrated that methane production and biodegradation of MSW in bioreactors could be significantly enhanced by EABM via enhanced hydrolysis and acidogenesis processes, and the results are of great economic importance for the future design and management of landfill. PMID:26601890

  9. Halotolerant aerobic heterotrophic bacteria from the Great Salt Plains of Oklahoma.

    PubMed

    Caton, T M; Witte, L R; Ngyuen, H D; Buchheim, J A; Buchheim, M A; Schneegurt, M A

    2004-11-01

    The Salt Plains National Wildlife Refuge (SPNWR) near Cherokee, Oklahoma, contains a barren salt flat where Permian brine rises to the surface and evaporates under dry conditions to leave a crust of white salt. Rainfall events dissolve the salt crust and create ephemeral streams and ponds. The rapidly changing salinity and high surface temperatures, salinity, and UV exposure make this an extreme environment. The Salt Plains Microbial Observatory (SPMO) examined the soil microbial community of this habitat using classic enrichment and isolation techniques and phylogenetic rDNA studies. Rich growth media have been emphasized that differ in total salt concentration and composition. Aerobic heterotrophic enrichments were performed under a variety of conditions. Heterotrophic enrichments and dilution plates have generated 105 bacterial isolates, representing 46 phylotypes. The bacterial isolates have been characterized phenotypically and subjected to rDNA sequencing and phylogenetic analyses. Fast-growing isolates obtained from enrichments with 10% salt are predominantly from the gamma subgroup of the Proteobacteria and from the low GC Gram-positive cluster. Several different areas on the salt flats have yielded a variety of isolates from the Gram-negative genera Halomonas, Idiomarina, Salinivibrio, and Bacteroidetes. Gram-positive bacteria are well represented in the culture collection including members of the Bacillus, Salibacillus, Oceanobacillus, and Halobacillus.

  10. Effects of exogenous aerobic bacteria on methane production and biodegradation of municipal solid waste in bioreactors.

    PubMed

    Ge, Sai; Liu, Lei; Xue, Qiang; Yuan, Zhiming

    2016-09-01

    Landfill is the most common and efficient ways of municipal solid waste (MSW) disposal and the landfill biogas, mostly methane, is currently utilized to generate electricity and heat. The aim of this work is to study the effects and the role of exogenous aerobic bacteria mixture (EABM) on methane production and biodegradation of MSW in bioreactors. The results showed that the addition of EABM could effectively enhance hydrolysis and acidogenesis processes of MSW degradation, resulting in 63.95% reduction of volatile solid (VS), the highest methane production rate (89.83Lkg(-1) organic matter) ever recorded and a threefold increase in accumulative methane production (362.9L) than the control (127.1L). In addition, it is demonstrated that white-rot fungi (WRF) might further promote the methane production through highly decomposing lignin, but the lower pH value in leachate and longer acidogenesis duration may cause methane production reduced. The data demonstrated that methane production and biodegradation of MSW in bioreactors could be significantly enhanced by EABM via enhanced hydrolysis and acidogenesis processes, and the results are of great economic importance for the future design and management of landfill.

  11. Self-sustained phototrophic microbial fuel cells based on the synergistic cooperation between photosynthetic microorganisms and heterotrophic bacteria.

    PubMed

    He, Zhen; Kan, Jinjun; Mansfeld, Florian; Angenent, Largus T; Nealson, Kenneth H

    2009-03-01

    A sediment-type self-sustained phototrophic microbial fuel cell (MFC) was developed to generate electricity through the synergistic interaction between photosynthetic microorganisms and heterotrophic bacteria. Under illumination, the MFC continuously produced electricity without the external input of exogenous organics or nutrients. The current increased in the dark and decreased with the light on, possibly because of the negative effect of the oxygen produced via photosynthesis. Continuous illumination inhibited the current production while the continuous dark period stimulated the current production. Extended darkness resulted in a decrease of current, probably because of the consumption of the organics accumulated during the light phase. Using color filters or increasing the thickness of the sediment resulted in a reduction of the oxygen-induced inhibition. Molecular taxonomic analysis revealed that photosynthetic microorganisms including cyanobacteria and microalgae predominated in the water phase, adjacent to the cathode and on the surface of the sediment. In contrast, the sediments were dominated by heterotrophic bacteria, becoming less diverse with increasing depth. In addition, results from the air-cathode phototrophic MFC confirmed the light-induced current production while the test with the two-chamber MFC (in the dark) indicated the presence of electricigenic bacteria in the sediment.

  12. Characterization of aerobic spore-forming bacteria associated with industrial dairy processing environments and product spoilage.

    PubMed

    Lücking, Genia; Stoeckel, Marina; Atamer, Zeynep; Hinrichs, Jörg; Ehling-Schulz, Monika

    2013-09-01

    Due to changes in the design of industrial food processing and increasing international trade, highly thermoresistant spore-forming bacteria are an emerging problem in food production. Minimally processed foods and products with extended shelf life, such as milk products, are at special risk for contamination and subsequent product damages, but information about origin and food quality related properties of highly heat-resistant spore-formers is still limited. Therefore, the aim of this study was to determine the biodiversity, heat resistance, and food quality and safety affecting characteristics of aerobic spore-formers in the dairy sector. Thus, a comprehensive panel of strains (n=467), which originated from dairy processing environments, raw materials and processed foods, was compiled. The set included isolates associated with recent food spoilage cases and product damages as well as isolates not linked to product spoilage. Identification of the isolates by means of Fourier-transform infrared spectroscopy and molecular methods revealed a large biodiversity of spore-formers, especially among the spoilage associated isolates. These could be assigned to 43 species, representing 11 genera, with Bacillus cereus s.l. and Bacillus licheniformis being predominant. A screening for isolates forming thermoresistant spores (TRS, surviving 100°C, 20 min) showed that about one third of the tested spore-formers was heat-resistant, with Bacillus subtilis and Geobacillus stearothermophilus being the prevalent species. Strains producing highly thermoresistant spores (HTRS, surviving 125°C, 30 min) were found among mesophilic as well as among thermophilic species. B. subtilis and Bacillus amyloliquefaciens were dominating the group of mesophilic HTRS, while Bacillus smithii and Geobacillus pallidus were dominating the group of thermophilic HTRS. Analysis of spoilage-related enzymes of the TRS isolates showed that mesophilic strains, belonging to the B. subtilis and B. cereus

  13. Detection of alternative nitrogenases in aerobic gram-negative nitrogen-fixing bacteria.

    PubMed Central

    Fallik, E; Chan, Y K; Robson, R L

    1991-01-01

    Strains of aerobic, microaerobic, nonsymbiotic, and symbiotic dinitrogen-fixing bacteria were screened for the presence of alternative nitrogenase (N2ase) genes by DNA hybridization between genomic DNA and DNA encoding structural genes for components 1 of three different enzymes. A nifDK gene probe was used as a control to test for the presence of the commonly occurring Mo-Fe N2ase, a vnfDGK gene probe was used to show the presence of V-Fe N2ase, and an anfDGK probe was used to detect Fe N2ase. Hitherto, all three enzymes have been identified in Azotobacter vinelandii OP, and all but the Fe N2ase are present in Azotobacter chroococcum ATCC 4412 (MCD1). Mo-Fe N2ase and V-Fe N2ase structural genes only were confirmed in this strain and in two other strains of A. chroococcum (ATCC 480 and ATCC 9043). A similar pattern was observed with Azotobacter beijerinckii ATCC 19360 and Azotobacter nigricans ATCC 35009. Genes for all three systems are apparently present in two strains of Azotobacter paspali (ATCC 23367 and ATCC 23833) and also in Azomonas agilis ATCC 7494. There was no good evidence for the existence of any genes other than Mo-Fe N2ase structural genes in several Rhizobium meliloti strains, cowpea Rhizobium strain 32H1, or Bradyrhizobium japonicum. Nitrogenase and nitrogenase genes in Azorhizobium caulinodans behaved in an intermediate fashion, showing (i) the formation of ethane from acetylene under Mo starvation, a characteristic of alternative nitrogenases, and (ii) a surprising degree of cross-hybridization to the vnfDGK, but not the anfDGK, probe. vnfDGK- and anfDGK-like sequences were not detected in two saccharolytic Pseudomonas species or Azospirillum brasilense Sp7. The occurrence of alternative N2ases seems restricted to members of the family Azotobacteraceae among the aerobic and microaerobic diazotrophs tested, suggesting that an ability to cope with O2 when fixing N2 may be an important factor influencing the distribution of alternative nitrogenases

  14. Characterization of aerobic spore-forming bacteria associated with industrial dairy processing environments and product spoilage.

    PubMed

    Lücking, Genia; Stoeckel, Marina; Atamer, Zeynep; Hinrichs, Jörg; Ehling-Schulz, Monika

    2013-09-01

    Due to changes in the design of industrial food processing and increasing international trade, highly thermoresistant spore-forming bacteria are an emerging problem in food production. Minimally processed foods and products with extended shelf life, such as milk products, are at special risk for contamination and subsequent product damages, but information about origin and food quality related properties of highly heat-resistant spore-formers is still limited. Therefore, the aim of this study was to determine the biodiversity, heat resistance, and food quality and safety affecting characteristics of aerobic spore-formers in the dairy sector. Thus, a comprehensive panel of strains (n=467), which originated from dairy processing environments, raw materials and processed foods, was compiled. The set included isolates associated with recent food spoilage cases and product damages as well as isolates not linked to product spoilage. Identification of the isolates by means of Fourier-transform infrared spectroscopy and molecular methods revealed a large biodiversity of spore-formers, especially among the spoilage associated isolates. These could be assigned to 43 species, representing 11 genera, with Bacillus cereus s.l. and Bacillus licheniformis being predominant. A screening for isolates forming thermoresistant spores (TRS, surviving 100°C, 20 min) showed that about one third of the tested spore-formers was heat-resistant, with Bacillus subtilis and Geobacillus stearothermophilus being the prevalent species. Strains producing highly thermoresistant spores (HTRS, surviving 125°C, 30 min) were found among mesophilic as well as among thermophilic species. B. subtilis and Bacillus amyloliquefaciens were dominating the group of mesophilic HTRS, while Bacillus smithii and Geobacillus pallidus were dominating the group of thermophilic HTRS. Analysis of spoilage-related enzymes of the TRS isolates showed that mesophilic strains, belonging to the B. subtilis and B. cereus

  15. Isolation and preliminary characterization of aerobic heterotrophic bacteria isolated from sub-glacial Antarctic water samples

    NASA Astrophysics Data System (ADS)

    Palma-Alvarez, R.; Lanoil, B. D.

    2002-05-01

    Recently, evidence has been accumulating supporting the presence of biogeochemically active microbial communities in cold, dark, and isolated subglacial environments. These environments are important sites of rock weathering, provide insight into global biogeochemistry during glacial periods, and are potential analogues for ancient Snowball Earth events and the ice-covered oceans of the Jovian moon, Europa. However, the extent of microbial influence on subglacial geochemistry is unclear. As part of an ongoing project to address the extent of that influence, we isolated aerobic heterotrophic bacteria from sediment-laden water from beneath Ice Stream C, a fast moving region of the Western Antarctic Ice Sheet (WAIS). Plates of a standard environmental media (R2A) were prepared at three dilutions (1x, 0.1x, 0.01x) and inoculated in duplicate in a HEPA-filtered environment. One replicate was incubated at 4oC, the other at room temperature in the dark. All plates showed abundant growth, although colony size was positively correlated with media concentration. One-hundred eighty-one colonies total were picked, grown in liquid R2A (1x concentration) at the same initial temperature, and characterized for Gram character, cell shape, cell size, and production of a diffusible yellow pigment with similar chemical characteristics to the siderophore, pyoverdine. Based on these characters, a moderate level of diversity was observed in these isolates. A few types dominated the samples, with several others found only rarely. Further characterization of these isolates is ongoing, and results of these studies and their possible implications for sub-glacial biogeochemistry are discussed.

  16. Preferential Use of Carbon Sources in Culturable Aerobic Mesophilic Bacteria of Coptotermes curvignathus's (Isoptera: Rhinotermitidae) Gut and Its Foraging Area.

    PubMed

    Wong, W Z; H'ng, P S; Chin, K L; Sajap, Ahmad Said; Tan, G H; Paridah, M T; Othman, Soni; Chai, E W; Go, W Z

    2015-10-01

    The lower termite, Coptotermes curvignathus, is one of the most prominent plantation pests that feed upon, digest, and receive nourishment from exclusive lignocellulose diets. The objective of this study was to examine the utilization of sole carbon sources by isolated culturable aerobic bacteria among communities from the gut and foraging pathway of C. curvignathus. We study the bacteria occurrence from the gut of C. curvignathus and its surrounding feeding area by comparing the obtained phenotypic fingerprint with Biolog's extensive species library. A total of 24 bacteria have been identified mainly from the family Enterobacteriaceae from the identification of Biolog Gen III. Overall, the bacteria species in the termite gut differ from those of foraging pathway within a location, except Acintobacter baumannii, which was the only bacteria species found in both habitats. Although termites from a different study area do not have the same species of bacteria in the gut, they do have a bacterial community with similar role in degrading certain carbon sources. Sugars were preferential in termite gut isolates, while nitrogen carbon sources were preferential in foraging pathway isolates. The preferential use of specific carbon sources by these two bacterial communities reflects the role of bacteria for regulation of carbon metabolism in the termite gut and foraging pathway. PMID:26314017

  17. Preferential Use of Carbon Sources in Culturable Aerobic Mesophilic Bacteria of Coptotermes curvignathus's (Isoptera: Rhinotermitidae) Gut and Its Foraging Area.

    PubMed

    Wong, W Z; H'ng, P S; Chin, K L; Sajap, Ahmad Said; Tan, G H; Paridah, M T; Othman, Soni; Chai, E W; Go, W Z

    2015-10-01

    The lower termite, Coptotermes curvignathus, is one of the most prominent plantation pests that feed upon, digest, and receive nourishment from exclusive lignocellulose diets. The objective of this study was to examine the utilization of sole carbon sources by isolated culturable aerobic bacteria among communities from the gut and foraging pathway of C. curvignathus. We study the bacteria occurrence from the gut of C. curvignathus and its surrounding feeding area by comparing the obtained phenotypic fingerprint with Biolog's extensive species library. A total of 24 bacteria have been identified mainly from the family Enterobacteriaceae from the identification of Biolog Gen III. Overall, the bacteria species in the termite gut differ from those of foraging pathway within a location, except Acintobacter baumannii, which was the only bacteria species found in both habitats. Although termites from a different study area do not have the same species of bacteria in the gut, they do have a bacterial community with similar role in degrading certain carbon sources. Sugars were preferential in termite gut isolates, while nitrogen carbon sources were preferential in foraging pathway isolates. The preferential use of specific carbon sources by these two bacterial communities reflects the role of bacteria for regulation of carbon metabolism in the termite gut and foraging pathway.

  18. Effectiveness of Active Packaging on Control of Escherichia Coli O157:H7 and Total Aerobic Bacteria on Iceberg Lettuce.

    PubMed

    Lu, Haixia; Zhu, Junli; Li, Jianrong; Chen, Jinru

    2015-06-01

    Contaminated leafy green vegetables have been linked to several outbreaks of human gastrointestinal infections. Antimicrobial interventions that are adoptable by the fresh produce industry for control of pathogen contamination are in great demand. This study was undertaken to evaluate the efficacy of sustained active packaging on control of Escherichia coli O157:H7 and total aerobic bacteria on lettuce. Commercial Iceberg lettuce was inoculated with a 3-strain mixture of E. coli O157:H7 at 10(2) or 10(4) CFU/g. The contaminated lettuce and un-inoculated controls were placed respectively in 5 different active packaging structures. Traditional, nonactive packaging structure was included as controls. Packaged lettuce was stored at 4, 10, or 22 °C for 3 wk and sampled weekly for the population of E. coli O157:H7 and total aerobic bacteria. Results showed that packaging structures with ClO2 generator, CO2 generator, or one of the O2 scavengers effectively controlled the growth of E. coli O157:H7 and total aerobic bacteria under all storage conditions. Packaging structure with the ClO2 generator was most effective and no E. coli O157:H7 was detected in samples packaged in this structure except for those that were inoculated with 4 log CFU/g of E. coli O157:H7 and stored at 22 °C. Packaging structures with an oxygen scavenger and the allyl isothiocyanate generator were mostly ineffective in control of the growth of the bacteria on Iceberg lettuce. The research suggests that some of the packaging structures evaluated in the study can be used to control the presence of foodborne pathogens on leafy green vegetables.

  19. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    PubMed Central

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-01-01

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850∗ states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs. PMID:26373989

  20. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    NASA Astrophysics Data System (ADS)

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-09-01

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850∗ states of LH2 in each of the 3 samples with a lifetime of ˜40-60 fs.

  1. Communication: Coherences observed in vivo in photosynthetic bacteria using two-dimensional electronic spectroscopy

    SciTech Connect

    Dahlberg, Peter D.; Norris, Graham J.; Wang, Cheng; Viswanathan, Subha; Singh, Ved P.; Engel, Gregory S.

    2015-09-14

    Energy transfer through large disordered antenna networks in photosynthetic organisms can occur with a quantum efficiency of nearly 100%. This energy transfer is facilitated by the electronic structure of the photosynthetic antennae as well as interactions between electronic states and the surrounding environment. Coherences in time-domain spectroscopy provide a fine probe of how a system interacts with its surroundings. In two-dimensional electronic spectroscopy, coherences can appear on both the ground and excited state surfaces revealing detailed information regarding electronic structure, system-bath coupling, energy transfer, and energetic coupling in complex chemical systems. Numerous studies have revealed coherences in isolated photosynthetic pigment-protein complexes, but these coherences have not been observed in vivo due to the small amplitude of these signals and the intense scatter from whole cells. Here, we present data acquired using ultrafast video-acquisition gradient-assisted photon echo spectroscopy to observe quantum beating signals from coherences in vivo. Experiments were conducted on isolated light harvesting complex II (LH2) from Rhodobacter sphaeroides, whole cells of R. sphaeroides, and whole cells of R. sphaeroides grown in 30% deuterated media. A vibronic coherence was observed following laser excitation at ambient temperature between the B850 and the B850{sup ∗} states of LH2 in each of the 3 samples with a lifetime of ∼40-60 fs.

  2. Aerobic organic carbon mineralization by sulfate-reducing bacteria in the oxygen-saturated photic zone of a hypersaline microbial mat.

    PubMed

    Jonkers, H M; Koh, I-O; Behrend, P; Muyzer, G; de Beer, D

    2005-02-01

    The sulfate-reducing bacterium strain SRB D2 isolated from the photic zone of a hypersaline microbial mat, from Lake Chiprana, NE Spain, respired pyruvate, alanine, and alpha-ketoglutarate but not formate, lactate, malate, succinate, and serine at significant rates under fully oxic conditions. Dehydrogenase enzymes of only the former substrates are likely oxygen-tolerant as all substrates supported anaerobic sulfate reduction. No indications were found, however, that aerobic respiration supported growth. Although strain SRB D2 appeared phylogenetically closely related to the oxygen-tolerant sulfate-reducing bacterium Desulfovibrio oxyclinae, substrate spectra were markedly different. Most-probable-number (MPN) estimates of sulfate-reducing bacteria and aerobic heterotrophic bacteria indicated that the latter were numerically dominant in both the photic and aphotic zones of the mat. Moreover, substrate spectra of representative isolates showed that the aerobic heterotrophic bacteria are metabolically more diverse. These findings indicate that sulfate-reducing bacteria in the fully oxic photic zone of mats have to compete with aerobic heterotrophic bacteria for organic substrates. Porewater analysis revealed that total carbohydrates and low-molecular-weight carbon compounds (LMWC) made up substantial fractions of the total dissolved organic carbon (DOC) pool and that nighttime degradation of the former was concomitant with increased concentration of the latter. Our findings indicate that aerobic respiration by sulfate-reducing bacteria contributes to organic carbon mineralization in the oxic zone of microbial mats as daytime porewater LMWC concentrations are above typical half-saturation constants.

  3. Aerobic organic carbon mineralization by sulfate-reducing bacteria in the oxygen-saturated photic zone of a hypersaline microbial mat.

    PubMed

    Jonkers, H M; Koh, I-O; Behrend, P; Muyzer, G; de Beer, D

    2005-02-01

    The sulfate-reducing bacterium strain SRB D2 isolated from the photic zone of a hypersaline microbial mat, from Lake Chiprana, NE Spain, respired pyruvate, alanine, and alpha-ketoglutarate but not formate, lactate, malate, succinate, and serine at significant rates under fully oxic conditions. Dehydrogenase enzymes of only the former substrates are likely oxygen-tolerant as all substrates supported anaerobic sulfate reduction. No indications were found, however, that aerobic respiration supported growth. Although strain SRB D2 appeared phylogenetically closely related to the oxygen-tolerant sulfate-reducing bacterium Desulfovibrio oxyclinae, substrate spectra were markedly different. Most-probable-number (MPN) estimates of sulfate-reducing bacteria and aerobic heterotrophic bacteria indicated that the latter were numerically dominant in both the photic and aphotic zones of the mat. Moreover, substrate spectra of representative isolates showed that the aerobic heterotrophic bacteria are metabolically more diverse. These findings indicate that sulfate-reducing bacteria in the fully oxic photic zone of mats have to compete with aerobic heterotrophic bacteria for organic substrates. Porewater analysis revealed that total carbohydrates and low-molecular-weight carbon compounds (LMWC) made up substantial fractions of the total dissolved organic carbon (DOC) pool and that nighttime degradation of the former was concomitant with increased concentration of the latter. Our findings indicate that aerobic respiration by sulfate-reducing bacteria contributes to organic carbon mineralization in the oxic zone of microbial mats as daytime porewater LMWC concentrations are above typical half-saturation constants. PMID:15965719

  4. Survival, injury and inactivation of Escherichia coli 0157:H7, salmonella and aerobic mesophilic bacteria in apple juice and cider amended with nisin-edta

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For health reasons, people are consuming fresh juices or minimally processed fruit and vegetable juices, thereby, exposing themselves to the risk of foodborne illness if such juices are contaminated with bacteria pathogens. Behavior of aerobic mesophilic bacteria, Escherichia coli O157:H7 and Salmon...

  5. A two-dimensional mass transfer model for an annular bioreactor using immobilized photosynthetic bacteria for hydrogen production.

    PubMed

    Zhang, Chuan; Wang, Ai-Jun; Zhang, Quan-Guo

    2013-10-01

    A two-dimensional model for substrate transfer and biodegradation in a novel, annular fiber-illuminating bioreactor (AFIBR) is proposed in which photosynthetic bacteria are immobilized on the surface of a side-glowing optical fiber to form a stable biofilm. When excited by light, the desired intensity and uniform light distribution can be obtained within the biofilm zone in bioreactor and then realize continuous hydrogen production. Substrate transfer and biodegradation within the biofilm zone, as well as substrate diffusion and convection within bulk fluid regions are considered simultaneously in this model. The validity of the model is verified experimentally. Based on the model analysis, influences of flow rate and light intensity on the substrate consumption rate and substrate degradation efficiency were investigated. The simulation results show that the optimum operational conditions for the substrate degradation within the AFIBR are: flow rate 100 ml h(-1) and light intensity 14.6 μmol photons m(-2 )s(-1).

  6. Separation of bacteriochlorophyll homologues from green photosynthetic sulfur bacteria by reversed-phase HPLC.

    PubMed

    Borrego, C M; Garcia-Gil, L J

    1994-07-01

    A reversed-phase High Performance Liquid Cromatography (HPLC) method has been developed to accurately separate bacteriochlorophyllsc, d ande homologues in a reasonably short run time of 60 minutes. By using this method, two well-defined groups of bacteriochlorophyll homologue peaks can be discriminated. The first one consists of 4 peaks (min 24 to 30), which corresponds to the four main farnesyl homologues. The second peak subset is formed by a cluster of up to 10 minor peaks (min 33 to 40). These peaks can be related with series of several alcohol esters of the different chlorosome chlorophylls. The number of homologues was, however, quite variable depending on both, the bacteriochlorophyll and the bacterial species. The method hereby described, also provides a good separation of other photosynthetic pigments, either bacterial (Bacteriochlorophylla, chlorobactene, isorenieratene and okenone) or algal ones (Chlorophylla, Pheophytina and β-carotene). A preliminary screening of the homologue composition of several green photosynthetic bacterial species and isolates, has revealed different relative quantitative patterns. These differences seem to be related to physiological aspects rather than to taxonomic ones. The application of the method to the study of natural populations avoids the typical drawbacks on the pigment identification of overlapping eukaryotic and prokaryotic phototrophic microorganisms, giving further information about their physiological status.

  7. Engineering of a modular and synthetic phosphoketolase pathway for photosynthetic production of acetone from CO2 in Synechococcus elongatus PCC 7942 under light and aerobic condition.

    PubMed

    Chwa, Jun-Won; Kim, Wook Jin; Sim, Sang Jun; Um, Youngsoon; Woo, Han Min

    2016-08-01

    Capture and conversion of CO2 to valuable chemicals is intended to answer global challenges on environmental issues, climate change and energy security. Engineered cyanobacteria have been enabled to produce industry-relevant chemicals from CO2 . However, the final products from cyanobacteria have often been mixed with fermented metabolites during dark fermentation. In this study, our engineering of Synechococcus elongatus PCC 7942 enabled continuous conversion of CO2 to volatile acetone as sole product. This process occurred during lighted, aerobic culture via both ATP-driven malonyl-CoA synthesis pathway and heterologous phosphoketolase (PHK)-phosphotransacetylase (Pta) pathway. Because of strong correlations between the metabolic pathways of acetate and acetone, supplying the acetyl-CoA directly from CO2 in the engineered strain, led to sole production of acetone (22.48 mg/L ± 1.00) without changing nutritional constraints, and without an anaerobic shift. Our engineered S. elongatus strains, designed for acetone production, could be modified to create biosolar cell factories for sustainable photosynthetic production of acetyl-CoA-derived biochemicals. PMID:26879003

  8. Diversity of cultivated and metabolically active aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Jeanthon, C.; Boeuf, D.; Dahan, O.; Le Gall, F.; Garczarek, L.; Bendif, E. M.; Lehours, A.-C.

    2011-05-01

    Aerobic anoxygenic phototrophic (AAP) bacteria play significant roles in the bacterioplankton productivity and biogeochemical cycles of the surface ocean. In this study, we applied both cultivation and mRNA-based molecular methods to explore the diversity of AAP bacteria along an oligotrophic gradient in the Mediterranean Sea in early summer 2008. Colony-forming units obtained on three different agar media were screened for the production of bacteriochlorophyll-a (BChl-a), the light-harvesting pigment of AAP bacteria. BChl-a-containing colonies represented a low part of the cultivable fraction. In total, 52 AAP strains were isolated and the phylogenetic analyses based on their 16S rRNA and pufM genes showed that they were all affiliated to the Alphaproteobacteria. The most frequently isolated strains belonged to Citromicrobium bathyomarinum, and Erythrobacter and Roseovarius species. Most other isolates were related to species not reported to produce BChl-a and/or may represent novel taxa. Direct extraction of RNA from seawater samples enabled the analysis of the expression of pufM, the gene coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis. Clone libraries of pufM gene transcripts revealed that most phylotypes were highly similar to sequences previously recovered from the Mediterranean Sea and a large majority (~94%) was affiliated with the Gammaproteobacteria. The most abundantly detected phylotypes occurred in the western and eastern Mediterranean basins. However, some were exclusively detected in the eastern basin, reflecting the highest diversity of pufM transcripts observed in this ultra-oligotrophic region. To our knowledge, this is the first study to document extensively the diversity of AAP isolates and to unveil the active AAP community in an oligotrophic marine environment. By pointing out the discrepancies between culture-based and molecular methods, this study highlights the existing gaps in the understanding

  9. Diversity of cultivated and metabolically active aerobic anoxygenic phototrophic bacteria along an oligotrophic gradient in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Jeanthon, C.; Boeuf, D.; Dahan, O.; Le Gall, F.; Garczarek, L.; Bendif, E. M.; Lehours, A.-C.

    2011-07-01

    Aerobic anoxygenic phototrophic (AAP) bacteria play significant roles in the bacterioplankton productivity and biogeochemical cycles of the surface ocean. In this study, we applied both cultivation and mRNA-based molecular methods to explore the diversity of AAP bacteria along an oligotrophic gradient in the Mediterranean Sea in early summer 2008. Colony-forming units obtained on three different agar media were screened for the production of bacteriochlorophyll-a (BChl-a), the light-harvesting pigment of AAP bacteria. BChl-a-containing colonies represented a low part of the cultivable fraction. In total, 54 AAP strains were isolated and the phylogenetic analyses based on their 16S rRNA and pufM genes showed that they were all affiliated to the Alphaproteobacteria. The most frequently isolated strains belonged to Citromicrobium bathyomarinum, and Erythrobacter and Roseovarius species. Most other isolates were related to species not reported to produce BChl-a and/or may represent novel taxa. Direct extraction of RNA from seawater samples enabled the analysis of the expression of pufM, the gene coding for the M subunit of the reaction centre complex of aerobic anoxygenic photosynthesis. Clone libraries of pufM gene transcripts revealed that most phylotypes were highly similar to sequences previously recovered from the Mediterranean Sea and a large majority (~94 %) was affiliated to the Gammaproteobacteria. The most abundantly detected phylotypes occurred in the western and eastern Mediterranean basins. However, some were exclusively detected in the eastern basin, reflecting the highest diversity of pufM transcripts observed in this ultra-oligotrophic region. To our knowledge, this is the first study to document extensively the diversity of AAP isolates and to unveil the active AAP community in an oligotrophic marine environment. By pointing out the discrepancies between culture-based and molecular methods, this study highlights the existing gaps in the understanding

  10. Validation of the Peel Plate™ AC for Detection of Total Aerobic Bacteria in Dairy and Nondairy Products.

    PubMed

    Salter, Robert S; Durbin, Gregory W; Bird, Patrick; Fisher, Kiel; Crowley, Erin; Hammack, Thomas; Chen, Yi; Clark, Dorn; Ziemer, Wayne

    2016-01-01

    Peel Plate™ AC (aerobic count) is a low-profile plastic 47 mm culture dish with adhesive top that contains a dried standard plate count medium with oxidation/reduction indicator triphenyl tetrazolium chloride (TTC) that turns red with dehydrogenase enzyme activity of growing aerobic bacteria. The method provides a conventional quantitative count with simple rehydration and incubation for 48 ± 3 h at 35 ± 1°C for most food matrixes and 32 ± 1°C for 48 ± 3 h for dairy products. Dairy matrixes claimed and supported with total aerobic count data are whole milk, skim milk, chocolate milk (2% fat), light cream (20% fat), pasteurized whole goat milk, ultra-high temperature pasteurized milk, nonfat dried milk, lactose-reduced milk, strawberry milk, raw cow milk, raw goat milk, raw sheep milk, condensed skim milk, and vanilla ice cream. Food matrixes claimed for aerobic count detection are raw ground beef, environmental sponge of stainless steel, raw ground turkey, dry dog food, liquid whole pasteurized eggs, milk chocolate, poultry carcass rinse, and large animal carcass sponge. The method has been independently evaluated for aerobic count in dairy products: whole milk, skim milk, chocolate milk, and light cream. The method was also independently evaluated for aerobic count in food matrixes: ground beef and sponge rinse from stainless steel surfaces. In the matrix study, each matrix was assessed separately at each contamination level in comparison to an appropriate reference method. Colony counts were determined for each level and then log10-transformed. The transformed data were evaluated for repeatability, mean comparison between methods with 95% confidence interval (CI), and r(2). A CI range of (-0.5, 0.5) on the mean difference was used as the acceptance criterion to establish significant statistical differences between methods. The evaluations demonstrate that the Peel Plate AC provides no statistical differences across most of the matrixes with r(2) > 0

  11. Validation of the Peel Plate™ AC for Detection of Total Aerobic Bacteria in Dairy and Nondairy Products.

    PubMed

    Salter, Robert S; Durbin, Gregory W; Bird, Patrick; Fisher, Kiel; Crowley, Erin; Hammack, Thomas; Chen, Yi; Clark, Dorn; Ziemer, Wayne

    2016-01-01

    Peel Plate™ AC (aerobic count) is a low-profile plastic 47 mm culture dish with adhesive top that contains a dried standard plate count medium with oxidation/reduction indicator triphenyl tetrazolium chloride (TTC) that turns red with dehydrogenase enzyme activity of growing aerobic bacteria. The method provides a conventional quantitative count with simple rehydration and incubation for 48 ± 3 h at 35 ± 1°C for most food matrixes and 32 ± 1°C for 48 ± 3 h for dairy products. Dairy matrixes claimed and supported with total aerobic count data are whole milk, skim milk, chocolate milk (2% fat), light cream (20% fat), pasteurized whole goat milk, ultra-high temperature pasteurized milk, nonfat dried milk, lactose-reduced milk, strawberry milk, raw cow milk, raw goat milk, raw sheep milk, condensed skim milk, and vanilla ice cream. Food matrixes claimed for aerobic count detection are raw ground beef, environmental sponge of stainless steel, raw ground turkey, dry dog food, liquid whole pasteurized eggs, milk chocolate, poultry carcass rinse, and large animal carcass sponge. The method has been independently evaluated for aerobic count in dairy products: whole milk, skim milk, chocolate milk, and light cream. The method was also independently evaluated for aerobic count in food matrixes: ground beef and sponge rinse from stainless steel surfaces. In the matrix study, each matrix was assessed separately at each contamination level in comparison to an appropriate reference method. Colony counts were determined for each level and then log10-transformed. The transformed data were evaluated for repeatability, mean comparison between methods with 95% confidence interval (CI), and r(2). A CI range of (-0.5, 0.5) on the mean difference was used as the acceptance criterion to establish significant statistical differences between methods. The evaluations demonstrate that the Peel Plate AC provides no statistical differences across most of the matrixes with r(2) > 0

  12. A genomic view of methane oxidation by aerobic bacteria and anaerobic archaea

    PubMed Central

    Chistoserdova, Ludmila; Vorholt, Julia A; Lidstrom, Mary E

    2005-01-01

    Recent sequencing of the genome and proteomic analysis of a model aerobic methanotrophic bacterium, Methylococcus capsulatus (Bath) has revealed a highly versatile metabolic potential. In parallel, environmental genomics has provided glimpses into anaerobic methane oxidation by certain archaea, further supporting the hypothesis of reverse methanogenesis. PMID:15693955

  13. Remediation of polychlorinated biphenyl impacted sediment by concurrent bioaugmentation with anaerobic halorespiring and aerobic degrading bacteria

    PubMed Central

    Payne, Rayford B.; Fagervold, Sonja K.; May, Harold D.; Sowers, Kevin R.

    2013-01-01

    Bioremediation of sediments contaminated with commercial PCBs is potentially achievable by the sequential activity of anaerobic halorespiration to convert higher chlorinated congeners to less chlorinated congeners that are susceptible to aerobic respiratory degradation. The efficacy of bioaugmentation with anaerobic halorespiring “Dehalobium chlorocoercia” DF1 and aerobic Burkholderia xenovorans LB400 added concurrently with GAC as a delivery system was determined in 2-liter laboratory mesocosms containing weathered Aroclor-contaminated sediment from Baltimore Harbor, MD. The greatest effect was seen in the mesocosm bioaugmented with both DF1 and LB400 together, which resulted in an 80% decrease by mass of PCBs, from 8 mg/kg to less than 2 mg/kg after 120 days. There was no significant increase in lesser-chlorinated congeners, indicating that both anaerobic dechlorination by DF1 and aerobic degradation by LB400 occurred. In contrast, non-bioaugmented controls containing filtered culture supernatant showed only 25% decrease in total levels of PCBs after 365 days, which was likely due to biostimulation of the indigenous population by the medium. Direct colony counts and molecular analysis targeting a putative reductive dehalogenase gene of D. chlorocoercia, or the bphA gene of LB400 showed the presence of viable DF1 and LB400 in bioaugmented mesocosms after 365 days, indicating that both non-indigenous strains were sustainable within the indigenous microbial community. These results suggest that an in situ treatment employing the simultaneous application of anaerobic and aerobic microorganisms could be an effective, environmentally sustainable strategy to reduce PCBs levels in contaminated sediment. PMID:23463900

  14. Biodesalination: A Case Study for Applications of Photosynthetic Bacteria in Water Treatment1[C

    PubMed Central

    Amezaga, Jaime M.; Amtmann, Anna; Biggs, Catherine A.; Bond, Tom; Gandy, Catherine J.; Honsbein, Annegret; Karunakaran, Esther; Lawton, Linda; Madsen, Mary Ann; Minas, Konstantinos; Templeton, Michael R.

    2014-01-01

    Shortage of freshwater is a serious problem in many regions worldwide, and is expected to become even more urgent over the next decades as a result of increased demand for food production and adverse effects of climate change. Vast water resources in the oceans can only be tapped into if sustainable, energy-efficient technologies for desalination are developed. Energization of desalination by sunlight through photosynthetic organisms offers a potential opportunity to exploit biological processes for this purpose. Cyanobacterial cultures in particular can generate a large biomass in brackish and seawater, thereby forming a low-salt reservoir within the saline water. The latter could be used as an ion exchanger through manipulation of transport proteins in the cell membrane. In this article, we use the example of biodesalination as a vehicle to review the availability of tools and methods for the exploitation of cyanobacteria in water biotechnology. Issues discussed relate to strain selection, environmental factors, genetic manipulation, ion transport, cell-water separation, process design, safety, and public acceptance. PMID:24610748

  15. Biodesalination: a case study for applications of photosynthetic bacteria in water treatment.

    PubMed

    Amezaga, Jaime M; Amtmann, Anna; Biggs, Catherine A; Bond, Tom; Gandy, Catherine J; Honsbein, Annegret; Karunakaran, Esther; Lawton, Linda; Madsen, Mary Ann; Minas, Konstantinos; Templeton, Michael R

    2014-04-01

    Shortage of freshwater is a serious problem in many regions worldwide, and is expected to become even more urgent over the next decades as a result of increased demand for food production and adverse effects of climate change. Vast water resources in the oceans can only be tapped into if sustainable, energy-efficient technologies for desalination are developed. Energization of desalination by sunlight through photosynthetic organisms offers a potential opportunity to exploit biological processes for this purpose. Cyanobacterial cultures in particular can generate a large biomass in brackish and seawater, thereby forming a low-salt reservoir within the saline water. The latter could be used as an ion exchanger through manipulation of transport proteins in the cell membrane. In this article, we use the example of biodesalination as a vehicle to review the availability of tools and methods for the exploitation of cyanobacteria in water biotechnology. Issues discussed relate to strain selection, environmental factors, genetic manipulation, ion transport, cell-water separation, process design, safety, and public acceptance.

  16. Biodesalination: a case study for applications of photosynthetic bacteria in water treatment.

    PubMed

    Amezaga, Jaime M; Amtmann, Anna; Biggs, Catherine A; Bond, Tom; Gandy, Catherine J; Honsbein, Annegret; Karunakaran, Esther; Lawton, Linda; Madsen, Mary Ann; Minas, Konstantinos; Templeton, Michael R

    2014-04-01

    Shortage of freshwater is a serious problem in many regions worldwide, and is expected to become even more urgent over the next decades as a result of increased demand for food production and adverse effects of climate change. Vast water resources in the oceans can only be tapped into if sustainable, energy-efficient technologies for desalination are developed. Energization of desalination by sunlight through photosynthetic organisms offers a potential opportunity to exploit biological processes for this purpose. Cyanobacterial cultures in particular can generate a large biomass in brackish and seawater, thereby forming a low-salt reservoir within the saline water. The latter could be used as an ion exchanger through manipulation of transport proteins in the cell membrane. In this article, we use the example of biodesalination as a vehicle to review the availability of tools and methods for the exploitation of cyanobacteria in water biotechnology. Issues discussed relate to strain selection, environmental factors, genetic manipulation, ion transport, cell-water separation, process design, safety, and public acceptance. PMID:24610748

  17. Isolation of culturable aerobic bacteria and evidence of Kerstersia gyiorum from the blowhole of captive Yangtze finless porpoises.

    PubMed

    Wan, Xiaoling; McLaughlin, Richard William; Zhou, Junying; Hao, Yujiang; Zheng, Jinsong; Wang, Ding

    2016-08-01

    Bacterial respiratory illnesses are problematic in aquatic mammals such as the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis; YFP), which is now at a critically endangered status. Yet little is known about the bacteria inhabiting the respiratory tract of YFPs. In this study, we preliminarily characterized the culturable aerobic bacteria from blow samples of captive YFPs. The bacterial diversity was assessed through cultivation by direct exhalation onto Columbia blood agar plates and identification of representative isolates through 16S rRNA gene sequence analysis. In total, eleven bacterial species belonging to four phyla Proteobacteria (71 %), Firmicutes (25 %), Bacteroidetes (3 %) and Actinobacteria (1 %) were identified. Most of these isolates were opportunistic pathogens found in respiratory illnesses in humans and animals. We also reported the first case of Kerstersia gyiorum isolated from an animal. This work provides a preliminary assessment of the bacteria present in the respiratory tract of captive YFPs, which will be an important first step in elucidating the roles of normal microbiota in maintaining respiratory health of YFPs. This study also points out the necessity of future long-term monitoring of blowhole microorganisms in the YFPs and making emergency preparedness plans for respiratory tract infections. These measures can aid in assessing the pathogenic risk of the critically endangered YFP populations. PMID:27251558

  18. Effects of maturity stage and lactic acid bacteria on the fermentation quality and aerobic stability of Siberian wildrye silage.

    PubMed

    Li, Ping; Bai, Shiqie; You, Minghong; Shen, Yixin

    2016-09-01

    It is difficult to make good quality of silage from alpine gramineous from the Qinghai Tibetan plateau. The effects of lactic acid bacteria (LAB) on the fermentation quality and aerobic stability of Siberian wildrye silage were studied in southeast of the Qinghai Tibetan plateau. Siberian wildrye materials were freshly cut at the sprouting stage, flowering stage, and milky stage. Silage was prepared by using a small-scale silage fermentation system (bag silos). Lactobacillus plantarum (LP, 5 × 10(8) cfu/kg FM), Lactobacillus buchneri (LB, 5 × 10(8) cfu/kg FM) and their mixture (LP+LB, 5 × 10(8) cfu/kg FM) as silage additives were separately added to ensiled forages, and no additive served as control (CK). These bag silos were kept at room temperature (<15°C), and the silage qualities were analyzed after 60 days of ensiling. The number of indigenous LAB on fresh materials was less than that of yeasts and molds, and LAB species showed specification adapted to low temperature. LAB inoculated silages had lower (P < 0.05) pH value, NH 3-N/TN and butyric acid content compared with control silage. Silage treated with LB had higher contents of acetic acid, propionic acid, WSC and CP. However, the aerobic stability of silages inoculated with LAB did not differ significantly between stages (P > 0.05). When fermentation characteristics, chemical composition, and aerobic stability were considered, treatment with L. plantarum resulted in high quality of Siberian wildrye silage harvested at the flowering stage in the alpine region. PMID:27625768

  19. Effects of maturity stage and lactic acid bacteria on the fermentation quality and aerobic stability of Siberian wildrye silage.

    PubMed

    Li, Ping; Bai, Shiqie; You, Minghong; Shen, Yixin

    2016-09-01

    It is difficult to make good quality of silage from alpine gramineous from the Qinghai Tibetan plateau. The effects of lactic acid bacteria (LAB) on the fermentation quality and aerobic stability of Siberian wildrye silage were studied in southeast of the Qinghai Tibetan plateau. Siberian wildrye materials were freshly cut at the sprouting stage, flowering stage, and milky stage. Silage was prepared by using a small-scale silage fermentation system (bag silos). Lactobacillus plantarum (LP, 5 × 10(8) cfu/kg FM), Lactobacillus buchneri (LB, 5 × 10(8) cfu/kg FM) and their mixture (LP+LB, 5 × 10(8) cfu/kg FM) as silage additives were separately added to ensiled forages, and no additive served as control (CK). These bag silos were kept at room temperature (<15°C), and the silage qualities were analyzed after 60 days of ensiling. The number of indigenous LAB on fresh materials was less than that of yeasts and molds, and LAB species showed specification adapted to low temperature. LAB inoculated silages had lower (P < 0.05) pH value, NH 3-N/TN and butyric acid content compared with control silage. Silage treated with LB had higher contents of acetic acid, propionic acid, WSC and CP. However, the aerobic stability of silages inoculated with LAB did not differ significantly between stages (P > 0.05). When fermentation characteristics, chemical composition, and aerobic stability were considered, treatment with L. plantarum resulted in high quality of Siberian wildrye silage harvested at the flowering stage in the alpine region.

  20. Isolation and Identification of Aerobic Bacteria Carrying Tetracycline and Sulfonamide Resistance Genes Obtained from a Meat Processing Plant.

    PubMed

    Li, Lili; Ye, Lei; Zhang, Sen; Meng, Hecheng

    2016-06-01

    Microbial contamination in food-processing plants can play a fundamental role in food quality and safety. The purpose of this study was to investigate aerobic bacteria carrying tetracycline and sulfonamide resistance genes from a meat processing plant as possible sources of meat contamination. One hundred swab samples from surfaces of conveyor belts, meat slicers, meat knives, benches, plastic trays, gloves, and aprons were analyzed. A total of 168 isolates belonging to 10 genera were obtained, including Pseudomonas sp. (n = 35), Acinetobacter sp. (n = 30), Aeromonas sp. (n = 20), Myroides sp. (n = 15), Serratia sp. (n = 15), Staphylococcus sp. (n = 14), Enterobacter sp. (n = 11), Escherichia coli (n = 10), Lactococcus sp. (n = 10), and Klebsiella sp. (n = 8). Of the 168 isolates investigated, 60.7% showed resistance to tetracycline and 57.7% to trimethoprim/sulfamethoxazole. The tetracycline resistance genes tetL, tetA, tetB, tetC, tetE, tetM, tetS, tetK, and tetX were found in the frequency of 7.7%, 6.0%, 4.8%, 4.8%, 3.6%, 3.6%, 3.6%, 1.2%, and 0.6%, respectively. Sulfonamide resistance genes sul1 and sul2 were observed in the frequency of 17.9% and 38.1%, respectively. The tetracycline resistance genes tetX was first found in Myroides sp. This investigation demonstrated that food contact surfaces in a meat processing plant may be sources of contamination of aerobic bacteria carrying tetracycline and sulfonamide antibiotic resistance genes. PMID:27100915

  1. Catalytic Properties and Regulatory Diversity of Inorganic Pyrophosphatases from Photosynthetic Bacteria

    PubMed Central

    Klemme, Jobst-Heinrich; Klemme, Brigitte; Gest, Howard

    1971-01-01

    Soluble inorganic pyrophosphatases of five species of nonsulfur purple bacteria were investigated in respect to reaction kinetics, regulatory behavior, and other characteristics. The enzymes appear to fall into two groups with correlated properties. The pyrophosphatases of Rhodopseudomonas capsulata and R. spheroides have molecular weights of ∼60,000, are stabilized by Co2+, and exhibit simple Michaelis-Menten reaction kinetics. On the other hand, the enzymes of R. palustris, R. gelatinosa, and Rhodospirillum rubrum are larger (molecular weight ∼100,000), require Zn2+ for maintenance of catalytic activity, and show complex reaction kinetics; these pyrophosphatases are activated by free Mg2+ ions and, in the absence of the latter, are inhibited by 2-phosphoglyceric acid. The results described indicate the existence of alternative control patterns for regulation of intracellular turnover of phosphate, which is in part mediated by pyrophosphatases. PMID:4333319

  2. Redox regulation of energy transfer efficiency in antennas of green photosynthetic bacteria

    NASA Technical Reports Server (NTRS)

    Blankenship, R. E.; Cheng, P.; Causgrove, T. P.; Brune, D. C.; Wang, J.

    1993-01-01

    The efficiency of energy transfer from the peripheral chlorosome antenna structure to the membrane-bound antenna in green sulfur bacteria depends strongly on the redox potential of the medium. The fluorescence spectra and lifetimes indicate that efficient quenching pathways are induced in the chlorosome at high redox potential. The midpoint redox potential for the induction of this effect in isolated chlorosomes from Chlorobium vibrioforme is -146 mV at pH 7 (vs the normal hydrogen electrode), and the observed midpoint potential (n = 1) decreases by 60 mV per pH unit over the pH range 7-10. Extraction of isolated chlorosomes with hexane has little effect on the redox-induced quenching, indicating that the component(s) responsible for this effect are bound and not readily extractable. We have purified and partially characterized the trimeric water-soluble bacteriochlorophyll a-containing protein from the thermophilic green sulfur bacterium Chlorobium tepidum. This protein is located between the chlorosome and the membrane. Fluorescence spectra of the purified protein indicate that it also contains groups that quench excitations at high redox potential. The results indicate that the energy transfer pathway in green sulfur bacteria is regulated by redox potential. This regulation appears to operate in at least two distinct places in the energy transfer pathway, the oligomeric pigments in the interior of the chlorosome and in the bacteriochlorophyll a protein. The regulatory effect may serve to protect the cell against superoxide-induced damage when oxygen is present. By quenching excitations before they reach the reaction center, reduction and subsequent autooxidation of the low potential electron acceptors found in these organisms is avoided.

  3. Redox regulation of energy transfer efficiency in antennas of green photosynthetic bacteria.

    PubMed

    Blankenship, R E; Cheng, P; Causgrove, T P; Brune, D C; Wang SH-H; Choh J-U; Wang, J

    1993-01-01

    The efficiency of energy transfer from the peripheral chlorosome antenna structure to the membrane-bound antenna in green sulfur bacteria depends strongly on the redox potential of the medium. The fluorescence spectra and lifetimes indicate that efficient quenching pathways are induced in the chlorosome at high redox potential. The midpoint redox potential for the induction of this effect in isolated chlorosomes from Chlorobium vibrioforme is -146 mV at pH 7 (vs the normal hydrogen electrode), and the observed midpoint potential (n = 1) decreases by 60 mV per pH unit over the pH range 7-10. Extraction of isolated chlorosomes with hexane has little effect on the redox-induced quenching, indicating that the component(s) responsible for this effect are bound and not readily extractable. We have purified and partially characterized the trimeric water-soluble bacteriochlorophyll a-containing protein from the thermophilic green sulfur bacterium Chlorobium tepidum. This protein is located between the chlorosome and the membrane. Fluorescence spectra of the purified protein indicate that it also contains groups that quench excitations at high redox potential. The results indicate that the energy transfer pathway in green sulfur bacteria is regulated by redox potential. This regulation appears to operate in at least two distinct places in the energy transfer pathway, the oligomeric pigments in the interior of the chlorosome and in the bacteriochlorophyll a protein. The regulatory effect may serve to protect the cell against superoxide-induced damage when oxygen is present. By quenching excitations before they reach the reaction center, reduction and subsequent autooxidation of the low potential electron acceptors found in these organisms is avoided.

  4. Occurrence and activity of sulphate reducing bacteria in aerobic activated sludge systems.

    PubMed

    van den Brand, T P H; Roest, K; Chen, G H; Brdjanovic, D; van Loosdrecht, M C M

    2015-03-01

    In the sewage or wastewater treatment plant, biological sulphate reduction can occur spontaneously or be applied beneficially for its treatment. The results of this study can be applied to control SRB in the sewage and WWTP. Therefore, population diversity analyses of SRB for nine activated sludge wastewater treatment plants (WWTP) in the Netherlands and the effect of long-term (months) oxygen exposures on the SRB activity were carried out. T-RFLP and clone sequencing analyses of winter and summer samples revealed that (1) all WWTP have a similar SRB population, (2) there is no seasonal impact (10-20 °C) on the SRB population present in the WWTP and (3) Desulfobacter postgatei, Desulfovibrio desulfuricans and Desulfovibrio intestinalis were the most common and dominant SRB species observed in these samples, and origin from the sewage. Short term activity tests demonstrated that SRB were not active in the aerobic WWTP, but while flushed with N2-gas SRB became slightly active after 3 h. In a laboratory reactor at a dissolved oxygen concentration of <2 %, sulphate reduction occurred and 89 % COD removal was achieved. SRB grew in granules, in order to protect themselves for oxygen exposures. SRB are naturally present in aerobic WWTP, which is due to the formation of granules. PMID:25649202

  5. Biomass recovery during municipal wastewater treatment using photosynthetic bacteria and prospect of production of single cell protein for feedstuff.

    PubMed

    Saejung, Chewapat; Thammaratana, Thani

    2016-12-01

    Utilization of photosynthetic bacteria (PSB) for wastewater treatment and production of biomass for economical single cell protein production is a feasible option. In this study, Rhodopseudomonas sp. CSK01 was used for municipal wastewater treatment and the effect of initial pH, light intensity and additional carbon source was investigated. Optimum chemical oxygen demand (COD) removal and biomass production were achieved when the initial pH and light intensity were 7 and 4000 lux, respectively. The specific growth rate, biomass yield and biomass productivity were found to be 0.4/d, 3.2 g/g COD and 2.1 g/L/d, respectively, which were improved by 100%, 167% and 200% relative to the original condition. Under the optimal conditions, COD removal reached 85% and maximum biomass was 6.2 g/L accomplished within three days of cultivation. The biomass had a relatively high protein content (60.1%) consisting of all essential amino acids. The contents of histidine, lysine, phenylalanine and leucine were superior to those of the previously described PSB. Results showed that COD removal was not improved in the presence of additional carbon sources (glucose, sucrose and malic acid). The addition of malic acid significantly increased the biomass accumulation by 279% relative to the original condition, whereas COD removal was declined due to carbon catabolite repression. In this study, PSB biomass recovery and catabolite repression are proposed in municipal wastewater treatment by Rhodopseudomonas sp.

  6. Colonization by aerobic bacteria in karst: laboratory and in situ experiments.

    PubMed

    Personné, J C; Poty, F; Mahler, B J; Drogue, C

    2004-01-01

    Experiments were carried out to investigate the potential for bacterial colonization of different substrates in karst aquifers and the nature of the colonizing bacteria. Laboratory batch experiments were performed using limestone and PVC as substrates, a natural bacterial isolate and a known laboratory strain (Escherichia coli [E. coli]) as inocula, and karst ground water and a synthetic formula as growth media. In parallel, fragments of limestone and granite were submerged in boreholes penetrating two karst aquifers for more than one year; the boreholes are periodically contaminated by enteric bacteria from waste water. Once a month, rock samples were removed and the colonizing bacteria quantified and identified. The batch experiments demonstrated that the natural isolate and E. coli both readily colonized limestone surfaces using karst ground water as the growth medium. In contrast, bacterial colonization of both the limestone and granite substrates, when submerged in the karst, was less intense. More than 300 bacterial strains were isolated over the period sampled, but no temporal pattern in colonization was seen as far as strain, and colonization by E. coli was notably absent, although strains of Salmonella and Citrobacter were each observed once. Samples suspended in boreholes penetrating highly fractured zones were less densely colonized than those in the borehole penetrating a less fractured zone. The results suggest that contamination of karst aquifers by enteric bacteria is unlikely to be persistent. We hypothesize that this may be a result of the high flow velocities found in karst conduits, and of predation of colonizing bacteria by autochthonous zooplankton.

  7. Colonization by aerobic bacteria in karst: Laboratory and in situ experiments

    USGS Publications Warehouse

    Personne, J.-C.; Poty, F.; Mahler, B.J.; Drogue, C.

    2004-01-01

    Experiments were carried out to investigate the potential for bacterial colonization of different substrates in karst aquifers and the nature of the colonizing bacteria. Laboratory batch experiments were performed using limestone and PVC as substrates, a natural bacterial isolate and a known laboratory strain (Escherichia coli [E. coli]) as inocula, and karst ground water and a synthetic formula as growth media. In parallel, fragments of limestone and granite were submerged in boreholes penetrating two karst aquifers for more than one year; the boreholes are periodically contaminated by enteric bacteria from waste water. Once a month, rock samples were removed and the colonizing bacteria quantified and identified. The batch experiments demonstrated that the natural isolate and E. coli both readily colonized limestone surfaces using karst ground water as the growth medium. In contrast, bacterial colonization of both the limestone and granite substrates, when submerged in the karst, was less intense. More than 300 bacterial strains were isolated over the period sampled, but no temporal pattern in colonization was seen as far as strain, and colonization by E. coli was notably absent, although strains of Salmonella and Citrobacter were each observed once. Samples suspended in boreholes penetrating highly fractured zones were less densely colonized than those in the borehole penetrating a less fractured zone. The results suggest that contamination of karst aquifers by enteric bacteria is unlikely to be persistent. We hypothesize that this may be a result of the high flow velocities found in karst conduits, and of predation of colonizing bacteria by autochthonous zooplankton.

  8. Effects of mass transfer and light intensity on substrate biological degradation by immobilized photosynthetic bacteria within an annular fiber-illuminating biofilm reactor.

    PubMed

    Zhang, Chuan; Zhang, Huan; Zhang, Zhiping; Jiao, Youzhou; Zhang, Quanguo

    2014-02-01

    In this work, effects of mass transfer and light intensity on performance of substrate biodegradation by cell-immobilized photosynthetic bacteria were investigated within an annular fiber-illuminating bioreactor (AFIBR). In AFIBR, stable biofilm of photosynthetic bacteria was generated on the surface of side-glowing optical fiber to provide sufficient light supply and uniform light distribution in cell-immobilized zone for continuous substrate biodegradation during hydrogen production process. To optimize operation parameters for substrate degradation, a two-dimensional mass transfer model based on experimental data to describe coupled processes of substrate transfer and biodegradation in biofilm with substrate diffusion and convection in bulk flow region was proposed. Investigations on influences of substrate concentration, flow rate and light intensity were carried out. It was showed that the optimum operational parameters for the substrate degradation in the AFIBR are: 10g/l substrate concentration, 100ml/h flow rate and 3.1W/m(2) light intensity.

  9. Genes involved in the biosynthesis of photosynthetic pigments in the purple sulfur photosynthetic bacterium Thiocapsa roseopersicina.

    PubMed

    Kovács, Akos T; Rákhely, Gábor; Kovács, Kornél L

    2003-06-01

    A pigment mutant strain of the purple sulfur photosynthetic bacterium Thiocapsa roseopersicina BBS was isolated by plasposon mutagenesis. Nineteen open reading frame, most of which are thought to be genes involved in the biosynthesis of carotenoids, bacteriochlorophyll, and the photosynthetic reaction center, were identified surrounding the plasposon in a 22-kb-long chromosomal locus. The general arrangement of the photosynthetic genes was similar to that in other purple photosynthetic bacteria; however, the locations of a few genes occurring in this region were unusual. Most of the gene products showed the highest similarity to the corresponding proteins in Rubrivivax gelatinosus. The plasposon was inserted into the crtD gene, likely inactivating crtC as well, and the carotenoid composition of the mutant strain corresponded to the aborted spirilloxanthin pathway. Homologous and heterologous complementation experiments indicated a conserved function of CrtC and CrtD in the purple photosynthetic bacteria. The crtDC and crtE genes were shown to be regulated by oxygen, and a role of CrtJ in aerobic repression was suggested.

  10. Plant pathogenic anaerobic bacteria use aromatic polyketides to access aerobic territory.

    PubMed

    Shabuer, Gulimila; Ishida, Keishi; Pidot, Sacha J; Roth, Martin; Dahse, Hans-Martin; Hertweck, Christian

    2015-11-01

    Around 25% of vegetable food is lost worldwide because of infectious plant diseases, including microbe-induced decay of harvested crops. In wet seasons and under humid storage conditions, potato tubers are readily infected and decomposed by anaerobic bacteria (Clostridium puniceum). We found that these anaerobic plant pathogens harbor a gene locus (type II polyketide synthase) to produce unusual polyketide metabolites (clostrubins) with dual functions. The clostrubins, which act as antibiotics against other microbial plant pathogens, enable the anaerobic bacteria to survive an oxygen-rich plant environment. PMID:26542569

  11. Denaturing gradient gel electrophoresis used to monitor the enrichment culture of aerobic chemoorganotrophic bacteria from a hot spring cyanobacterial mat.

    PubMed Central

    Santegoeds, C M; Nold, S C; Ward, D M

    1996-01-01

    Previous studies investigating microbial diversity in the Octopus Spring cyanobacterial mat community (Yellowstone National Park) have shown a discrepancy between bacterial populations observed by molecular retrieval and cultivation techniques. To investigate how selective enrichment culture techniques affect species composition, we used denaturing gradient gel electrophoresis (DGGE) separation of PCR-amplified 16S rRNA gene fragments to monitor the populations contained within enrichment cultures of aerobic chemoorganotrophic bacteria from the ca. 50 degrees C region of the mat community. By varying the degree of dilution of the inoculum, medium composition, and enrichment conditions and duration and by analyzing the cultures by DGGE, we detected 14 unique 16S rRNA sequence types. These corresponded to alpha-, beta-, gamma-, and delta-proteobacteria, Thermus relatives, and gram-positive bacteria with high G + C ratio and, at the highest inoculum dilutions, Chloroflexus aurantiacus relatives, which were estimated to still be approximately 300 times less abundant than cells of the mat primary producer, Synechococcus spp. Only three of these populations were previously cultivated on solidified medium after similar enrichment. Only two of these population have 16S rRNA sequences which were previously cloned directly from the mat. These results reveal a diversity of bacterial populations in enrichment culture which were not detected by either molecular retrieval or strain purification techniques. PMID:8899977

  12. Anaerobic and aerobic bacteriology of the saliva and gingiva from 16 captive Komodo dragons (Varanus komodoensis): new implications for the "bacteria as venom" model.

    PubMed

    Goldstein, Ellie J C; Tyrrell, Kerin L; Citron, Diane M; Cox, Cathleen R; Recchio, Ian M; Okimoto, Ben; Bryja, Judith; Fry, Bryan G

    2013-06-01

    It has been speculated that the oral flora of the Komodo dragon (Varanus komodoensis) exerts a lethal effect on its prey; yet, scant information about their specific oral flora bacteriology, especially anaerobes, exists. Consequently, the aerobic and anaerobic oral bacteriology of 16 captive Komodo dragons (10 adults and six neonates), aged 2-17 yr for adults and 7-10 days for neonates, from three U.S. zoos were studied. Saliva and gingival samples were collected by zoo personnel, inoculated into anaerobic transport media, and delivered by courier to a reference laboratory. Samples were cultured for aerobes and anaerobes. Strains were identified by standard methods and 16S rRNA gene sequencing when required. The oral flora consisted of 39 aerobic and 21 anaerobic species, with some variation by zoo. Adult dragons grew 128 isolates, including 37 aerobic gram-negative rods (one to eight per specimen), especially Enterobacteriaceae; 50 aerobic gram-positive bacteria (two to nine per specimen), especially Staphylococcus sciuri and Enterococcusfaecalis, present in eight of 10 and nine of 10 dragons, respectively; and 41 anaerobes (one to six per specimen), especially clostridia. All hatchlings grew aerobes but none grew anaerobes. No virulent species were isolated. As with other carnivores, captive Komodo oral flora is simply reflective of the gut and skin flora of their recent meals and environment and is unlikely to cause rapid fatal infection.

  13. Effect of applying lactic acid bacteria and propionic acid on fermentation quality and aerobic stability of oats-common vetch mixed silage on the Tibetan plateau.

    PubMed

    Zhang, Jie; Guo, Gang; Chen, Lei; Li, Junfeng; Yuan, Xianjun; Yu, Chengqun; Shimojo, Masataka; Shao, Tao

    2015-06-01

    The objective of this study was to evaluate effects of lactic acid bacteria and propionic acid on the fermentation quality and aerobic stability of oats-common vetch mixed silage by using a small-scale fermentation system on the Tibetan plateau. (i) An inoculant (Lactobacillus plantarum) (L) or (ii) propionic acid (P) or (iii) inoculant + propionic acid (PL) were used as additives. After fermenting for 60 days, silos were opened and the aerobic stability was tested for the following 15 days. The results showed that all silages were well preserved with low pH and NH3 -N, and high lactic acid content and V-scores. L and PL silages showed higher (P < 0.05) lactic acid and crude protein content than the control silage. P silage inhibited lactic acid production. Under aerobic conditions, L silage had similar yeast counts as the control silage (> 10(5) cfu/g fresh matter (FM)); however, it numerically reduced aerobic stability for 6 h. P and PL silages showed fewer yeasts (< 10(5) cfu/g FM) (P < 0.05) and markedly improved the aerobic stability (> 360 h). The result suggested that PL is the best additive as it could not only improved fermentation quality, but also aerobic stability of oats-common vetch mixed silage on the Tibetan plateau.

  14. Anaerobic and aerobic bacteriology of the saliva and gingiva from 16 captive Komodo dragons (Varanus komodoensis): new implications for the "bacteria as venom" model.

    PubMed

    Goldstein, Ellie J C; Tyrrell, Kerin L; Citron, Diane M; Cox, Cathleen R; Recchio, Ian M; Okimoto, Ben; Bryja, Judith; Fry, Bryan G

    2013-06-01

    It has been speculated that the oral flora of the Komodo dragon (Varanus komodoensis) exerts a lethal effect on its prey; yet, scant information about their specific oral flora bacteriology, especially anaerobes, exists. Consequently, the aerobic and anaerobic oral bacteriology of 16 captive Komodo dragons (10 adults and six neonates), aged 2-17 yr for adults and 7-10 days for neonates, from three U.S. zoos were studied. Saliva and gingival samples were collected by zoo personnel, inoculated into anaerobic transport media, and delivered by courier to a reference laboratory. Samples were cultured for aerobes and anaerobes. Strains were identified by standard methods and 16S rRNA gene sequencing when required. The oral flora consisted of 39 aerobic and 21 anaerobic species, with some variation by zoo. Adult dragons grew 128 isolates, including 37 aerobic gram-negative rods (one to eight per specimen), especially Enterobacteriaceae; 50 aerobic gram-positive bacteria (two to nine per specimen), especially Staphylococcus sciuri and Enterococcusfaecalis, present in eight of 10 and nine of 10 dragons, respectively; and 41 anaerobes (one to six per specimen), especially clostridia. All hatchlings grew aerobes but none grew anaerobes. No virulent species were isolated. As with other carnivores, captive Komodo oral flora is simply reflective of the gut and skin flora of their recent meals and environment and is unlikely to cause rapid fatal infection. PMID:23805543

  15. Patterns in Abundance, Cell Size and Pigment Content of Aerobic Anoxygenic Phototrophic Bacteria along Environmental Gradients in Northern Lakes

    PubMed Central

    Fauteux, Lisa; Cottrell, Matthew T.; Kirchman, David L.; Borrego, Carles M.; Garcia-Chaves, Maria Carolina; del Giorgio, Paul A.

    2015-01-01

    There is now evidence that aerobic anoxygenic phototrophic (AAP) bacteria are widespread across aquatic systems, yet the factors that determine their abundance and activity are still not well understood, particularly in freshwaters. Here we describe the patterns in AAP abundance, cell size and pigment content across wide environmental gradients in 43 temperate and boreal lakes of Québec. AAP bacterial abundance varied from 1.51 to 5.49 x 105 cells mL-1, representing <1 to 37% of total bacterial abundance. AAP bacteria were present year-round, including the ice-cover period, but their abundance relative to total bacterial abundance was significantly lower in winter than in summer (2.6% and 7.7%, respectively). AAP bacterial cells were on average two-fold larger than the average bacterial cell size, thus AAP cells made a greater relative contribution to biomass than to abundance. Bacteriochlorophyll a (BChla) concentration varied widely across lakes, and was not related to AAP bacterial abundance, suggesting a large intrinsic variability in the cellular pigment content. Absolute and relative AAP bacterial abundance increased with dissolved organic carbon (DOC), whereas cell-specific BChla content was negatively related to chlorophyll a (Chla). As a result, both the contribution of AAP bacteria to total prokaryotic abundance, and the cell-specific BChla pigment content were positively correlated with the DOC:Chla ratio, both peaking in highly colored, low-chlorophyll lakes. Our results suggest that photoheterotrophy might represent a significant ecological advantage in highly colored, low-chlorophyll lakes, where DOC pool is chemically and structurally more complex. PMID:25927833

  16. Aerobic degradation of a mixture of azo dyes in a packed bed reactor having bacteria-coated laterite pebbles.

    PubMed

    Senan, Resmi C; Shaffiqu, T S; Roy, J Jegan; Abraham, T Emilia

    2003-01-01

    A microbial consortium capable of aerobic degradation of a mixture of azo dyes consisting of two isolated strains (RRL,TVM) and one known strain of Pseudomonas putida (MTCC 1194) was immobilized on laterite stones. The amount of bacterial biomass attached to the laterite stones was 8.64 g per 100 g of the stone on a dry weight basis. The packed bed reactor was filled with these stones and had a total capacity of 850 mL and a void volume of 210 mL. The feed consisted of an equal mixture of seven azo dyes both in water as well as in a simulated textile effluent, at a pH of 9.0 and a salinity of 900 mg/L. The dye concentrations of influent were 25, 50, and 100 microg/mL. The residence time was varied between 0.78 and 6.23 h. It was found that at the lowest residence time 23.55, 45.73, and 79.95 microg of dye was degraded per hour at an initial dye concentration of 25, 50, and 100 microg, respectively. The pH was reduced from 9.0 to 7.0. Simulated textile effluent containing 50 microg/mL dye was degraded by 61.7%. Analysis of degradation products by TLC and HPLC showed that the dye mixture was degraded to nontoxic smaller molecules. The bacteria-coated pebbles were stable, there was no washout even after 2 months, and the reactor was found to be suitable for the aerobic degradation of azo dyes. PMID:12675610

  17. Aerobic degradation of a mixture of azo dyes in a packed bed reactor having bacteria-coated laterite pebbles.

    PubMed

    Senan, Resmi C; Shaffiqu, T S; Roy, J Jegan; Abraham, T Emilia

    2003-01-01

    A microbial consortium capable of aerobic degradation of a mixture of azo dyes consisting of two isolated strains (RRL,TVM) and one known strain of Pseudomonas putida (MTCC 1194) was immobilized on laterite stones. The amount of bacterial biomass attached to the laterite stones was 8.64 g per 100 g of the stone on a dry weight basis. The packed bed reactor was filled with these stones and had a total capacity of 850 mL and a void volume of 210 mL. The feed consisted of an equal mixture of seven azo dyes both in water as well as in a simulated textile effluent, at a pH of 9.0 and a salinity of 900 mg/L. The dye concentrations of influent were 25, 50, and 100 microg/mL. The residence time was varied between 0.78 and 6.23 h. It was found that at the lowest residence time 23.55, 45.73, and 79.95 microg of dye was degraded per hour at an initial dye concentration of 25, 50, and 100 microg, respectively. The pH was reduced from 9.0 to 7.0. Simulated textile effluent containing 50 microg/mL dye was degraded by 61.7%. Analysis of degradation products by TLC and HPLC showed that the dye mixture was degraded to nontoxic smaller molecules. The bacteria-coated pebbles were stable, there was no washout even after 2 months, and the reactor was found to be suitable for the aerobic degradation of azo dyes.

  18. Comprehensive analysis of aerobic and anaerobic bacteria found on dental bib clips.

    PubMed

    Alt-Holland, Addy; Murphy, Christina M; Powers, Anne; Kublin, Claire L; Jeong, Youjin Natalie; DiMattia, Michelle; Pham, Linh; Park, Angel; Finkelman, Matthew; Lombard, Maureen; Hanley, James B; Paster, Bruce J; Kugel, Gerard

    2013-04-01

    Multiple-use dental bib clips are considered to present relatively low risks for transmitting infections and, thus, are thought to only require disinfection between patient visits. This study was designed to: 1) determine the presence and composition of bacterial contaminants on reusable rubber-faced metal bib clips after dental treatment at the hygiene clinic at Tufts University School of Dental Medicine and 2) evaluate the effectiveness of the disinfection for this clip type. Aerobic and anaerobic bacterial contaminant loads on the surfaces of the clips were investigated immediately after hygiene treatments were rendered and again after clips were disinfected. The species and strains of bacterial isolates were identified using 16S rDNA sequencing and Human Oral Microbe Identification Microarray analyses. The results demonstrated that although the use of disinfection proved to be significantly effective, some clips retained at least one bacterium on their surfaces after disinfection. Although the bacterial species present on disinfected clips were typical skin or environmental isolates, some were oral in origin. In the study's settings, bacterial presence on the clips did not indicate an infectious disease problem. The different bacterial loads on clips suggest that cross-contamination risks may not be the same for all clinics, and that this difference may be related to the type of treatments and services performed.

  19. Pathways and key intermediates required for obligate aerobic ammonia-dependent chemolithotrophy in bacteria and Thaumarchaeota.

    PubMed

    Kozlowski, Jessica A; Stieglmeier, Michaela; Schleper, Christa; Klotz, Martin G; Stein, Lisa Y

    2016-08-01

    Chemolithotrophic ammonia-oxidizing bacteria and Thaumarchaeota are central players in the global nitrogen cycle. Obligate ammonia chemolithotrophy has been characterized for bacteria; however, large gaps remain in the Thaumarchaeotal pathway. Using batch growth experiments and instantaneous microrespirometry measurements of resting biomass, we show that the terrestrial Thaumarchaeon Nitrososphaera viennensis EN76(T) exhibits tight control over production and consumption of nitric oxide (NO) during ammonia catabolism, unlike the ammonia-oxidizing bacterium Nitrosospira multiformis ATCC 25196(T). In particular, pulses of hydroxylamine into a microelectrode chamber as the sole substrate for N. viennensis resulted in iterative production and consumption of NO followed by conversion of hydroxylamine to nitrite. In support of these observations, oxidation of ammonia in growing cultures of N. viennensis, but not of N. multiformis, was inhibited by the NO-scavenger PTIO. When based on the marginal nitrous oxide (N2O) levels detected in cell-free media controls, the higher levels produced by N. multiformis were explained by enzyme activity, whereas N2O in N. viennensis cultures was attributed to abiotic reactions of released N-oxide intermediates with media components. Our results are conceptualized in a pathway for ammonia-dependent chemolithotrophy in Thaumarchaea, which identifies NO as an essential intermediate in the pathway and implements known biochemistry to be executed by a proposed but still elusive copper enzyme. Taken together, this work identifies differences in ammonia-dependent chemolithotrophy between bacteria and the Thaumarchaeota, advances a central catabolic role of NO only in the Thaumarchaeotal pathway and reveals stark differences in how the two microbial cohorts contribute to N2O emissions.

  20. Aerobic respiration metabolism in lactic acid bacteria and uses in biotechnology.

    PubMed

    Pedersen, Martin B; Gaudu, Philippe; Lechardeur, Delphine; Petit, Marie-Agnès; Gruss, Alexandra

    2012-01-01

    The lactic acid bacteria (LAB) are essential for food fermentations and their impact on gut physiology and health is under active exploration. In addition to their well-studied fermentation metabolism, many species belonging to this heterogeneous group are genetically equipped for respiration metabolism. In LAB, respiration is activated by exogenous heme, and for some species, heme and menaquinone. Respiration metabolism increases growth yield and improves fitness. In this review, we aim to present the basics of respiration metabolism in LAB, its genetic requirements, and the dramatic physiological changes it engenders. We address the question of how LAB acquired the genetic equipment for respiration. We present at length how respiration can be used advantageously in an industrial setting, both in the context of food-related technologies and in novel potential applications.

  1. Real-time PCR assays compared to culture-based approaches for identification of aerobic bacteria in chronic wounds.

    PubMed

    Melendez, J H; Frankel, Y M; An, A T; Williams, L; Price, L B; Wang, N-Y; Lazarus, G S; Zenilman, J M

    2010-12-01

    Chronic wounds cause substantial morbidity and disability. Infection in chronic wounds is clinically defined by routine culture methods that can take several days to obtain a final result, and may not fully describe the community of organisms or biome within these wounds. Molecular diagnostic approaches offer promise for a more rapid and complete assessment. We report the development of a suite of real-time PCR assays for rapid identification of bacteria directly from tissue samples. The panel of assays targets 14 common, clinically relevant, aerobic pathogens and demonstrates a high degree of sensitivity and specificity using a panel of organisms commonly associated with chronic wound infection. Thirty-nine tissue samples from 29 chronic wounds were evaluated and the results compared with those obtained by culture. As revealed by culture and PCR, the most common organisms were methicillin-resistant Staphylococcus aureus (MRSA) followed by Streptococcus agalactiae (Group B streptococcus) and Pseudomonas aeruginosa. The sensitivities of the PCR assays were 100% and 90% when quantitative and qualitative culture results were used as the reference standard, respectively. The assays allowed the identification of bacterial DNA from ten additional organisms that were not revealed by quantitative or qualitative cultures. Under optimal conditions, the turnaround time for PCR results is as short as 4-6 h. Real-time PCR is a rapid and inexpensive approach that can be easily introduced into clinical practice for detection of organisms directly from tissue samples. Characterization of the anaerobic microflora by real-time PCR of chronic wounds is warranted.

  2. Isolation of aerobic cultivable cellulolytic bacteria from different regions of the gastrointestinal tract of giant land snail Achatina fulica

    PubMed Central

    Pinheiro, Guilherme L.; Correa, Raquel F.; Cunha, Raquel S.; Cardoso, Alexander M.; Chaia, Catia; Clementino, Maysa M.; Garcia, Eloi S.; de Souza, Wanderley; Frasés, Susana

    2015-01-01

    The enzymatic hydrolysis of cellulose by cellulases is one of the major limiting steps in the conversion of lignocellulosic biomass to yield bioethanol. To overcome this hindrance, significant efforts are underway to identify novel cellulases. The snail Achatina fulica is a gastropod with high cellulolytic activity, mainly due to the abundance of glycoside hydrolases produced by both the animal and its resident microbiota. In this study, we partially assessed the cellulolytic aerobic bacterial diversity inside the gastrointestinal tract of A. fulica by culture-dependent methods and evaluated the hydrolytic repertoire of the isolates. Forty bacterial isolates were recovered from distinct segments of the snail gut and identified to the genus level by 16S rRNA gene sequence analysis. Additional phenotypic characterization was performed using biochemical tests provided by the Vitek2 identification system. The overall enzymatic repertoire of the isolated strains was investigated by enzymatic plate assays, containing the following substrates: powdered sugarcane bagasse, carboxymethylcellulose (CMC), p-nitrophenyl-β-D-glucopyranoside (pNPG), p-nitrophenyl-β-D-cellobioside (pNPC), 4-methylumbelliferyl-β-D-glucopyranoside (MUG), 4-methylumbelliferyl-β-D-cellobioside (MUC), and 4-methylumbelliferyl-β-D-xylopyranoside (MUX). Our results indicate that the snail A. fulica is an attractive source of cultivable bacteria that showed to be valuable resources for the production of different types of biomass-degrading enzymes. PMID:26347735

  3. Isolation of aerobic cultivable cellulolytic bacteria from different regions of the gastrointestinal tract of giant land snail Achatina fulica.

    PubMed

    Pinheiro, Guilherme L; Correa, Raquel F; Cunha, Raquel S; Cardoso, Alexander M; Chaia, Catia; Clementino, Maysa M; Garcia, Eloi S; de Souza, Wanderley; Frasés, Susana

    2015-01-01

    The enzymatic hydrolysis of cellulose by cellulases is one of the major limiting steps in the conversion of lignocellulosic biomass to yield bioethanol. To overcome this hindrance, significant efforts are underway to identify novel cellulases. The snail Achatina fulica is a gastropod with high cellulolytic activity, mainly due to the abundance of glycoside hydrolases produced by both the animal and its resident microbiota. In this study, we partially assessed the cellulolytic aerobic bacterial diversity inside the gastrointestinal tract of A. fulica by culture-dependent methods and evaluated the hydrolytic repertoire of the isolates. Forty bacterial isolates were recovered from distinct segments of the snail gut and identified to the genus level by 16S rRNA gene sequence analysis. Additional phenotypic characterization was performed using biochemical tests provided by the Vitek2 identification system. The overall enzymatic repertoire of the isolated strains was investigated by enzymatic plate assays, containing the following substrates: powdered sugarcane bagasse, carboxymethylcellulose (CMC), p-nitrophenyl-β-D-glucopyranoside (pNPG), p-nitrophenyl-β-D-cellobioside (pNPC), 4-methylumbelliferyl-β-D-glucopyranoside (MUG), 4-methylumbelliferyl-β-D-cellobioside (MUC), and 4-methylumbelliferyl-β-D-xylopyranoside (MUX). Our results indicate that the snail A. fulica is an attractive source of cultivable bacteria that showed to be valuable resources for the production of different types of biomass-degrading enzymes.

  4. Production of autoinducer-2 by aerobic endospore-forming bacteria isolated from the West African fermented foods.

    PubMed

    Qian, Yang; Kando, Christine Kere; Thorsen, Line; Larsen, Nadja; Jespersen, Lene

    2015-11-01

    Autoinducer-2 (AI-2) is a quorum-sensing (QS) molecule which mediates interspecies signaling and affects various bacterial behaviors in food fermentation. Biosynthesis of AI-2 is controlled by S-ribosylhomocysteine lyase encoded by the luxS gene. The objective of this study was to investigate production of AI-2 by aerobic endospore-forming bacteria (AEB) isolated from the West African alkaline fermented seed products Mantchoua and Maari. The study included 13 AEB strains of Bacillus subtilis, B. cereus, B. altitudinis, B. amyloliquefaciens, B. licheniformis, B. aryabhattai, B. safensis, Lysinibacillus macroides and Paenibacillus polymyxa. All the tested strains harbored the luxS gene and all strains except for P. polymyxa B314 were able to produce AI-2 during incubation in laboratory medium. Production of AI-2 by AEB was growth phase dependent, showing maximum activity at the late exponential phase. AI-2 was depleted from the culture medium at the beginning of the stationary growth phase, indicating that the tested AEB possess a functional AI-2 receptor that internalizes AI-2. This study provides the evidences of QS system in Bacillus spp. and L. macroides and new knowledge of AI-2 production by AEB. This knowledge contributes to the development of QS-based strategies for better control of alkaline fermentation. PMID:26449556

  5. Production of autoinducer-2 by aerobic endospore-forming bacteria isolated from the West African fermented foods.

    PubMed

    Qian, Yang; Kando, Christine Kere; Thorsen, Line; Larsen, Nadja; Jespersen, Lene

    2015-11-01

    Autoinducer-2 (AI-2) is a quorum-sensing (QS) molecule which mediates interspecies signaling and affects various bacterial behaviors in food fermentation. Biosynthesis of AI-2 is controlled by S-ribosylhomocysteine lyase encoded by the luxS gene. The objective of this study was to investigate production of AI-2 by aerobic endospore-forming bacteria (AEB) isolated from the West African alkaline fermented seed products Mantchoua and Maari. The study included 13 AEB strains of Bacillus subtilis, B. cereus, B. altitudinis, B. amyloliquefaciens, B. licheniformis, B. aryabhattai, B. safensis, Lysinibacillus macroides and Paenibacillus polymyxa. All the tested strains harbored the luxS gene and all strains except for P. polymyxa B314 were able to produce AI-2 during incubation in laboratory medium. Production of AI-2 by AEB was growth phase dependent, showing maximum activity at the late exponential phase. AI-2 was depleted from the culture medium at the beginning of the stationary growth phase, indicating that the tested AEB possess a functional AI-2 receptor that internalizes AI-2. This study provides the evidences of QS system in Bacillus spp. and L. macroides and new knowledge of AI-2 production by AEB. This knowledge contributes to the development of QS-based strategies for better control of alkaline fermentation.

  6. Aerobic uranium (VI) bioprecipitation by metal-resistant bacteria isolated from radionuclide- and metal-contaminated subsurface soils.

    PubMed

    Martinez, Robert J; Beazley, Melanie J; Taillefert, Martial; Arakaki, Adrian K; Skolnick, Jeffrey; Sobecky, Patricia A

    2007-12-01

    In this study, the immobilization of toxic uranium [U(VI)] mediated by the intrinsic phosphatase activities of naturally occurring bacteria isolated from contaminated subsurface soils was examined. The phosphatase phenotypes of strains belonging to the genera, Arthrobacter, Bacillus and Rahnella, previously isolated from subsurface soils at the US Department of Energy's (DOE) Oak Ridge Field Research Center (ORFRC), were determined. The ORFRC represents a unique, extreme environment consisting of highly acidic soils with co-occurring heavy metals, radionuclides and high nitrate concentrations. Isolates exhibiting phosphatase-positive phenotypes indicative of constitutive phosphatase activity were subsequently tested in U(VI) bioprecipitation assays. When aerobically grown in synthetic groundwater (pH 5.5) amended with 10 mM glycerol-3-phosphate (G3P), phosphatase-positive Bacillus and Rahnella spp. strains Y9-2 and Y9602 liberated sufficient phosphate to precipitate 73% and 95% of total soluble U added as 200 microM uranyl acetate respectively. In contrast, an Arthrobacter sp. X34 exhibiting a phosphatase-negative phenotype did not liberate phosphate from G3P or promote U(VI) precipitation. This study provides the first evidence of U(VI) precipitation via the phosphatase activity of naturally occurring Bacillus and Rahnella spp. isolated from the acidic subsurface at the DOE ORFRC.

  7. Isolation of aerobic cultivable cellulolytic bacteria from different regions of the gastrointestinal tract of giant land snail Achatina fulica.

    PubMed

    Pinheiro, Guilherme L; Correa, Raquel F; Cunha, Raquel S; Cardoso, Alexander M; Chaia, Catia; Clementino, Maysa M; Garcia, Eloi S; de Souza, Wanderley; Frasés, Susana

    2015-01-01

    The enzymatic hydrolysis of cellulose by cellulases is one of the major limiting steps in the conversion of lignocellulosic biomass to yield bioethanol. To overcome this hindrance, significant efforts are underway to identify novel cellulases. The snail Achatina fulica is a gastropod with high cellulolytic activity, mainly due to the abundance of glycoside hydrolases produced by both the animal and its resident microbiota. In this study, we partially assessed the cellulolytic aerobic bacterial diversity inside the gastrointestinal tract of A. fulica by culture-dependent methods and evaluated the hydrolytic repertoire of the isolates. Forty bacterial isolates were recovered from distinct segments of the snail gut and identified to the genus level by 16S rRNA gene sequence analysis. Additional phenotypic characterization was performed using biochemical tests provided by the Vitek2 identification system. The overall enzymatic repertoire of the isolated strains was investigated by enzymatic plate assays, containing the following substrates: powdered sugarcane bagasse, carboxymethylcellulose (CMC), p-nitrophenyl-β-D-glucopyranoside (pNPG), p-nitrophenyl-β-D-cellobioside (pNPC), 4-methylumbelliferyl-β-D-glucopyranoside (MUG), 4-methylumbelliferyl-β-D-cellobioside (MUC), and 4-methylumbelliferyl-β-D-xylopyranoside (MUX). Our results indicate that the snail A. fulica is an attractive source of cultivable bacteria that showed to be valuable resources for the production of different types of biomass-degrading enzymes. PMID:26347735

  8. Aminopeptidase activity by spoilage bacteria and its relationship to microbial load and sensory attributes of poultry legs during aerobic cold storage.

    PubMed

    Guevara-Franco, José Alfredo; Alonso-Calleja, Carlos; Capita, Rosa

    2010-02-01

    The shelf life of poultry legs stored aerobically and the possible role of the aminopeptidase activity of gram-negative bacteria (p-nitroaniline test) as a predictor of poultry spoilage were evaluated on the basis of microbiological and sensory parameters. Chicken legs (n = 30) obtained immediately after evisceration in a local poultry processing plant were kept under aerobic refrigeration (4 +/- 1 degrees C) for 7 days. Microbiological (counts of aerobic bacteria and psychrotrophs) and sensory (odor, color, and general acceptability on a hedonic scale of 1 to 9) parameters and aminopeptidase activity (absorbance at 390 nm [A(390)]) determinations were performed after 0, 1, 3, 5, and 7 days of storage. Aerobic plate counts of 7 log CFU/g and a score of 6 for general acceptability were used as indicators of the end point of shelf life. Strong correlations (r > or = 0.76; P < 0.001) were obtained between bacterial counts, hedonic scores, and A(390) values. Samples were judged as unacceptable (shelf-life end point) after 2 and 4 days on the basis of sensory and microbiological analyses, respectively. A(390) values of 0.52 and 0.89 (corresponding to p-nitroaniline concentrations of 6.25 and 10.7 microg/ml, respectively) are proposed as the upper limits for acceptability on the basis of sensory and microbiological determinations, respectively. However, these recommendations are based on a small set of samples, and their general application is yet to be verified.

  9. [The study of mycolytic properties of aerobic spore-forming bacteria producing extracellular chitinases].

    PubMed

    Aktuganov, G E; Melent'ev, A I; Galimzianova, N F; Shirokov, A V

    2008-01-01

    The mycolytic activity of 27 strains of antagonistic bacilli belonging to two taxonomic groups (18 strains of Bacillus subtilis and 9 strains of Paenibacillus ehimensis) capable of induced synthesis of chitinolytic enzymes was studied. Most of the B. subtilis strains neither displayed visible mycolytic effects on the phytopathogenic fungus Bipolaris sorokiniana in vitro, nor produced chitinases in the presence of an auto-claved mycelium. On the contrary, P. ehimensis strains grown under conditions favorable for induction of chitinases and other hydrolases exhibited a pronounced lytic effect on B. sorokiniana and actively grew by utilizing mycelium as the sole source of carbon and nitrogen. Comparison of the mycolytic activities of extracellular hydrolases in the studied strains demonstrated low correlation between chitinase production and the ability of the strains to degrade the cell walls of B. sorokiniana. Characterization of enzyme profiles in the studied strains revealed that beta-1,3-glucanase was a more significant factor than chitinase for determining the mycolytic potential of bacteria and their ability to utilize the mycelium of phytopathogenic fungi as a growth substrate.

  10. A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically.

    PubMed

    Koeth, Laura M; DiFranco-Fisher, Jeanna M; McCurdy, Sandra

    2015-09-09

    Antimicrobial susceptibility testing (AST) is performed to assess the in vitro activity of antimicrobial agents against various bacteria. The AST results, which are expressed as minimum inhibitory concentrations (MICs) are used in research for antimicrobial development and monitoring of resistance development and in the clinical setting for antimicrobial therapy guidance. Dalbavancin is a semi-synthetic lipoglycopeptide antimicrobial agent that was approved in May 2014 by the Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections caused by Gram-positive organisms. The advantage of dalbavancin over current anti-staphylococcal therapies is its long half-life, which allows for once-weekly dosing. Dalbavancin has activity against Staphylococcus aureus (including both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]), coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus anginosus group, β-hemolytic streptococci and vancomycin susceptible enterococci. Similar to other recent lipoglycopeptide agents, optimization of CLSI and ISO broth susceptibility test methods includes the use of dimethyl sulfoxide (DMSO) as a solvent when preparing stock solutions and polysorbate 80 (P80) to alleviate adherence of the agent to plastic. Prior to the clinical studies and during the initial development of dalbavancin, susceptibility studies were not performed with the use of P-80 and MIC results tended to be 2-4 fold higher and similarly higher MIC results were obtained with the agar dilution susceptibility method. Dalbavancin was first included in CLSI broth microdilution methodology tables in 2005 and amended in 2006 to clarify use of DMSO and P-80. The broth microdilution (BMD) procedure shown here is specific to dalbavancin and is in accordance with the CLSI and ISO methods, with step-by-step detail and focus on the critical steps added for clarity.

  11. A Reference Broth Microdilution Method for Dalbavancin In Vitro Susceptibility Testing of Bacteria that Grow Aerobically.

    PubMed

    Koeth, Laura M; DiFranco-Fisher, Jeanna M; McCurdy, Sandra

    2015-01-01

    Antimicrobial susceptibility testing (AST) is performed to assess the in vitro activity of antimicrobial agents against various bacteria. The AST results, which are expressed as minimum inhibitory concentrations (MICs) are used in research for antimicrobial development and monitoring of resistance development and in the clinical setting for antimicrobial therapy guidance. Dalbavancin is a semi-synthetic lipoglycopeptide antimicrobial agent that was approved in May 2014 by the Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections caused by Gram-positive organisms. The advantage of dalbavancin over current anti-staphylococcal therapies is its long half-life, which allows for once-weekly dosing. Dalbavancin has activity against Staphylococcus aureus (including both methicillin-susceptible S. aureus [MSSA] and methicillin-resistant S. aureus [MRSA]), coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus anginosus group, β-hemolytic streptococci and vancomycin susceptible enterococci. Similar to other recent lipoglycopeptide agents, optimization of CLSI and ISO broth susceptibility test methods includes the use of dimethyl sulfoxide (DMSO) as a solvent when preparing stock solutions and polysorbate 80 (P80) to alleviate adherence of the agent to plastic. Prior to the clinical studies and during the initial development of dalbavancin, susceptibility studies were not performed with the use of P-80 and MIC results tended to be 2-4 fold higher and similarly higher MIC results were obtained with the agar dilution susceptibility method. Dalbavancin was first included in CLSI broth microdilution methodology tables in 2005 and amended in 2006 to clarify use of DMSO and P-80. The broth microdilution (BMD) procedure shown here is specific to dalbavancin and is in accordance with the CLSI and ISO methods, with step-by-step detail and focus on the critical steps added for clarity. PMID:26381422

  12. Chirality-Based Signatures of Local Protein Environments in Two-Dimensional Optical Spectroscopy of Two Species Photosynthetic Complexes of Green Sulfur Bacteria: Simulation Study

    PubMed Central

    Voronine, Dmitri V.; Abramavicius, Darius; Mukamel, Shaul

    2008-01-01

    Two-dimensional electronic chirality-induced signals of excitons in the photosynthetic Fenna-Matthews-Olson complex from two species of green sulfur bacteria (Chlorobium tepidum and Prosthecochloris aestuarii) are compared. The spectra are predicted to provide sensitive probes of local protein environment of the constituent bacteriochlorophyll a chromophores and reflect electronic structure variations (site energies and couplings) of the two complexes. Pulse polarization configurations are designed that can separate the coherent and incoherent exciton dynamics contributions to the two-dimensional spectra. PMID:18676650

  13. Structure and Excitation Transfer Pathways in the Chlorophyll-Carotenoid Aggregate of the Photosynthetic Unit of Purple Bacteria

    NASA Astrophysics Data System (ADS)

    Schulten, Klaus

    1998-03-01

    The absorption of light by light harvesting complexes and transfer of electronic excitation to the photosynthetic reaction center (RC) has been investigated on the basis of an atomic level model of the so-called photosynthetic unit of the photosynthetic bacterium Rb. sphaeroides. The photosynthetic unit combines in the intracytoplasmic membrane a nanometric (20-100 nm) assembly of three protein complexes: (i) the photosynthetic reaction center, (ii) a ring-shaped light harvesting complex LH-I, and (iii) multiple copies of a similar complex, LH-II. The unit has been modeled using the known structure of LH-II of Rs. molischianum. The lecture describes in detail the organization of chromophores involved in primary light absorption and excitation transfer: a hierarchy of ring-shaped chlorophyl aggregates with attached carotenoids. A quantum-mechanical description of the entire light harvesting process is developed employing electron structure calculations of individual and aggregated chlorophylls and carotenoids and associated effective Hamiltonian descriptions. The transfer times calculated, ranging between 100 fs and 100 ps for various processes, are found in close agreement with measured transfer rates. The results suggest that excitons are the key carriers of the excitation transfered. The photoprotection of chlorophylls by chlorophylls through triplet excitation transfer is also described.

  14. Practical removal of radioactivity from soil in Fukushima using immobilized photosynthetic bacteria combined with anaerobic digestion and lactic acid fermentation as pre-treatment.

    PubMed

    Sasaki, Ken; Morikawa, Hiroyo; Kishibe, Takashi; Takeno, Kenji; Mikami, Ayaka; Harada, Toshihiko; Ohta, Masahiro

    2012-01-01

    Practical removal of radioactivity from polluted soil in Fukushima, Japan was done using a photosynthetic bacterium, Rhodobacter sphaeroides SSI, immobilized in alginate beads. The beads were put in a mesh bag and soaked in which soil was suspended (5 kg of soil/10 L of tap water). The radioactivity of the broth decreased by 31% after 15 d of aerobic treatment. When lactic acid bacterial culture broth was added to the suspend broth, about 50% of the radioactivity was transferred to a suspend broth fraction consisting of small particles from the soil after 3 d of fermentation and 20 s of sedimentation. The results suggest that organic matter in the soil was decomposed by anaerobic digestion and lactic acid fermentation simultaneously, and was then transferred into the liquid as small particles. With combined treatment by anaerobic digestion and lactic acid fermentation for 5 d and immobilized bead aerobic treatment for an additional 19 d, the radioactivity of suspend broth decreased by 66%. The radioactivity of the original soil (10.56 µSv/h) ultimately decreased by 67% (3.52 µSv/h) after the combined treatment.

  15. The determination of the real nano-scale sizes of bacteria in chernozem during microbial succession by means of hatching of a soil in aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Gorbacheva, M.

    2012-04-01

    M.A. Gorbacheva,L.M. Polyanskaya The Faculty of Soil Science, Moscow State University, Leninskie Gory, GSP-1, Moscow,119991,Russia In recent years there's been particular attention paid to the smallest life's forms- bacteria which size can be measured in nanometer. These are the forms of bacteria with diameter of 5-200 nm. Theoretical calculations based on the content of the minimum number of DNA, enzyme, lipids in and ribosome in cells indicates impossibility of existence of a living cells within diameter less than 300 nm. It is theoretically possible for a living cell to exist within possible diameter of approximately 140 nm. Using a fluorescence microscope there's been indicated in a number of samples from lakes, rivers, soil, snow and rain water that 200 nm is the smallest diameter of a living cell. Supposingly, such a small size of bacteria in soil is determined by natural conditions which limit their development by nutritious substances and stress-factors. Rejuvenescence of nanobacteria under unfavourable natural conditions and stress-factors is studied in laboratory environment. The object of the current study has become the samples of typical arable chernozem of the Central Chernozem State Biosphere Reserve in Kursk. The detailed morphological description of the soil profile and its basic analytical characteristics are widely represented in scientific publications. The soil is characterized by a high carbon content which makes up 3,96% ,3,8% , and 2,9% for the upper layers of the A horizon, and 0,79% for the layer of the B horizon. A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in upper A horizons and B horizon of a chernozem. The final aim is to identify the cells size of bacteria in aerobic and anaerobic soil conditions in chernozem during the microbial succession, by dampening and application of chitin by means of «cascade filtration» method. The study of the microcosms is important for

  16. Small-molecule inhibition of choline catabolism in Pseudomonas aeruginosa and other aerobic choline-catabolizing bacteria.

    PubMed

    Fitzsimmons, Liam F; Flemer, Stevenson; Wurthmann, A Sandy; Deker, P Bruce; Sarkar, Indra Neil; Wargo, Matthew J

    2011-07-01

    Choline is abundant in association with eukaryotes and plays roles in osmoprotection, thermoprotection, and membrane biosynthesis in many bacteria. Aerobic catabolism of choline is widespread among soil proteobacteria, particularly those associated with eukaryotes. Catabolism of choline as a carbon, nitrogen, and/or energy source may play important roles in association with eukaryotes, including pathogenesis, symbioses, and nutrient cycling. We sought to generate choline analogues to study bacterial choline catabolism in vitro and in situ. Here we report the characterization of a choline analogue, propargylcholine, which inhibits choline catabolism at the level of Dgc enzyme-catalyzed dimethylglycine demethylation in Pseudomonas aeruginosa. We used genetic analyses and 13C nuclear magnetic resonance to demonstrate that propargylcholine is catabolized to its inhibitory form, propargylmethylglycine. Chemically synthesized propargylmethylglycine was also an inhibitor of growth on choline. Bioinformatic analysis suggests that there are genes encoding DgcA homologues in a variety of proteobacteria. We examined the broader utility of propargylcholine and propargylmethylglycine by assessing growth of other members of the proteobacteria that are known to grow on choline and possess putative DgcA homologues. Propargylcholine showed utility as a growth inhibitor in P. aeruginosa but did not inhibit growth in other proteobacteria tested. In contrast, propargylmethylglycine was able to inhibit choline-dependent growth in all tested proteobacteria, including Pseudomonas mendocina, Pseudomonas fluorescens, Pseudomonas putida, Burkholderia cepacia, Burkholderia ambifaria, and Sinorhizobium meliloti. We predict that chemical inhibitors of choline catabolism will be useful for studying this pathway in clinical and environmental isolates and could be a useful tool to study proteobacterial choline catabolism in situ.

  17. Effects of mass transfer and light intensity on substrate biological degradation by immobilized photosynthetic bacteria within an annular fiber-illuminating biofilm reactor.

    PubMed

    Zhang, Chuan; Zhang, Huan; Zhang, Zhiping; Jiao, Youzhou; Zhang, Quanguo

    2014-02-01

    In this work, effects of mass transfer and light intensity on performance of substrate biodegradation by cell-immobilized photosynthetic bacteria were investigated within an annular fiber-illuminating bioreactor (AFIBR). In AFIBR, stable biofilm of photosynthetic bacteria was generated on the surface of side-glowing optical fiber to provide sufficient light supply and uniform light distribution in cell-immobilized zone for continuous substrate biodegradation during hydrogen production process. To optimize operation parameters for substrate degradation, a two-dimensional mass transfer model based on experimental data to describe coupled processes of substrate transfer and biodegradation in biofilm with substrate diffusion and convection in bulk flow region was proposed. Investigations on influences of substrate concentration, flow rate and light intensity were carried out. It was showed that the optimum operational parameters for the substrate degradation in the AFIBR are: 10g/l substrate concentration, 100ml/h flow rate and 3.1W/m(2) light intensity. PMID:24531266

  18. Genome sequence of Fulvimarina pelagi HTCC2506T, a Mn(II)-oxidizing alphaproteobacterium possessing an aerobic anoxygenic photosynthetic gene cluster and Xanthorhodopsin.

    PubMed

    Kang, Ilnam; Oh, Hyun-Myung; Lim, Seung-Il; Ferriera, Steve; Giovannoni, Stephen J; Cho, Jang-Cheon

    2010-09-01

    Fulvimarina pelagi is a Mn(II)-oxidizing marine heterotrophic bacterium in the order Rhizobiales. Here we announce the draft genome sequence of F. pelagi HTCC2506(T), which was isolated from the Sargasso Sea by using dilution-to-extinction culturing. The genome sequence contained a xanthorhodopsin gene as well as a photosynthetic gene cluster, which suggests the coexistence of two different phototrophic mechanisms in a single microorganism. PMID:20639329

  19. Lactic Acid Bacteria in Total Mixed Ration Silage Containing Soybean Curd Residue: Their Isolation, Identification and Ability to Inhibit Aerobic Deterioration

    PubMed Central

    Li, Y.; Wang, F.; Nishino, N.

    2016-01-01

    We investigated the effects of the predominant lactic acid bacteria (LAB) on the fermentation characteristics and aerobic stability of total mixed ration (TMR) silage containing soybean curd residue (SC-TMR silage). The SC-TMR materials were ensiled in laboratory silos for 14 or 56 days. LAB predominant in SC-TMR silage were identified (Exp. 1). Lactobacillus fermentum (L. fermentum) and Streptococcus bovis (S. bovis) were found in the untreated materials, Leuconostoc pseudomesenteroides (L. pseudomesenteroides) in 14-day silage and Lactobacillus plantarum (L. plantarum) in all silages. Pediococcus acidilactici (P. acidilactici), Lactobacillus paracasei (L. paracasei), and Lactobacillus brevis (L. brevis) formed more than 90% of the isolates in 56-day silage. Italian ryegrass and whole crop maize were inoculated with P. acidilactici and L. brevis isolates and the fermentation and aerobic stability determined (Exp. 2). Inoculation with P. acidilactici and L. brevis alone or combined improved the fermentation products in ryegrass silage and markedly enhanced its aerobic stability. In maize silage, P. acidilactici and L. brevis inoculation caused no changes and suppressed deterioration when combined with increases in acetic acid content. The results indicate that P. acidilactici and L. brevis may produce a synergistic effect to inhibit SC-TMR silage deterioration. Further studies are needed to identify the inhibitory substances, which may be useful for developing potential antifungal agents. PMID:26949952

  20. Lactic Acid Bacteria in Total Mixed Ration Silage Containing Soybean Curd Residue: Their Isolation, Identification and Ability to Inhibit Aerobic Deterioration.

    PubMed

    Li, Y; Wang, F; Nishino, N

    2016-04-01

    We investigated the effects of the predominant lactic acid bacteria (LAB) on the fermentation characteristics and aerobic stability of total mixed ration (TMR) silage containing soybean curd residue (SC-TMR silage). The SC-TMR materials were ensiled in laboratory silos for 14 or 56 days. LAB predominant in SC-TMR silage were identified (Exp. 1). Lactobacillus fermentum (L. fermentum) and Streptococcus bovis (S. bovis) were found in the untreated materials, Leuconostoc pseudomesenteroides (L. pseudomesenteroides) in 14-day silage and Lactobacillus plantarum (L. plantarum) in all silages. Pediococcus acidilactici (P. acidilactici), Lactobacillus paracasei (L. paracasei), and Lactobacillus brevis (L. brevis) formed more than 90% of the isolates in 56-day silage. Italian ryegrass and whole crop maize were inoculated with P. acidilactici and L. brevis isolates and the fermentation and aerobic stability determined (Exp. 2). Inoculation with P. acidilactici and L. brevis alone or combined improved the fermentation products in ryegrass silage and markedly enhanced its aerobic stability. In maize silage, P. acidilactici and L. brevis inoculation caused no changes and suppressed deterioration when combined with increases in acetic acid content. The results indicate that P. acidilactici and L. brevis may produce a synergistic effect to inhibit SC-TMR silage deterioration. Further studies are needed to identify the inhibitory substances, which may be useful for developing potential antifungal agents.

  1. Extracellular Electron Transfer from Aerobic Bacteria to Au-Loaded TiO2 Semiconductor without Light: A New Bacteria-Killing Mechanism Other than Localized Surface Plasmon Resonance or Microbial Fuel Cells.

    PubMed

    Wang, Guomin; Feng, Hongqing; Gao, Ang; Hao, Qi; Jin, Weihong; Peng, Xiang; Li, Wan; Wu, Guosong; Chu, Paul K

    2016-09-21

    Titania loaded with noble metal nanoparticles exhibits enhanced photocatalytic killing of bacteria under light illumination due to the localized surface plasmon resonance (LSPR) property. It has been shown recently that loading with Au or Ag can also endow TiO2 with the antibacterial ability in the absence of light. In this work, the antibacterial mechanism of Au-loaded TiO2 nanotubes (Au@TiO2-NT) in the dark environment is studied, and a novel type of extracellular electron transfer (EET) between the bacteria and the surface of the materials is observed to cause bacteria death. Although the EET-induced bacteria current is similar to the LSPR-related photocurrent, the former takes place without light, and no reactive oxygen species (ROS) are produced during the process. The EET is also different from that commonly attributed to microbial fuel cells (MFC) because it is dominated mainly by the materials' surface, but not the bacteria, and the environment is aerobic. EET on the Au@TiO2-NT surface kills Staphylococcus aureus, but if it is combined with special MFC bacteria, the efficiency of MFC may be improved significantly. PMID:27580379

  2. Extracellular Electron Transfer from Aerobic Bacteria to Au-Loaded TiO2 Semiconductor without Light: A New Bacteria-Killing Mechanism Other than Localized Surface Plasmon Resonance or Microbial Fuel Cells.

    PubMed

    Wang, Guomin; Feng, Hongqing; Gao, Ang; Hao, Qi; Jin, Weihong; Peng, Xiang; Li, Wan; Wu, Guosong; Chu, Paul K

    2016-09-21

    Titania loaded with noble metal nanoparticles exhibits enhanced photocatalytic killing of bacteria under light illumination due to the localized surface plasmon resonance (LSPR) property. It has been shown recently that loading with Au or Ag can also endow TiO2 with the antibacterial ability in the absence of light. In this work, the antibacterial mechanism of Au-loaded TiO2 nanotubes (Au@TiO2-NT) in the dark environment is studied, and a novel type of extracellular electron transfer (EET) between the bacteria and the surface of the materials is observed to cause bacteria death. Although the EET-induced bacteria current is similar to the LSPR-related photocurrent, the former takes place without light, and no reactive oxygen species (ROS) are produced during the process. The EET is also different from that commonly attributed to microbial fuel cells (MFC) because it is dominated mainly by the materials' surface, but not the bacteria, and the environment is aerobic. EET on the Au@TiO2-NT surface kills Staphylococcus aureus, but if it is combined with special MFC bacteria, the efficiency of MFC may be improved significantly.

  3. Supramolecular energy transfer from photoexcited chlorosomal zinc porphyrin self-aggregates to a chlorin or bacteriochlorin monomer as models of main light-harvesting antenna systems in green photosynthetic bacteria.

    PubMed

    Kataoka, Yumiko; Shibata, Yutaka; Tamiaki, Hitoshi

    2012-08-15

    Self-aggregates of a synthetic zinc porphyrin worked as a light absorber and photoexcited energy donor, transferred the collected energy to a small amount of 3-acetyl-(bacterio)chlorin monomer, and induced near-infrared fluorescence from the acceptors in aqueous micellar solution. These artificial supramolecular systems are novel models of the main light-harvesting antennas of green photosynthetic bacteria, chlorosomes.

  4. The human gut and groundwater harbor non-photosynthetic bacteria belonging to a new candidate phylum sibling to Cyanobacteria.

    PubMed

    Di Rienzi, Sara C; Sharon, Itai; Wrighton, Kelly C; Koren, Omry; Hug, Laura A; Thomas, Brian C; Goodrich, Julia K; Bell, Jordana T; Spector, Timothy D; Banfield, Jillian F; Ley, Ruth E

    2013-10-01

    Cyanobacteria were responsible for the oxygenation of the ancient atmosphere; however, the evolution of this phylum is enigmatic, as relatives have not been characterized. Here we use whole genome reconstruction of human fecal and subsurface aquifer metagenomic samples to obtain complete genomes for members of a new candidate phylum sibling to Cyanobacteria, for which we propose the designation 'Melainabacteria'. Metabolic analysis suggests that the ancestors to both lineages were non-photosynthetic, anaerobic, motile, and obligately fermentative. Cyanobacterial light sensing may have been facilitated by regulators present in the ancestor of these lineages. The subsurface organism has the capacity for nitrogen fixation using a nitrogenase distinct from that in Cyanobacteria, suggesting nitrogen fixation evolved separately in the two lineages. We hypothesize that Cyanobacteria split from Melainabacteria prior or due to the acquisition of oxygenic photosynthesis. Melainabacteria remained in anoxic zones and differentiated by niche adaptation, including for symbiosis in the mammalian gut. DOI:http://dx.doi.org/10.7554/eLife.01102.001.

  5. The human gut and groundwater harbor non-photosynthetic bacteria belonging to a new candidate phylum sibling to Cyanobacteria

    PubMed Central

    Di Rienzi, Sara C; Sharon, Itai; Wrighton, Kelly C; Koren, Omry; Hug, Laura A; Thomas, Brian C; Goodrich, Julia K; Bell, Jordana T; Spector, Timothy D; Banfield, Jillian F; Ley, Ruth E

    2013-01-01

    Cyanobacteria were responsible for the oxygenation of the ancient atmosphere; however, the evolution of this phylum is enigmatic, as relatives have not been characterized. Here we use whole genome reconstruction of human fecal and subsurface aquifer metagenomic samples to obtain complete genomes for members of a new candidate phylum sibling to Cyanobacteria, for which we propose the designation ‘Melainabacteria’. Metabolic analysis suggests that the ancestors to both lineages were non-photosynthetic, anaerobic, motile, and obligately fermentative. Cyanobacterial light sensing may have been facilitated by regulators present in the ancestor of these lineages. The subsurface organism has the capacity for nitrogen fixation using a nitrogenase distinct from that in Cyanobacteria, suggesting nitrogen fixation evolved separately in the two lineages. We hypothesize that Cyanobacteria split from Melainabacteria prior or due to the acquisition of oxygenic photosynthesis. Melainabacteria remained in anoxic zones and differentiated by niche adaptation, including for symbiosis in the mammalian gut. DOI: http://dx.doi.org/10.7554/eLife.01102.001 PMID:24137540

  6. Efficiency of autothermal thermophilic aerobic digestion and thermophilic anaerobic digestion of municipal wastewater sludge in removing Salmonella spp. and indicator bacteria.

    PubMed

    Zábranská, J; Dohányos, M; Jenícek, P; Růziciková, H; Vránová, A

    2003-01-01

    The study is focused on the comparison of autothermal thermophilic aerobic digestion, thermophilic and mesophilic anaerobic digestion, based on long-term monitoring of all processes in full-scale wastewater treatment plants, with an emphasis on the efficiency in destroying pathogens. The hygienisation effect was evaluated as a removal of counts of indicator bacteria, thermotolerant coliforms and enterococci as CFU/g total sludge solids and a frequency of a positive Salmonella spp. detection. Both thermophilic technologies of municipal wastewater sludge stabilisation had the capability of producing sludge A biosolids suitable for agricultural land application when all operational parameters (mainly temperature, mixing and retention time) were stable and maintained at an appropriate level.

  7. Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria

    PubMed Central

    Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

    2013-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

  8. Iodide accumulation by aerobic bacteria isolated from subsurface sediments of a 129I-contaminated aquifer at the Savannah River site, South Carolina.

    PubMed

    Li, Hsiu-Ping; Brinkmeyer, Robin; Jones, Whitney L; Zhang, Saijin; Xu, Chen; Schwehr, Kathy A; Santschi, Peter H; Kaplan, Daniel I; Yeager, Chris M

    2011-03-01

    (129)I is of major concern because of its mobility in the environment, excessive inventory, toxicity (it accumulates in the thyroid), and long half-life (∼16 million years). The aim of this study was to determine if bacteria from a (129)I-contaminated oxic aquifer at the F area of the U.S. Department of Energy's Savannah River Site, SC, could accumulate iodide at environmentally relevant concentrations (0.1 μM I(-)). Iodide accumulation capability was found in 3 out of 136 aerobic bacterial strains isolated from the F area that were closely related to Streptomyces/Kitasatospora spp., Bacillus mycoides, and Ralstonia/Cupriavidus spp. Two previously described iodide-accumulating marine strains, a Flexibacter aggregans strain and an Arenibacter troitsensis strain, accumulated 2 to 50% total iodide (0.1 μM), whereas the F-area strains accumulated just 0.2 to 2.0%. Iodide accumulation by FA-30 was stimulated by the addition of H(2)O(2), was not inhibited by chloride ions (27 mM), did not exhibit substrate saturation kinetics with regard to I(-) concentration (up to 10 μM I(-)), and increased at pH values of <6. Overall, the data indicate that I(-) accumulation likely results from electrophilic substitution of cellular organic molecules. This study demonstrates that readily culturable, aerobic bacteria of the F-area aquifer do not accumulate significant amounts of iodide; however, this mechanism may contribute to the long-term fate and transport of (129)I and to the biogeochemical cycling of iodine over geologic time.

  9. Dai nippon printing co., ltd, Medi-Ca AC for enumeration of aerobic bacteria. Performance tested method 041302.

    PubMed

    Okochi, Norihiko; Yamazaki, Mamoru; Kiso, Shoichi; Kinoshita, Mai; Okita, Yurie; Kazama, Keisuke; Saito, Rui

    2014-01-01

    A ready-made dry medium method for aerobic count, the MediCa AC method, was compared to the AOAC Official Method 966.23, Microbiological Methods, for seven different heat-processed meat matrixes: cooked roast beef, Chinese barbecued pork (barbecued pork seasoned with honey-based sauce), bacon, cooked ham, frankfurter (made from beef and pork), and boiled and cooked pork sausage. The 95% confidence interval for the mean difference between the two methods at each contamination level for each matrix fell within the range of -0.50 to 0.50, and no statistical difference was observed at all three contamination levels for five matrixes. These results demonstrate that the Medi-Ca AC method is a reasonable alternative to the AOAC 966.23 method for cooked meat products.

  10. Novel pod for chlorine dioxide generation and delivery to control aerobic bacteria on the inner surface of floor drains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Floor drains in poultry processing and further processing plants are a harborage site for bacteria both free swimming and in biofilms. This population can include Listeria monocytogenes which has been shown to have potential for airborne spreading from mishandled open drains. Chlorine dioxide (ClO...

  11. Picoplankton Bloom in Global South? A High Fraction of Aerobic Anoxygenic Phototrophic Bacteria in Metagenomes from a Coastal Bay (Arraial do Cabo—Brazil)

    PubMed Central

    Cuadrat, Rafael R. C.; Ferrera, Isabel; Grossart, Hans-Peter; Dávila, Alberto M. R.

    2016-01-01

    Abstract Marine habitats harbor a great diversity of microorganism from the three domains of life, only a small fraction of which can be cultivated. Metagenomic approaches are increasingly popular for addressing microbial diversity without culture, serving as sensitive and relatively unbiased methods for identifying and cataloging the diversity of nucleic acid sequences derived from organisms in environmental samples. Aerobic anoxygenic phototrophic bacteria (AAP) play important roles in carbon and energy cycling in aquatic systems. In oceans, those bacteria are widely distributed; however, their abundance and importance are still poorly understood. The aim of this study was to estimate abundance and diversity of AAPs in metagenomes from an upwelling affected coastal bay in Arraial do Cabo, Brazil, using in silico screening for the anoxygenic photosynthesis core genes. Metagenomes from the Global Ocean Sample Expedition (GOS) were screened for comparative purposes. AAPs were highly abundant in the free-living bacterial fraction from Arraial do Cabo: 23.88% of total bacterial cells, compared with 15% in the GOS dataset. Of the ten most AAP abundant samples from GOS, eight were collected close to the Equator where solar irradiation is high year-round. We were able to assign most retrieved sequences to phylo-groups, with a particularly high abundance of Roseobacter in Arraial do Cabo samples. The high abundance of AAP in this tropical bay may be related to the upwelling phenomenon and subsequent picoplankton bloom. These results suggest a link between upwelling and light abundance and demonstrate AAP even in oligotrophic tropical and subtropical environments. Longitudinal studies in the Arraial do Cabo region are warranted to understand the dynamics of AAP at different locations and seasons, and the ecological role of these unique bacteria for biogeochemical and energy cycling in the ocean. PMID:26871866

  12. Picoplankton Bloom in Global South? A High Fraction of Aerobic Anoxygenic Phototrophic Bacteria in Metagenomes from a Coastal Bay (Arraial do Cabo--Brazil).

    PubMed

    Cuadrat, Rafael R C; Ferrera, Isabel; Grossart, Hans-Peter; Dávila, Alberto M R

    2016-02-01

    Marine habitats harbor a great diversity of microorganism from the three domains of life, only a small fraction of which can be cultivated. Metagenomic approaches are increasingly popular for addressing microbial diversity without culture, serving as sensitive and relatively unbiased methods for identifying and cataloging the diversity of nucleic acid sequences derived from organisms in environmental samples. Aerobic anoxygenic phototrophic bacteria (AAP) play important roles in carbon and energy cycling in aquatic systems. In oceans, those bacteria are widely distributed; however, their abundance and importance are still poorly understood. The aim of this study was to estimate abundance and diversity of AAPs in metagenomes from an upwelling affected coastal bay in Arraial do Cabo, Brazil, using in silico screening for the anoxygenic photosynthesis core genes. Metagenomes from the Global Ocean Sample Expedition (GOS) were screened for comparative purposes. AAPs were highly abundant in the free-living bacterial fraction from Arraial do Cabo: 23.88% of total bacterial cells, compared with 15% in the GOS dataset. Of the ten most AAP abundant samples from GOS, eight were collected close to the Equator where solar irradiation is high year-round. We were able to assign most retrieved sequences to phylo-groups, with a particularly high abundance of Roseobacter in Arraial do Cabo samples. The high abundance of AAP in this tropical bay may be related to the upwelling phenomenon and subsequent picoplankton bloom. These results suggest a link between upwelling and light abundance and demonstrate AAP even in oligotrophic tropical and subtropical environments. Longitudinal studies in the Arraial do Cabo region are warranted to understand the dynamics of AAP at different locations and seasons, and the ecological role of these unique bacteria for biogeochemical and energy cycling in the ocean. PMID:26871866

  13. Effect of hot water spray on broiler carcasses for reduction of loosely attached, intermediately attached, and tightly attached pathogenic (Salmonella and Campylobacter) and mesophilic aerobic bacteria.

    PubMed

    Zhang, L; Singh, P; Lee, H C; Kang, I

    2013-03-01

    Chickens are known to harbor many bacteria, including pathogenic microorganisms such as Salmonella and Campylobacter. The objective of this study was to evaluate the efficacy of hot water spray (HWS, 71°C for 1 min) in reducing bacterial contamination of prechilled broiler carcasses. For each of 4 replications, skin samples from 5 broilers were collected at 3 processing stages: after bleeding (feathers removed manually), after evisceration (with/without HWS), and after water chilling. Broiler skin was quantitatively assessed for loosely attached (by rinsing the skin), intermediately attached (by stomaching the rinsed skin), and tightly attached (by grinding the rinsed/stomached skin) mesophilic aerobic bacteria (MAB) and Campylobacter as well as for the prevalence of Salmonella and Campylobacter. Broiler skins possessed 6.4 to 6.6 log cfu/g, 3.8 to 4.1 log cfu/g, and 2.8 to 3.5 log cfu/g of MAB populations after bleeding, evisceration, and chilling, respectively. The HWS resulted in more than 1 log unit of reduction in MAB immediately after evisceration and immediately after chilling regardless of microbial sampling method. Compared with MAB, the contamination of Campylobacter was low (1.7 to 2.6 log cfu/g) after bleeding, but the level was not reduced throughout the processing steps regardless of HWS. The application of HWS reduced the prevalence of Salmonella after chilling, but not for Campylobacter except for loosely attached cells. After hot water exposure, a partially cooked appearance was seen on both broiler skin and skinless breast surface. More research is required to effectively eliminate pathogenic organisms during processing and suppress any recovery of bacteria regardless of attachment type after chilling.

  14. Isolation and characterization of aerobic culturable arsenic-resistant bacteria from surfacewater and groundwater of Rautahat District, Nepal.

    PubMed

    Shakya, S; Pradhan, B; Smith, L; Shrestha, J; Tuladhar, S

    2012-03-01

    Arsenic (As) contamination of groundwater is a serious Environmental Health Management issue of drinking water sources especially in Terai region of Nepal. Many studies have reported that due to natural abundance of arsenic in the environment, various bacteria have developed different resistance mechanisms for arsenic compound. In this study, the culturable arsenic-resistant bacteria indigenous to surfacewater as well as groundwater from Rautahat District of Nepal were randomly isolated by standard plate count method on the basis of viable growth on plate count agar amended with arsenate ranging from 0, 0.5, 10, 40, 80 to 160 milligram per liter (mg/l). With respect to the morphological and biochemical tests, nine morphologically distinct potent arsenate tolerant bacteria showed relatedness with Micrococcus varians, Micrococcus roseus, Micrococcus luteus, Pseudomonas maltophilia, Pseudomonas sp., Vibrio parahaemolyticus, Bacillus cereus, Bacillus smithii 1 and Bacillus smithii 2. The isolates were capable of tolerating more than 1000 mg/l of arsenate and 749 mg/l of arsenite. Likewise, bioaccumulation capability was highest with M. roseus (85.61%) and the least with B. smithii (47.88%) indicating the potential of the organisms in arsenic resistance and most probably in bioremediation.

  15. Isolation and characterization of aerobic culturable arsenic-resistant bacteria from surfacewater and groundwater of Rautahat District, Nepal.

    PubMed

    Shakya, S; Pradhan, B; Smith, L; Shrestha, J; Tuladhar, S

    2012-03-01

    Arsenic (As) contamination of groundwater is a serious Environmental Health Management issue of drinking water sources especially in Terai region of Nepal. Many studies have reported that due to natural abundance of arsenic in the environment, various bacteria have developed different resistance mechanisms for arsenic compound. In this study, the culturable arsenic-resistant bacteria indigenous to surfacewater as well as groundwater from Rautahat District of Nepal were randomly isolated by standard plate count method on the basis of viable growth on plate count agar amended with arsenate ranging from 0, 0.5, 10, 40, 80 to 160 milligram per liter (mg/l). With respect to the morphological and biochemical tests, nine morphologically distinct potent arsenate tolerant bacteria showed relatedness with Micrococcus varians, Micrococcus roseus, Micrococcus luteus, Pseudomonas maltophilia, Pseudomonas sp., Vibrio parahaemolyticus, Bacillus cereus, Bacillus smithii 1 and Bacillus smithii 2. The isolates were capable of tolerating more than 1000 mg/l of arsenate and 749 mg/l of arsenite. Likewise, bioaccumulation capability was highest with M. roseus (85.61%) and the least with B. smithii (47.88%) indicating the potential of the organisms in arsenic resistance and most probably in bioremediation. PMID:21868146

  16. Central Role of Dynamic Tidal Biofilms Dominated by Aerobic Hydrocarbonoclastic Bacteria and Diatoms in the Biodegradation of Hydrocarbons in Coastal Mudflats

    PubMed Central

    Coulon, Frédéric; Chronopoulou, Panagiota-Myrsini; Fahy, Anne; Païssé, Sandrine; Goñi-Urriza, Marisol; Peperzak, Louis; Acuña Alvarez, Laura; McKew, Boyd A.; Brussaard, Corina P. D.; Underwood, Graham J. C.; Timmis, Kenneth N.; Duran, Robert

    2012-01-01

    Mudflats and salt marshes are habitats at the interface of aquatic and terrestrial systems that provide valuable services to ecosystems. Therefore, it is important to determine how catastrophic incidents, such as oil spills, influence the microbial communities in sediment that are pivotal to the function of the ecosystem and to identify the oil-degrading microbes that mitigate damage to the ecosystem. In this study, an oil spill was simulated by use of a tidal chamber containing intact diatom-dominated sediment cores from a temperate mudflat. Changes in the composition of bacteria and diatoms from both the sediment and tidal biofilms that had detached from the sediment surface were monitored as a function of hydrocarbon removal. The hydrocarbon concentration in the upper 1.5 cm of sediments decreased by 78% over 21 days, with at least 60% being attributed to biodegradation. Most phylotypes were minimally perturbed by the addition of oil, but at day 21, there was a 10-fold increase in the amount of cyanobacteria in the oiled sediment. Throughout the experiment, phylotypes associated with the aerobic degradation of hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs) (Cycloclasticus) and alkanes (Alcanivorax, Oleibacter, and Oceanospirillales strain ME113), substantively increased in oiled mesocosms, collectively representing 2% of the pyrosequences in the oiled sediments at day 21. Tidal biofilms from oiled cores at day 22, however, consisted mostly of phylotypes related to Alcanivorax borkumensis (49% of clones), Oceanospirillales strain ME113 (11% of clones), and diatoms (14% of clones). Thus, aerobic hydrocarbon biodegradation is most likely to be the main mechanism of attenuation of crude oil in the early weeks of an oil spill, with tidal biofilms representing zones of high hydrocarbon-degrading activity. PMID:22407688

  17. Evaluation of the Removal of Indicator Bacteria from Domestic Sludge Processed by Autothermal Thermophilic Aerobic Digestion (ATAD)

    PubMed Central

    Piterina, Anna V.; Bartlett, John; Pembroke, Tony J.

    2010-01-01

    The degradation of sludge solids in an insulated reactor during Autothermal Thermophilic Aerobic Digestion (ATAD) processing results in auto-heating, thermal treatment and total solids reduction, however, the ability to eliminate pathogenic organisms has not been analysed under large scale process conditions. We evaluated the ATAD process over a period of one year in a two stage, full scale Irish ATAD plant established in Killarney and treating mixed primary and secondary sludge, by examining the sludge microbiologically at various stages during and following ATAD processing to determine its ability to eliminate indicator organisms. Salmonella spp. (pathogen) and fecal-coliform (indicator) densities were well below the limits used to validate class A biosolids in the final product. Enteric pathogens present at inlet were deactivated during the ATAD process and were not detected in the final product using both traditional microbial culture and molecular phylogenetic techniques. A high DNase activity was detected in the bulk sludge during the thermophilic digestion stage which may be responsible for the rapid turn over of DNA from lysed cells and the removal of mobile DNA. These results offer assurance for the safe use of ATAD sludge as a soil supplement following processing. PMID:20948933

  18. Evaluation of the removal of indicator bacteria from domestic sludge processed by Autothermal Thermophilic Aerobic Digestion (ATAD).

    PubMed

    Piterina, Anna V; Bartlett, John; Pembroke, Tony J

    2010-09-01

    The degradation of sludge solids in an insulated reactor during Autothermal Thermophilic Aerobic Digestion (ATAD) processing results in auto-heating, thermal treatment and total solids reduction, however, the ability to eliminate pathogenic organisms has not been analysed under large scale process conditions. We evaluated the ATAD process over a period of one year in a two stage, full scale Irish ATAD plant established in Killarney and treating mixed primary and secondary sludge, by examining the sludge microbiologically at various stages during and following ATAD processing to determine its ability to eliminate indicator organisms. Salmonella spp. (pathogen) and fecal-coliform (indicator) densities were well below the limits used to validate class A biosolids in the final product. Enteric pathogens present at inlet were deactivated during the ATAD process and were not detected in the final product using both traditional microbial culture and molecular phylogenetic techniques. A high DNase activity was detected in the bulk sludge during the thermophilic digestion stage which may be responsible for the rapid turn over of DNA from lysed cells and the removal of mobile DNA. These results offer assurance for the safe use of ATAD sludge as a soil supplement following processing.

  19. Matrix Extension Study: Validation of the Compact Dry TC Method for Enumeration of Total Aerobic Bacteria in Selected Foods.

    PubMed

    Mizuochi, Shingo; Nelson, Maria; Baylis, Chris; Jewell, Keith; Green, Becky; Limbum, Rob; Fernandez, Maria Cristina; Salfinger, Yvonne; Chen, Yi

    2016-01-01

    A validation study was conducted to extend the matrix claim for the Nissui Compact Dry Total Count (TC), Performance Tested Method(s)(SM) (PTM) Certification No. 010404, to cooked chicken, lettuce, frozen fish, milk powder, and pasteurized whole milk. The method was originally certified by the AOAC Research Institute Performance Tested Method(s)(SM) Program for raw meat products. The Compact Dry TC is a ready-to-use dry media sheet that is rehydrated by adding 1 mL of diluted sample. A total aerobic colony count can be determined in the sample following 48 h of incubation. Matrix extension studies were conducted by Campden BRI (formerly Campden and Chorleywood Food Research Association Technology Limited), Chipping Campden, UK. Single-laboratory data were collected for cooked chicken, lettuce, frozen fish, and milk powder, whereas a multilaboratory study was conducted on pasteurized milk. Fourteen laboratories participated in the collaborative study. The Compact Dry TC was tested at two time points, 48 ± 3 h and 72 ± 3 h and compared with the current International Organization for Standardization (ISO) method at the time of the study, ISO 4833:2003 (this standard is withdrawn and has been replaced by: ISO 4833-1:2013 and ISO 4833-2:2013), Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of microorganisms-Colony-count technique at 30°C. The data were logarithmically transformed and evaluated for repeatability (plus reproducibility for pasteurized milk), RSD of repeatability (plus RSD of reproducibility for milk), r(2), and mean difference between methods with 95% confidence interval (CI). A CI outside of (-0.5 to 0.5) on the log10 mean difference was used as the criterion to establish significant statistical difference between methods. No significant differences were found between the Compact Dry TC 48 and 72 h time points, with the exception of one contamination level of cooked chicken and one contamination level of dry milk

  20. Matrix Extension Study: Validation of the Compact Dry TC Method for Enumeration of Total Aerobic Bacteria in Selected Foods.

    PubMed

    Mizuochi, Shingo; Nelson, Maria; Baylis, Chris; Jewell, Keith; Green, Becky; Limbum, Rob; Fernandez, Maria Cristina; Salfinger, Yvonne; Chen, Yi

    2016-01-01

    A validation study was conducted to extend the matrix claim for the Nissui Compact Dry Total Count (TC), Performance Tested Method(s)(SM) (PTM) Certification No. 010404, to cooked chicken, lettuce, frozen fish, milk powder, and pasteurized whole milk. The method was originally certified by the AOAC Research Institute Performance Tested Method(s)(SM) Program for raw meat products. The Compact Dry TC is a ready-to-use dry media sheet that is rehydrated by adding 1 mL of diluted sample. A total aerobic colony count can be determined in the sample following 48 h of incubation. Matrix extension studies were conducted by Campden BRI (formerly Campden and Chorleywood Food Research Association Technology Limited), Chipping Campden, UK. Single-laboratory data were collected for cooked chicken, lettuce, frozen fish, and milk powder, whereas a multilaboratory study was conducted on pasteurized milk. Fourteen laboratories participated in the collaborative study. The Compact Dry TC was tested at two time points, 48 ± 3 h and 72 ± 3 h and compared with the current International Organization for Standardization (ISO) method at the time of the study, ISO 4833:2003 (this standard is withdrawn and has been replaced by: ISO 4833-1:2013 and ISO 4833-2:2013), Microbiology of food and animal feeding stuffs-Horizontal method for the enumeration of microorganisms-Colony-count technique at 30°C. The data were logarithmically transformed and evaluated for repeatability (plus reproducibility for pasteurized milk), RSD of repeatability (plus RSD of reproducibility for milk), r(2), and mean difference between methods with 95% confidence interval (CI). A CI outside of (-0.5 to 0.5) on the log10 mean difference was used as the criterion to establish significant statistical difference between methods. No significant differences were found between the Compact Dry TC 48 and 72 h time points, with the exception of one contamination level of cooked chicken and one contamination level of dry milk

  1. Evaluation of the use of PCR and reverse transcriptase PCR for detection of pathogenic bacteria in biosolids from anaerobic digestors and aerobic composters.

    PubMed

    Burtscher, Carola; Wuertz, Stefan

    2003-08-01

    A PCR-based method and a reverse transcriptase PCR (RT-PCR)-based method were developed for the detection of pathogenic bacteria in organic waste, using Salmonella spp., Listeria monocytogenes, Yersinia enterocolitica, and Staphylococcus aureus as model organisms. In seeded organic waste samples, detection limits of less than 10 cells per g of organic waste were achieved after one-step enrichment of bacteria, isolation, and purification of DNA or RNA before PCR or RT-PCR amplification. To test the reproducibility and reliability of the newly developed methods, 46 unseeded samples were collected from diverse aerobic (composting) facilities and anaerobic digestors and analyzed by both culture-based classical and newly developed PCR-based procedures. No false-positive but some false-negative results were generated by the PCR- or RT-PCR-based methods after one-step enrichment when compared to the classical detection methods. The results indicated that the level of activity of the tested bacteria in unseeded samples was very low compared to that of freshly inoculated cells, preventing samples from reaching the cell density required for PCR-based detection after one-step enrichment. However, for Salmonella spp., a distinct PCR product could be obtained for all 22 nonamended samples that tested positive for Salmonella spp. by the classical detection procedure when a selective two-step enrichment (20 h in peptone water at 37 degrees C and 24 h in Rappaport Vassiliadis medium at 43 degrees C) was performed prior to nucleic acid extraction and PCR. Hence, the classical procedure was shortened, since cell plating and further differentiation of isolated colonies can be omitted, substituted for by highly sensitive and reliable detection based on nucleic acid extraction and PCR. Similarly, 2 of the 22 samples in which Salmonella spp. were detected also tested positive for Listeria monocytogenes according to a two-step enrichment procedure followed by PCR, compared to 3 samples

  2. Microbiological Quality of Ready-to-Eat Vegetables Collected in Mexico City: Occurrence of Aerobic-Mesophilic Bacteria, Fecal Coliforms, and Potentially Pathogenic Nontuberculous Mycobacteria.

    PubMed

    Cerna-Cortes, Jorge Francisco; Leon-Montes, Nancy; Cortes-Cueto, Ana Laura; Salas-Rangel, Laura P; Helguera-Repetto, Addy Cecilia; Lopez-Hernandez, Daniel; Rivera-Gutierrez, Sandra; Fernandez-Rendon, Elizabeth; Gonzalez-y-Merchand, Jorge Alberto

    2015-01-01

    The aims of this study were to evaluate the microbiological quality and the occurrence of nontuberculous mycobacteria (NTM) in a variety of salads and sprouts from supermarkets and street vendors in Mexico City. Aerobic-mesophilic bacteria (AMB) were present in 100% of RTE-salads samples; 59% of samples were outside guidelines range (>5.17 log10 CFU per g). Although fecal coliforms (FC) were present in 32% of samples, only 8% of them exceeded the permissible limit (100 MPN/g). Regarding the 100 RTE-sprouts, all samples were also positive for AMB and total coliforms (TC) and 69% for FC. Seven NTM species were recovered from 7 salad samples; they included three M. fortuitum, two M. chelonae, one M. mucogenicum, and one M. sp. Twelve RTE-sprouts samples harbored NTM, which were identified as M. porcinum (five), M. abscessus (two), M. gordonae (two), M. mucogenicum (two), and M. avium complex (one). Most RTE-salads and RTE-sprouts had unsatisfactory microbiological quality and some harbored NTM associated with illness. No correlation between the presence of coliforms and NTM was found. Overall, these results suggest that RTE-salads and RTE-sprouts might function as vehicles for NTM transmission in humans; hence, proper handling and treatment before consumption of such products might be recommendable.

  3. Adequacy of Petrifilm™ Aerobic Count plates supplemented with de Man, Rogosa & Sharpe broth and chlorophenol red for enumeration of lactic acid bacteria in salami.

    PubMed

    de Castilho, Natália Parma Augusto; Okamura, Vivian Tiemi; Camargo, Anderson Carlos; Pieri, Fábio Alessandro; Nero, Luís Augusto

    2015-12-01

    The present study aimed to assess the performance of alternative protocols to enumerate lactic acid bacteria (LAB) in salami. Fourteen cultures and two mixed starter cultures were plated using six protocols: 1) Petrifilm™ Aerobic Count (AC) with MRS broth and chlorophenol red (CR), incubated under aerobiosis or 2) under anaerobiosis, 3) MRS agar with CR, 4) MRS agar with bromocresol purple, 5) MRS agar at pH5.7, and 6) All Purpose Tween agar. Samples of salami were obtained and the LAB microbiota was enumerated by plating according protocols 1, 2, 3 and 5. Regression analysis showed a significant correlation between the tested protocols, based on culture counts (p<0.05). Similar results were observed for salami, and no significant differences of mean LAB counts between selected protocols (ANOVA, p>0.05). Colonies were confirmed as LAB, indicating proper selectivity of the protocols. The results showed the adequacy of Petrifilm™ AC supplemented with CR for the enumeration of LAB in salami. PMID:26291606

  4. Aerobic bacteria from mucous membranes, ear canals, and skin wounds of feral cats in Grenada, and the antimicrobial drug susceptibility of major isolates.

    PubMed

    Hariharan, Harry; Matthew, Vanessa; Fountain, Jacqueline; Snell, Alicia; Doherty, Devin; King, Brittany; Shemer, Eran; Oliveira, Simone; Sharma, Ravindra N

    2011-03-01

    In a 2-year period 54 feral cats were captured in Grenada, West Indies, and a total of 383 samples consisting of swabs from rectum, vagina, ears, eyes, mouth, nose and wounds/abscesses, were cultured for aerobic bacteria and campylobacters. A total of 251 bacterial isolates were obtained, of which 205 were identified to species level and 46 to genus level. A commercial bacterial identification system (API/Biomerieux), was used for this purpose. The most common species was Escherichia coli (N=60), followed by Staphylococcus felis/simulans (40), S. hominis (16), S. haemolyticus (12), Streptococcus canis (9), Proteus mirabilis (8), Pasteurella multocida (7), Streptococcus mitis (7), Staphylococcus xylosus (7), S. capitis (6), S. chromogenes (4), S. sciuri (3), S. auricularis (2), S. lentus (2), S. hyicus (2), Streptococcus suis (2) and Pseudomonas argentinensis (2). Sixteen other isolates were identified to species level. A molecular method using 16S rRNA sequencing was used to confirm/identify 22 isolates. Salmonella or campylobacters were not isolated from rectal swabs. E. coli and S. felis/simulans together constituted 50% of isolates from vagina. S. felis/simulans was the most common species from culture positive ear and eye samples. P. multocida was isolated from 15% of mouth samples. Coagulase-negative staphylococci were the most common isolates from nose and wound swabs. Staphylococcus aureus, or S. intemedius/S. pseudintermedius were not isolated from any sample. Antimicrobial drug resistance was minimal, most isolates being susceptible to all drugs tested against, including tetracycline.

  5. Susceptibility to antibiotics of aerobic bacteria isolated from community acquired secondary peritonitis in children: therapeutic guidelines might not always fit with and everyday experience.

    PubMed

    Castagnola, Elio; Bandettini, Roberto; Ginocchio, Francesca; Perotti, Maddalena; Masa, Daniela La; Ciucci, Antonella; Loy, Anna; Caviglia, Ilaria; Haupt, Riccardo; Guida, Edoardo; Pini Prato, Alessio; Mattioli, Girolamo; Buffa, Piero

    2013-08-01

    Appendicitis is a frequent clinical condition in normal children that may be complicated by community-acquired secondary peritonitis (CASP). We evaluated the potential efficacy of different drugs for initial treatment of this condition, as recommended by recent Consensus Conference and Guidelines for paediatric patients. Susceptibility to ampicillin-sulbactam, ertapenem, gentamycin, piperacillin, piperacillin-tazobactam, vancomycin, and teicoplanin was evaluated according to EUCST 2012 recommendations in aerobic bacteria isolated from peritoneal fluid in CASP diagnosed from 2005 to 2011 at 'Istituto Giannina Gaslini', Genoa, Italy. A total of 114 strains were analysed: 83 E. coli, 15 P. aeruginosa, 6 Enterococci, and 10 other Gram-negatives. Resistance to ampicillin-sulbactam was detected in 37% of strains, while ertapenem showed a potential resistance of 13% (all P. aeruginosa strains). However, the combination of these drugs with gentamicin would have been increased the efficacy of the treatment to 99 and 100%, respectively. Resistance to piperacillin-tazobactam was 3%, while no strain was resistant to meropenem. Our data suggest that monotherapy with ampicillin-sulbactam or ertapenem for community-acquired secondary peritonitis would present a non-negligible rate of failure, but the addition of gentamycin to these drugs could reset to zero this risk. On the contrary, monotherapy with piperacillin-tazobactam or meropenem is highly effective.

  6. Adequacy of Petrifilm™ Aerobic Count plates supplemented with de Man, Rogosa & Sharpe broth and chlorophenol red for enumeration of lactic acid bacteria in salami.

    PubMed

    de Castilho, Natália Parma Augusto; Okamura, Vivian Tiemi; Camargo, Anderson Carlos; Pieri, Fábio Alessandro; Nero, Luís Augusto

    2015-12-01

    The present study aimed to assess the performance of alternative protocols to enumerate lactic acid bacteria (LAB) in salami. Fourteen cultures and two mixed starter cultures were plated using six protocols: 1) Petrifilm™ Aerobic Count (AC) with MRS broth and chlorophenol red (CR), incubated under aerobiosis or 2) under anaerobiosis, 3) MRS agar with CR, 4) MRS agar with bromocresol purple, 5) MRS agar at pH5.7, and 6) All Purpose Tween agar. Samples of salami were obtained and the LAB microbiota was enumerated by plating according protocols 1, 2, 3 and 5. Regression analysis showed a significant correlation between the tested protocols, based on culture counts (p<0.05). Similar results were observed for salami, and no significant differences of mean LAB counts between selected protocols (ANOVA, p>0.05). Colonies were confirmed as LAB, indicating proper selectivity of the protocols. The results showed the adequacy of Petrifilm™ AC supplemented with CR for the enumeration of LAB in salami.

  7. Marked seasonality of aerobic anoxygenic phototrophic bacteria in the coastal NW Mediterranean Sea as revealed by cell abundance, pigment concentration and pyrosequencing of pufM gene.

    PubMed

    Ferrera, Isabel; Borrego, Carles M; Salazar, Guillem; Gasol, Josep M

    2014-09-01

    The abundance and diversity of aerobic anoxygenic phototrophs (AAPs) were studied for a year cycle at the Blanes Bay Microbial Observatory (NW Mediterranean) and their potential links to an array of environmental variables were explored. Cell numbers were low in winter and peaked in summer, showing a marked seasonality that positively correlated with day length and light at the surface. Bacteriochlorophyll a concentration, their light-harvesting pigment, was only detected between April and October, and pigment cell quota showed large variations during this period. Pyrosequencing analysis of the pufM gene revealed that the most abundant operational taxonomic units (OTUs) were affiliated to phylogroup K (Gammaproteobacteria) and uncultured phylogroup C, although they were outnumbered by alphaproteobacterial OTUs in spring. Overall, richness was higher in winter than in summer, showing an opposite trend to abundance and day length. Clustering of samples by multivariate analyses showed a clear seasonality that suggests a succession of different AAP subpopulations over time. Temperature, chlorophyll a and day length were the environmental drivers that best explained the distribution of AAP assemblages. These results indicate that AAP bacteria are highly dynamic and undergo seasonal variations in diversity and abundance mostly dictated by environmental conditions as exemplified by light availability.

  8. Fate of mesophilic aerobic bacteria and Salmonella enterica on the surface of eggs as affected by chicken feces, storage temperature, and relative humidity.

    PubMed

    Park, Sunhyung; Choi, Seonyeong; Kim, Hoikyung; Kim, Yoonsook; Kim, Byeong-sam; Beuchat, Larry R; Ryu, Jee-Hoon

    2015-06-01

    We compared the microbiological quality of chicken eggshells obtained from a traditional wholesale market and a modern supermarket. We also determined the survival and growth characteristics of naturally occurring mesophilic aerobic bacteria (MAB) and artificially inoculated Salmonella enterica on eggshells under various environmental conditions (presence of chicken feces, temperature [4, 12, or 25 °C], and relative humidity [RH; 43 or 85%]). The populations of MAB, coliforms, and molds and yeasts on eggshells purchased from a traditional wholesale market were significantly (P ≤ 0.05) higher than those from a modern supermarket. In the second study, when we stored uninoculated eggs under various storage conditions, the population of MAB on eggshells (4.7-4.9 log CFU/egg) remained constant for 21 days, regardless of storage conditions. However, when eggshells were inoculated with S. enterica and stored under the same conditions, populations of the pathogen decreased significantly (P ≤ 0.05) under all tested conditions. Survival of S. enterica increased significantly (P ≤ 0.05) in the presence of feces, at low temperatures, and at low RH. These observations will be of value when predicting the behavior of microorganisms on eggshells and selecting storage conditions that reduce the populations of S. enterica on eggshells during distribution.

  9. Microbiological Quality of Ready-to-Eat Vegetables Collected in Mexico City: Occurrence of Aerobic-Mesophilic Bacteria, Fecal Coliforms, and Potentially Pathogenic Nontuberculous Mycobacteria

    PubMed Central

    Cerna-Cortes, Jorge Francisco; Leon-Montes, Nancy; Cortes-Cueto, Ana Laura; Salas-Rangel, Laura P.; Helguera-Repetto, Addy Cecilia; Lopez-Hernandez, Daniel; Rivera-Gutierrez, Sandra; Fernandez-Rendon, Elizabeth; Gonzalez-y-Merchand, Jorge Alberto

    2015-01-01

    The aims of this study were to evaluate the microbiological quality and the occurrence of nontuberculous mycobacteria (NTM) in a variety of salads and sprouts from supermarkets and street vendors in Mexico City. Aerobic-mesophilic bacteria (AMB) were present in 100% of RTE-salads samples; 59% of samples were outside guidelines range (>5.17 log10 CFU per g). Although fecal coliforms (FC) were present in 32% of samples, only 8% of them exceeded the permissible limit (100 MPN/g). Regarding the 100 RTE-sprouts, all samples were also positive for AMB and total coliforms (TC) and 69% for FC. Seven NTM species were recovered from 7 salad samples; they included three M. fortuitum, two M. chelonae, one M. mucogenicum, and one M. sp. Twelve RTE-sprouts samples harbored NTM, which were identified as M. porcinum (five), M. abscessus (two), M. gordonae (two), M. mucogenicum (two), and M. avium complex (one). Most RTE-salads and RTE-sprouts had unsatisfactory microbiological quality and some harbored NTM associated with illness. No correlation between the presence of coliforms and NTM was found. Overall, these results suggest that RTE-salads and RTE-sprouts might function as vehicles for NTM transmission in humans; hence, proper handling and treatment before consumption of such products might be recommendable. PMID:25918721

  10. Aerobic bacteria from mucous membranes, ear canals, and skin wounds of feral cats in Grenada, and the antimicrobial drug susceptibility of major isolates.

    PubMed

    Hariharan, Harry; Matthew, Vanessa; Fountain, Jacqueline; Snell, Alicia; Doherty, Devin; King, Brittany; Shemer, Eran; Oliveira, Simone; Sharma, Ravindra N

    2011-03-01

    In a 2-year period 54 feral cats were captured in Grenada, West Indies, and a total of 383 samples consisting of swabs from rectum, vagina, ears, eyes, mouth, nose and wounds/abscesses, were cultured for aerobic bacteria and campylobacters. A total of 251 bacterial isolates were obtained, of which 205 were identified to species level and 46 to genus level. A commercial bacterial identification system (API/Biomerieux), was used for this purpose. The most common species was Escherichia coli (N=60), followed by Staphylococcus felis/simulans (40), S. hominis (16), S. haemolyticus (12), Streptococcus canis (9), Proteus mirabilis (8), Pasteurella multocida (7), Streptococcus mitis (7), Staphylococcus xylosus (7), S. capitis (6), S. chromogenes (4), S. sciuri (3), S. auricularis (2), S. lentus (2), S. hyicus (2), Streptococcus suis (2) and Pseudomonas argentinensis (2). Sixteen other isolates were identified to species level. A molecular method using 16S rRNA sequencing was used to confirm/identify 22 isolates. Salmonella or campylobacters were not isolated from rectal swabs. E. coli and S. felis/simulans together constituted 50% of isolates from vagina. S. felis/simulans was the most common species from culture positive ear and eye samples. P. multocida was isolated from 15% of mouth samples. Coagulase-negative staphylococci were the most common isolates from nose and wound swabs. Staphylococcus aureus, or S. intemedius/S. pseudintermedius were not isolated from any sample. Antimicrobial drug resistance was minimal, most isolates being susceptible to all drugs tested against, including tetracycline. PMID:20627391

  11. Guidelines for interpretation of 16S rRNA gene sequence-based results for identification of medically important aerobic Gram-positive bacteria.

    PubMed

    Woo, Patrick C Y; Teng, Jade L L; Wu, Jeff K L; Leung, Fion P S; Tse, Herman; Fung, Ami M Y; Lau, Susanna K P; Yuen, Kwok-Yung

    2009-08-01

    This study is believed to be the first to provide guidelines for facilitating interpretation of results based on full and 527 bp 16S rRNA gene sequencing and MicroSeq databases used for identifying medically important aerobic Gram-positive bacteria. Overall, full and 527 bp 16S rRNA gene sequencing can identify 24 and 40 % of medically important Gram-positive cocci (GPC), and 21 and 34 % of medically important Gram-positive rods (GPR) confidently to the species level, whereas the full-MicroSeq and 500-MicroSeq databases can identify 15 and 34 % of medically important GPC and 14 and 25 % of medically important GPR confidently to the species level. Among staphylococci, streptococci, enterococci, mycobacteria, corynebacteria, nocardia and members of Bacillus and related taxa (Paenibacillus, Brevibacillus, Geobacillus and Virgibacillus), the methods and databases are least useful for identification of staphylococci and nocardia. Only 0-2 and 2-13 % of staphylococci, and 0 and 0-10 % of nocardia, can be confidently and doubtfully identified, respectively. However, these methods and databases are most useful for identification of Bacillus and related taxa, with 36-56 and 11-14 % of Bacillus and related taxa confidently and doubtfully identified, respectively. A total of 15 medically important GPC and 18 medically important GPR that should be confidently identified by full 16S rRNA gene sequencing are not included in the full-MicroSeq database. A total of 9 medically important GPC and 21 medically important GPR that should be confidently identified by 527 bp 16S rRNA gene sequencing are not included in the 500-MicroSeq database. 16S rRNA gene sequence results of Gram-positive bacteria should be interpreted with basic phenotypic tests results. Additional biochemical tests or sequencing of additional gene loci are often required for definitive identification. To improve the usefulness of the MicroSeq databases, bacterial species that can be confidently identified by 16S r

  12. Regulatory RNAs in photosynthetic cyanobacteria.

    PubMed

    Kopf, Matthias; Hess, Wolfgang R

    2015-05-01

    Regulatory RNAs play versatile roles in bacteria in the coordination of gene expression during various physiological processes, especially during stress adaptation. Photosynthetic bacteria use sunlight as their major energy source. Therefore, they are particularly vulnerable to the damaging effects of excess light or UV irradiation. In addition, like all bacteria, photosynthetic bacteria must adapt to limiting nutrient concentrations and abiotic and biotic stress factors. Transcriptome analyses have identified hundreds of potential regulatory small RNAs (sRNAs) in model cyanobacteria such as Synechocystis sp. PCC 6803 or Anabaena sp. PCC 7120, and in environmentally relevant genera such as Trichodesmium, Synechococcus and Prochlorococcus. Some sRNAs have been shown to actually contain μORFs and encode short proteins. Examples include the 40-amino-acid product of the sml0013 gene, which encodes the NdhP subunit of the NDH1 complex. In contrast, the functional characterization of the non-coding sRNA PsrR1 revealed that the 131 nt long sRNA controls photosynthetic functions by targeting multiple mRNAs, providing a paradigm for sRNA functions in photosynthetic bacteria. We suggest that actuatons comprise a new class of genetic elements in which an sRNA gene is inserted upstream of a coding region to modify or enable transcription of that region.

  13. Photosynthetic units.

    PubMed

    Schmid, G H; Gaffron, H

    1968-08-01

    Leaf tissues of aurea mutants of tobacco and Lespedeza have been shown to have higher photosynthetic capacity per molecule of chlorophyll, a higher saturation intensity, a simpler lamellar structure, and the same quantum yield as their dark green parents. Here we report on the values of photosynthetic units for both types of plants and some algae. The unit has been assumed to be about as uniform and steady in the plant world as the quantum efficiency. The number on which all theoretical discussions have been based so far is 2400 per O(2) evolved or CO(2) reduced. With dark green plants and algae our determinations of units by means of 40 microsec flashes superimposed on a steady rate of background photosynthesis at 900 ergs cm(-2) sec(-1) of red light yielded mostly numbers between 2000 and 2700. However, the photosynthetic unit turned out to be very variable, even in these objects. In aurea mutants the unit was distinctly smaller, averaging 600 chl/CO(2). By choosing the right combination of colors for flash and background light, units as low as 300 chl/CO(2) or 40 chl/e(-) could be measured consistently. We found five well-defined groups of units composed of multiples of its smallest member. These new findings are discussed in terms of structural entities that double or divide under the influence of far-red light.

  14. Hydrogen production by photosynthetic microorganisms

    SciTech Connect

    Akano, T.; Fukatsu, K.; Miyasaka, H. |

    1996-12-31

    Hydrogen is a clean energy alternative to the fossil fuels, the main source of greenhouse gas emissions. We developed a stable system for the conversion of solar energy into hydrogen using photosynthetic microorganisms. Our system consists of the following three stages: (1) Photosynthetic starch accumulation in green microalgae (400 L x2); (2) Dark anaerobic fermentation of the algal starch biomass to produce hydrogen and organic compounds (155 L x2); and (3) Further conversion of the organic compounds to produce hydrogen using photosynthetic bacteria (three types of reactors, parallel plate, raceway, and tubular). We constructed a test plant of this process at Nankoh power plant of Kansai Electric Power Company in Osaka, Japan, and carried out a series of tests using CO{sub 2} obtained from a chemical absorption pilot-plant. The photobiological hydrogen production process used a combination of a marine alga, Chlamydomonas sp. MGA 161 and marine photosynthetic bacterium, Rhodopseudomonas sp. W-1S. The dark anaerobic fermentation of algal starch biomass was also investigated. Sustained and stable starch accumulation, starch degradation in the algal cell, and hydrogen production from algal fermentation and photosynthetic bacteria in the light were demonstrated during several experiments. 3 refs., 12 figs., 1 tab.

  15. Protein structure, electron transfer and evolution of prokaryotic photosynthetic reaction centers

    NASA Technical Reports Server (NTRS)

    Blankenship, R. E.

    1994-01-01

    Photosynthetic reaction centers from a variety of organisms have been isolated and characterized. The groups of prokaryotic photosynthetic organisms include the purple bacteria, the filamentous green bacteria, the green sulfur bacteria and the heliobacteria as anoxygenic representatives as well as the cyanobacteria and prochlorophytes as oxygenic representatives. This review focuses on structural and functional comparisons of the various groups of photosynthetic reaction centers and considers possible evolutionary scenarios to explain the diversity of existing photosynthetic organisms.

  16. The history of photosynthetic thermoluminescence.

    PubMed

    Vass, Imre

    2003-01-01

    A fundamental discovery of photosynthetis research in the 1950s was the detection of thermally stimulated light emission from preilluminated photosynthetic material [Arnold W and Sherwood H (1957) Proc Natl Acad Sci USA 43: 105-114]. This phenomenon, called thermoluminescence (TL), is characteristic of a wide range of materials (minerals, semiconductors, inorganic and organic crystals, and complex biological systems), which share the ability of storing radiant energy in thermally stabilized trap states. The original discovery of TL in dried chloroplasts later proved to be a phenomenon common to all photosynthetic organisms: photosynthetic bacteria, cyanobacteria, algae and higher plants, which can be observed in isolated membrane particles, intact chloroplasts and unicellular organisms, and whole leaves. Following the initial observations considerable effort has been devoted to the identification and characterization of photosynthetic TL components. This work has firmly established the participation of various oxidation states of the water-oxidizing complex, the redox-active tyrosines, and the quinone electron acceptors of Photosystem II (PS II) in the generation of photosynthetic glow curves. Since TL characteristics are very sensitive to subtle changes in the redox properties of the involved electron transport components, the TL method has become a powerful tool in probing a wide range of PS II redox reactions and their modifications by environmental stress effects. Here, the main milestones of research in photosynthetic TL are covered until the present day. PMID:16228589

  17. High Efficiency Light Harvesting by Carotenoids in the LH2 Complex from Photosynthetic Bacteria: Unique Adaptation to Growth under Low-Light Conditions

    PubMed Central

    2015-01-01

    Rhodopin, rhodopinal, and their glucoside derivatives are carotenoids that accumulate in different amounts in the photosynthetic bacterium, Rhodoblastus (Rbl.) acidophilus strain 7050, depending on the intensity of the light under which the organism is grown. The different growth conditions also have a profound effect on the spectra of the bacteriochlorophyll (BChl) pigments that assemble in the major LH2 light-harvesting pigment–protein complex. Under high-light conditions the well-characterized B800-850 LH2 complex is formed and accumulates rhodopin and rhodopin glucoside as the primary carotenoids. Under low-light conditions, a variant LH2, denoted B800-820, is formed, and rhodopinal and rhodopinal glucoside are the most abundant carotenoids. The present investigation compares and contrasts the spectral properties and dynamics of the excited states of rhodopin and rhodopinal in solution. In addition, the systematic differences in pigment composition and structure of the chromophores in the LH2 complexes provide an opportunity to explore the effect of these factors on the rate and efficiency of carotenoid-to-BChl energy transfer. It is found that the enzymatic conversion of rhodopin to rhodopinal by Rbl. acidophilus 7050 grown under low-light conditions results in nearly 100% carotenoid-to-BChl energy transfer efficiency in the LH2 complex. This comparative analysis provides insight into how photosynthetic systems are able to adapt and survive under challenging environmental conditions. PMID:25171303

  18. High efficiency light harvesting by carotenoids in the LH2 complex from photosynthetic bacteria: unique adaptation to growth under low-light conditions.

    PubMed

    Magdaong, Nikki M; LaFountain, Amy M; Greco, Jordan A; Gardiner, Alastair T; Carey, Anne-Marie; Cogdell, Richard J; Gibson, George N; Birge, Robert R; Frank, Harry A

    2014-09-25

    Rhodopin, rhodopinal, and their glucoside derivatives are carotenoids that accumulate in different amounts in the photosynthetic bacterium, Rhodoblastus (Rbl.) acidophilus strain 7050, depending on the intensity of the light under which the organism is grown. The different growth conditions also have a profound effect on the spectra of the bacteriochlorophyll (BChl) pigments that assemble in the major LH2 light-harvesting pigment-protein complex. Under high-light conditions the well-characterized B800-850 LH2 complex is formed and accumulates rhodopin and rhodopin glucoside as the primary carotenoids. Under low-light conditions, a variant LH2, denoted B800-820, is formed, and rhodopinal and rhodopinal glucoside are the most abundant carotenoids. The present investigation compares and contrasts the spectral properties and dynamics of the excited states of rhodopin and rhodopinal in solution. In addition, the systematic differences in pigment composition and structure of the chromophores in the LH2 complexes provide an opportunity to explore the effect of these factors on the rate and efficiency of carotenoid-to-BChl energy transfer. It is found that the enzymatic conversion of rhodopin to rhodopinal by Rbl. acidophilus 7050 grown under low-light conditions results in nearly 100% carotenoid-to-BChl energy transfer efficiency in the LH2 complex. This comparative analysis provides insight into how photosynthetic systems are able to adapt and survive under challenging environmental conditions.

  19. (Per)Chlorate-Reducing Bacteria Can Utilize Aerobic and Anaerobic Pathways of Aromatic Degradation with (Per)Chlorate as an Electron Acceptor

    PubMed Central

    Carlström, Charlotte I.; Loutey, Dana; Bauer, Stefan; Clark, Iain C.; Rohde, Robert A.; Iavarone, Anthony T.; Lucas, Lauren

    2015-01-01

    ABSTRACT The pathways involved in aromatic compound oxidation under perchlorate and chlorate [collectively known as (per)chlorate]-reducing conditions are poorly understood. Previous studies suggest that these are oxygenase-dependent pathways involving O2 biogenically produced during (per)chlorate respiration. Recently, we described Sedimenticola selenatireducens CUZ and Dechloromarinus chlorophilus NSS, which oxidized phenylacetate and benzoate, two key intermediates in aromatic compound catabolism, coupled to the reduction of perchlorate or chlorate, respectively, and nitrate. While strain CUZ also oxidized benzoate and phenylacetate with oxygen as an electron acceptor, strain NSS oxidized only the latter, even at a very low oxygen concentration (1%, vol/vol). Strains CUZ and NSS contain similar genes for both the anaerobic and aerobic-hybrid pathways of benzoate and phenylacetate degradation; however, the key genes (paaABCD) encoding the epoxidase of the aerobic-hybrid phenylacetate pathway were not found in either genome. By using transcriptomics and proteomics, as well as by monitoring metabolic intermediates, we investigated the utilization of the anaerobic and aerobic-hybrid pathways on different electron acceptors. For strain CUZ, the results indicated utilization of the anaerobic pathways with perchlorate and nitrate as electron acceptors and of the aerobic-hybrid pathways in the presence of oxygen. In contrast, proteomic results suggest that strain NSS may use a combination of the anaerobic and aerobic-hybrid pathways when growing on phenylacetate with chlorate. Though microbial (per)chlorate reduction produces molecular oxygen through the dismutation of chlorite (ClO2−), this study demonstrates that anaerobic pathways for the degradation of aromatics can still be utilized by these novel organisms. PMID:25805732

  20. On the biphoton excitation of the fluorescence of the bacteriochlorophyll molecules of purple photosynthetic bacteria by powerful near IR femto-picosecond pulses

    SciTech Connect

    Borisov, A. Yu.

    2011-11-15

    The authors of a number of experimental works detected nonresonance biphoton excitation of bacteriochlorophyll molecules, which represent the main pigment in the light-absorbing natural 'antenna' complexes of photosynthesizing purple bacteria, by femtosecond IR pulses (1250-1500 nm). They believe that IR quanta excite hypothetic forbidden levels of the pigments of these bacteria in the double frequency range 625-750 nm. We propose and ground an alternative triplet mechanism to describe this phenomenon. According to our hypothesis, the mechanism of biphoton excitation of molecules by IR quanta can manifest itself specifically, through high triplet levels of molecules in the high fields induced by femtosecond-picosecond laser pulses.

  1. Aerobic microbial enhanced oil recovery

    SciTech Connect

    Torsvik, T.; Gilje, E.; Sunde, E.

    1995-12-31

    In aerobic MEOR, the ability of oil-degrading bacteria to mobilize oil is used to increase oil recovery. In this process, oxygen and mineral nutrients are injected into the oil reservoir in order to stimulate growth of aerobic oil-degrading bacteria in the reservoir. Experiments carried out in a model sandstone with stock tank oil and bacteria isolated from offshore wells showed that residual oil saturation was lowered from 27% to 3%. The process was time dependent, not pore volume dependent. During MEOR flooding, the relative permeability of water was lowered. Oxygen and active bacteria were needed for the process to take place. Maximum efficiency was reached at low oxygen concentrations, approximately 1 mg O{sub 2}/liter.

  2. Evidence for a cysteine-mediated mechanism of excitation energy regulation in a photosynthetic antenna complex.

    PubMed

    Orf, Gregory S; Saer, Rafael G; Niedzwiedzki, Dariusz M; Zhang, Hao; McIntosh, Chelsea L; Schultz, Jason W; Mirica, Liviu M; Blankenship, Robert E

    2016-08-01

    Light-harvesting antenna complexes not only aid in the capture of solar energy for photosynthesis, but regulate the quantity of transferred energy as well. Light-harvesting regulation is important for protecting reaction center complexes from overexcitation, generation of reactive oxygen species, and metabolic overload. Usually, this regulation is controlled by the association of light-harvesting antennas with accessory quenchers such as carotenoids. One antenna complex, the Fenna-Matthews-Olson (FMO) antenna protein from green sulfur bacteria, completely lacks carotenoids and other known accessory quenchers. Nonetheless, the FMO protein is able to quench energy transfer in aerobic conditions effectively, indicating a previously unidentified type of regulatory mechanism. Through de novo sequencing MS, chemical modification, and mutagenesis, we have pinpointed the source of the quenching action to cysteine residues (Cys49 and Cys353) situated near two low-energy bacteriochlorophylls in the FMO protein from Chlorobaculum tepidum Removal of these cysteines (particularly removal of the completely conserved Cys353) through N-ethylmaleimide modification or mutagenesis to alanine abolishes the aerobic quenching effect. Electrochemical analysis and electron paramagnetic resonance spectra suggest that in aerobic conditions the cysteine thiols are converted to thiyl radicals which then are capable of quenching bacteriochlorophyll excited states through electron transfer photochemistry. This simple mechanism has implications for the design of bio-inspired light-harvesting antennas and the redesign of natural photosynthetic systems. PMID:27335466

  3. Photosynthetic reaction center complexes from heliobacteria

    NASA Technical Reports Server (NTRS)

    Trost, J. T.; Vermaas, W. F. J.; Blankenship, R. E.

    1991-01-01

    Photosynthetic reaction centers are pigment-protein complexes that are responsible for the transduction of light energy into chemical energy. Considerable evidence indicates that photosynthetic organisms were present very early in the evolution of life on Earth. The goal of this project is to understand the early evolutionary development of photosynthesis by examining the properties of reaction centers isolated from certain contemporary organisms that appear to contain the simplest photosynthetic reaction centers. The major focus is on the family of newly discovered strictly anaerobic photosynthetic organisms that are grouped with the gram-positive phylum of bacteria. The properties of these reactions centers suggest that they may be the descendants of an ancestor that also gave rise to Photosystem 1 found in oxygen-evolving photosynthetic organisms. Photoactive reaction center-core antenna complexes were isolated from the photosynthetic bacteria, Heliobacillus mobilis and Heliobacterium gestii, by extraction of membranes with Deriphat 160C followed by differential centrifugation and sucrose density gradient centrifugation. Other aspects of this investigation are briefly discussed.

  4. A Rapid Method for the Extraction and Analysis of Carotenoids and Other Hydrophobic Substances Suitable for Systems Biology Studies with Photosynthetic Bacteria

    PubMed Central

    Bóna-Lovász, Judit; Bóna, Aron; Ederer, Michael; Sawodny, Oliver; Ghosh, Robin

    2013-01-01

    A simple, rapid, and inexpensive extraction method for carotenoids and other non-polar compounds present in phototrophic bacteria has been developed. The method, which has been extensively tested on the phototrophic purple non-sulphur bacterium Rhodospirillum rubrum, is suitable for extracting large numbers of samples, which is common in systems biology studies, and yields material suitable for subsequent analysis using HPLC and mass spectroscopy. The procedure is particularly suitable for carotenoids and other terpenoids, including quinones, bacteriochlorophyll a and bacteriopheophytin a, and is also useful for the analysis of polar phospholipids. The extraction procedure requires only a single step extraction with a hexane/methanol/water mixture, followed by HPLC using a Spherisorb C18 column, with a mobile phase consisting of acetone-water and a non-linear gradient of 50%–100% acetone. The method was employed for examining the carotenoid composition observed during microaerophilic growth of R. rubrum strains, and was able to determine 18 carotenoids, 4 isoprenoid-quinones, bacteriochlorophyll a and bacteriopheophytin a as well as four different phosphatidylglycerol species of different acyl chain compositions. The analytical procedure was used to examine the dynamics of carotenoid biosynthesis in the major and minor pathways operating simultaneously in a carotenoid biosynthesis mutant of R. rubrum. PMID:24958257

  5. A rapid method for the extraction and analysis of carotenoids and other hydrophobic substances suitable for systems biology studies with photosynthetic bacteria.

    PubMed

    Bóna-Lovász, Judit; Bóna, Aron; Ederer, Michael; Sawodny, Oliver; Ghosh, Robin

    2013-01-01

    A simple, rapid, and inexpensive extraction method for carotenoids and other non-polar compounds present in phototrophic bacteria has been developed. The method, which has been extensively tested on the phototrophic purple non-sulphur bacterium Rhodospirillum rubrum, is suitable for extracting large numbers of samples, which is common in systems biology studies, and yields material suitable for subsequent analysis using HPLC and mass spectroscopy. The procedure is particularly suitable for carotenoids and other terpenoids, including quinones, bacteriochlorophyll a and bacteriopheophytin a, and is also useful for the analysis of polar phospholipids. The extraction procedure requires only a single step extraction with a hexane/methanol/water mixture, followed by HPLC using a Spherisorb C18 column, with a mobile phase consisting of acetone-water and a non-linear gradient of 50%-100% acetone. The method was employed for examining the carotenoid composition observed during microaerophilic growth of R. rubrum strains, and was able to determine 18 carotenoids, 4 isoprenoid-quinones, bacteriochlorophyll a and bacteriopheophytin a as well as four different phosphatidylglycerol species of different acyl chain compositions. The analytical procedure was used to examine the dynamics of carotenoid biosynthesis in the major and minor pathways operating simultaneously in a carotenoid biosynthesis mutant of R. rubrum. PMID:24958257

  6. Isolation and characterization of heterotrophic bacteria able to grow aerobically with quaternary ammonium alcohols as sole source of carbon and nitrogen.

    PubMed

    Kaech, Andres; Vallotton, Nathalie; Egli, Thomas

    2005-04-01

    The quaternary ammonium alcohols (QAAs) 2,3-dihydroxypropyl-trimethyl-ammonium (TM), dimethyl-diethanol-ammonium (DM) and methyl-triethanol-ammonium (MM) are hydrolysis products of their parent esterquat surfactants, which are widely used as softeners in fabric care. We isolated several bacteria growing with QAAs as the sole source of carbon and nitrogen. The strains were compared with a previously isolated TM-degrading bacterium, which was identified as a representative of the species Pseudomonas putida (Syst. Appl. Microbiol. 24 (2001) 252). Two bacteria were isolated with DM, referred to as strains DM 1 and DM 2, respectively. Based on 16S-rDNA analysis, they provided 97% (DM 1) and 98% (DM 2) identities to the closest related strain Zoogloea ramigera Itzigsohn 1868AL. Both strains were long, slim, motile rods but only DM 1 showed the floc forming activity, which is typical for representatives of the genus Zoogloea. Using MM we isolated a Gram-negative, non-motile rod referred to as strain MM 1. The 16S-rDNA sequence of the isolated bacterium revealed 94% identities (best match) to Rhodobacter sphaeroides only. The strains MM 1 and DM 1 exclusively grew with the QAA which was used for their isolation. DM 2 was also utilizing TM as sole source of carbon and nitrogen. However, all of the isolated bacteria were growing with the natural and structurally related compound choline. PMID:15900970

  7. Isolation, Characterization, and Polyaromatic Hydrocarbon Degradation Potential of Aerobic Bacteria from Marine Macrofaunal Burrow Sediments and Description of Lutibacterium anuloederans gen. nov., sp. nov., and Cycloclasticus spirillensus sp. nov.†

    PubMed Central

    Chung, W. K.; King, G. M.

    2001-01-01

    Two new polyaromatic hydrocarbon-degrading marine bacteria have been isolated from burrow wall sediments of benthic macrofauna by using enrichments on phenanthrene. Strain LC8 (from a polychaete) and strain M4-6 (from a mollusc) are aerobic and gram negative and require sodium chloride (>1%) for growth. Both strains can use 2- and 3-ring polycyclic aromatic hydrocarbons as their sole carbon and energy sources, but they are nutritionally versatile. Physiological and phylogenetic analyses based on 16S ribosomal DNA sequences suggest that strain M4-6 belongs to the genus Cycloclasticus and represents a new species, Cycloclasticus spirillensus sp. nov. Strain LC8 appears to represent a new genus and species, Lutibacterium anuloederans gen. nov., sp. nov., within the Sphingomonadaceae. However, when inoculated into sediment slurries with or without exogenous phenanthrene, only L. anuloederans appeared to sustain a significant phenanthrene uptake potential throughout a 35-day incubation. In addition, only L. anuloederans appeared to enhance phenanthrene degradation in heavily contaminated sediment from Little Mystic Cove, Boston Harbor, Boston, Mass. PMID:11722910

  8. Photosynthetic reaction center complexes from heliobacteria

    NASA Technical Reports Server (NTRS)

    Trost, J. T.; Vermaas, W. F. J.; Blankenship, R. E.

    1991-01-01

    The goal of this project is to understand the early evolutionary development of photosynthesis by examining the properties of reaction centers isolated from certain contemporary organisms that appear to contain the simplest photosynthetic reaction centers. The major focus of this project is the family of newly discovered strictly anaerobic photosynthetic organisms known as Heliobacteria. These organisms are the only known photosynthetic organisms that are grouped with the gram-positive phylum of bacteria. The properties of these reaction centers suggest that they might be the decendants of an ancestor that also gave rise to Photosystem 1 found in oxygen-evolving photosynthetic organisms. Photoactive reaction center-core antenna complexes have been isolated from the photosynthetic bacteria Heliobacillus mobilis and Heliobacterium gestii. The absorption and fluorescence properties of membranes and reaction centers are almost identical, suggesting that a single pigment-protein complex serves as both antenna and reaction center. Experiments in progress include sequence determination of the 48,000 Mr reaction center protein, and evolutionary comparisons with other reaction center proteins.

  9. Influence of an aerobic fungus grown on solid culture on ruminal degradability and on a mixture culture of anaerobic cellulolytic bacteria.

    PubMed

    Hernández-Díaz, R; Pimentel-González, D J; Figueira, A C; Viniegra-González, G; Campos-Montiel, R G

    2010-06-01

    In this work, the effect of a solid fungal culture of Aspergillus niger (An) grown on coffee pulp on the in situ ruminal degradability (RD) of corn stover was evaluated. In addition, the effect of its extracts on the in vitro dry matter disappearance (IVDMD) and on a mixed culture of anaerobic cellulolytic bacteria (MCACB) was also investigated. The solid ferment was a crude culture of An, grown on coffee pulp. Regarding in situ RD, a significant difference (p < 0.05) was found between treatment with 200 g/day of the solid culture and control (no solid culture added) on dry matter, crude protein and neutral detergent fibre on RD. All the water extracts (pH 4, 7 and 10) enhanced IVDMD and stimulated the cellulolytic activity on a MCACB. Ultrafiltration results showed that active compounds with a molecular weight lower than 30 kDa were responsible for the effect on MCACB. Such results suggest that the effects of the solid An culture in RD are related to the presence of water soluble compounds having a molecular weight lower than 30 kDa.

  10. Natural hot spots for gain of multiple resistances: arsenic and antibiotic resistances in heterotrophic, aerobic bacteria from marine hydrothermal vent fields.

    PubMed

    Farias, Pedro; Espírito Santo, Christophe; Branco, Rita; Francisco, Romeu; Santos, Susana; Hansen, Lars; Sorensen, Soren; Morais, Paula V

    2015-04-01

    Microorganisms are responsible for multiple antibiotic resistances that have been associated with resistance/tolerance to heavy metals, with consequences to public health. Many genes conferring these resistances are located on mobile genetic elements, easily exchanged among phylogenetically distant bacteria. The objective of the present work was to isolate arsenic-, antimonite-, and antibiotic-resistant strains and to determine the existence of plasmids harboring antibiotic/arsenic/antimonite resistance traits in phenotypically resistant strains, in a nonanthropogenically impacted environment. The hydrothermal Lucky Strike field in the Azores archipelago (North Atlantic, between 11°N and 38°N), at the Mid-Atlantic Ridge, protected under the OSPAR Convention, was sampled as a metal-rich pristine environment. A total of 35 strains from 8 different species were isolated in the presence of arsenate, arsenite, and antimonite. ACR3 and arsB genes were amplified from the sediment's total DNA, and 4 isolates also carried ACR3 genes. Phenotypic multiple resistances were found in all strains, and 7 strains had recoverable plasmids. Purified plasmids were sequenced by Illumina and assembled by EDENA V3, and contig annotation was performed using the "Rapid Annotation using the Subsystems Technology" server. Determinants of resistance to copper, zinc, cadmium, cobalt, and chromium as well as to the antibiotics β-lactams and fluoroquinolones were found in the 3 sequenced plasmids. Genes coding for heavy metal resistance and antibiotic resistance in the same mobile element were found, suggesting the possibility of horizontal gene transfer and distribution of theses resistances in the bacterial population. PMID:25636836

  11. Natural Hot Spots for Gain of Multiple Resistances: Arsenic and Antibiotic Resistances in Heterotrophic, Aerobic Bacteria from Marine Hydrothermal Vent Fields

    PubMed Central

    Farias, Pedro; Espírito Santo, Christophe; Branco, Rita; Francisco, Romeu; Santos, Susana; Hansen, Lars; Sorensen, Soren

    2015-01-01

    Microorganisms are responsible for multiple antibiotic resistances that have been associated with resistance/tolerance to heavy metals, with consequences to public health. Many genes conferring these resistances are located on mobile genetic elements, easily exchanged among phylogenetically distant bacteria. The objective of the present work was to isolate arsenic-, antimonite-, and antibiotic-resistant strains and to determine the existence of plasmids harboring antibiotic/arsenic/antimonite resistance traits in phenotypically resistant strains, in a nonanthropogenically impacted environment. The hydrothermal Lucky Strike field in the Azores archipelago (North Atlantic, between 11°N and 38°N), at the Mid-Atlantic Ridge, protected under the OSPAR Convention, was sampled as a metal-rich pristine environment. A total of 35 strains from 8 different species were isolated in the presence of arsenate, arsenite, and antimonite. ACR3 and arsB genes were amplified from the sediment's total DNA, and 4 isolates also carried ACR3 genes. Phenotypic multiple resistances were found in all strains, and 7 strains had recoverable plasmids. Purified plasmids were sequenced by Illumina and assembled by EDENA V3, and contig annotation was performed using the “Rapid Annotation using the Subsystems Technology” server. Determinants of resistance to copper, zinc, cadmium, cobalt, and chromium as well as to the antibiotics β-lactams and fluoroquinolones were found in the 3 sequenced plasmids. Genes coding for heavy metal resistance and antibiotic resistance in the same mobile element were found, suggesting the possibility of horizontal gene transfer and distribution of theses resistances in the bacterial population. PMID:25636836

  12. (Carbon monoxide metabolism by photosynthetic bacteria)

    SciTech Connect

    Not Available

    1989-01-01

    Research continued on the metabolism of carbon monoxide by Rhodospirillum rubrum. This report discusses progress on the activity, induction, inhibition, and spectroscopic analysis of the enzyme Carbon Monoxide Dehydrogenase. (CBS)

  13. Anaerobic bacteria in otitis media.

    PubMed

    Fulghum, R S; Daniel, H J; Yarborough, J G

    1977-01-01

    Anaerobic bacteria, Peptostrepotococcus intermedius and Propionibacterium acnes, were found in mixed culture specimens from four to ten tested cases of chronic secretory otitis media. These anaerobic bacteria were in a mixed infection flora with aerobic bacteria most often Staphylococcus epidermidis and Cornybacterium sp. which do not fit any established species. The findings of anaerobic bacteria in otitis media is consistent with the sporadic report of the involvement of anaerobic bacteria in otitis media in the literature since 1898.

  14. Melatonin immunoreactivity in the photosynthetic prokaryote Rhodospirillum rubrum: implications for an ancient antioxidant system.

    PubMed

    Manchester, L C; Poeggeler, B; Alvares, F L; Ogden, G B; Reiter, R J

    1995-01-01

    Rhodospirillum rubrum is a spiral anoxygenic photosynthetic bacterium that can exist under either aerobic or anaerobic conditions. The organism thrives in the presence of light or complete darkness and represents one of the oldest species of living organisms, possibly 2-3.5 billion years old. The success of this prokaryotic species may be attributed to the evolution of certain indole compounds that offer protection against life-threatening oxygen radicals produced by an evolutionary harsh environment. Melatonin, N-acetyl-5-methoxytryptamine, is an indolic highly conserved molecule that exists in protists, plants, and animals. This study was undertaken to determine the presence of an immunoreactive melatonin in the kingdom Monera and particularly in the photosynthetic bacterium, R. rubrum, under conditions of prolonged darkness or prolonged light. Immunoreactive melatonin was measured during both the extended day and extended night. Significantly more melatonin was observed during the scotophase than the photophase. This study marks the first demonstration of melatonin in a bacterium. The high level of melatonin observed in bacteria may provide on-site protection of bacterial DNA against free radical attack.

  15. Summary report on the aerobic degradation of diesel fuel and the degradation of toluene under aerobic, denitrifying and sulfate reducing conditions

    SciTech Connect

    Coyne, P.; Smith, G.

    1995-08-15

    This report contains a number of studies that were performed to better understand the technology of the biodegradation of petroleum hydrocarbons. Topics of investigation include the following: diesel fuel degradation by Rhodococcus erythropolis; BTEX degradation by soil isolates; aerobic degradation of diesel fuel-respirometry; aerobic degradation of diesel fuel-shake culture; aerobic toluene degradation by A3; effect of HEPES, B1, and myo-inositol addition on the growth of A3; aerobic and anaerobic toluene degradation by contaminated soils; denitrifying bacteria MPNs; sulfate-reducing bacteria MPNs; and aerobic, DNB and SRB enrichments.

  16. Photosynthetic water splitting

    SciTech Connect

    Greenbaum, E.

    1981-01-01

    The photosynthetic unit of hydrogen evolution, the turnover time of photosynthetic hydrogen production, and hydrogenic photosynthesis are discussed in the section on previous work. Recent results are given on simultaneous photoproduction of hydrogen and oxygen, kinetic studies, microscopic marine algae-seaweeds, and oxygen profiles.

  17. Oxygen concentration inside a functioning photosynthetic cell.

    PubMed

    Kihara, Shigeharu; Hartzler, Daniel A; Savikhin, Sergei

    2014-05-01

    The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth's atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere.

  18. Teaching Aerobic Fitness Concepts.

    ERIC Educational Resources Information Center

    Sander, Allan N.; Ratliffe, Tom

    2002-01-01

    Discusses how to teach aerobic fitness concepts to elementary students. Some of the K-2 activities include location, size, and purpose of the heart and lungs; the exercise pulse; respiration rate; and activities to measure aerobic endurance. Some of the 3-6 activities include: definition of aerobic endurance; heart disease risk factors;…

  19. Mutagenicity of anaerobic fenitrothion metabolites after aerobic biodegradation.

    PubMed

    Matsushita, Taku; Matsui, Yoshihiko; Saeki, Ryo; Inoue, Takanobu

    2005-12-01

    Previous studies have revealed that the mutagenicity of fenitrothion increases during anaerobic biodegradation, suggesting that this insecticide's mutagenicity could effectively increase after it pollutes anaerobic environments such as lake sediments. To investigate possible changes to the mutagenicity of fenitrothion under aerobic conditions after it had already been increased by anaerobic biodegradation, batch incubation cultures were maintained under aerobic conditions. The mutagenicity, which had increased during anaerobic biodegradation, decreased under aerobic conditions with aerobic or facultative bacteria, but did not disappear completely in 22 days. In contrast, it did not change under aerobic conditions without bacteria or under continued anaerobic conditions. These observations suggest that the mutagenicity of anaerobically metabolized fenitrothion would not necessarily decrease after it arrives in an aerobic environment: this would depend on the presence of suitable bacteria. Therefore, fenitrothion-derived mutagenic compounds may pollute the water environment, including our drinking water sources, after accidental pollution of aerobic waters. Although amino-fenitrothion generated during anaerobic biodegradation of fenitrothion was the principal mutagen, non-trivial contributions of other, unidentified metabolites to the mutagenicity were also observed. PMID:16263383

  20. Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

    NASA Astrophysics Data System (ADS)

    Megonigal, J. P.; Hines, M. E.; Visscher, P. T.

    2003-12-01

    Life evolved and flourished in the absence of molecular oxygen (O2). As the O2 content of the atmosphere rose to the present level of 21% beginning about two billion years ago, anaerobic metabolism was gradually supplanted by aerobic metabolism. Anaerobic environments have persisted on Earth despite the transformation to an oxidized state because of the combined influence of water and organic matter. Molecular oxygen diffuses about 104 times more slowly through water than air, and organic matter supports a large biotic O2 demand that consumes the supply faster than it is replaced by diffusion. Such conditions exist in wetlands, rivers, estuaries, coastal marine sediments, aquifers, anoxic water columns, sewage digesters, landfills, the intestinal tracts of animals, and the rumen of herbivores. Anaerobic microsites are also embedded in oxic environments such as upland soils and marine water columns. Appreciable rates of aerobic respiration are restricted to areas that are in direct contact with air or those inhabited by organisms that produce O2.Rising atmospheric O2 reduced the global area of anaerobic habitat, but enhanced the overall rate of anaerobic metabolism (at least on an area basis) by increasing the supply of electron donors and acceptors. Organic carbon production increased dramatically, as did oxidized forms of nitrogen, manganese, iron, sulfur, and many other elements. In contemporary anaerobic ecosystems, nearly all of the reducing power is derived from photosynthesis, and most of it eventually returns to O2, the most electronegative electron acceptor that is abundant. This photosynthetically driven redox gradient has been thoroughly exploited by aerobic and anaerobic microorganisms for metabolism. The same is true of hydrothermal vents (Tunnicliffe, 1992) and some deep subsurface environments ( Chapelle et al., 2002), where thermal energy is the ultimate source of the reducing power.Although anaerobic habitats are currently a small fraction of Earth

  1. Photosynthetic CO{sub 2} fixation and energy production - microalgae as a main subject

    SciTech Connect

    Asada, Yasuo

    1993-12-31

    Research activities for application of microalgal photosynthesis to CO{sub 2} fixation in Japan are overviewed. Presenter`s studies on energy (hydrogen gas) production by cyanobacteria (blue-green algae) and photosynthetic bacteria are also introduced.

  2. Nuclear quantum beats observed from photosynthetic charge separation

    SciTech Connect

    Weber, S.; Werst, M.; Thurnauer, M.

    1995-12-31

    In natural photosynthesis, efficient photoinduced charge-separation is achieved because of the unique structural and energetic relationships between the co-factors involved in this process. In turn, these unique properties give rise to unusual magnetic resonance responses when monitoring the charge-separation process with time-resolved electron paramagnetic resonance (epr). We have observed (at low temperatures) photo-induced low frequency oscillations in the transient epr responses from cyanobacterial Photosystem I (PSI) and pure photosynthetic bacteria. By comparing the signals from fully deuterated photosynthetic material having {sup 14}N or {sup 15}N we have identified these oscillations as nuclear quantum beats associated with the non-adiabatic change of the spin Hamiltonian at the instant of the laser pulse. The nuclear quantum beats can provide details of the electronic structures of the photo-oxidized primary electron donors in PSI and purple photosynthetic bacteria.

  3. Aerobic Conditioning Class.

    ERIC Educational Resources Information Center

    Johnson, Neil R.

    1980-01-01

    An aerobic exercise class that focuses on the conditioning of the cardiovascular and muscular systems is presented. Students complete data cards on heart rate, pulse, and exercises to be completed during the forty minute course. (CJ)

  4. Evolution of heliobacteria: implications for photosynthetic reaction center complexes

    NASA Technical Reports Server (NTRS)

    Vermaas, W. F.; Blankenship, R. E. (Principal Investigator)

    1994-01-01

    The evolutionary position of the heliobacteria, a group of green photosynthetic bacteria with a photosynthetic apparatus functionally resembling Photosystem I of plants and cyanobacteria, has been investigated with respect to the evolutionary relationship to Gram-positive bacteria and cyanobacteria. On the basis of 16S rRNA sequence analysis, the heliobacteria appear to be most closely related to Gram-positive bacteria, but also an evolutionary link to cyanobacteria is evident. Interestingly, a 46-residue domain including the putative sixth membrane-spanning region of the heliobacterial reaction center protein show rather strong similarity (33% identity and 72% similarity) to a region including the sixth membrane-spanning region of the CP47 protein, a chlorophyll-binding core antenna polypeptide of Photosystem II. The N-terminal half of the heliobacterial reaction center polypeptide shows a moderate sequence similarity (22% identity over 232 residues) with the CP47 protein, which is significantly more than the similarity with the Photosystem I core polypeptides in this region. An evolutionary model for photosynthetic reaction center complexes is discussed, in which an ancestral homodimeric reaction center protein (possibly resembling the heliobacterial reaction center protein) with 11 membrane-spanning regions per polypeptide has diverged to give rise to the core of Photosystem I, Photosystem II, and of the photosynthetic apparatus in green, purple, and heliobacteria.

  5. Production of bioplastics and hydrogen gas by photosynthetic microorganisms

    NASA Astrophysics Data System (ADS)

    Yasuo, Asada; Masato, Miyake; Jun, Miyake

    1998-03-01

    Our efforts have been aimed at the technological basis of photosynthetic-microbial production of materials and an energy carrier. We report here accumulation of poly-(3-hydroxybutyrate) (PHB), a raw material of biodegradable plastics and for production of hydrogen gas, and a renewable energy carrier by photosynthetic microorganisms (tentatively defined as cyanobacteria plus photosynthetic bateria, in this report). A thermophilic cyanobacterium, Synechococcus sp. MA19 that accumulates PHB at more than 20% of cell dry wt under nitrogen-starved conditions was isolated and microbiologically identified. The mechanism of PHB accumulation was studied. A mesophilic Synechococcus PCC7942 was transformed with the genes encoding PHB-synthesizing enzymes from Alcaligenes eutrophus. The transformant accumulated PHB under nitrogen-starved conditions. The optimal conditions for PHB accumulation by a photosynthetic bacterium grown on acetate were studied. Hydrogen production by photosynthetic microorganisms was studied. Cyanobacteria can produce hydrogen gas by nitrogenase or hydrogenase. Hydrogen production mediated by native hydrogenase in cyanobacteria was revealed to be in the dark anaerobic degradation of intracellular glycogen. A new system for light-dependent hydrogen production was targeted. In vitro and in vivo coupling of cyanobacterial ferredoxin with a heterologous hydrogenase was shown to produce hydrogen under light conditions. A trial for genetic trasformation of Synechococcus PCC7942 with the hydrogenase gene from Clostridium pasteurianum is going on. The strong hydrogen producers among photosynthetic bacteria were isolated and characterized. Co-culture of Rhodobacter and Clostriumdium was applied to produce hydrogen from glucose. Conversely in the case of cyanobacteria, genetic regulation of photosynthetic proteins was intended to improve conversion efficiency in hydrogen production by the photosynthetic bacterium, Rhodobacter sphaeroides RV. A mutant acquired by

  6. Sulfate-Reducing Bacteria and Their Activities in Cyanobacterial Mats of Solar Lake (Sinai, Egypt)

    PubMed Central

    Teske, Andreas; Ramsing, Niels B.; Habicht, Kirsten; Fukui, Manabu; Küver, Jan; Jørgensen, Bo Barker; Cohen, Yehuda

    1998-01-01

    The sulfate-reducing bacteria within the surface layer of the hypersaline cyanobacterial mat of Solar Lake (Sinai, Egypt) were investigated with combined microbiological, molecular, and biogeochemical approaches. The diurnally oxic surface layer contained between 106 and 107 cultivable sulfate-reducing bacteria ml−1 and showed sulfate reduction rates between 1,000 and 2,200 nmol ml−1 day−1, both in the same range as and sometimes higher than those in anaerobic deeper mat layers. In the oxic surface layer and in the mat layers below, filamentous sulfate-reducing Desulfonema bacteria were found in variable densities of 104 to 106 cells ml−1. A Desulfonema-related, diurnally migrating bacterium was detected with PCR and denaturing gradient gel electrophoresis within and below the oxic surface layer. Facultative aerobic respiration, filamentous morphology, motility, diurnal migration, and aggregate formation were the most conspicuous adaptations of Solar Lake sulfate-reducing bacteria to the mat matrix and to diurnal oxygen stress. A comparison of sulfate reduction rates within the mat and previously published photosynthesis rates showed that CO2 from sulfate reduction in the upper 5 mm accounted for 7 to 8% of the total photosynthetic CO2 demand of the mat. PMID:9687455

  7. Sulfate-reducing bacteria and their activities in cyanobacterial mats of Solar Lake (Sinai, Egypt)

    SciTech Connect

    Teske, A.; Ramsing, N.B.; Habicht, K.; Kuever, J.; Joergensen, B.B.; Fukui, Manabu; Cohen, Y.

    1998-08-01

    The sulfate-reducing bacteria within the surface layer of the hypersaline cyanobacterial mat of Solar Lake (Sinai, Egypt) were investigated with combined microbiological, molecular, and biogeochemical approaches. The diurnally oxic surface layer contained between 10{sup 6} and 10{sup 7} cultivable sulfate-reducing bacteria ml{sup {minus}1} day{sup {minus}1}, both in the same range as and sometimes higher than those in anaerobic deeper mat layers. In the oxic surface layer and in the mat layers below, filamentous sulfate-reducing Desulfonema bacteria were found in variable densities of 10{sup 4} and 10{sup 6} cells ml{sup {minus}1}. A Desulfonema-related, diurnally migrating bacterium was detected with PCR and denaturing gradient gel electrophoresis within and below the oxic surface layer. Facultative aerobic respiration, filamentous morphology, motility, diurnal migration, and aggregate formation were the most conspicuous adaptations of Solar Lake sulfate-reducing bacteria to the mat matrix and to diurnal oxygen stress. A comparison of sulfate reduction rates within the mat and previously published photosynthesis rates showed that CO{sub 2} from sulfate reduction in the upper 5 mm accounted for 7 to 8% of the total photosynthetic CO{sub 2} demand of the mat.

  8. Sulfate-reducing bacteria and their activities in cyanobacterial mats of solar lake (Sinai, Egypt).

    PubMed

    Teske, A; Ramsing, N B; Habicht, K; Fukui, M; Küver, J; Jørgensen, B B; Cohen, Y

    1998-08-01

    The sulfate-reducing bacteria within the surface layer of the hypersaline cyanobacterial mat of Solar Lake (Sinai, Egypt) were investigated with combined microbiological, molecular, and biogeochemical approaches. The diurnally oxic surface layer contained between 10(6) and 10(7) cultivable sulfate-reducing bacteria ml-1 and showed sulfate reduction rates between 1,000 and 2, 200 nmol ml-1 day-1, both in the same range as and sometimes higher than those in anaerobic deeper mat layers. In the oxic surface layer and in the mat layers below, filamentous sulfate-reducing Desulfonema bacteria were found in variable densities of 10(4) to 10(6) cells ml-1. A Desulfonema-related, diurnally migrating bacterium was detected with PCR and denaturing gradient gel electrophoresis within and below the oxic surface layer. Facultative aerobic respiration, filamentous morphology, motility, diurnal migration, and aggregate formation were the most conspicuous adaptations of Solar Lake sulfate-reducing bacteria to the mat matrix and to diurnal oxygen stress. A comparison of sulfate reduction rates within the mat and previously published photosynthesis rates showed that CO2 from sulfate reduction in the upper 5 mm accounted for 7 to 8% of the total photosynthetic CO2 demand of the mat. PMID:9687455

  9. Photosynthetic Pigments in Diatoms

    PubMed Central

    Kuczynska, Paulina; Jemiola-Rzeminska, Malgorzata; Strzalka, Kazimierz

    2015-01-01

    Photosynthetic pigments are bioactive compounds of great importance for the food, cosmetic, and pharmaceutical industries. They are not only responsible for capturing solar energy to carry out photosynthesis, but also play a role in photoprotective processes and display antioxidant activity, all of which contribute to effective biomass and oxygen production. Diatoms are organisms of a distinct pigment composition, substantially different from that present in plants. Apart from light-harvesting pigments such as chlorophyll a, chlorophyll c, and fucoxanthin, there is a group of photoprotective carotenoids which includes β-carotene and the xanthophylls, diatoxanthin, diadinoxanthin, violaxanthin, antheraxanthin, and zeaxanthin, which are engaged in the xanthophyll cycle. Additionally, some intermediate products of biosynthetic pathways have been identified in diatoms as well as unusual pigments, e.g., marennine. Marine algae have become widely recognized as a source of unique bioactive compounds for potential industrial, pharmaceutical, and medical applications. In this review, we summarize current knowledge on diatom photosynthetic pigments complemented by some new insights regarding their physico-chemical properties, biological role, and biosynthetic pathways, as well as the regulation of pigment level in the cell, methods of purification, and significance in industries. PMID:26389924

  10. The Photosynthetic Cycle

    DOE R&D Accomplishments Database

    Calvin, Melvin

    1955-03-21

    A cyclic sequence of transformations, including the carboxylation of RuDP (ribulose diphosphate) and its re-formation, has been deduced as the route for the creation of reduced carbon compounds in photosynthetic organisms. With the demonstration of RuDP as substrate for the carboxylation in a cell-free system, each of the reactions has now been carried out independently in vitro. Further purification of this last enzyme system has confirmed the deduction that the carboxylation of RuDP leads directly to the two molecules of PGA (phosphoglyceric acid) involving an internal dismutation and suggesting the name "carboxydismutase" for the enzyme. As a consequence of this knowledge of each of the steps in the photosynthetic CO{sub 2} reduction cycle, it is possible to define the reagent requirements to maintain it. The net requirement for the reduction of one molecule of CO{sub 2} is four equivalents of [H]and three molecules of ATP (adenine triphosphate). These must ultimately be supplied by the photochemical reaction. Some possible ways in which this may be accomplished are discussed.

  11. Enhanced aerobic nitrifying granulation by static magnetic field.

    PubMed

    Wang, Xin-Hua; Diao, Mu-He; Yang, Ying; Shi, Yi-Jing; Gao, Ming-Ming; Wang, Shu-Guang

    2012-04-01

    One of the main challenging issues for aerobic nitrifying granules in treating high strength ammonia wastewater is the long granulation time required for activated sludge to transform into aerobic granules. The present study provides a novel strategy for enhancing aerobic nitrifying granulation by applying an intensity of 48.0mT static magnetic field. The element analysis showed that the applied magnetic field could promote the accumulation of iron compounds in the sludge. And then the aggregation of iron decreased the full granulation time from 41 to 25days by enhancing the setting properties of granules and stimulating the secretion of extracellular polymeric substances (EPS). Long-term, cycle experiments and fluorescence in-situ hybridization (FISH) analysis proved that an intensity of 48.0mT magnetic field could enhance the activities and growth of nitrite-oxidizing bacteria (NOB). These findings suggest that magnetic field is helpful and reliable for accelerating the aerobic nitrifying granulation.

  12. Dance--Aerobic and Anaerobic.

    ERIC Educational Resources Information Center

    Cohen, Arlette

    1984-01-01

    This article defines and explains aerobic exercise and its effects on the cardiovascular system. Various studies on dancers are cited indicating that dance is an anaerobic activity with some small degree of aerobic benefit. (DF)

  13. Acetic Acid Increases Stability of Silage under Aerobic Conditions

    PubMed Central

    Danner, H.; Holzer, M.; Mayrhuber, E.; Braun, R.

    2003-01-01

    The effects of various compounds on the aerobic stability of silages were evaluated. It has been observed that inoculation of whole-crop maize with homofermentative lactic acid bacteria leads to silages which have low stability against aerobic deterioration, while inoculation with heterofermentative lactic acid bacteria, such as Lactobacillus brevis or Lactobacillus buchneri, increases stability. Acetic acid has been proven to be the sole substance responsible for the increased aerobic stability, and this acid acts as an inhibitor of spoilage organisms. Therefore, stability increases exponentially with acetic acid concentration. Only butyric acid has a similar effect. Other compounds, like lactic acid, 1,2-propanediol, and 1-propanol, have been shown to have no effect, while fructose and mannitol reduce stability. PMID:12514042

  14. Growth of Campylobacter Incubated Aerobically in Media Supplemented with Peptones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growth of Campylobacter cultures incubated aerobically in media supplemented with peptones was studied, and additional experiments were conducted to compare growth of the bacteria in media supplemented with peptones to growth in media supplemented with fumarate-pyruvate-minerals-vitamins (FPMV). A b...

  15. Photosynthetic H2 metabolism in Chlamydomonas reinhardtii (unicellular green algae).

    PubMed

    Melis, Anastasios

    2007-10-01

    Unicellular green algae have the ability to operate in two distinctly different environments (aerobic and anaerobic), and to photosynthetically generate molecular hydrogen (H2). A recently developed metabolic protocol in the green alga Chlamydomonas reinhardtii permitted separation of photosynthetic O2-evolution and carbon accumulation from anaerobic consumption of cellular metabolites and concomitant photosynthetic H2-evolution. The H2 evolution process was induced upon sulfate nutrient deprivation of the cells, which reversibly inhibits photosystem-II and O2-evolution in their chloroplast. In the absence of O2, and in order to generate ATP, green algae resorted to anaerobic photosynthetic metabolism, evolved H2 in the light and consumed endogenous substrate. This study summarizes recent advances on green algal hydrogen metabolism and discusses avenues of research for the further development of this method. Included is the mechanism of a substantial tenfold starch accumulation in the cells, observed promptly upon S-deprivation, and the regulated starch and protein catabolism during the subsequent H2-evolution. Also discussed is the function of a chloroplast envelope-localized sulfate permease, and the photosynthesis-respiration relationship in green algae as potential tools by which to stabilize and enhance H2 metabolism. In addition to potential practical applications of H2, approaches discussed in this work are beginning to address the biochemistry of anaerobic H2 photoproduction, its genes, proteins, regulation, and communication with other metabolic pathways in microalgae. Photosynthetic H2 production by green algae may hold the promise of generating a renewable fuel from nature's most plentiful resources, sunlight and water. The process potentially concerns global warming and the question of energy supply and demand. PMID:17721788

  16. Photosynthetic approaches to chemical biotechnology.

    PubMed

    Desai, Shuchi H; Atsumi, Shota

    2013-12-01

    National interest and environmental advocates encourage alternatives to petroleum-based products. Besides biofuels, many other valuable chemicals used in every-day life are petroleum derivatives or require petroleum for their production. A plausible alternative to production using petroleum for chemical production is to harvest the abundant carbon dioxide resources in the environment to produce valuable hydrocarbons. Currently, efforts are being made to utilize a natural biological system, photosynthetic microorganisms, to perform this task. Photosynthetic microorganisms are attractive to use for biochemical production because they utilize economical resources for survival: sunlight and carbon dioxide. This review examines the various compounds produced by photosynthetic microorganisms.

  17. Photosynthetic proteins for technological applications.

    PubMed

    Giardi, Maria Teresa; Pace, Emanuela

    2005-05-01

    Photosynthetic proteins are a source of biological material well-suited to technological applications. They exhibit light-induced electron transfer across lipid membranes that can be exploited for the construction of photo-optical electrical devices. The structure and function of photosynthetic proteins differ across the photosynthetic evolutionary scale, allowing for their application in a range of technologies. Here we provide a general description of the basic and technical research in this sector and an overview of biochips and biosensors based on photochemical activity that have been developed for the bioassay of pollutants.

  18. Ecology of aerobic anoxygenic phototrophs in aquatic environments.

    PubMed

    Koblížek, Michal

    2015-11-01

    Recognition of the environmental role of photoheterotrophic bacteria has been one of the main themes of aquatic microbiology over the last 15 years. Aside from cyanobacteria and proteorhodopsin-containing bacteria, aerobic anoxygenic phototrophic (AAP) bacteria are the third most numerous group of phototrophic prokaryotes in the ocean. This functional group represents a diverse assembly of species which taxonomically belong to various subgroups of Alpha-, Beta- and Gammaproteobacteria. AAP bacteria are facultative photoheterotrophs which use bacteriochlorophyll-containing reaction centers to harvest light energy. The light-derived energy increases their bacterial growth efficiency, which provides a competitive advantage over heterotrophic species. Thanks to their enzymatic machinery AAP bacteria are active, rapidly growing organisms which contribute significantly to the recycling of organic matter. This chapter summarizes the current knowledge of the ecology of AAP bacteria in aquatic environments, implying their specific role in the microbial loop.

  19. Aerobic biodegradation of the chloroethenes: pathways, enzymes, ecology, and evolution.

    PubMed

    Mattes, Timothy E; Alexander, Anne K; Coleman, Nicholas V

    2010-07-01

    Extensive use and inadequate disposal of chloroethenes have led to prevalent groundwater contamination worldwide. The occurrence of the lesser chlorinated ethenes [i.e. vinyl chloride (VC) and cis-1,2-dichloroethene (cDCE)] in groundwater is primarily a consequence of incomplete anaerobic reductive dechlorination of the more highly chlorinated ethenes (tetrachloroethene and trichloroethene). VC and cDCE are toxic and VC is a known human carcinogen. Therefore, their presence in groundwater is undesirable. In situ cleanup of VC- and cDCE-contaminated groundwater via oxidation by aerobic microorganisms is an attractive and potentially cost-effective alternative to physical and chemical approaches. Of particular interest are aerobic bacteria that use VC or cDCE as growth substrates (known as the VC- and cDCE-assimilating bacteria). Bacteria that grow on VC are readily isolated from contaminated and uncontaminated environments, suggesting that they are widespread and influential in aerobic natural attenuation of VC. In contrast, only one cDCE-assimilating strain has been isolated, suggesting that their environmental occurrence is rare. In this review, we will summarize the current knowledge of the physiology, biodegradation pathways, genetics, ecology, and evolution of VC- and cDCE-assimilating bacteria. Techniques (e.g. PCR, proteomics, and compound-specific isotope analysis) that aim to determine the presence, numbers, and activity of these bacteria in the environment will also be discussed.

  20. Inactivation of Mg chelatase during transition from anaerobic to aerobic growth in Rhodobacter capsulatus.

    PubMed

    Willows, Robert D; Lake, Vanessa; Roberts, Thomas Hugh; Beale, Samuel I

    2003-06-01

    The facultative photosynthetic bacterium Rhodobacter capsulatus can adapt from an anaerobic photosynthetic mode of growth to aerobic heterotrophic metabolism. As this adaptation occurs, the cells must rapidly halt bacteriochlorophyll synthesis to prevent phototoxic tetrapyrroles from accumulating, while still allowing heme synthesis to continue. A likely control point is Mg chelatase, the enzyme that diverts protoporphyrin IX from heme biosynthesis toward the bacteriochlorophyll biosynthetic pathway by inserting Mg(2+) to form Mg-protoporphyrin IX. Mg chelatase is composed of three subunits that are encoded by the bchI, bchD, and bchH genes in R. capsulatus. We report that BchH is the rate-limiting component of Mg chelatase activity in cell extracts. BchH binds protoporphyrin IX, and BchH that has been expressed and purified from Escherichia coli is red in color due to the bound protoporphyrin IX. Recombinant BchH is rapidly inactivated by light in the presence of O(2), and the inactivation results in the formation of a covalent adduct between the protein and the bound protoporphyrin IX. When photosynthetically growing R. capsulatus cells are transferred to aerobic conditions, Mg chelatase is rapidly inactivated, and BchH is the component that is most rapidly inactivated in vivo when cells are exposed to aerobic conditions. The light- and O(2)-stimulated inactivation of BchH could account for the rapid inactivation of Mg chelatase in vivo and provide a mechanism for inhibiting the synthesis of bacteriochlorophyll during adaptation of photosynthetically grown cells to aerobic conditions while still allowing heme synthesis to occur for aerobic respiration.

  1. Aerobic bacterial catabolism of persistent organic pollutants - potential impact of biotic and abiotic interaction.

    PubMed

    Jeon, Jong-Rok; Murugesan, Kumarasamy; Baldrian, Petr; Schmidt, Stefan; Chang, Yoon-Seok

    2016-04-01

    Several aerobic bacteria possess unique catabolic pathways enabling them to degrade persistent organic pollutants (POPs), including polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polybrominated diphenylethers (PBDEs), and polychlorinated biphenyls (PCBs). The catabolic activity of aerobic bacteria employed for removal of POPs in the environment may be modulated by several biotic (i.e. fungi, plants, algae, earthworms, and other bacteria) and abiotic (i.e. zero-valent iron, advanced oxidation, and electricity) agents. This review describes the basic biochemistry of the aerobic bacterial catabolism of selected POPs and discusses how biotic and abiotic agents enhance or inhibit the process. Solutions allowing biotic and abiotic agents to exert physical and chemical assistance to aerobic bacterial catabolism of POPs are also discussed.

  2. Improvement of Photosynthetic Efficiency Through Reduction of Chlorophyll Antenna Size

    SciTech Connect

    Blankinship, S.L.; Greenbaum, E.; Lee, J.W.; Mets, L.

    1999-05-03

    We have previously presented a graphical illustration of a strategy to improve photosynthetic conversion efficiencies by a reduction of the antenna size in photosynthetic reaction centers. During the current reporting period, we have made progress in demonstrating the conceptual correctness of this idea. Light-saturation studies for CO, in air were performed with an antenna-deficient mutant of Chlamydomonas (DS521) and the wild type (DES15). The light-saturated rate for CO(2), assimilation in mutant DS521 was about two times higher (187 Mu-mol.h(-1).mg chl(-1)) than that of the wild type, DES15 (95 Mu-mol.h(-1).mg chl(-1). Significantly, a partial linearization of the light-saturation curve was also observed. The light intensities that give half-saturation of the photosynthetic rate were 276 and 152 Mu-E.m(-2).s(-1) in DS521 and DES15, respectively. These results confirmed that DS521 has a smaller chlorophyll antenna size and demonstrated that the reduction of antenna size can indeed improve the overall efficiency of photon utilization. Corresponding experiments were also performed with CO(2), in helium. Under this anaerobic condition, no photoinhibition was observed, even at elevated light intensities. Photoinhibition occurs under aerobic conditions. The antenna-deficient mutant DS521 can also provide significant resistance to photoinhibition, in addition to the improvement in the overall efficiency in CO(2), fixation.

  3. Aerobic and Anaerobic Bacteriology of Hidradenitis Suppurativa: A Study of 22 Cases

    PubMed Central

    Katoulis, Alexandros C.; Koumaki, Dimitra; Liakou, Aikaterini I.; Vrioni, Georgia; Koumaki, Vasiliki; Kontogiorgi, Dimitra; Tzima, Korina; Tsakris, Athanasios; Rigopoulos, Dimitris

    2015-01-01

    Introduction Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease of unclear etiology. The role of bacteria in the pathogenesis of disease remains controversial. Materials and Methods Specimens were obtained from 22 HS patients by direct percutaneous needle aspiration. The collected material was cultured in aerobic and anaerobic conditions, and sensitivity tests were performed. Results Of the 22 patients, 32% were culture negative and 68% were culture positive. A total of 16 isolates was obtained, 14 aerobic and 2 anaerobic. Aerobic bacteria were present in 86% of the specimens, whereas only anaerobic bacteria were isolated in 7%. The predominant aerobic species were Proteus mirabilis, Staphylococcus haemolyticus and Staphylococcus lugdunensis. The isolated anaerobic bacteria were Dermacoccus nishinomiyaensis and Propionibacterium granulosum. Conclusion A variety of aerobic and anaerobic bacteria was isolated from the HS lesions of our patients. In contrast to previous studies, fewer patients were found to be culture positive, and Staphylococcus aureus was isolated in only 1 of them. More studies are necessary to elucidate the controversial role of bacteria in the pathogenesis of HS. PMID:27170935

  4. Characterization of a Rhodospirillum rubrum plasmid: loss of photosynthetic growth in plasmidless strains.

    PubMed Central

    Kuhl, S A; Nix, D W; Yoch, D C

    1983-01-01

    A single plasmid of 55 kilobases was found in crude cell lysates of each of nine strains of Rhodospirillum rubrum. Restriction endonuclease analysis showed identical fragment patterns with a given nuclease for all plasmids except one, for which an additional EcoRI site was observed. Elimination of the plasmid required that the cells be passaged several times in 25 mM calcium-containing medium, followed by at least two passages under photosynthetic growth conditions in low-calcium medium before treatment with ethyl methanesulfonate. The resulting plasmidless mutants only grew aerobically and were all incapable of pigment formation and photosynthetic growth, suggesting that plasmid DNA is required for photosynthetic competence in R. rubrum. Images PMID:6313617

  5. Aerobic landfill bioreactor

    DOEpatents

    Hudgins, Mark P; Bessette, Bernard J; March, John C; McComb, Scott T.

    2002-01-01

    The present invention includes a system of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120.degree. F. and 140.degree. F. in steady state.

  6. Aerobic landfill bioreactor

    DOEpatents

    Hudgins, Mark P; Bessette, Bernard J; March, John; McComb, Scott T.

    2000-01-01

    The present invention includes a method of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120.degree. F. and 140.degree. F. in steady state.

  7. Aerobic landfill bioreactor

    SciTech Connect

    Hudgins, M.P.; Bessette, B.J.; March, J.; McComb, S.T.

    2000-02-15

    The present invention includes a method of decomposing municipal solid waste (MSW) within a landfill by converting the landfill to aerobic degradation in the following manner: (1) injecting air via the landfill leachate collection system (2) injecting air via vertical air injection wells installed within the waste mass; (3) applying leachate to the waste mass using a pressurized drip irrigation system; (4) allowing landfill gases to vent; and (5) adjusting air injection and recirculated leachate to achieve a 40% to 60% moisture level and a temperature between 120 F and 140 F in steady state.

  8. Low-Impact Aerobics: Better than Traditional Aerobic Dance?

    ERIC Educational Resources Information Center

    Koszuta, Laurie Einstein

    1986-01-01

    A form of dance exercise called low-impact aerobics is being touted as a misery-free form of aerobic dance. Because this activity is relatively new, the exact kinds and frequencies of injuries are not known and the fitness benefits have not been examined. (MT)

  9. Arsenic biomethylation by photosynthetic organisms

    PubMed Central

    Ye, Jun; Rensing, Christopher; Rosen, Barry P.; Zhu, Yong-Guan

    2013-01-01

    Arsenic (As) is a ubiquitous element that is widespread in the environment and causes numerous health problems. Biomethylation of As has implications for its mobility and toxicity. Photosynthetic organisms may play a significant role in As geochemical cycling by methylating it to different As species, but little is known about the mechanisms of methylation. Methylated As species have been found in many photosynthetic organisms, and several arsenite S-adenosylmethionine (SAM) methyltransferases have been characterized in cyanobacteria and algae. However, higher plants may not have the ability to methylate As. Instead, methylated arsenicals in plants probably originate from microorganisms in soils and the rhizosphere. Here, we propose possible approaches for developing ‘smart’ photosynthetic organisms with an enhanced and sensitive biomethylation capacity for bioremediation and safer food. PMID:22257759

  10. ‘Candidatus Thermochlorobacter aerophilum:' an aerobic chlorophotoheterotrophic member of the phylum Chlorobi defined by metagenomics and metatranscriptomics

    PubMed Central

    Liu, Zhenfeng; Klatt, Christian G; Ludwig, Marcus; Rusch, Douglas B; Jensen, Sheila I; Kühl, Michael; Ward, David M; Bryant, Donald A

    2012-01-01

    An uncultured member of the phylum Chlorobi, provisionally named ‘Candidatus Thermochlorobacter aerophilum', occurs in the microbial mats of alkaline siliceous hot springs at the Yellowstone National Park. ‘Ca. T. aerophilum' was investigated through metagenomic and metatranscriptomic approaches. ‘Ca. T. aerophilum' is a member of a novel, family-level lineage of Chlorobi, a chlorophototroph that synthesizes type-1 reaction centers and chlorosomes similar to cultivated relatives among the green sulfur bacteria, but is otherwise very different physiologically. ‘Ca. T. aerophilum' is proposed to be an aerobic photoheterotroph that cannot oxidize sulfur compounds, cannot fix N2, and does not fix CO2 autotrophically. Metagenomic analyses suggest that ‘Ca. T. aerophilum' depends on other mat organisms for fixed carbon and nitrogen, several amino acids, and other important nutrients. The failure to detect bchU suggests that ‘Ca. T. aerophilum' synthesizes bacteriochlorophyll (BChl) d, and thus it occupies a different ecological niche than other chlorosome-containing chlorophototrophs in the mat. Transcription profiling throughout a diel cycle revealed distinctive gene expression patterns. Although ‘Ca. T. aerophilum' probably photoassimilates organic carbon sources and synthesizes most of its cell materials during the day, it mainly transcribes genes for BChl synthesis during late afternoon and early morning, and it synthesizes and assembles its photosynthetic apparatus during the night. PMID:22456447

  11. Aerobic Fitness and School Children.

    ERIC Educational Resources Information Center

    Hinkle, J. Scott

    1997-01-01

    Provides school counselors with information on aerobic exercise (specifically running) and the psychological, behavioral, and physical benefits children obtained by participating in fitness programs. Recommends collaboration between school counselors and physical education teachers and gives a preliminary discussion of aerobic running and its…

  12. Aerobic Fitness and School Children.

    ERIC Educational Resources Information Center

    Hinkle, J. Scott

    1992-01-01

    Provides school counselors with information regarding aerobic exercise (specifically running), and the psychological, behavioral, and physical benefits children obtain by participating in fitness programs. Presents methods of collaboration between school counselors and physical education teachers. Offers preliminary discussion of aerobic running…

  13. Exercise, Animal Aerobics, and Interpretation?

    ERIC Educational Resources Information Center

    Oliver, Valerie

    1996-01-01

    Describes an aerobic activity set to music for children that mimics animal movements. Example exercises include walking like a penguin or jumping like a cricket. Stresses basic aerobic principles and designing the program at the level of children's motor skills. Benefits include reaching people who normally don't visit nature centers, and bridging…

  14. Anaerobic bacteria

    MedlinePlus

    Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these ... Goldstein EJ. Diseases caused by non-spore forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman's ...

  15. What are the differences between aerobic and anaerobic toxic effects of sulfonamides on Escherichia coli?

    PubMed

    Qin, Mengnan; Lin, Zhifen; Wang, Dali; Long, Xi; Zheng, Min; Qiu, Yanling

    2016-01-01

    Bacteria in the environment face the threat of antibiotics. However, most studies investigating the toxicity and toxicity mechanisms of antibiotics have been conducted on microorganisms in aerobic conditions, while studies examining the anaerobic toxicity and toxicity mechanisms of antibiotics are still limited. In this study, we determined the aerobic and anaerobic toxicities of sulfonamides (SAs) on Escherichia coli. Next, a comparison of the aerobic and anaerobic toxicities indicated that the SAs could be divided into three groups: Group I: log(1/EC50-anaerobic)>log(1/EC50-aerobic) (EC50-anaerobic/EC50-aerobic, the median effective concentration under anaerobic/aerobic conditions), Group II: log(1/EC50-anaerobic)≈log(1/EC50-aerobic), and Group III: log(1/EC50-anaerobic)aerobic). Furthermore, this division was not based on the reactive oxygen species (ROS) level or the interaction energy (Ebinding) value, which represents the affinity between SAs and dihydropteroate synthase (dhps) but rather on the total binding energy. Furthermore, SAs with greatly similar structures were categorized into different groups. This deep insight into the difference between aerobic and anaerobic toxicities will benefit environmental science, and the results of this study will serve as a reference for the risk assessment of chemicals in the environment.

  16. The Twin Arginine Translocation System Is Essential for Aerobic Growth and Full Virulence of Burkholderia thailandensis

    PubMed Central

    Wagley, Sariqa; Hemsley, Claudia; Thomas, Rachael; Moule, Madeleine G.; Vanaporn, Muthita; Andreae, Clio; Robinson, Matthew; Goldman, Stan; Wren, Brendan W.; Butler, Clive S.

    2014-01-01

    The twin arginine translocation (Tat) system in bacteria is responsible for transporting folded proteins across the cytoplasmic membrane, and in some bacteria, Tat-exported substrates have been linked to virulence. We report here that the Tat machinery is present in Burkholderia pseudomallei, B. mallei, and B. thailandensis, and we show that the system is essential for aerobic but not anaerobic growth. Switching off of the Tat system in B. thailandensis grown anaerobically resulted in filamentous bacteria, and bacteria showed increased sensitivity to some β-lactam antibiotics. In Galleria mellonella and zebrafish infection models, the Tat conditional mutant was attenuated. The aerobic growth-restricted phenotype indicates that Tat substrates may play a functional role in oxygen-dependent energy conservation. In other bacteria, aerobic growth restriction in Tat mutants has been attributed to the inability to translocate PetA, the Rieske iron-sulfur protein which forms part of the quinol-cytochrome c oxidoreductase complex. Here, we show that PetA is not responsible for aerobic growth restriction in B. thailandensis. However, we have identified an operon encoding 2 proteins of unknown function (BTH_I2176 and BTH_I2175) that play a role in aerobic growth restriction, and we present evidence that BTH_I2176 is Tat translocated. PMID:24214943

  17. Influence of thermal light correlations on photosynthetic structures

    NASA Astrophysics Data System (ADS)

    de Mendoza, Adriana; Manrique, Pedro; Caycedo-Soler, Felipe; Johnson, Neil F.; Rodríguez, Ferney J.; Quiroga, Luis

    2014-03-01

    The thermal light from the sun is characterized by both classical and quantum mechanical correlations. These correlations have left a fingerprint on the natural harvesting structures developed through five billion years of evolutionary pressure, specially in photosynthetic organisms. In this work, based upon previous extensive studies of spatio-temporal correlations of light fields, we hypothesize that structures involving photosensitive pigments like those present in purple bacteria vesicles emerge as an evolutionary response to the different properties of incident light. By using burstiness and memory as measures that quantify higher moments of the photon arrival statistics, we generate photon-time traces. They are used to simulate absorption on detectors spatially extended over regions comparable to these light fields coherence length. Finally, we provide some insights into the connection between these photo-statistical features with the photosynthetic membrane architecture and the lights' spatial correlation. Facultad de Ciencias Uniandes.

  18. Pigment oligomers as natural and artificial photosynthetic antennas

    SciTech Connect

    Blankenship, R.E.

    1996-12-31

    Green photosynthetic bacteria contain antenna complexes known as chlorosomes. These complexes are appressed to the cytoplasmic side of the inner cell membrane and function to absorb light and transfer the energy to the photochemical reaction center, where photochemical energy storage takes place. Chlorosomes differ from all other known photosynthetic antenna complexes in that the geometrical arrangement of pigments is determined primarily by pigment-pigment interactions instead of pigment-protein interactions. The bacteriochlorophyll c, d or e pigments found in chlorosomes form large oligomers with characteristic spectral properties significantly perturbed from those exhibited by monomeric pigments. Because of their close spatial interaction, the pigments are thought to be strongly coupled electronically, and many of the optical properties result from exciton interactions. This presentation will summarize existing knowledge on the chemical composition and properties of chlorosomes, the evidence for the oligomeric nature of chlorosome pigment organization and proposed structures for the oligomers, and the kinetics and mechanisms of energy transfer in chlorosomes.

  19. PEP Carboxykinase Exchange Reaction in Photosynthetic Bacteria 1

    PubMed Central

    Cooper, T. G.; Benedict, C. R.

    1968-01-01

    This paper describes some new characteristics of the phosphoenolpyruvate carboxykinase CO2-oxaloacetate exchange reaction in purified preparations of Rhodospirillum rubrum. The enzymatic activity has been purified 169-fold. Nucleotide diphosphates substitute for nucleotide triphosphates in the exchange reaction. Nucleotide diphosphates will not support the synthesis of phosphoenolpyruvate from oxaloacetate. This reaction differs significantly from the CO2-oxaloacetate exchange reaction in higher plants and animals. PMID:5661493

  20. Photobiological hydrogen production in green algae and photosynthetic bacteria

    SciTech Connect

    Greenbaum, E.

    1986-01-01

    We have shown that, under appropriate physiological conditions, certain freshwater and marine green algae are capable of splitting water to molecular hydrogen and oxygen in a sustained steady-state reaction. In these algae, the gaseous-fuel-producing reaction can be driven by light throughout the visible portion of the solar emission spectrum, including the long wavelength (red) 700-nm region. No external energy sources are required.

  1. [Carbon monoxide metabolism by photosynthetic bacteria]. Progress report

    SciTech Connect

    Not Available

    1989-12-31

    Research continued on the metabolism of carbon monoxide by Rhodospirillum rubrum. This report discusses progress on the activity, induction, inhibition, and spectroscopic analysis of the enzyme Carbon Monoxide Dehydrogenase. (CBS)

  2. Photoproduction of hydrogen by membranes of green photosynthetic bacteria

    SciTech Connect

    Bernstein, J D; Olson, J M

    1980-01-01

    Photoproduction of H/sub 2/ from ascorbate by unit-membrane vesicles from Chlorobium limicola f. thiosulfatophilum was achieved with a system containing gramicidin D, tetramethyl-p-phenylenediamine, methyl viologen, dithioerythritol, Clostridium hydrogenase, and an oxygen-scavenging mixture of glucose, glucose oxidase, ethanol, and catalase. Maximum quantum yield was less than one percent. Half maximum rate of H/sub 2/ production occurred at a white-light intensity of approximately 0.15 cm/sup -2/. The reaction was inhibited completely by 0.3% sodium dodecylbenzene sulfonate, 1% Triton X-100, or preheating the vesicles at 100/sup 0/C for 5 minutes. Low concentrations (0.01 and 0.05%) of Triton X-100 about doubled the reaction rate.

  3. Late Archean rise of aerobic microbial ecosystems

    PubMed Central

    Eigenbrode, Jennifer L.; Freeman, Katherine H.

    2006-01-01

    We report the 13C content of preserved organic carbon for a 150 million-year section of late Archean shallow and deepwater sediments of the Hamersley Province in Western Australia. We find a 13C enrichment of ≈10‰ in organic carbon of post-2.7-billion-year-old shallow-water carbonate rocks relative to deepwater sediments. The shallow-water organic-carbon 13C content has a 29‰ range in values (−57 to −28‰), and it contrasts with the less variable but strongly 13C-depleted (−40 to −45‰) organic carbon in deepwater sediments. The 13C enrichment likely represents microbial habitats not as strongly influenced by assimilation of methane or other 13C-depleted substrates. We propose that continued oxidation of shallow settings favored the expansion of aerobic ecosystems and respiring organisms, and, as a result, isotopic signatures of preserved organic carbon in shallow settings approached that of photosynthetic biomass. Facies analysis of published carbon-isotopic records indicates that the Hamersley shallow-water signal may be representative of a late Archean global signature and that it preceded a similar, but delayed, 13C enrichment of deepwater deposits. The data suggest that a global-scale expansion of oxygenated habitats accompanied the progression away from anaerobic ecosystems toward respiring microbial communities fueled by oxygenic photosynthesis before the oxygenation of the atmosphere after 2.45 billion years ago. PMID:17043234

  4. [The aerobic air microflora in airplanes on various international routes].

    PubMed

    Năstoiu, I; Răduică, C; Soitu, V; Gavrilă, I

    1989-01-01

    Aerobic microflora (bacteria, fungi), in the cock pits of the TAROM company (Boeing 707 and Il 62 M) airships flying on various international routes and airports was studied during November 1988-January 1989. 157-8,800 bacteria and 78-1,336 fungi per m3 air were recorded. Except for Staphylococcus aureus (hemolytic and non hemolytic) the greatest part of the isolated microorganisms was nonpathogenic for man: Bacillus, Corynebacterium, Neisseria, Staphylococcus epidermidis, Sarcina, Aspergillus, Penicillium etc. Several airships on the Asian airports contained a higher amount of bacteria and fungi but not higher than in the living rooms. Likewise, in high altitude flights, the microorganism amount was less than on the ground. The taxonomic spectrum of the bacteria and fungi isolated was almost identical on all the 9 international airports, thus suggesting the homogeneous and international character of saprophyte and pathogenic air microflora by means of the passenger and goods air flights.

  5. SANS Investigation of the Photosynthetic Machinery of Chloroflexus Aurantiacus

    SciTech Connect

    Tang, Kuo-Hsiang; Urban, Volker S; Jianzhong, Wen; Yueyong, Xin; Blankenship, Robert E

    2010-01-01

    Green photosynthetic bacteria harvest light and perform photosynthesis in low light environments, and contain specialized antenna complexes to adapt to this condition. In this report, we present studies using small-angle neutron scattering (SANS) to elucidate structural information about the photosynthetic apparatus, including the peripheral light harvesting chlorosome complex, the integral membrane light-harvesting B808-866 complex and the reaction center (RC) in the thermophilic green phototrophic bacterium Chloroflexus aurantiacus. Using contract variation in SANS measurments, our studies suggest that the B808-866 comples is wrapped around the RC in Cfx. aurantiacus, and the overall size and conformation for the B808-866 complex of Cfx. aurantiacus is roughly comparable to the LH1 antenna complex of the purple bacteria. A similar size for the isolated B808-866 complex is also suggested via dynamic light scattering measurements. Alos, a smaller size of the RC of Cfx. aurantiacus that the RC of the purple bacteria is observed. Further, our SANS measurements indicate that the chlorosome is a lipid body with rod-like shape, and that the self-assembly of bacteriochlorophylls, the major component of the chlorosome, is lipid-like. Finally, two populations of chlorosome particles are suggested in our SANS measurements.

  6. Clinical microbiology of coryneform bacteria.

    PubMed Central

    Funke, G; von Graevenitz, A; Clarridge, J E; Bernard, K A

    1997-01-01

    Coryneform bacteria are aerobically growing, asporogenous, non-partially-acid-fast, gram-positive rods of irregular morphology. Within the last few years, there has been a massive increase in the number of publications related to all aspects of their clinical microbiology. Clinical microbiologists are often confronted with making identifications within this heterogeneous group as well as with considerations of the clinical significance of such isolates. This review provides comprehensive information on the identification of coryneform bacteria and outlines recent changes in taxonomy. The following genera are covered: Corynebacterium, Turicella, Arthrobacter, Brevibacterium, Dermabacter. Propionibacterium, Rothia, Exiguobacterium, Oerskovia, Cellulomonas, Sanguibacter, Microbacterium, Aureobacterium, "Corynebacterium aquaticum," Arcanobacterium, and Actinomyces. Case reports claiming disease associations of coryneform bacteria are critically reviewed. Minimal microbiological requirements for publications on disease associations of coryneform bacteria are proposed. PMID:8993861

  7. Electron Paramagnetic Resonance Study of a Photosynthetic Microbial Mat and Comparison with Archean Cherts

    NASA Astrophysics Data System (ADS)

    Bourbin, M.; Derenne, S.; Gourier, D.; Rouzaud, J.-N.; Gautret, P.; Westall, F.

    2012-12-01

    Organic radicals in artificially carbonized biomass dominated by oxygenic and non-oxygenic photosynthetic bacteria, Microcoleus chthonoplastes-like and Chloroflexus-like bacteria respectively, were studied by Electron Paramagnetic Resonance (EPR) spectroscopy. The two bacteria species were sampled in mats from a hypersaline lake. They underwent accelerated ageing by cumulative thermal treatments to induce progressive carbonization of the biological material, mimicking the natural maturation of carbonaceous material of Archean age. For thermal treatments at temperatures higher than 620 °C, a drastic increase in the EPR linewidth is observed in the carbonaceous matter from oxygenic photosynthetic bacteria and not anoxygenic photosynthetic bacteria. This selective EPR linewidth broadening reflects the presence of a catalytic element inducing formation of radical aggregates, without affecting the molecular structure or the microstructure of the organic matter, as shown by Raman spectroscopy and Transmission Electron Microscopy. For comparison, we carried out an EPR study of organic radicals in silicified carbonaceous rocks (cherts) from various localities, of different ages (0.42 to 3.5 Gyr) and having undergone various degrees of metamorphism, i.e. various degrees of natural carbonization. EPR linewidth dispersion for the most primitive samples was quite significant, pointing to a selective dipolar broadening similar to that observed for carbonized bacteria. This surprising result merits further evaluation in the light of its potential use as a marker of past bacterial metabolisms, in particular oxygenic photosynthesis, in Archean cherts.

  8. Electron paramagnetic resonance study of a photosynthetic microbial mat and comparison with Archean cherts.

    PubMed

    Bourbin, M; Derenne, S; Gourier, D; Rouzaud, J-N; Gautret, P; Westall, F

    2012-12-01

    Organic radicals in artificially carbonized biomass dominated by oxygenic and non-oxygenic photosynthetic bacteria, Microcoleus chthonoplastes-like and Chloroflexus-like bacteria respectively, were studied by Electron Paramagnetic Resonance (EPR) spectroscopy. The two bacteria species were sampled in mats from a hypersaline lake. They underwent accelerated ageing by cumulative thermal treatments to induce progressive carbonization of the biological material, mimicking the natural maturation of carbonaceous material of Archean age. For thermal treatments at temperatures higher than 620 °C, a drastic increase in the EPR linewidth is observed in the carbonaceous matter from oxygenic photosynthetic bacteria and not anoxygenic photosynthetic bacteria. This selective EPR linewidth broadening reflects the presence of a catalytic element inducing formation of radical aggregates, without affecting the molecular structure or the microstructure of the organic matter, as shown by Raman spectroscopy and Transmission Electron Microscopy. For comparison, we carried out an EPR study of organic radicals in silicified carbonaceous rocks (cherts) from various localities, of different ages (0.42 to 3.5 Gyr) and having undergone various degrees of metamorphism, i.e. various degrees of natural carbonization. EPR linewidth dispersion for the most primitive samples was quite significant, pointing to a selective dipolar broadening similar to that observed for carbonized bacteria. This surprising result merits further evaluation in the light of its potential use as a marker of past bacterial metabolisms, in particular oxygenic photosynthesis, in Archean cherts.

  9. Electron paramagnetic resonance study of a photosynthetic microbial mat and comparison with Archean cherts.

    PubMed

    Bourbin, M; Derenne, S; Gourier, D; Rouzaud, J-N; Gautret, P; Westall, F

    2012-12-01

    Organic radicals in artificially carbonized biomass dominated by oxygenic and non-oxygenic photosynthetic bacteria, Microcoleus chthonoplastes-like and Chloroflexus-like bacteria respectively, were studied by Electron Paramagnetic Resonance (EPR) spectroscopy. The two bacteria species were sampled in mats from a hypersaline lake. They underwent accelerated ageing by cumulative thermal treatments to induce progressive carbonization of the biological material, mimicking the natural maturation of carbonaceous material of Archean age. For thermal treatments at temperatures higher than 620 °C, a drastic increase in the EPR linewidth is observed in the carbonaceous matter from oxygenic photosynthetic bacteria and not anoxygenic photosynthetic bacteria. This selective EPR linewidth broadening reflects the presence of a catalytic element inducing formation of radical aggregates, without affecting the molecular structure or the microstructure of the organic matter, as shown by Raman spectroscopy and Transmission Electron Microscopy. For comparison, we carried out an EPR study of organic radicals in silicified carbonaceous rocks (cherts) from various localities, of different ages (0.42 to 3.5 Gyr) and having undergone various degrees of metamorphism, i.e. various degrees of natural carbonization. EPR linewidth dispersion for the most primitive samples was quite significant, pointing to a selective dipolar broadening similar to that observed for carbonized bacteria. This surprising result merits further evaluation in the light of its potential use as a marker of past bacterial metabolisms, in particular oxygenic photosynthesis, in Archean cherts. PMID:23254854

  10. Quantifying factors limiting aerobic degradation during aerobic bioreactor landfilling.

    PubMed

    Yazdani, Ramin; Mostafid, M Erfan; Han, Byunghyun; Imhoff, Paul T; Chiu, Pei; Augenstein, Don; Kayhanian, Masoud; Tchobanoglous, George

    2010-08-15

    A bioreactor landfill cell at Yolo County, California was operated aerobically for six months to quantify the extent of aerobic degradation and mechanisms limiting aerobic activity during air injection and liquid addition. The portion of the solid waste degraded anaerobically was estimated and tracked through time. From an analysis of in situ aerobic respiration and gas tracer data, it was found that a large fraction of the gas-filled pore space was in immobile zones where it was difficult to maintain aerobic conditions, even at relatively moderate landfill cell-average moisture contents of 33-36%. Even with the intentional injection of air, anaerobic activity was never less than 13%, and sometimes exceeded 65%. Analyses of gas tracer and respiration data were used to quantify rates of respiration and rates of mass transfer to immobile gas zones. The similarity of these rates indicated that waste degradation was influenced significantly by rates of oxygen transfer to immobile gas zones, which comprised 32-92% of the gas-filled pore space. Gas tracer tests might be useful for estimating the size of the mobile/immobile gas zones, rates of mass transfer between these regions, and the difficulty of degrading waste aerobically in particular waste bodies. PMID:20704218

  11. Photosynthetic gene expression in higher plants.

    PubMed

    Berry, James O; Yerramsetty, Pradeep; Zielinski, Amy M; Mure, Christopher M

    2013-11-01

    Within the chloroplasts of higher plants and algae, photosynthesis converts light into biological energy, fueling the assimilation of atmospheric carbon dioxide into biologically useful molecules. Two major steps, photosynthetic electron transport and the Calvin-Benson cycle, require many gene products encoded from chloroplast as well as nuclear genomes. The expression of genes in both cellular compartments is highly dynamic and influenced by a diverse range of factors. Light is the primary environmental determinant of photosynthetic gene expression. Working through photoreceptors such as phytochrome, light regulates photosynthetic genes at transcriptional and posttranscriptional levels. Other processes that affect photosynthetic gene expression include photosynthetic activity, development, and biotic and abiotic stress. Anterograde (from nucleus to chloroplast) and retrograde (from chloroplast to nucleus) signaling insures the highly coordinated expression of the many photosynthetic genes between these different compartments. Anterograde signaling incorporates nuclear-encoded transcriptional and posttranscriptional regulators, such as sigma factors and RNA-binding proteins, respectively. Retrograde signaling utilizes photosynthetic processes such as photosynthetic electron transport and redox signaling to influence the expression of photosynthetic genes in the nucleus. The basic C3 photosynthetic pathway serves as the default form used by most of the plant species on earth. High temperature and water stress associated with arid environments have led to the development of specialized C4 and CAM photosynthesis, which evolved as modifications of the basic default expression program. The goal of this article is to explain and summarize the many gene expression and regulatory processes that work together to support photosynthetic function in plants.

  12. Structure-function studies of the photosynthetic reaction center using herbicides that compete for the quinone binding site

    SciTech Connect

    Bylina, E.J.

    1995-12-31

    Certain classes of herbicides act as competitive inhibitors of the photosynthetic reaction center. Genetic engineering techniques can be used to generate photosynthetic reaction centers which contain altered quinone binding sites. A genetic system for rapidly screening herbicides developed in the photosynthetic bacterium Rhodobacter capsulatus has been used to examine the effect of different s-triazine herbicides on the growth of bacteria containing reaction centers with altered quinone binding sites. Structural insights into herbicide binding have been obtained by determining the level of resistance or sensitivity to structurally related herbicides in these modified reaction centers.

  13. Phytochromes in photosynthetically competent plants

    SciTech Connect

    Pratt, L.H.

    1990-07-01

    Plants utilize light as a source of information in photomorphogenesis and of free energy in photosynthesis, two processes that are interrelated in that the former serves to increase the efficiency with which plants can perform the latter. Only one pigment involved in photomorphogenesis has been identified unequivocally, namely phytochrome. The thrust of this proposal is to investigate this pigment and its mode(s) of action in photosynthetically competent plants. Our long term objective is to characterize phytochrome and its functions in photosynthetically competent plants from molecular, biochemical and cellular perspectives. It is anticipated that others will continue to contribute indirectly to these efforts at the physiological level. The ultimate goal will be to develop this information from a comparative perspective in order to learn whether the different phytochromes have significantly different physicochemical properties, whether they fulfill independent functions and if so what these different functions are, and how each of the different phytochromes acts at primary molecular and cellular levels.

  14. Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

    NASA Technical Reports Server (NTRS)

    Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

    1995-01-01

    Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

  15. Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

    NASA Astrophysics Data System (ADS)

    Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

    1995-03-01

    Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

  16. C4-Dicarboxylate Utilization in Aerobic and Anaerobic Growth.

    PubMed

    Unden, Gottfried; Strecker, Alexander; Kleefeld, Alexandra; Kim, Ok Bin

    2016-06-01

    C4-dicarboxylates and the C4-dicarboxylic amino acid l-aspartate support aerobic and anaerobic growth of Escherichia coli and related bacteria. In aerobic growth, succinate, fumarate, D- and L-malate, L-aspartate, and L-tartrate are metabolized by the citric acid cycle and associated reactions. Because of the interruption of the citric acid cycle under anaerobic conditions, anaerobic metabolism of C4-dicarboxylates depends on fumarate reduction to succinate (fumarate respiration). In some related bacteria (e.g., Klebsiella), utilization of C4-dicarboxylates, such as tartrate, is independent of fumarate respiration and uses a Na+-dependent membrane-bound oxaloacetate decarboxylase. Uptake of the C4-dicarboxylates into the bacteria (and anaerobic export of succinate) is achieved under aerobic and anaerobic conditions by different sets of secondary transporters. Expression of the genes for C4-dicarboxylate metabolism is induced in the presence of external C4-dicarboxylates by the membrane-bound DcuS-DcuR two-component system. Noncommon C4-dicarboxylates like l-tartrate or D-malate are perceived by cytoplasmic one-component sensors/transcriptional regulators. This article describes the pathways of aerobic and anaerobic C4-dicarboxylate metabolism and their regulation. The citric acid cycle, fumarate respiration, and fumarate reductase are covered in other articles and discussed here only in the context of C4-dicarboxylate metabolism. Recent aspects of C4-dicarboxylate metabolism like transport, sensing, and regulation will be treated in more detail. This article is an updated version of an article published in 2004 in EcoSal Plus. The update includes new literature, but, in particular, the sections on the metabolism of noncommon C4-dicarboxylates and their regulation, on the DcuS-DcuR regulatory system, and on succinate production by engineered E. coli are largely revised or new.

  17. C4-Dicarboxylate Utilization in Aerobic and Anaerobic Growth.

    PubMed

    Unden, Gottfried; Strecker, Alexander; Kleefeld, Alexandra; Kim, Ok Bin

    2016-06-01

    C4-dicarboxylates and the C4-dicarboxylic amino acid l-aspartate support aerobic and anaerobic growth of Escherichia coli and related bacteria. In aerobic growth, succinate, fumarate, D- and L-malate, L-aspartate, and L-tartrate are metabolized by the citric acid cycle and associated reactions. Because of the interruption of the citric acid cycle under anaerobic conditions, anaerobic metabolism of C4-dicarboxylates depends on fumarate reduction to succinate (fumarate respiration). In some related bacteria (e.g., Klebsiella), utilization of C4-dicarboxylates, such as tartrate, is independent of fumarate respiration and uses a Na+-dependent membrane-bound oxaloacetate decarboxylase. Uptake of the C4-dicarboxylates into the bacteria (and anaerobic export of succinate) is achieved under aerobic and anaerobic conditions by different sets of secondary transporters. Expression of the genes for C4-dicarboxylate metabolism is induced in the presence of external C4-dicarboxylates by the membrane-bound DcuS-DcuR two-component system. Noncommon C4-dicarboxylates like l-tartrate or D-malate are perceived by cytoplasmic one-component sensors/transcriptional regulators. This article describes the pathways of aerobic and anaerobic C4-dicarboxylate metabolism and their regulation. The citric acid cycle, fumarate respiration, and fumarate reductase are covered in other articles and discussed here only in the context of C4-dicarboxylate metabolism. Recent aspects of C4-dicarboxylate metabolism like transport, sensing, and regulation will be treated in more detail. This article is an updated version of an article published in 2004 in EcoSal Plus. The update includes new literature, but, in particular, the sections on the metabolism of noncommon C4-dicarboxylates and their regulation, on the DcuS-DcuR regulatory system, and on succinate production by engineered E. coli are largely revised or new. PMID:27415771

  18. Virtual intermediates in photosynthetic electron transfer.

    PubMed Central

    Joseph, J S; Bialek, W

    1992-01-01

    We explore the possibility of virtual transfer in the primary charge separation of photosynthetic bacteria within the context of several types of experimental data. We show that the peak that might be expected in the virtual rate as electric fields vary the intermediate state energy is severely broadened by coupling to high-frequency modes. The Stark absorption kinetics data are thus consistent with virtual transfer in the primary charge separation. High-frequency coupling also makes the temperature dependence weak over a wide range of parameters. We demonstrate that Stark fluorescence anisotropy data, usually taken as evidence of virtual transfer, can in fact be consistent with two-step transfer. We suggest a two-pulse excitation experiment to quantify the contributions from two-step and virtual transfer. We show that virtual absorption into a charge transfer state can make a substantial contribution to the Stark absorption spectrum in a way that is not related to any derivative of the absorption spectrum. PMID:1420886

  19. Photocurrent of a single photosynthetic protein

    NASA Astrophysics Data System (ADS)

    Gerster, Daniel; Reichert, Joachim; Bi, Hai; Barth, Johannes V.; Kaniber, Simone M.; Holleitner, Alexander W.; Visoly-Fisher, Iris; Sergani, Shlomi; Carmeli, Itai

    2012-10-01

    Photosynthesis is used by plants, algae and bacteria to convert solar energy into stable chemical energy. The initial stages of this process--where light is absorbed and energy and electrons are transferred--are mediated by reaction centres composed of chlorophyll and carotenoid complexes. It has been previously shown that single small molecules can be used as functional components in electric and optoelectronic circuits, but it has proved difficult to control and probe individual molecules for photovoltaic and photoelectrochemical applications. Here, we show that the photocurrent generated by a single photosynthetic protein--photosystem I--can be measured using a scanning near-field optical microscope set-up. One side of the protein is anchored to a gold surface that acts as an electrode, and the other is contacted by a gold-covered glass tip. The tip functions as both counter electrode and light source. A photocurrent of ~10 pA is recorded from the covalently bound single-protein junctions, which is in agreement with the internal electron transfer times of photosystem I.

  20. Petrifilm plates for enumeration of bacteria counts in goat milk

    Technology Transfer Automated Retrieval System (TEKTRAN)

    PetrifilmTM Aerobic Count (AC) and Coliform Count (CC) plates were validated against standard methods for enumeration of coliforms, total bacteria, and psychrotrophic bacteria in raw (n = 39) and pasteurized goat milk (n = 17) samples. All microbiological data were transformed into log form and sta...

  1. Photosynthetic reaction center as a quantum heat engine.

    PubMed

    Dorfman, Konstantin E; Voronine, Dmitri V; Mukamel, Shaul; Scully, Marlan O

    2013-02-19

    Two seemingly unrelated effects attributed to quantum coherence have been reported recently in natural and artificial light-harvesting systems. First, an enhanced solar cell efficiency was predicted and second, population oscillations were measured in photosynthetic antennae excited by sequences of coherent ultrashort laser pulses. Because both systems operate as quantum heat engines (QHEs) that convert the solar photon energy to useful work (electric currents or chemical energy, respectively), the question arises whether coherence could also enhance the photosynthetic yield. Here, we show that both effects arise from the same population-coherence coupling term which is induced by noise, does not require coherent light, and will therefore work for incoherent excitation under natural conditions of solar excitation. Charge separation in light-harvesting complexes occurs in a pair of tightly coupled chlorophylls (the special pair) at the heart of photosynthetic reaction centers of both plants and bacteria. We show the analogy between the energy level schemes of the special pair and of the laser/photocell QHEs, and that both population oscillations and enhanced yield have a common origin and are expected to coexist for typical parameters. We predict an enhanced yield of 27% in a QHE motivated by the reaction center. This suggests nature-mimicking architectures for artificial solar energy devices. PMID:23365138

  2. Forster Energy Transfer Theory as Reflected in the Structures of Photosynthetic Light-Harvesting Systems

    SciTech Connect

    Sener, Melih; Strumpfer, Johan; Hsin, Jen; Chandler, Danielle; Scheuring, Simon; Hunter, C. Neil; Schulten, Klaus

    2011-02-22

    Förster's theory of resonant energy transfer underlies a fundamental process in nature, namely the harvesting of sunlight by photosynthetic life forms. The theoretical framework developed by Förster and others describes how electronic excitation migrates in the photosynthetic apparatus of plants, algae, and bacteria from light absorbing pigments to reaction centers where light energy is utilized for the eventual conversion into chemical energy. The demand for highest possible efficiency of light harvesting appears to have shaped the evolution of photosynthetic species from bacteria to plants which, despite a great variation in architecture, display common structural themes founded on the quantum physics of energy transfer as described first by Förster. Herein, Förster’s theory of excitation transfer is summarized, including recent extensions, and the relevance of the theory to photosynthetic systems as evolved in purple bacteria, cyanobacteria, and plants is demonstrated. Förster's energy transfer formula, as used widely today in many fields of science, is also derived.

  3. Dynamics Associated with Prolonged Ensiling and Aerobic Deterioration of Total Mixed Ration Silage Containing Whole Crop Corn

    PubMed Central

    Wang, Huili; Ning, Tingting; Hao, Wei; Zheng, Mingli; Xu, Chuncheng

    2016-01-01

    This study investigated the dynamics associated with prolonged ensiling and aerobic deterioration of whole crop corn (WCC) silages and total mixed ration (TMR) silages containing WCC (C-TMR silages) to clarify the differences that account for the enhanced aerobic stability of TMR silages. Laboratory-scale barrel silos were randomly opened after 7, 14, 28, and 56 d of ensiling and were subjected to analyses of fermentation quality, microbial and temperature dynamics during aerobic exposure. WCC and C-TMR silages were both well preserved and microorganisms were inhibited with prolonged ensiling, including lactic acid bacteria. Yeast were inhibited to below the detection limit of 500 cfu/g fresh matter within 28 d of ensiling. Aerobic stability of both silages was enhanced with prolonged ensiling, whereas C-TMR silages were more aerobically stable than WCC silages for the same ensiling period. Besides the high moisture content, the weak aerobic stability of WCC silage is likely attributable to the higher lactic acid content and yeast count, which result from the high water-soluble carbohydrates content in WCC. After silo opening, yeast were the first to propagate and the increase in yeast levels is greater than that of other microorganisms in silages before deterioration. Besides, increased levels of aerobic bacteria were also detected before heating of WCC silages. The temperature dynamics also indicated that yeast are closely associated with the onset of the aerobic deterioration of C-TMR silage, whereas for WCC silages, besides yeast, aerobic bacteria also function in the aerobic deterioration. Therefore, the inclusion of WCC might contribute to the survival of yeast during ensiling but not influence the role of yeast in deterioration of C-TMR silages. PMID:26732329

  4. Dynamics Associated with Prolonged Ensiling and Aerobic Deterioration of Total Mixed Ration Silage Containing Whole Crop Corn.

    PubMed

    Wang, Huili; Ning, Tingting; Hao, Wei; Zheng, Mingli; Xu, Chuncheng

    2016-01-01

    This study investigated the dynamics associated with prolonged ensiling and aerobic deterioration of whole crop corn (WCC) silages and total mixed ration (TMR) silages containing WCC (C-TMR silages) to clarify the differences that account for the enhanced aerobic stability of TMR silages. Laboratory-scale barrel silos were randomly opened after 7, 14, 28, and 56 d of ensiling and were subjected to analyses of fermentation quality, microbial and temperature dynamics during aerobic exposure. WCC and C-TMR silages were both well preserved and microorganisms were inhibited with prolonged ensiling, including lactic acid bacteria. Yeast were inhibited to below the detection limit of 500 cfu/g fresh matter within 28 d of ensiling. Aerobic stability of both silages was enhanced with prolonged ensiling, whereas C-TMR silages were more aerobically stable than WCC silages for the same ensiling period. Besides the high moisture content, the weak aerobic stability of WCC silage is likely attributable to the higher lactic acid content and yeast count, which result from the high water-soluble carbohydrates content in WCC. After silo opening, yeast were the first to propagate and the increase in yeast levels is greater than that of other microorganisms in silages before deterioration. Besides, increased levels of aerobic bacteria were also detected before heating of WCC silages. The temperature dynamics also indicated that yeast are closely associated with the onset of the aerobic deterioration of C-TMR silage, whereas for WCC silages, besides yeast, aerobic bacteria also function in the aerobic deterioration. Therefore, the inclusion of WCC might contribute to the survival of yeast during ensiling but not influence the role of yeast in deterioration of C-TMR silages. PMID:26732329

  5. A novel carotenoid 1,2-hydratase (CruF) from two species of the non-photosynthetic bacterium Deinococcus.

    PubMed

    Sun, Zongtao; Shen, Shaochuan; Wang, Chao; Wang, Hu; Hu, Yaping; Jiao, Jiandong; Ma, Tingting; Tian, Bing; Hua, Yuejin

    2009-08-01

    A novel carotenoid 1,2-hydratase (CruF) responsible for the C-1',2' hydration of gamma-carotene was identified in the non-photosynthetic bacteria Deinococcus radiodurans R1 and Deinococcus geothermalis DSM 11300. Gene expression and disruption experiments demonstrated that dr0091 and dgeo2309 encode CruF in D. radiodurans and D. geothermalis, respectively. Their homologues were also found in the genomes of cyanobacteria, and exhibited little homology to the hydroxyneurosporene synthase (CrtC) proteins found mainly in photosynthetic bacteria. Phylogenetic analysis showed that CruF homologues form a separate family, which is evolutionarily distant from the known CrtC family.

  6. Die aerobe Glykolyse der Tumorzelle

    NASA Astrophysics Data System (ADS)

    Schneider, Friedhelm

    1981-01-01

    A high aerobic glycolysis (aerobic lactate production) is the most significant feature of the energy metabolism of rapidly growing tumor cells. Several mechanisms, which may be different in different cell lines, seem to be involved in this characteristic of energy metabolism of the tumor cell. Changes in the cell membrane leading to increased uptake and utilization of glucose, a high level of fetal types of isoenzymes, a decreased number of mitochondria and a reduced capacity to metabolize pyruvate are some factors which must be taken into consideration. It is not possible to favour one of them at the present time.

  7. Light-Dependent Sulfide Oxidation in the Anoxic Zone of the Chesapeake Bay Can Be Explained by Small Populations of Phototrophic Bacteria

    PubMed Central

    Bennett, Alexa J.; Hanson, Thomas E.; Luther, George W.

    2015-01-01

    Microbial sulfide oxidation in aquatic environments is an important ecosystem process, as sulfide is potently toxic to aerobic organisms. Sulfide oxidation in anoxic waters can prevent the efflux of sulfide to aerobic water masses, thus mitigating toxicity. The contribution of phototrophic sulfide-oxidizing bacteria to anaerobic sulfide oxidation in the Chesapeake Bay and the redox chemistry of the stratified water column were investigated in the summers of 2011 to 2014. In 2011 and 2013, phototrophic sulfide-oxidizing bacteria closely related to Prosthecochloris species of the phylum Chlorobi were cultivated from waters sampled at and below the oxic-anoxic interface, where measured light penetration was sufficient to support populations of low-light-adapted photosynthetic bacteria. In 2012, 2013, and 2014, light-dependent sulfide loss was observed in freshly collected water column samples. In these samples, extremely low light levels caused 2- to 10-fold increases in the sulfide uptake rate over the sulfide uptake rate under dark conditions. An enrichment, CB11, dominated by Prosthecochloris species, oxidized sulfide with a Ks value of 11 μM and a Vmax value of 51 μM min−1 (mg protein−1). Using these kinetic values with in situ sulfide concentrations and light fluxes, we calculated that a small population of Chlorobi similar to those in enrichment CB11 can account for the observed anaerobic light-dependent sulfide consumption activity in natural water samples. We conclude that Chlorobi play a far larger role in the Chesapeake Bay than currently appreciated. This result has potential implications for coastal anoxic waters and expanding oxygen-minimum zones as they begin to impinge on the photic zone. PMID:26296727

  8. Light-dependent sulfide oxidation in the anoxic zone of the Chesapeake Bay can be explained by small populations of phototrophic bacteria.

    PubMed

    Findlay, Alyssa J; Bennett, Alexa J; Hanson, Thomas E; Luther, George W

    2015-11-01

    Microbial sulfide oxidation in aquatic environments is an important ecosystem process, as sulfide is potently toxic to aerobic organisms. Sulfide oxidation in anoxic waters can prevent the efflux of sulfide to aerobic water masses, thus mitigating toxicity. The contribution of phototrophic sulfide-oxidizing bacteria to anaerobic sulfide oxidation in the Chesapeake Bay and the redox chemistry of the stratified water column were investigated in the summers of 2011 to 2014. In 2011 and 2013, phototrophic sulfide-oxidizing bacteria closely related to Prosthecochloris species of the phylum Chlorobi were cultivated from waters sampled at and below the oxic-anoxic interface, where measured light penetration was sufficient to support populations of low-light-adapted photosynthetic bacteria. In 2012, 2013, and 2014, light-dependent sulfide loss was observed in freshly collected water column samples. In these samples, extremely low light levels caused 2- to 10-fold increases in the sulfide uptake rate over the sulfide uptake rate under dark conditions. An enrichment, CB11, dominated by Prosthecochloris species, oxidized sulfide with a Ks value of 11 μM and a Vmax value of 51 μM min(-1) (mg protein(-1)). Using these kinetic values with in situ sulfide concentrations and light fluxes, we calculated that a small population of Chlorobi similar to those in enrichment CB11 can account for the observed anaerobic light-dependent sulfide consumption activity in natural water samples. We conclude that Chlorobi play a far larger role in the Chesapeake Bay than currently appreciated. This result has potential implications for coastal anoxic waters and expanding oxygen-minimum zones as they begin to impinge on the photic zone. PMID:26296727

  9. Light-dependent sulfide oxidation in the anoxic zone of the Chesapeake Bay can be explained by small populations of phototrophic bacteria.

    PubMed

    Findlay, Alyssa J; Bennett, Alexa J; Hanson, Thomas E; Luther, George W

    2015-11-01

    Microbial sulfide oxidation in aquatic environments is an important ecosystem process, as sulfide is potently toxic to aerobic organisms. Sulfide oxidation in anoxic waters can prevent the efflux of sulfide to aerobic water masses, thus mitigating toxicity. The contribution of phototrophic sulfide-oxidizing bacteria to anaerobic sulfide oxidation in the Chesapeake Bay and the redox chemistry of the stratified water column were investigated in the summers of 2011 to 2014. In 2011 and 2013, phototrophic sulfide-oxidizing bacteria closely related to Prosthecochloris species of the phylum Chlorobi were cultivated from waters sampled at and below the oxic-anoxic interface, where measured light penetration was sufficient to support populations of low-light-adapted photosynthetic bacteria. In 2012, 2013, and 2014, light-dependent sulfide loss was observed in freshly collected water column samples. In these samples, extremely low light levels caused 2- to 10-fold increases in the sulfide uptake rate over the sulfide uptake rate under dark conditions. An enrichment, CB11, dominated by Prosthecochloris species, oxidized sulfide with a Ks value of 11 μM and a Vmax value of 51 μM min(-1) (mg protein(-1)). Using these kinetic values with in situ sulfide concentrations and light fluxes, we calculated that a small population of Chlorobi similar to those in enrichment CB11 can account for the observed anaerobic light-dependent sulfide consumption activity in natural water samples. We conclude that Chlorobi play a far larger role in the Chesapeake Bay than currently appreciated. This result has potential implications for coastal anoxic waters and expanding oxygen-minimum zones as they begin to impinge on the photic zone.

  10. Aerobic conditions increase isoprenoid biosynthesis pathway gene expression levels for carotenoid production in Enterococcus gilvus.

    PubMed

    Hagi, Tatsuro; Kobayashi, Miho; Nomura, Masaru

    2015-06-01

    Some lactic acid bacteria that harbour carotenoid biosynthesis genes (crtNM) can produce carotenoids. Although aerobic conditions can increase carotenoid production and crtNM expression levels, their effects on the pathways that synthesize carotenoid precursors such as mevalonate and isoprene are not completely understood. In this study, we investigated whether aerobic conditions affected gene expression levels involved in the isoprenoid biosynthesis pathway that includes the mevalonate and isoprene biosynthesis pathways in Enterococcus gilvus using real-time quantitative reverse transcription PCR. NADH oxidase (nox) and superoxide dismutase (sod) gene expression levels were investigated as controls for aerobic conditions. The expression levels of nox and sod under aerobic conditions were 7.2- and 8.0-fold higher, respectively, than those under anaerobic conditions. Aerobic conditions concomitantly increased the expression levels of crtNM carotenoid biosynthesis genes. HMG-CoA synthase gene expression levels in the mevalonate pathway were only slightly increased under aerobic conditions, whereas the expression levels of HMG-CoA reductase and five other genes in the isoprene biosynthesis pathways were 1.2-2.3-fold higher than those under anaerobic conditions. These results demonstrated that aerobic conditions could increase the expression levels of genes involved in the isoprenoid biosynthesis pathway via mevalonate in E. gilvus.

  11. The Transition from Aerobic to Anaerobic Metabolism.

    ERIC Educational Resources Information Center

    Skinner, James S.; McLellan, Thomas H.

    1980-01-01

    The transition from aerobic to anaerobic metabolism is discussed. More research is needed on different kinds of athletes and athletic activities and how they may affect aerobic and anaerobic metabolisms. (CJ)

  12. Genome sequence of aerobic anoxygenic phototrophic bacterium Erythrobacter sp. JL475, isolated from the South China Sea.

    PubMed

    Zheng, Qiang; Liu, Yanting; Sun, Jia; Jiao, Nianzhi

    2015-06-01

    Erythrobacter sp. JL475 is a bacteriochlorophyll a-containing aerobic anoxygenic photo-heterotrophic bacterium. Here, we report the draft genome sequence of Erythrobacter sp. JL475 isolated from the South China Sea. It comprises ~3.26Mbp in 7 contigs with the G+C content of 61.7%. A total of 3042 protein-coding genes were obtained, and one complete photosynthetic gene cluster (~38Kbp) was found.

  13. Bacterial survival and association with sludge flocs during aerobic and anaerobic digestion of wastewater sludge under laboratory conditions.

    PubMed Central

    Farrah, S R; Bitton, G

    1983-01-01

    The fate of indicator bacteria, a bacterial pathogen, and total aerobic bacteria during aerobic and anaerobic digestion of wastewater sludge under laboratory conditions was determined. Correlation coefficients were calculated between physical and chemical parameters (temperature, dissolved oxygen, pH, total solids, and volatile solids) and either the daily change in bacterial numbers or the percentage of bacteria in the supernatant. The major factor influencing survival of Salmonella typhimurium and indicator bacteria during aerobic digestion was the temperature of sludge digestion. At 28 degrees C with greater than 4 mg of dissolved oxygen per liter, the daily change in numbers of these bacteria was approximately -1.0 log10/ml. At 6 degrees C, the daily change was less than -0.3 log10/ml. Most of the bacteria were associated with the sludge flocs during aerobic digestion of sludge at 28 degrees C with greater than 2.4 mg of dissolved oxygen per liter. Lowering the temperature or the amount of dissolved oxygen decreased the fraction of bacteria associated with the flocs and increased the fraction found in the supernatant. PMID:6401978

  14. [Photosynthetic characteristics of Gynostemma pentaphyllum under shade].

    PubMed

    Huang, Chenglin; Wu, Zemin; Yao, Yongkang; Xu, Xiaoniu

    2004-11-01

    The study showed that under summer shade condition, the diurnal variation of net photosynthetic rate of Gynostemma pentaphyllum presented nontypical double apex, the first apex being 13.8 micromol CO2 x m(-2) x s(-1) at 11:00, and the diurnal net photosynthetic rate was about 176.97 micromol CO2 x m(-2), 3.1 times of that under full sunlight. There was a positive correlation between net photosynthetic rate and photon flux density (PFD), and relative humidity had a small effect on net photosynthetic rate. Under full sunlight, the typical "midday depression" of photosynthesis was observed, and the diurnal variation of net photosynthetic rate presented double apex, with the first apex being 3.0 micromol CO2 x m(-2) x s(-1) at 10:00 and the second being 1.25 micromol CO2 x m(-2) x s(-1) at 14:00. There was a positive correlation between net photosynthetic rate and relative humidity, and the latter had a strong effect on net photosynthetic rate. When PFD was higher than 700 micromol CO2 x m(-2) x s(-1), it had a negative correlation with net photosynthetic rate. Stoma conductance was the main factor affecting the transpiration rate of Gynostemma pentaphyllum. Therefore, Gynostemma pentaphyllum was a typical sciophytic plant, and light factor should be considered firstly in its cultivation. PMID:15707321

  15. An obligately photosynthetic bacterial anaerobe from a deep-sea hydrothermal vent.

    PubMed

    Beatty, J Thomas; Overmann, Jörg; Lince, Michael T; Manske, Ann K; Lang, Andrew S; Blankenship, Robert E; Van Dover, Cindy L; Martinson, Tracey A; Plumley, F Gerald

    2005-06-28

    The abundance of life on Earth is almost entirely due to biological photosynthesis, which depends on light energy. The source of light in natural habitats has heretofore been thought to be the sun, thus restricting photosynthesis to solar photic environments on the surface of the Earth. If photosynthesis could take place in geothermally illuminated environments, it would increase the diversity of photosynthetic habitats both on Earth and on other worlds that have been proposed to possibly harbor life. Green sulfur bacteria are anaerobes that require light for growth by the oxidation of sulfur compounds to reduce CO2 to organic carbon, and are capable of photosynthetic growth at extremely low light intensities. We describe the isolation and cultivation of a previously unknown green sulfur bacterial species from a deep-sea hydrothermal vent, where the only source of light is geothermal radiation that includes wavelengths absorbed by photosynthetic pigments of this organism.

  16. Membrane thickening aerobic digestion processes.

    PubMed

    Woo, Bryen

    2014-01-01

    Sludge management accounts for approximately 60% of the total wastewater treatment plant expenditure and laws for sludge disposal are becoming increasingly stringent, therefore much consideration is required when designing a solids handling process. A membrane thickening aerobic digestion process integrates a controlled aerobic digestion process with pre-thickening waste activated sludge using membrane technology. This process typically features an anoxic tank, an aerated membrane thickener operating in loop with a first-stage digester followed by second-stage digestion. Membrane thickening aerobic digestion processes can handle sludge from any liquid treatment process and is best for facilities obligated to meet low total phosphorus and nitrogen discharge limits. Membrane thickening aerobic digestion processes offer many advantages including: producing a reusable quality permeate with minimal levels of total phosphorus and nitrogen that can be recycled to the head works of a plant, protecting the performance of a biological nutrient removal liquid treatment process without requiring chemical addition, providing reliable thickening up to 4% solids concentration without the use of polymers or attention to decanting, increasing sludge storage capacities in existing tanks, minimizing the footprint of new tanks, reducing disposal costs, and providing Class B stabilization.

  17. Molecular characterization of bacterial community in aerobic granular sludge stressed by pentachlorophenol.

    PubMed

    Liu, He; Li, Guangwei; Li, Xiufen; Chen, Jian

    2008-01-01

    To characterize the effects of pentachlorophenol (PCP) on the performance and microbial community of aerobic granular sludge in sequencing batch reactor (SBR), the web-based terminal restriction fragment length polymorphism (T-RFLP) and real-time PCR (RT-PCR) techniques were used to explore the bacterial community structure. When PCP increased from 0 to 50 mg/L, the COD removal rate changed little, while the ammonia removal rate dropped from 100% to 64.9%. The results of molecular characterization showed that the quantity of ammonia oxidizing bacteria (AOB) kept constantly, although the number of bacteria species decreased with the increase of PCP concentration. Significant shift in bacterial community structure at different PCP stresses was observed within aerobic granular sludge. When the PCP was absent, there are 69 strains in aerobic granular sludge detected by T-RFLP method. With the increase of PCP, most of bacteria disappeared and only 19 bacteria existed at all five PCP concentrations. These results contributed to comprehensive understanding of the microbial community structure under the PCP stress and its relationship with the performance for wastewater treatment by aerobic granular sludge.

  18. Arthritis and Aerobic Exercise: A Review.

    ERIC Educational Resources Information Center

    Ike, Robert W.; And Others

    1989-01-01

    Arthritic patients who regularly do aerobic exercise make significant gains in aerobic and functional status, and in subjective areas like pain tolerance and mood. Still, they are often advised to curtail physical activity. Guidelines are presented for physicians prescribing aerobic exercise. An exercise tolerance test is recommended. (SM)

  19. Developmental intestinal aerobic microflora in the kori bustard (Ardeotis kori).

    PubMed

    Naldo, J L; Silvanose, C D; Samour, J H; Bailey, T A

    1998-01-01

    A study was carried out to investigate the normal aerobic bacterial flora of developing kori bustard (Ardeotis kori) chicks, captive bred at the National Avian Research Center, Abu Dhabi, United Arab Emirates. Faecal samples were collected from 14 birds at different ages from the first day of hatching until 99 days old and were cultured for aerobic bacteria. Several bacterial species were isolated from the cultures, they included Escherichia coli, Streptococcus viridians, Enterococcus faecalis, Klebsiella oxytoca, Proteus spp., Enterobacter, spp. and Serratia marcescens. Gram-negative bacilli were isolated from all but one of the faecal samples collected. They were also the predominant bacteria, accounting for between 55.6 and 73.4% of the mean colony count of faecal cultures from all age groups. E. coli was the most frequently isolated bacteria, the frequency and mean colony count increased as the birds grew older. Gram-positive cocci were isolated from between 50 and 100% of the faecal samples from all age groups, and they accounted for between 26.6 and 44.4% of the mean colony count. Results from this study indicated that Gram-negative bacilli and Gram-positive cocci can be isolated frequently from the faeces of developing, clinically normal, captive bred kori bustard chicks. PMID:18484014

  20. Developmental intestinal aerobic microflora in the kori bustard (Ardeotis kori).

    PubMed

    Naldo, J L; Silvanose, C D; Samour, J H; Bailey, T A

    1998-01-01

    A study was carried out to investigate the normal aerobic bacterial flora of developing kori bustard (Ardeotis kori) chicks, captive bred at the National Avian Research Center, Abu Dhabi, United Arab Emirates. Faecal samples were collected from 14 birds at different ages from the first day of hatching until 99 days old and were cultured for aerobic bacteria. Several bacterial species were isolated from the cultures, they included Escherichia coli, Streptococcus viridians, Enterococcus faecalis, Klebsiella oxytoca, Proteus spp., Enterobacter, spp. and Serratia marcescens. Gram-negative bacilli were isolated from all but one of the faecal samples collected. They were also the predominant bacteria, accounting for between 55.6 and 73.4% of the mean colony count of faecal cultures from all age groups. E. coli was the most frequently isolated bacteria, the frequency and mean colony count increased as the birds grew older. Gram-positive cocci were isolated from between 50 and 100% of the faecal samples from all age groups, and they accounted for between 26.6 and 44.4% of the mean colony count. Results from this study indicated that Gram-negative bacilli and Gram-positive cocci can be isolated frequently from the faeces of developing, clinically normal, captive bred kori bustard chicks.

  1. Calculation of the radiative properties of photosynthetic microorganisms

    NASA Astrophysics Data System (ADS)

    Dauchet, Jérémi; Blanco, Stéphane; Cornet, Jean-François; Fournier, Richard

    2015-08-01

    photosynthetic bacteria, cyanobacteria and eukaryotic microalgae. The obtained results are in very good agreement with the experimental measurements when the shape of the microorganisms is well described (in comparison to the standard volume-equivalent sphere approximation). As a main perspective, the consideration of the helical shape of Arthrospira platensis appears to be a key to an accurate estimation of its radiative properties. On the whole, the presented methodological chain also appears of great interest for other scientific communities such as atmospheric science, oceanography, astrophysics and engineering.

  2. Role of an elliptical structure in photosynthetic energy transfer: Collaboration between quantum entanglement and thermal fluctuation.

    PubMed

    Oka, Hisaki

    2016-05-13

    Recent experiments have revealed that the light-harvesting complex 1 (LH1) in purple photosynthetic bacteria has an elliptical structure. Generally, symmetry lowering in a structure leads to a decrease in quantum effects (quantum coherence and entanglement), which have recently been considered to play a role in photosynthetic energy transfer, and hence, elliptical structure seems to work against efficient photosynthetic energy transfer. Here we analyse the effect of an elliptical structure on energy transfer in a purple photosynthetic bacterium and reveal that the elliptical distortion rather enhances energy transfer from peripheral LH2 to LH1 at room temperature. Numerical results show that quantum entanglement between LH1 and LH2 is formed over a wider range of high energy levels than would have been the case with circular LH1. Light energy absorbed by LH2 is thermally pumped via thermal fluctuation and is effectively transferred to LH1 through the entangled states at room temperature rather than at low temperature. This result indicates the possibility that photosynthetic systems adopt an elliptical structure to effectively utilise both quantum entanglement and thermal fluctuation at physiological temperature.

  3. Role of an elliptical structure in photosynthetic energy transfer: Collaboration between quantum entanglement and thermal fluctuation

    NASA Astrophysics Data System (ADS)

    Oka, Hisaki

    2016-05-01

    Recent experiments have revealed that the light-harvesting complex 1 (LH1) in purple photosynthetic bacteria has an elliptical structure. Generally, symmetry lowering in a structure leads to a decrease in quantum effects (quantum coherence and entanglement), which have recently been considered to play a role in photosynthetic energy transfer, and hence, elliptical structure seems to work against efficient photosynthetic energy transfer. Here we analyse the effect of an elliptical structure on energy transfer in a purple photosynthetic bacterium and reveal that the elliptical distortion rather enhances energy transfer from peripheral LH2 to LH1 at room temperature. Numerical results show that quantum entanglement between LH1 and LH2 is formed over a wider range of high energy levels than would have been the case with circular LH1. Light energy absorbed by LH2 is thermally pumped via thermal fluctuation and is effectively transferred to LH1 through the entangled states at room temperature rather than at low temperature. This result indicates the possibility that photosynthetic systems adopt an elliptical structure to effectively utilise both quantum entanglement and thermal fluctuation at physiological temperature.

  4. Role of an elliptical structure in photosynthetic energy transfer: Collaboration between quantum entanglement and thermal fluctuation

    PubMed Central

    Oka, Hisaki

    2016-01-01

    Recent experiments have revealed that the light-harvesting complex 1 (LH1) in purple photosynthetic bacteria has an elliptical structure. Generally, symmetry lowering in a structure leads to a decrease in quantum effects (quantum coherence and entanglement), which have recently been considered to play a role in photosynthetic energy transfer, and hence, elliptical structure seems to work against efficient photosynthetic energy transfer. Here we analyse the effect of an elliptical structure on energy transfer in a purple photosynthetic bacterium and reveal that the elliptical distortion rather enhances energy transfer from peripheral LH2 to LH1 at room temperature. Numerical results show that quantum entanglement between LH1 and LH2 is formed over a wider range of high energy levels than would have been the case with circular LH1. Light energy absorbed by LH2 is thermally pumped via thermal fluctuation and is effectively transferred to LH1 through the entangled states at room temperature rather than at low temperature. This result indicates the possibility that photosynthetic systems adopt an elliptical structure to effectively utilise both quantum entanglement and thermal fluctuation at physiological temperature. PMID:27173144

  5. Development of a gene cloning system for the hydrogen-producing marine photosynthetic bacterium Rhodopseudomonas sp

    SciTech Connect

    Matsunaga, T.; Matsunaga, N.; Tsubaki, K.; Tanaka, T.

    1986-10-01

    Seventy-six strains of marine photosynthetic bacteria were analyzed by agarose gel electrophoresis for plasmid DNA content. Among these strains, 12 carried two to four different plasmids with sizes ranging from 3.1 to 11.0 megadaltons. The marine photosynthetic bacterium Rhodopseudomonas sp. NKPB002106 had two plasmids, pRD06S and pRD06L. The smaller plasmid, pRD06S, had a molecular weight of 3.8 megadaltons and was cut at a single site by restriction endonucleases SalI, SmaI, PstI, XhoI, and BglII. Moreover, the marine photosynthetic bacterium Rhodopseudomonas sp. NKPB002106 containing plasmid pRD06 had a satisfactory growth rate (doubling time, 7.5 h), a hydrogen-producing rate of 0.96 ..mu..mol/mg (dry weight) of cells per h, and nitrogen fixation capability. Plasmid pRD06S, however, had neither drug resistance nor heavy-metal resistance, and its copy number was less than 10. Therefore, a recombinant plasmid consisting of pRD06S and Escherichia coli cloning vector pUC13 was constructed and cloned in E. coli. The recombinant plasmid was transformed into Rhodopseudomonas sp. NKPB002106. As a result, Rhodopseudomonas sp. NKPB002106 developed ampicillin resistance. Thus, a shuttle vector for gene transfer was constructed for marine photosynthetic bacteria.

  6. Development of a gene cloning system for the hydrogen-producing marine photosynthetic bacterium Rhodopseudomonas sp.

    PubMed Central

    Matsunaga, T; Matsunaga, N; Tsubaki, K; Tanaka, T

    1986-01-01

    Seventy-six strains of marine photosynthetic bacteria were analyzed by agarose gel electrophoresis for plasmid DNA content. Among these strains, 12 carried two to four different plasmids with sizes ranging from 3.1 to 11.0 megadaltons. The marine photosynthetic bacterium Rhodopseudomonas sp. NKPB002106 had two plasmids, pRD06S and pRD06L. The smaller plasmid, pRD06S, had a molecular weight of 3.8 megadaltons and was cut at a single site by restriction endonucleases SalI, SmaI, PstI, XhoI, and BglII. Moreover, the marine photosynthetic bacterium Rhodopseudomonas sp. NKPB002106 containing plasmid pRD06 had a satisfactory growth rate (doubling time, 7.5 h), a hydrogen-producing rate of 0.96 mumol/mg (dry weight) of cells per h, and nitrogen fixation capability. Plasmid pRD06S, however, had neither drug resistance nor heavy-metal resistance, and its copy number was less than 10. Therefore, a recombinant plasmid consisting of pRD06S and Escherichia coli cloning vector pUC13 was constructed and cloned in E. coli. The recombinant plasmid was transformed into Rhodopseudomonas sp. NKPB002106. As a result, Rhodopseudomonas sp. NKPB002106 developed ampicillin resistance. Thus, a shuttle vector for gene transfer was constructed for marine photosynthetic bacteria. PMID:3020006

  7. [Oropharyngeal aerobic flora in patients hospitalized in an ORL department].

    PubMed

    Dumont, Y; Borderon, E; Farcy, M C; Penot, J C

    1986-01-01

    As patients with E.N.T. carcinoma have relative frequent infectious complications of E.N.T. area, we have carried out a study or oropharyngeal colonization by aerobic bacteria and fungi in 84 hospitalized patients. The results of the tests are analysed according to different parameters, essentially the presence or the absence of neoplasia and antibiotherapy. The presence of one of these two factors does not substantially modify oropharyngeal flora of patients. However their association coincides with a height percentage of colonies of enterobacteriaceae, of pseudomonas and of fungi.

  8. Aerobic bacterial flora of addled raptor eggs in Saskatchewan.

    PubMed

    Houston, C S; Saunders, J R; Crawford, R D

    1997-04-01

    In south-central Saskatchewan, Canada, in 1986, 1987 and 1989, the aerobic bacterial flora was evaluated from 75 unhatched raptor eggs of three species: 42 of the Swainson's hawk (Buteo Swainsoni), 21 of the ferruginous hawk (Buteo regalis), and 12 of the great horned owl (Bubo virginianus). In addled Swainson's hawk eggs, the most common bacterial genera were Enterobacter (18 eggs), Escherichia (12), and Streptococcus (10). Seven great horned owl eggs and six ferruginous hawk eggs also contained Escherichia coli. Salmonella spp. were not isolated. These bacteria were interpreted as secondary contaminants and not the primary cause of reproductive failure. PMID:9131569

  9. Structural model and spectroscopic characteristics of the FMO antenna protein from the aerobic chlorophototroph, Candidatus Chloracidobacterium thermophilum.

    PubMed

    Wen, Jianzhong; Tsukatani, Yusuke; Cui, Weidong; Zhang, Hao; Gross, Michael L; Bryant, Donald A; Blankenship, Robert E

    2011-01-01

    The Fenna-Matthews-Olson protein (FMO) binds seven or eight bacteriochlorophyll a (BChl a) molecules and is an important model antenna system for understanding pigment-protein interactions and mechanistic aspects of photosynthetic light harvesting. FMO proteins of green sulfur bacteria (Chlorobiales) have been extensively studied using a wide range of spectroscopic and theoretical approaches because of their stability, the spectral resolution of their pigments, their water-soluble nature, and the availability of high-resolution structural data. We obtained new structural and spectroscopic insights by studying the FMO protein from the recently discovered, aerobic phototrophic acidobacterium, Candidatus Chloracidobacterium thermophilum. Native C. thermophilum FMO is a trimer according to both analytical gel filtration and native-electrospray mass spectrometry. Furthermore, the mass of intact FMO trimer is consistent with the presence of 21-24 BChl a in each. Homology modeling of the C. thermophilum FMO was performed by using the structure of the FMO protein from Chlorobaculum tepidum as a template. C. thermophilum FMO differs from C. tepidum FMO in two distinct regions: the baseplate, CsmA-binding region and a region that is proposed to bind the reaction center subunit, PscA. C. thermophilum FMO has two fluorescence emission peaks at room temperature but only one at 77K. Temperature-dependent fluorescence spectroscopy showed that the two room-temperature emission peaks result from two excited-state BChl a populations that have identical fluorescence lifetimes. Modeling of the data suggests that the two populations contain 1-2 BChl and 5-6 BChl a molecules and that thermal equilibrium effects modulate the relative population of the two emitting states.

  10. Silicification-induced cell aggregation for the sustainable production of H2 under aerobic conditions.

    PubMed

    Xiong, Wei; Zhao, Xiaohong; Zhu, Genxing; Shao, Changyu; Li, Yaling; Ma, Weimin; Xu, Xurong; Tang, Ruikang

    2015-10-01

    Photobiological hydrogen production is of great importance because of its promise for generating clean renewable energy. In nature, green algae cannot produce hydrogen as a result of the extreme sensitivity of hydrogenase to oxygen. However, we find that silicification-induced green algae aggregates can achieve sustainable photobiological hydrogen production even under natural aerobic conditions. The core-shell structure of the green algae aggregates creates a balance between photosynthetic electron generation and hydrogenase activity, thus allowing the production of hydrogen. This finding provides a viable pathway for the solar-driven splitting of water into hydrogen and oxygen to develop green energy alternatives by using rationally designed cell-material complexes.

  11. Bacterial community composition and abundance in leachate of semi-aerobic and anaerobic landfills.

    PubMed

    Zhang, Wei; Yue, Bo; Wang, Qi; Huang, Zechun; Huang, Qifei; Zhang, Zengqiang

    2011-01-01

    The abundance and phylogenetic composition of bacterial community in leachate of semi-aerobic and anaerobic landfill were compared through real-time polymerase chain reaction and denaturing gradient gel electrophoresis. In semi-aerobic landfill scenario, the bacterial 16S rRNA copy numbers in leachate had no significant reduction from initial stage to stable period. In the scenario of anaerobic landfill, the largest bacterial 16S rRNA gene copy number was found in leachate at initial stage, but it reduced significantly at stable period. Moreover, methane-oxidizing bacteria population in stable period was lower than that in initial period in both two landfill processes. However, semi-aerobic landfill leachate had more methanotrophic bacteria populations than that in the anaerobic one. Furthermore, according to the sequences and phylogenetic analysis, obvious difference could be detected in bacterial community composition in different scenarios. Proteobacteria and bacteroidetes took up a dominantly higher proportion in semi-aerobic landfill leachate. To summarize up, different landfill methods and its landfill ages had crucial impacts on bacterial abundance and composition in leachate of semi-aerobic and anaerobic landfills.

  12. [Effects of light quality on photosynthetic pigment contents and photosynthetic characteristics of peanut seedling leaves].

    PubMed

    Yan, Meng-Meng; Wang, Ming-Lun; Wang, Hong-Bo; Wang, Yue-Fu; Zhao, Chang-Xing

    2014-02-01

    This study explored the effects of different light quality on photosynthetic pigment contents and photosynthetic characteristics of peanut (Qinhua 6) seedling leaves. The results showed that, compared with natural light, blue light (445-470 nm) could significantly improve the specific leaf area (SLA), chlorophyll a/b value and carotenoid content of peanut seedlings. Meanwhile, the net photosynthetic rate, stomatal conductance, and transpiration rate were higher, the intercellular CO2 content was lower, and the photosynthetic efficiency was improved significantly under blue light. Red light (610-660 nm) could improve the chlorophyll content significantly, and reduce SLA, chlorophyll a/b value and carotenoid content, with a lower photosynthetic efficiency than natural light. Green light (515-520 nm) and yellow light (590-595 nm) were not conducive to photosynthetic pigment accumulation of leaves, and significantly inhibited leaf photosynthesis of peanut seedlings.

  13. Bacteria Provide Cleanup of Oil Spills, Wastewater

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Through Small Business Innovation Research (SBIR) contracts with Marshall Space Flight Center, Micro-Bac International Inc., of Round Rock, Texas, developed a phototrophic cell for water purification in space. Inside the cell: millions of photosynthetic bacteria. Micro-Bac proceeded to commercialize the bacterial formulation it developed for the SBIR project. The formulation is now used for the remediation of wastewater systems and waste from livestock farms and food manufacturers. Strains of the SBIR-derived bacteria also feature in microbial solutions that treat environmentally damaging oil spills, such as that resulting from the catastrophic 2010 Deepwater Horizon oil rig explosion in the Gulf of Mexico.

  14. Aerobic and anaerobic growth of Paracoccus denitrificans on methanol.

    PubMed

    Bamforth, C W; Quayle, J R

    1978-10-01

    1. The dye-linked methanol dehydrogenase from Paracoccus denitrificans grown aerobically on methanol has been purified and its properties compared with similar enzymes from other bacteria. It was shown to be specific and to have high affinity for primary alcohols and formaldehyde as substrate, ammonia was the best activator and the enzyme could be linked to reduction of phenazine methosulphate. 2. Paracoccus denitrificans could be grown anaerobically on methanol, using nitrate or nitrite as electron acceptor. The methanol dehydrogenase synthesized under these conditions could not be differentiated from the aerobically-synthesized enzyme. 3. Activities of methanol dehydrogenase, formaldehyde dehydrogenase, formate dehydrogenase, nitrate reductase and nitrite reductase were measured under aerobic and anaerobic growth conditions. 4. Difference spectra of reduced and oxidized cytochromes in membrane and supernatant fractions of methanol-grown P. denitrificans were measured. 5. From the results of the spectral and enzymatic analyses it has been suggested that anaerobic growth on methanol/nitrate is made possible by reduction of nitrate to nitrite using electrons derived from the pyridine nucleotide-linked dehydrogenations of formaldehyde and formate, the nitrite so produced then functioning as electron acceptor for methanol dehydrogenase via cytochrome c and nitrite reductase. PMID:718372

  15. Magnetic Bacteria.

    ERIC Educational Resources Information Center

    Nelson, Jane Bray; Nelson, Jim

    1992-01-01

    Describes the history of Richard Blakemore's discovery of magnetotaxic organisms. Discusses possible reasons why the magnetic response in bacteria developed. Proposes research experiments integrating biology and physics in which students investigate problems using cultures of magnetotaxic organisms. (MDH)

  16. Synergistic Two-Photon Absorption Enhancement in Photosynthetic Light Harvesting

    NASA Astrophysics Data System (ADS)

    Chen, Kuo-Mei; Chen, Yu-Wei; Gao, Ting-Fong

    2012-06-01

    The grand scale fixation of solar energies into chemical substances by photosynthetic reactions of light-harvesting organisms provides Earth's other life forms a thriving environment. Scientific explorations in the past decades have unraveled the fundamental photophysical and photochemical processes in photosynthesis. Higher plants, green algae, and light-harvesting bacteria utilize organized pigment-protein complexes to harvest solar power efficiently and the resultant electronic excitations are funneled into a reaction center, where the first charge separation process takes place. Here we show experimental evidences that green algae (Chlorella vulgaris) in vivo display a synergistic two-photon absorption enhancement in their photosynthetic light harvesting. Their absorption coefficients at various wavelengths display dramatic dependence on the photon flux. This newly found phenomenon is attributed to a coherence-electronic-energy-transfer-mediated (CEETRAM) photon absorption process of light-harvesting pigment-protein complexes of green algae. Under the ambient light level, algae and higher plants can utilize this quantum mechanical mechanism to create two entangled electronic excitations adjacently in their light-harvesting networks. Concerted multiple electron transfer reactions in the reaction centers and oxygen evolving complexes can be implemented efficiently by the coherent motion of two entangled excitons from antennae to the charge separation reaction sites. To fabricate nanostructured, synthetic light-harvesting apparatus, the paramount role of the CEETRAM photon absorption mechanism should be seriously considered in the strategic guidelines.

  17. Primary Photosynthetic Energy Conversion in Bacterial Reaction Centers

    NASA Astrophysics Data System (ADS)

    Zinth, Wolfgang; Wachtveitl, J.

    The development of human societies is strongly influenced by the available energetic resources. In a period where the limitations of conventional fossil energy carriers become as evident as the often uncontrollable dangers of nuclear energy, one has to reconsider regenerative energy resources. Here photovoltaic or photochemical use of solar energy is an important approach. Since the early days of evolution some two billion years ago, the dominant energetic input into the life system on earth occurs via the conversion of solar energy performed in photosynthetic organisms. The fossil energy carriers that we use and waste today have been produced by photosynthesis over millions of years. In the race for an extended and versatile use of solar energy, semiconductorbased photovoltaic devices have been developed. However, even after decades of intense engineering they cannot serve as a competitive alternative to fossil energy. Under these circumstances new alternatives are required. One line of scientific development may use the operational principles of photosynthesis since photosynthesis is still our main energy source. In this respect, we will present results on the basic concepts of energy conversion in photosynthetic bacteria, which could be used as a guideline to alternative light energy conversion systems.

  18. Phosphorylation stoichiometry determination in plant photosynthetic membranes.

    PubMed

    Ingelsson, Björn; Fristedt, Rikard; Turkina, Maria V

    2015-01-01

    This chapter describes different strategies for the study of phosphorylation dynamics and stoichiometry in photosynthetic membranes. Detailed procedures for the detection, large-scale identification, and quantification of phosphorylated proteins optimized for plant thylakoid proteins are given. PMID:25930698

  19. Regulation of Carotenoid Biosynthesis in Photosynthetic Organs.

    PubMed

    Llorente, Briardo

    2016-01-01

    A substantial proportion of the dazzling diversity of colors displayed by living organisms throughout the tree of life is determined by the presence of carotenoids, which most often provide distinctive yellow, orange and red hues. These metabolites play fundamental roles in nature that extend far beyond their importance as pigments. In photosynthetic lineages, carotenoids are essential to sustain life, since they have been exploited to maximize light harvesting and protect the photosynthetic machinery from photooxidative stress. Consequently, photosynthetic organisms have evolved several mechanisms that adjust the carotenoid metabolism to efficiently cope with constantly fluctuating light environments. This chapter will focus on the current knowledge concerning the regulation of the carotenoid biosynthetic pathway in leaves, which are the primary photosynthetic organs of most land plants. PMID:27485221

  20. Hybrid system of semiconductor and photosynthetic protein.

    PubMed

    Kim, Younghye; Shin, Seon Ae; Lee, Jaehun; Yang, Ki Dong; Nam, Ki Tae

    2014-08-29

    Photosynthetic protein has the potential to be a new attractive material for solar energy absorption and conversion. The development of semiconductor/photosynthetic protein hybrids is an example of recent progress toward efficient, clean and nanostructured photoelectric systems. In the review, two biohybrid systems interacting through different communicating methods are addressed: (1) a photosynthetic protein immobilized semiconductor electrode operating via electron transfer and (2) a hybrid of semiconductor quantum dots and photosynthetic protein operating via energy transfer. The proper selection of materials and functional and structural modification of the components and optimal conjugation between them are the main issues discussed in the review. In conclusion, we propose the direction of future biohybrid systems for solar energy conversion systems, optical biosensors and photoelectric devices.

  1. Swimming bacteria power microscopic gears

    SciTech Connect

    Sokolov, Andrey; Apodaca, Mario M.; Grzybowski, Bartosz A.; Aranson, Igor S.

    2010-01-19

    Whereas the laws of thermodynamics prohibit extraction of useful work from the Brownian motion of particles in equilibrium, these motions can be “rectified” under nonequilibrium conditions, for example, in the presence of asymmetric geometrical obstacles. Here, we describe a class of systems in which aerobic bacteria Bacillus subtilis moving randomly in a fluid film power submillimeter gears and primitive systems of gears decorated with asymmetric teeth. The directional rotation is observed only in the regime of collective bacterial swimming and the gears’ angular velocities depend on and can be controlled by the amount of oxygen available to the bacteria. The ability to harness and control the power of collective motions appears an important requirement for further development of mechanical systems driven by microorganisms.

  2. Swimming bacteria power microscopic gears.

    SciTech Connect

    Sokolov, A.; Apodaca, M. M.; Grzybowski, B. A.; Aranson, I. S.; Materials Science Division; Princeton Univ.; Northwestern Univ.

    2010-01-19

    Whereas the laws of thermodynamics prohibit extraction of useful work from the Brownian motion of particles in equilibrium, these motions can be 'rectified' under nonequilibrium conditions, for example, in the presence of asymmetric geometrical obstacles. Here, we describe a class of systems in which aerobic bacteria Bacillus subtilis moving randomly in a fluid film power submillimeter gears and primitive systems of gears decorated with asymmetric teeth. The directional rotation is observed only in the regime of collective bacterial swimming and the gears angular velocities depend on and can be controlled by the amount of oxygen available to the bacteria. The ability to harness and control the power of collective motions appears an important requirement for further development of mechanical systems driven by microorganisms.

  3. Methods to determine aerobic endurance.

    PubMed

    Bosquet, Laurent; Léger, Luc; Legros, Patrick

    2002-01-01

    Physiological testing of elite athletes requires the correct identification and assessment of sports-specific underlying factors. It is now recognised that performance in long-distance events is determined by maximal oxygen uptake (V(2 max)), energy cost of exercise and the maximal fractional utilisation of V(2 max) in any realised performance or as a corollary a set percentage of V(2 max) that could be endured as long as possible. This later ability is defined as endurance, and more precisely aerobic endurance, since V(2 max) sets the upper limit of aerobic pathway. It should be distinguished from endurance ability or endurance performance, which are synonymous with performance in long-distance events. The present review examines methods available in the literature to assess aerobic endurance. They are numerous and can be classified into two categories, namely direct and indirect methods. Direct methods bring together all indices that allow either a complete or a partial representation of the power-duration relationship, while indirect methods revolve around the determination of the so-called anaerobic threshold (AT). With regard to direct methods, performance in a series of tests provides a more complete and presumably more valid description of the power-duration relationship than performance in a single test, even if both approaches are well correlated with each other. However, the question remains open to determine which systems model should be employed among the several available in the literature, and how to use them in the prescription of training intensities. As for indirect methods, there is quantitative accumulation of data supporting the utilisation of the AT to assess aerobic endurance and to prescribe training intensities. However, it appears that: there is no unique intensity corresponding to the AT, since criteria available in the literature provide inconsistent results; and the non-invasive determination of the AT using ventilatory and heart rate

  4. Elimination of bacteria from dogs with antibiotics*

    PubMed Central

    Hayes, Norman R.; van der Waaij, D.; Cohen, Bennett J.

    1974-01-01

    The effect of oral administration of neomycin cephalothin or kanamycin cephalothin on the aerobic intestinal bacterial flora, was studied in dogs maintained under isolation conditions in a conventional animal room. The dogs were successfully freed of aerobic bacteria with both combinations within two to seven days after the start of antibiotic treatment, and were maintained bacteria free for up to 21 days. Decontamination was attained more rapidly in dogs that were bathed in hexachlorophene surgical soap before and during the first and third days of antibiotic treatment. There was no evidence of toxicity from either of the antibiotic combinations. These results indicate that, as with mice and monkeys, decontamination of dogs with oral antibiotics is feasible. The technique is of potential value in preventing endogenous bacterial infections in canine experimental studies involving use of immunosuppressive agents. PMID:4529233

  5. Process for photosynthetically splitting water

    SciTech Connect

    Greenbaum, E.

    1982-01-28

    In one form of the invention, hydrogen is produced by providing a reactor containing a body of water. The water contains photolytic material, i.e., photoactive material containing a hydrogen-catalyst. The interior of the reactor is isolated from atmosphere and includes a volume for receiving gases evolved from the body of water. The photolytic material is exposed to light to effect photosynthetic splitting of the water into gaseous hydrogen and oxygen. The gas-receiving volume is continuously evacuated by pumping to promote evolution of gaseous hydrogen and oxygen into that volume and to withdraw them therefrom. In another form of the invention, separation of the hydrogen and oxygen is effected by selectively diffusing the hydrogen through a heated semipermeable membrane in a separation zone while maintaining across the zone a magnetic field gradient biasing the oxygen away from the membrane. In a third form of the invention, the withdrawn gas is contacted with a membrane blocking flow of water vapor to the region for effecting recovery of the hydrogen. In a fourth embodiment, the invention comprises a process for selectively recovering hydrogen from a gas mixture comprising hydrogen and oxygen. The process is conducted in a separation zone and comprises contacting the mixture with a semipermeable membrane effecting selective diffusion of hydrogen while maintaining across the zone a magnetic field gradient effecting movement of oxygen in a direction away from the membrane.

  6. Rings, ellipses and horseshoes: how purple bacteria harvest solar energy.

    PubMed

    Cogdell, Richard J; Gardiner, Alastair T; Roszak, Aleksander W; Law, Christopher J; Southall, June; Isaacs, Neil W

    2004-01-01

    This Review summarises the current state of research on the structure and function of light-harvesting apparatus in purple photosynthetic bacteria. Particular emphasis is placed on the major open questions still outstanding in this field in addition to what is already known.

  7. Toxic effects of butyl elastomers on aerobic methane oxidation

    NASA Astrophysics Data System (ADS)

    Niemann, Helge; Steinle, Lea I.; Blees, Jan H.; Krause, Stefan; Bussmann, Ingeborg; Lehmann, Moritz F.; Treude, Tina

    2013-04-01

    Large quantities of the potent greenhouse gas methane are liberated into the water column of marine and lacustrine environments where it may be consumed by aerobic methane oxidising bacteria before reaching the atmosphere.The reliable quantification of aerobic methane oxidation (MOx) rates is consequently of paramount importance for estimating methane budgets and to understand the controls on water column methane cycling. A widely used set of methods for measuring MOx rates is based on the incubation of water samples during which the consumption of methane is monitored, for instance with radio-tracer assays. Typically, incubation vessels are sealed with butyl rubber stoppers because these elastomers are essentially impermeable for gases at the relevant time scales. We tested the effect of different stopper materials (unmodified- and halogenated butyl rubber) on MOx activity in environmental samples and in cultures of methane oxidising bacteria. MOx rates in samples sealed with unmodified butyl rubber were > 75% lower compared to parallel incubations with halogenated butyl rubber seals, suggesting inhibiting/toxic effects associated with the use of unmodified butyl elastomers. To further explore the cause of these effects, we analysed aqueous extracts of the different stoppers. Halogenated butyl rubber stoppers appeared to bleed off comparably little amounts of organics. In stark contrast, extracts of unmodified butyl rubber were contaminated with various organic compounds including potential bactericides such as benzyltoluenes, phenylalkanes and benzuothiazoles. We also found tetramethylthiourea, a scavenger of active oxygen species, which may inhibit the MOx pathway.

  8. Improvement of activated sludge bacteria growth by low intensity ultrasound

    NASA Astrophysics Data System (ADS)

    Yan, Y. X.; Ding, J. Y.; Gao, J. L.

    2016-08-01

    Influence of low intensity ultrasound (US) on growth rate of bacteria separated from aerobic activated sludge was studied. In order to reveal the optimal ultrasonic conditions,specific oxygen uptake rate (SOUR) of activated sludge was first detected and results showed that the maximum SOUR was obtained (increased by 40%) at US intensity of 3 Wcm-2 and irradiation time of 10min. Under the optimal conditions, 2 species of bacteria isolated from activated sludge were sonicated and then cultivated for 36h, and increment of 6% and 10% of growth rate were detected for the 2 species of bacteria, respectively, indicating US irradiation of suitable parameters effectively improved activated sludge bacteria growth.

  9. Transcriptome dynamics during the transition from anaerobic photosynthesis to aerobic respiration in Rhodobacter sphaeroides 2.4.1.

    PubMed

    Arai, Hiroyuki; Roh, Jung Hyeob; Kaplan, Samuel

    2008-01-01

    Rhodobacter sphaeroides 2.4.1 is a facultative photosynthetic anaerobe that grows by anoxygenic photosynthesis under anaerobic-light conditions. Changes in energy generation pathways under photosynthetic and aerobic respiratory conditions are primarily controlled by oxygen tensions. In this study, we performed time series microarray analyses to investigate transcriptome dynamics during the transition from anaerobic photosynthesis to aerobic respiration. Major changes in gene expression profiles occurred in the initial 15 min after the shift from anaerobic-light to aerobic-dark conditions, with changes continuing to occur up to 4 hours postshift. Those genes whose expression levels changed significantly during the time series were grouped into three major classes by clustering analysis. Class I contained genes, such as that for the aa3 cytochrome oxidase, whose expression levels increased after the shift. Class II contained genes, such as those for the photosynthetic apparatus and Calvin cycle enzymes, whose expression levels decreased after the shift. Class III contained genes whose expression levels temporarily increased during the time series. Many genes for metabolism and transport of carbohydrates or lipids were significantly induced early during the transition, suggesting that those endogenous compounds were initially utilized as carbon sources. Oxidation of those compounds might also be required for maintenance of redox homeostasis after exposure to oxygen. Genes for the repair of protein and sulfur groups and uptake of ferric iron were temporarily upregulated soon after the shift, suggesting they were involved in a response to oxidative stress. The flagellar-biosynthesis genes were expressed in a hierarchical manner at 15 to 60 min after the shift. Numerous transporters were induced at various time points, suggesting that the cellular composition went through significant changes during the transition from anaerobic photosynthesis to aerobic respiration

  10. Aerobic granular processes: Current research trends.

    PubMed

    Zhang, Quanguo; Hu, Jianjun; Lee, Duu-Jong

    2016-06-01

    Aerobic granules are large biological aggregates with compact interiors that can be used in efficient wastewater treatment. This mini-review presents new researches on the development of aerobic granular processes, extended treatments for complicated pollutants, granulation mechanisms and enhancements of granule stability in long-term operation or storage, and the reuse of waste biomass as renewable resources. A discussion on the challenges of, and prospects for, the commercialization of aerobic granular process is provided. PMID:26873285

  11. Lower limb loading in step aerobic dance.

    PubMed

    Wu, H-W; Hsieh, H-M; Chang, Y-W; Wang, L-H

    2012-11-01

    Participation in aerobic dance is associated with a number of lower extremity injuries, and abnormal joint loading seems to be a factor in these. However, information on joint loading is limited. The purpose of this study was to investigate the kinetics of the lower extremity in step aerobic dance and to compare the differences of high-impact and low-impact step aerobic dance in 4 aerobic movements (mambo, kick, L step and leg curl). 18 subjects were recruited for this study. High-impact aerobic dance requires a significantly greater range of motion, joint force and joint moment than low-impact step aerobic dance. The peak joint forces and moments in high-impact step aerobic dance were found to be 1.4 times higher than in low-impact step aerobic dance. Understanding the nature of joint loading may help choreographers develop dance combinations that are less injury-prone. Furthermore, increased knowledge about joint loading may be helpful in lowering the risk of injuries in aerobic dance instructors and students.

  12. Acidophilic, heterotrophic bacteria of acidic mine waters

    SciTech Connect

    Wichlacz, P.L.; Unz, R.F.

    1981-05-01

    Obligately acidophilic, heterotrophic bacteria were isolated both from enrichment cultures developed with acidic mine water and from natural mine drainage. The bacteria were grouped by the ability to utilize a number of organic acids as sole carbon sources. None of the strains were capable of chemolithotrophic growth on inorganic reduced iron and sulfur compounds. All bacteria were rod shaped, gram negative, nonencapsulated, motile, capable of growth at pH 2.6 but not at pH 6.0, catalase and oxidase positive, strictly aerobic, and capable of growth on citric acid. The bacteria were cultivatable on solid nutrient media only if agarose was employed as the hardening agent. Bacterial densities in natural mine waters ranged from approximately 20 to 250 cells per ml, depending upon source and culture medium.

  13. Methanotrophic bacteria.

    PubMed Central

    Hanson, R S; Hanson, T E

    1996-01-01

    Methane-utilizing bacteria (methanotrophs) are a diverse group of gram-negative bacteria that are related to other members of the Proteobacteria. These bacteria are classified into three groups based on the pathways used for assimilation of formaldehyde, the major source of cell carbon, and other physiological and morphological features. The type I and type X methanotrophs are found within the gamma subdivision of the Proteobacteria and employ the ribulose monophosphate pathway for formaldehyde assimilation, whereas type II methanotrophs, which employ the serine pathway for formaldehyde assimilation, form a coherent cluster within the beta subdivision of the Proteobacteria. Methanotrophic bacteria are ubiquitous. The growth of type II bacteria appears to be favored in environments that contain relatively high levels of methane, low levels of dissolved oxygen, and limiting concentrations of combined nitrogen and/or copper. Type I methanotrophs appear to be dominant in environments in which methane is limiting and combined nitrogen and copper levels are relatively high. These bacteria serve as biofilters for the oxidation of methane produced in anaerobic environments, and when oxygen is present in soils, atmospheric methane is oxidized. Their activities in nature are greatly influenced by agricultural practices and other human activities. Recent evidence indicates that naturally occurring, uncultured methanotrophs represent new genera. Methanotrophs that are capable of oxidizing methane at atmospheric levels exhibit methane oxidation kinetics different from those of methanotrophs available in pure cultures. A limited number of methanotrophs have the genetic capacity to synthesize a soluble methane monooxygenase which catalyzes the rapid oxidation of environmental pollutants including trichloroethylene. PMID:8801441

  14. PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems

    SciTech Connect

    Niederman, Robert A.; Blankenship, Robert E.; Frank, Harry A.

    2015-02-07

    represented a diverse international and multidisciplinary group, with over 160 individuals attending from a total of 17 different countries. Attendees came from a wide range of fields assuring that the widest possible interdisciplinary exchanges. They included prominent biochemists, biophysicists, plant physiologists, chemical physicists, as well as theoretical and computational physical chemists, who presented their research findings or to hear the latest advances in this very dynamic field. In the choice of speakers, a balance was created between established scientists and young, emerging researchers, given this opportunity to showcase their results. Sessions were held on electronic and vibrational coherence including coherent sharing of excitations among donor and acceptor molecules during excitation energy transfer, nonphotochemical quenching, acclimation to light environments, evolution, adaptation and biodiversity of light-harvesting pigment-protein complexes, their structure and membrane organization, spectroscopy and dynamics, as well as artificial antenna systems. A joint session was also held with the participants from the Cyanobacterial Satellite Conference. A special issue of Photosynthesis Research devoted to light harvesting (Volume 121, Issue No. 1, July 2014) has recently appeared which contains peer-reviewed original research contributions arising from talks and posters presented at the PS2013 Satellite Workshop on Photosynthetic Light-Harvesting Systems. Edited by the Organizers of the Workshop, Robert E. Blankenship, Harry A. Frank and Robert A. Niederman, it includes topics ranging from the isolation of new bacteriochlorophyll species from green bacteria, temperature effects on the excited states of the newly discovered chlorophyll (Chl) ƒ, new architectures for enhancing energy capture by biohybrid light-harvesting complexes, forces governing the formation of light-harvesting rings, spectroscopy of carotenoids of algae and diatoms and the supramolecular

  15. Förster energy transfer theory as reflected in the structures of photosynthetic light-harvesting systems.

    PubMed

    Şener, Melih; Strümpfer, Johan; Hsin, Jen; Chandler, Danielle; Scheuring, Simon; Hunter, C Neil; Schulten, Klaus

    2011-02-25

    Förster’s theory of resonant energy transfer underlies a fundamental process in nature, namely the harvesting of sunlight by photosynthetic life forms. The theoretical framework developed by Förster and others describes how electronic excitation migrates in the photosynthetic apparatus of plants, algae, and bacteria from light absorbing pigments to reaction centers where light energy is utilized for the eventual conversion into chemical energy. The demand for highest possible efficiency of light harvesting appears to have shaped the evolution of photosynthetic species from bacteria to plants which, despite a great variation in architecture, display common structural themes founded on the quantum physics of energy transfer as described first by Förster. Herein, Förster’s theory of excitation transfer is summarized, including recent extensions, and the relevance of the theory to photosynthetic systems as evolved in purple bacteria, cyanobacteria, and plants is demonstrated. Förster’s energy transfer formula, as used widely today in many fields of science, is also derived.

  16. Isolation and biological characteristics of aerobic marine magnetotactic bacterium YSC-1

    NASA Astrophysics Data System (ADS)

    Gao, Jun; Pan, Hongmiao; Yue, Haidong; Song, Tao; Zhao, Yong; Chen, Guanjun; Wu, Longfei; Xiao, Tian

    2006-12-01

    Magnetotactic bacteria have become a hot spot of research in microbiology attracting intensive interest of researchers in multiple disciplinary fields. However, the studies were limited in few fastidious bacteria. The objective of this study aims at isolating new marine magnetic bacteria and better comprehension of magnetotactic bacteria. In this study, an aerobic magnetotactic bacterium YSC-1 was isolated from sediments in the Yellow Sea Cold Water Mass (YSCWM). In TEM, magnetic cells have one or several circular magnetosomes in diameter of 100nm, and consist of Fe and Co shown on energy dispersive X-ray spectrum. The biological and physiological characteristics of this bacterium were also described. The colour of YSC-1 colony is white in small rod. The gram stain is negative. Results showed that Strain YSC-1 differs from microaerophile magnetotactic bacteria MS-1 and WD-1 in biology.

  17. Simulation of wastewater treatment by aerobic granules in a sequencing batch reactor based on cellular automata.

    PubMed

    Benzhai, Hai; Lei, Liu; Ge, Qin; Yuwan, Peng; Ping, Li; Qingxiang, Yang; Hailei, Wang

    2014-10-01

    In the present paper, aerobic granules were developed in a sequencing batch reactor (SBR) using synthetic wastewater, and 81 % of granular rate was obtained after 15-day cultivation. Aerobic granules have a 96 % BOD removal to the wastewater, and the reactor harbors a mount of biomass including bacteria, fungi and protozoa. In view of the complexity of kinetic behaviors of sludge and biological mechanisms of the granular SBR, a cellular automata model was established to simulate the process of wastewater treatment. The results indicate that the model not only visualized the complex adsorption and degradation process of aerobic granules, but also well described the BOD removal of wastewater and microbial growth in the reactor. Thus, CA model is suitable for simulation of synthetic wastewater treatment. This is the first report about dynamical and visual simulation of treatment process of synthetic wastewater in a granular SBR.

  18. Regulation of Photosynthetic Electron Transport and Photoinhibition

    PubMed Central

    Roach, Thomas; Krieger-Liszkay, Anja Krieger

    2014-01-01

    Photosynthetic organisms and isolated photosystems are of interest for technical applications. In nature, photosynthetic electron transport has to work efficiently in contrasting environments such as shade and full sunlight at noon. Photosynthetic electron transport is regulated on many levels, starting with the energy transfer processes in antenna and ending with how reducing power is ultimately partitioned. This review starts by explaining how light energy can be dissipated or distributed by the various mechanisms of non-photochemical quenching, including thermal dissipation and state transitions, and how these processes influence photoinhibition of photosystem II (PSII). Furthermore, we will highlight the importance of the various alternative electron transport pathways, including the use of oxygen as the terminal electron acceptor and cyclic flow around photosystem I (PSI), the latter which seem particularly relevant to preventing photoinhibition of photosystem I. The control of excitation pressure in combination with the partitioning of reducing power influences the light-dependent formation of reactive oxygen species in PSII and in PSI, which may be a very important consideration to any artificial photosynthetic system or technical device using photosynthetic organisms. PMID:24678670

  19. Toward understanding as photosynthetic biosignatures: light harvesting and energy transfer calculation

    NASA Astrophysics Data System (ADS)

    Komatsu, Y.; Umemura, M.; Shoji, M.; Shiraishi, K.; Kayanuma, M.; Yabana, K.

    2014-03-01

    Among several proposed biosignatures, red edge is a direct evidence of photosynthetic life if it is detected (Kiang et al 2007). Red edge is a sharp change in reflectance spectra of vegetation in NIR region (about 700-750 nm). The sign of red edge is observed by Earthshine or remote sensing (Wolstencroft & Raven 2002, Woolf et al 2002). But, why around 700-750 nm? The photosynthetic organisms on Earth have evolved to optimize the sunlight condition. However, if we consider about photosynthetic organism on extrasolar planets, they should have developed to utilize the spectra of its principal star. Thus, it is not strange even if it shows different vegetation spectra. In this study, we focused on the light absorption mechanism of photosynthetic organisms on Earth and investigated the fundamental properties of the light harvesting mechanisms, which is the first stage for the light absorption. Light harvesting complexes contain photosynthetic pigments like chlorophylls. Effective light absorption and the energy transfer are accomplished by the electronic excitations of collective photosynthetic pigments. In order to investigate this mechanism, we constructed an energy transfer model by using a dipole-dipole approximation for the interactions between electronic excitations. Transition moments and transition energies of each pigment are calculated at the time-dependent density functional theory (TDDFT) level (Marques & Gross 2004). Quantum dynamics simulation for the excitation energy transfer was calculated by the Liouvelle's equation. We adopted the model to purple bacteria, which has been studied experimentally and known to absorb lower energy. It is meaningful to focus on the mechanism of this bacteria, since in the future mission, M planets will become a important target. We calculated the oscillator strengths in one light harvesting complex and confirmed the validity by comparing to the experimental data. This complex is made of an inner and an outer ring. The

  20. Two Cyanobacterial Photoreceptors Regulate Photosynthetic Light Harvesting by Sensing Teal, Green, Yellow, and Red Light

    PubMed Central

    Wiltbank, Lisa B.

    2016-01-01

    ABSTRACT The genomes of many photosynthetic and nonphotosynthetic bacteria encode numerous phytochrome superfamily photoreceptors whose functions and interactions are largely unknown. Cyanobacterial genomes encode particularly large numbers of phytochrome superfamily members called cyanobacteriochromes. These have diverse light color-sensing abilities, and their functions and interactions are just beginning to be understood. One of the best characterized of these functions is the regulation of photosynthetic light-harvesting antenna composition in the cyanobacterium Fremyella diplosiphon by the cyanobacteriochrome RcaE in response to red and green light, a process known as chromatic acclimation. We have identified a new cyanobacteriochrome named DpxA that maximally senses teal (absorption maximum, 494 nm) and yellow (absorption maximum, 568 nm) light and represses the accumulation of a key light-harvesting protein called phycoerythrin, which is also regulated by RcaE during chromatic acclimation. Like RcaE, DpxA is a two-component system kinase, although these two photoreceptors can influence phycoerythrin expression through different signaling pathways. The peak responsiveness of DpxA to teal and yellow light provides highly refined color discrimination in the green spectral region, which provides important wavelengths for photosynthetic light harvesting in cyanobacteria. These results redefine chromatic acclimation in cyanobacteria and demonstrate that cyanobacteriochromes can coordinately impart sophisticated light color sensing across the visible spectrum to regulate important photosynthetic acclimation processes. PMID:26861023

  1. Effect of enzyme secreting bacterial pretreatment on enhancement of aerobic digestion potential of waste activated sludge interceded through EDTA.

    PubMed

    Kavitha, S; Adish Kumar, S; Yogalakshmi, K N; Kaliappan, S; Rajesh Banu, J

    2013-12-01

    In this study, the effect of Ethylene diamine tetra acetic acid (EDTA) on Extracellular polymeric substance (EPS) removal tailed with bacterial enzymatic pretreatment on aerobic digestion of activated sludge was studied. In order to enhance the accessibility of sludge to the enzyme secreting bacteria; the extracellular polymeric substances were removed using EDTA. EDTA efficiently removed the EPS with limited cell lysis and enhanced the sludge enzyme activity at its lower concentration of 0.2 g/g SS. The sludge was then subjected to bacterial pretreatment to enhance the aerobic digestion. In aerobic digestion the best results in terms of Suspended solids (SS) reduction (48.5%) and COD (Chemical oxygen demand) solubilization (47.3%) was obtained in experimental reactor than in control. These results imply that aerobic digestion can be enhanced efficiently through bacterial pretreatment of EPS removed sludge.

  2. Aerobic rice mechanization: techniques for crop establishment

    NASA Astrophysics Data System (ADS)

    Khusairy, K. M.; Ayob, H.; Chan, C. S.; Fauzi, M. I. Mohamed; Mohamad Fakhrul, Z. O.; Shahril Shah, G. S. M.; Azlan, O.; Rasad, M. A.; Hashim, A. M.; Arshad, Z.; E, E. Ibrahim; Saifulizan, M. N.

    2015-12-01

    Rice being the staple food crops, hundreds of land races in it makes the diversity of rice crops. Aerobic rice production was introduced which requires much less water input to safeguard and sustain the rice production and conserve water due to decreasing water resources, climatic changes and competition from urban and industrial users. Mechanization system plays an important role for the success of aerobic rice cultivation. All farming activities for aerobic rice production are run on aerobic soil conditions. Row seeder mechanization system is developed to replace conventional seeding technique on the aerobic rice field. It is targeted for small and the large scale aerobic rice farmers. The aero - seeder machine is used for the small scale aerobic rice field, while the accord - seeder is used for the large scale aerobic rice field. The use of this mechanization machine can eliminate the tedious and inaccurate seeding operations reduce labour costs and increases work rate. The machine is easy to operate and it can increase crop establishment rate. It reduce missing hill, increasing planting and crop with high yield can be produce. This machine is designed for low costs maintenance and it is easy to dismantle and assemble during maintenance and it is safe to be used.

  3. Aerobic Dancing--A Rhythmic Sport.

    ERIC Educational Resources Information Center

    Sorensen, Jacki

    Fitness programs now and in the future must offer built-in cardiovascular conditioning, variety, novelty, and change to meet the physical, mental, and emotional needs of our society. Aerobic dancing (dancing designed to train and strengthen the heart, lungs, and vascular system) is one of the first indoor group Aerobic exercise programs designed…

  4. Skeletal Muscle Hypertrophy after Aerobic Exercise Training

    PubMed Central

    Konopka, Adam R.; Harber, Matthew P.

    2014-01-01

    Current dogma suggests aerobic exercise training has minimal effect on skeletal muscle size. We and others have demonstrated that aerobic exercise acutely and chronically alters protein metabolism and induces skeletal muscle hypertrophy. These findings promote an antithesis to the status quo by providing novel perspective on skeletal muscle mass regulation and insight into exercise-countermeasures for populations prone to muscle loss. PMID:24508740

  5. Rapid Redox Signal Transmission by “Cable Bacteria” beneath a Photosynthetic Biofilm

    PubMed Central

    Meysman, F. J. R.

    2014-01-01

    Recently, long filamentous bacteria, belonging to the family Desulfobulbaceae, were shown to induce electrical currents over long distances in the surface layer of marine sediments. These “cable bacteria” are capable of harvesting electrons from free sulfide in deeper sediment horizons and transferring these electrons along their longitudinal axes to oxygen present near the sediment-water interface. In the present work, we investigated the relationship between cable bacteria and a photosynthetic algal biofilm. In a first experiment, we investigated sediment that hosted both cable bacteria and a photosynthetic biofilm and tested the effect of an imposed diel light-dark cycle by continuously monitoring sulfide at depth. Changes in photosynthesis at the sediment surface had an immediate and repeatable effect on sulfide concentrations at depth, indicating that cable bacteria can rapidly transmit a geochemical effect to centimeters of depth in response to changing conditions at the sediment surface. We also observed a secondary response of the free sulfide at depth manifest on the time scale of hours, suggesting that cable bacteria adjust to a moving oxygen front with a regulatory or a behavioral response, such as motility. Finally, we show that on the time scale of days, the presence of an oxygenic biofilm results in a deeper and more acidic suboxic zone, indicating that a greater oxygen supply can enable cable bacteria to harvest a greater quantity of electrons from marine sediments. Rapid acclimation strategies and highly efficient electron harvesting are likely key advantages of cable bacteria, enabling their success in high sulfide generating coastal sediments. PMID:25416774

  6. BOREAS TE-10 Photosynthetic Response Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Papagno, Andrea (Editor); Middleton, Elizabeth; Sullivan, Joseph

    2000-01-01

    The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-10 (Terrestrial Ecology) team collected several data sets in support of its efforts to characterize and interpret information on the gas exchange, reflectance, transmittance, chlorophyll content, carbon content, hydrogen content, nitrogen content, and photosynthetic response of boreal vegetation. This data set contains measurements of quantitative parameters and leaf photosynthetic response to increases in light conducted in the SSA during the growing seasons of 1994 and 1996 using an oxygen electrode system. Leaf photosynthetic responses were not collected in 1996. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  7. Hot Stuff: Lability of Forest Floor DOM to Aerobic Degradation

    NASA Astrophysics Data System (ADS)

    Bourbonniere, R. A.; Creed, I. F.; Kapila, R.; Collins, J.

    2004-05-01

    The hypothesis that the lability of DOM to aerobic microbial degradation to CO2 is related to its age and character is tested in an incubation study conducted using an assemblage of soil bacteria in their natural state. Extracts (WF) of leaf and forest floor material characterized by different degrees of degradation: green leaves, fresh fallen leaves, litter (one year weathering), fibric matter, hemic matter and peat were used in this study. The working hypothesis is that these extracts represent a chronosequence of degradation and DOM extracted from them might also represent a similar lability sequence. As well aliquots of the WF extracts were processed to remove DOM fractions. Thus a fulvic acid (FA) fraction was made by precipitating and removing humic acid, and a hydrophilic fraction (HPI) by removing hydrophobics from the FA using XAD-8 resin. Incubations were carried out on all three DOM solutions from each extract to determine if there were differences in lability among the fractions. When comparing the WF solutions for CO2 production, the green leaves, litter, fibric and hemic extracts showed approximately the same CO2 yield, on an equal C basis, and the fresh fallen leaves and peat produced less. For five of the six extracts the respective WF and HPI solutions yielded nearly the same quantity of CO2 per mg C suggesting that the HPI component contributes almost all the lability. Furthermore the magnitudes of the C-normalized CO2 yield for these solutions are similar to that for glucose, which fractionates as HPI. For the same five extracts the FA solution yielded lower quantities of CO2, on an equal C basis, than WF and HPI suggesting that the hydrophobic content of the extracts may inhibit aerobic degradation. The peat extract solutions yielded a different CO2 production distribution with the HPI only slightly higher than the FA which in turn was much greater than WF. The material from which this extract was made is much older and contains significant HA

  8. Reproducing stone monument photosynthetic-based colonization under laboratory conditions.

    PubMed

    Miller, Ana Zélia; Laiz, Leonila; Gonzalez, Juan Miguel; Dionísio, Amélia; Macedo, Maria Filomena; Saiz-Jimenez, Cesareo

    2008-11-01

    In order to understand the biodeterioration process occurring on stone monuments, we analyzed the microbial communities involved in these processes and studied their ability to colonize stones under controlled laboratory experiments. In this study, a natural green biofilm from a limestone monument was cultivated, inoculated on stone probes of the same lithotype and incubated in a laboratory chamber. This incubation system, which exposes stone samples to intermittently sprinkling water, allowed the development of photosynthetic biofilms similar to those occurring on stone monuments. Denaturing gradient gel electrophoresis (DGGE) analysis was used to evaluate the major microbial components of the laboratory biofilms. Cyanobacteria, green microalgae, bacteria and fungi were identified by DNA-based molecular analysis targeting the 16S and 18S ribosomal RNA genes. The natural green biofilm was mainly composed by the Chlorophyta Chlorella, Stichococcus, and Trebouxia, and by Cyanobacteria belonging to the genera Leptolyngbya and Pleurocapsa. A number of bacteria belonging to Alphaproteobacteria, Bacteroidetes and Verrucomicrobia were identified, as well as fungi from the Ascomycota. The laboratory colonization experiment on stone probes showed a colonization pattern similar to that occurring on stone monuments. The methodology described in this paper allowed to reproduce a colonization equivalent to the natural biodeteriorating process.

  9. Photosynthetic complex stoichiometry dynamics in higher plants: environmental acclimation and photosynthetic flux control

    PubMed Central

    Schöttler, Mark A.; Tóth, Szilvia Z.

    2014-01-01

    The composition of the photosynthetic apparatus of higher plants is dynamically adjusted to long-term changes in environmental conditions such as growth light intensity and light quality, and to changing metabolic demands for ATP and NADPH imposed by stresses and leaf aging. By changing photosynthetic complex stoichiometry, a long-term imbalance between the photosynthetic production of ATP and NADPH and their metabolic consumption is avoided, and cytotoxic side reactions are minimized. Otherwise, an excess capacity of the light reactions, relative to the demands of primary metabolism, could result in a disturbance of cellular redox homeostasis and an increased production of reactive oxygen species, leading to the destruction of the photosynthetic apparatus and the initiation of cell death programs. In this review, changes of the abundances of the different constituents of the photosynthetic apparatus in response to environmental conditions and during leaf ontogenesis are summarized. The contributions of the different photosynthetic complexes to photosynthetic flux control and the regulation of electron transport are discussed. PMID:24860580

  10. Enhanced practical photosynthetic CO2 mitigation

    DOEpatents

    Bayless, David J.; Vis-Chiasson, Morgan L.; Kremer, Gregory G.

    2003-12-23

    This process is unique in photosynthetic carbon sequestration. An on-site biological sequestration system directly decreases the concentration of carbon-containing compounds in the emissions of fossil generation units. In this process, photosynthetic microbes are attached to a growth surface arranged in a containment chamber that is lit by solar photons. A harvesting system ensures maximum organism growth and rate of CO.sub.2 uptake. Soluble carbon and nitrogen concentrations delivered to the cyanobacteria are enhanced, further increasing growth rate and carbon utilization.

  11. Design criteria for optimal photosynthetic energy conversion

    NASA Astrophysics Data System (ADS)

    Fingerhut, Benjamin P.; Zinth, Wolfgang; de Vivie-Riedle, Regina

    2008-12-01

    Photochemical solar energy conversion is considered as an alternative of clean energy. For future light converting nano-machines photosynthetic reaction centers are used as prototypes optimized during evolution. We introduce a reaction scheme for global optimization and simulate the ultrafast charge separation in photochemical energy conversion. Multiple molecular charge carriers are involved in this process and are linked by Marcus-type electron transfer. In combination with evolutionary algorithms, we unravel the biological strategies for high quantum efficiency in photosynthetic reaction centers and extend these concepts to the design of artificial photochemical devices for energy conversion.

  12. [Application of Micro-aerobic Hydrolysis Acidification in the Pretreatment of Petrochemical Wastewater].

    PubMed

    Zhu, Chen; Wu, Chang-yong; Zhou, Yue-xi; Fu, Xiao-yong; Chen, Xue-min; Qiu, Yan-bo; Wu, Xiao-feng

    2015-10-01

    Micro-aerobic hydrolysis acidification technology was applied in the reconstruction of ananaerobic hydrolysis acidification tank in a north petrochemical wastewater treatment plant. After put into operation, the monitoring results showed that the average removal rate of COD was 11.7% when influent COD was 490.3-673.2 mg x L(-1), hydraulic retention time (HRT) was 24 and the dissolved oxygen (DO) was 0.2-0.35 mg x L(-1). In addition, the BOD5/COD value was increased by 12.4%, the UV254 removal rate reached 11.2%, and the VFA concentration was increased by 23.0%. The relative molecular weight distribution (MWD) results showed that the small molecule organic matter (< 1 x 10(3)) percentage was increased from 59.5% to 82.1% and the high molecular organic matter ( > 100 x 10(3)) percentage was decreased from 31.8% to 14.0% after micro-aerobic hydrolysis acidification. The aerobic biodegradation batch test showed that the degradation of petrochemical wastewater was significantly improved by the pretreatment of micro-aerobic hydrolysis acidification. The COD of influent can be degraded to 102.2 mg x L(-1) by 48h aerobic treatment while the micro-aerobic hydrolysis acidification effluent COD can be degraded to 71.5 mg x L(-1) on the same condition. The effluent sulfate concentration of micro-aerobic hydrolysis acidification tank [(930.7 ± 60.1) mg x L(-1)] was higher than that of the influent [(854.3 ± 41.5) mg x L(-1)], indicating that sulfate reducing bacteria (SRB) was inhibited. The toxic and malodorous gases generation was reduced with the improvement of environment.

  13. Could petroleum biodegradation be a joint achievement of aerobic and anaerobic microrganisms in deep sea reservoirs?

    PubMed Central

    2011-01-01

    Several studies suggest that petroleum biodegradation can be achieved by either aerobic or anaerobic microorganisms, depending on oxygen input or other electron acceptors and appropriate nutrients. Evidence from in vitro experiments with samples of petroleum formation water and oils from Pampo Field indicate that petroleum biodegradation is more likely to be a joint achievement of both aerobic and anaerobic bacterial consortium, refining our previous observations of aerobic degradation. The aerobic consortium depleted, in decreasing order, hydrocarbons > hopanes > steranes > tricyclic terpanes while the anaerobic consortium depleted hydrocarbons > steranes > hopanes > tricyclic terpanes. The oxygen content of the mixed consortia was measured from time to time revealing alternating periods of microaerobicity (O2 ~0.8 mg.L-1) and of aerobicity (O2~6.0 mg.L-1). In this experiment, the petroleum biodegradation changed from time to time, alternating periods of biodegradation similar to the aerobic process and periods of biodegradation similar to the anaerobic process. The consortia showed preferences for metabolizing hydrocarbons > hopanes > steranes > tricyclic terpanes during a 90-day period, after which this trend changed and steranes were more biodegraded than hopanes. The analysis of aerobic oil degrading microbiota by the 16S rRNA gene clone library detected the presence of Bacillus, Brevibacterium, Mesorhizobium and Achromobacter, and the analysis of the anaerobic oil degrading microbiota using the same technique detected the presence of Bacillus and Acinetobacter (facultative strains). In the mixed consortia Stenotrophomonas, Brevibacterium, Bacillus, Rhizobium, Achromobacter and 5% uncultured bacteria were detected. This is certainly a new contribution to the study of reservoir biodegradation processes, combining two of the more important accepted hypotheses. PMID:22196374

  14. Could petroleum biodegradation be a joint achievement of aerobic and anaerobic microrganisms in deep sea reservoirs?

    PubMed

    da Cruz, Georgiana F; de Vasconcellos, Suzan P; Angolini, Célio Ff; Dellagnezze, Bruna M; Garcia, Isabel Ns; de Oliveira, Valéria M; Dos Santos Neto, Eugenio V; Marsaioli, Anita J

    2011-12-23

    Several studies suggest that petroleum biodegradation can be achieved by either aerobic or anaerobic microorganisms, depending on oxygen input or other electron acceptors and appropriate nutrients. Evidence from in vitro experiments with samples of petroleum formation water and oils from Pampo Field indicate that petroleum biodegradation is more likely to be a joint achievement of both aerobic and anaerobic bacterial consortium, refining our previous observations of aerobic degradation. The aerobic consortium depleted, in decreasing order, hydrocarbons > hopanes > steranes > tricyclic terpanes while the anaerobic consortium depleted hydrocarbons > steranes > hopanes > tricyclic terpanes. The oxygen content of the mixed consortia was measured from time to time revealing alternating periods of microaerobicity (O2 ~0.8 mg.L-1) and of aerobicity (O2~6.0 mg.L-1). In this experiment, the petroleum biodegradation changed from time to time, alternating periods of biodegradation similar to the aerobic process and periods of biodegradation similar to the anaerobic process. The consortia showed preferences for metabolizing hydrocarbons > hopanes > steranes > tricyclic terpanes during a 90-day period, after which this trend changed and steranes were more biodegraded than hopanes. The analysis of aerobic oil degrading microbiota by the 16S rRNA gene clone library detected the presence of Bacillus, Brevibacterium, Mesorhizobium and Achromobacter, and the analysis of the anaerobic oil degrading microbiota using the same technique detected the presence of Bacillus and Acinetobacter (facultative strains). In the mixed consortia Stenotrophomonas, Brevibacterium, Bacillus, Rhizobium, Achromobacter and 5% uncultured bacteria were detected. This is certainly a new contribution to the study of reservoir biodegradation processes, combining two of the more important accepted hypotheses.

  15. The effects of wilting and storage temperatures on the fermentation quality and aerobic stability of stylo silage.

    PubMed

    Liu, Qinghua; Zhang, Jianguo; Shi, Shangli; Sun, Qizhong

    2011-08-01

    In order to clarify the ensiling characteristics of stylo (Stylosanthes guianensis Swartz), the effects of wilting (no wilting, light wilting and heavy wilting) and storage temperatures (10°C, 20°C, 30°C and 40°C) on the fermentation quality and aerobic stability of stylo silage were investigated. Wilting had no significant influence on the contents of crude protein, ether extract and acid detergent fiber, and numbers of lactic acid bacteria, aerobic bacteria, yeasts and mold (P > 0.05). Heavy wilted material, wilted for 12 h, had higher neutral detergent fiber content and lower water-soluble carbohydrate content than unwilted and light wilted materials (P < 0.05). Wilting and storage temperatures had significant effects on pH value, acetic acid, butyric acid and NH(3) -N contents of stylo silage (P < 0.01 or P < 0.05). Wilting tended to reduce acetic acid and NH(3) -N contents and improve the fermentation quality of stylo silage. In all the silages, no wilting silage ensiled at 30°C had the highest butyric acid content (P < 0.05). High temperature of 40°C markedly restricted the growth of lactic acid bacteria and aerobic bacteria in silage, irrespective of wilting. The wilted silage or silage stored at low temperature had poor aerobic stability. PMID:21794013

  16. Water quality parameters and total aerobic bacterial and vibrionaceae loads in eastern oysters (Crassostrea virginica) from oyster gardening sites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oyster gardening is a practice designed to restore habitat for marine life and to improve water quality. This study determined physical and chemical water quality parameters at two oyster gardening sites in the Delaware Inland Bays and compared them with total aerobic bacteria and Vibrionaceae conc...

  17. Bacteria Counter

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Science Applications, Inc.'s ATP Photometer makes a rapid and accurate count of the bacteria in a body fluid sample. Instrument provides information on the presence and quantity of bacteria by measuring the amount of light emitted by the reaction between two substances. Substances are ATP adenosine triphosphate and luciferase. The reactants are applied to a human body sample and the ATP Photometer observes the intensity of the light emitted displaying its findings in a numerical output. Total time lapse is usually less than 10 minutes, which represents a significant time savings in comparison of other techniques. Other applications are measuring organisms in fresh and ocean waters, determining bacterial contamination of foodstuffs, biological process control in the beverage industry, and in assay of activated sewage sludge.

  18. Performance of aerobic granular sludge in a sequencing batch bioreactor for slaughterhouse wastewater treatment.

    PubMed

    Liu, Yali; Kang, Xiaorong; Li, Xin; Yuan, Yixing

    2015-08-01

    Lab-scale experiment was conducted to investigate the formation and characteristics of aerobic granular sludge for biological nutrient removal of slaughterhouse wastewater. Experimental results showed that removal performances of chemical oxygen demand (COD), ammonia and phosphate were enhanced with sludge granulation, and their removal efficiencies reached 95.1%, 99.3% and 83.5%, respectively. The aerobic granular sludge was matured after 90days cultivation, and protein-like substances were the main components. Simultaneously, the mass ratio of proteins and polysaccharides (PN/PS) was enhanced to 2.5 from 1.7. The granules with particle sizes of 0.6-1.2 and 1.2-1.8mm, accounting for 69.6%, were benefit for the growth of ammonia oxidizing bacteria (AOB) and nitrate oxidizing bacteria (NOB), and corresponding specific oxygen demand rates (SOUR) of AOB and NOB were 31.4 and 23.3mgO2/gMLSSh, respectively.

  19. Metagenomics of Hydrocarbon Resource Environments Indicates Aerobic Taxa and Genes to be Unexpectedly Common

    PubMed Central

    2013-01-01

    Oil in subsurface reservoirs is biodegraded by resident microbial communities. Water-mediated, anaerobic conversion of hydrocarbons to methane and CO2, catalyzed by syntrophic bacteria and methanogenic archaea, is thought to be one of the dominant processes. We compared 160 microbial community compositions in ten hydrocarbon resource environments (HREs) and sequenced twelve metagenomes to characterize their metabolic potential. Although anaerobic communities were common, cores from oil sands and coal beds had unexpectedly high proportions of aerobic hydrocarbon-degrading bacteria. Likewise, most metagenomes had high proportions of genes for enzymes involved in aerobic hydrocarbon metabolism. Hence, although HREs may have been strictly anaerobic and typically methanogenic for much of their history, this may not hold today for coal beds and for the Alberta oil sands, one of the largest remaining oil reservoirs in the world. This finding may influence strategies to recover energy or chemicals from these HREs by in situ microbial processes. PMID:23889694

  20. Trans unsaturated fatty acids in bacteria.

    PubMed

    Keweloh, H; Heipieper, H J

    1996-02-01

    The occurrence of trans unsaturated fatty acids as by-products of fatty acid transformations carried out by the obligate anaerobic ruminal microflora has been well known for a long time. In recent years, fatty acids with trans configurations also have been detected in the membrane lipids of various aerobic bacteria. Besides several psychrophilic organisms, bacteria-degrading pollutants, such as Pseudomonas putida, are able to synthesize these compounds de novo. In contrast to the trans fatty acids formed by rumen bacteria, the membrane constituents of aerobic bacteria are synthesized by a direct isomerization of the complementary cis configuration of the double bond without a shift of the position. This system of isomerization is located in the cytoplasmic membrane. The conversion of cis unsaturated fatty acids to trans changes the membrane fluidity in response to environmental stimuli, particularly where growth is inhibited due to the presence of high concentrations of toxic substances. Under these conditions, lipid synthesis also stops so that the cells are not able to modify their membrane fluidity by any other mechanism.

  1. Importance of excitation and trapping conditions in photosynthetic environment-assisted energy transport.

    PubMed

    León-Montiel, Roberto de J; Kassal, Ivan; Torres, Juan P

    2014-09-11

    It has been argued that excitonic energy transport in photosynthetic complexes is efficient because of a balance between coherent evolution and decoherence, a phenomenon called environment-assisted quantum transport (ENAQT). Studies of ENAQT have usually assumed that the excitation is initially localized on a particular chromophore, and that it is transferred to a reaction center through a similarly localized trap. However, these assumptions are not physically accurate. We show that more realistic models of excitation and trapping can lead to very different predictions about the importance of ENAQT. In particular, although ENAQT is a robust effect if one assumes a localized trap, its effect can be negligible if the trapping is more accurately modeled as Förster transfer to a reaction center. Our results call into question the suggested role of ENAQT in the photosynthetic process of green sulfur bacteria and highlight the subtleties associated with drawing lessons for designing biomimetic light-harvesting complexes.

  2. Atomic Detail Visualization of Photosynthetic Membranes with GPU-Accelerated Ray Tracing

    PubMed Central

    Vandivort, Kirby L.; Barragan, Angela; Singharoy, Abhishek; Teo, Ivan; Ribeiro, João V.; Isralewitz, Barry; Liu, Bo; Goh, Boon Chong; Phillips, James C.; MacGregor-Chatwin, Craig; Johnson, Matthew P.; Kourkoutis, Lena F.; Hunter, C. Neil

    2016-01-01

    The cellular process responsible for providing energy for most life on Earth, namely photosynthetic light-harvesting, requires the cooperation of hundreds of proteins across an organelle, involving length and time scales spanning several orders of magnitude over quantum and classical regimes. Simulation and visualization of this fundamental energy conversion process pose many unique methodological and computational challenges. We present, in two accompanying movies, light-harvesting in the photosynthetic apparatus found in purple bacteria, the so-called chromatophore. The movies are the culmination of three decades of modeling efforts, featuring the collaboration of theoretical, experimental, and computational scientists. We describe the techniques that were used to build, simulate, analyze, and visualize the structures shown in the movies, and we highlight cases where scientific needs spurred the development of new parallel algorithms that efficiently harness GPU accelerators and petascale computers. PMID:27274603

  3. Spectroscopic Studies of Photosynthetic Systems and Their Application in Photovoltaic Devices - Equipment Only: Cooperative Research and Development Final Report, CRADA Number CRD-06-175

    SciTech Connect

    Seibert, M.

    2014-09-01

    Spectral hole-burning (SHB) and single photosynthetic complex spectroscopy (SPCS) will be used to study the excitonic structure and excitation energy transfer (EET) processes of several photosynthetic protein complexes at low temperatures. The combination of SHB on bulk samples and SPCS is a powerful frequency domain approach for obtaining data that will address a number of issues that are key to understanding excitonic structure and energy transfer dynamics. The long-term goal is to reach a better understanding of the ultrafast solar energy driven primary events of photosynthesis as they occur in higher plants, cyanobacteria, purple bacteria, and green algae. A better understanding of the EET and charge separation (CS) processes taking place in photosynthetic complexes is of great interest, since photosynthetic complexes might offer attractive architectures for a future generation of circuitry in which proteins are crystallized.

  4. Was photosynthetic RuBisCO recruited by acquisitive evolution from RuBisCO-like proteins involved in sulfur metabolism?

    PubMed

    Ashida, Hiroki; Danchin, Antoine; Yokota, Akiho

    2005-01-01

    Genome analyses have revealed that the genomes of non-photosynthetic bacteria including Bacillus subtilis code for proteins similar to the large subunit of RuBisCO (called RuBisCO-like protein (RLP)). This raises a fundamental question as to their functional relationship to photosynthetic RuBisCO. Recently, we identified the RLP of B. subtilis as the 2,3-diketo-5-methylthiopentyl-1-phosphate enolase in the methionine salvage pathway. In this mini-review, we suggest functional and evolutionary links between B. subtilis RLP and photosynthetic RuBisCO. Furthermore, we propose that photosynthetic RuBisCOs evolved from RLPs similar to that found in B. subtilis.

  5. Fit women are not able to use the whole aerobic capacity during aerobic dance.

    PubMed

    Edvardsen, Elisabeth; Ingjer, Frank; Bø, Kari

    2011-12-01

    Edvardsen, E, Ingjer, F, and Bø, K. Fit women are not able to use the whole aerobic capacity during aerobic dance. J Strength Cond Res 25(12): 3479-3485, 2011-This study compared the aerobic capacity during maximal aerobic dance and treadmill running in fit women. Thirteen well-trained female aerobic dance instructors aged 30 ± 8.17 years (mean ± SD) exercised to exhaustion by running on a treadmill for measurement of maximal oxygen uptake (VO(2)max) and peak heart rate (HRpeak). Additionally, all subjects performed aerobic dancing until exhaustion after a choreographed videotaped routine trying to reach the same HRpeak as during maximal running. The p value for statistical significance between running and aerobic dance was set to ≤0.05. The results (mean ± SD) showed a lower VO(2)max in aerobic dance (52.2 ± 4.02 ml·kg·min) compared with treadmill running (55.9 ± 5.03 ml·kg·min) (p = 0.0003). Further, the mean ± SD HRpeak was 182 ± 9.15 b·min in aerobic dance and 192 ± 9.62 b·min in treadmill running, giving no difference in oxygen pulse between the 2 exercise forms (p = 0.32). There was no difference in peak ventilation (aerobic dance: 108 ± 10.81 L·min vs. running: 113 ± 11.49 L·min). In conclusion, aerobic dance does not seem to be able to use the whole aerobic capacity as in running. For well endurance-trained women, this may result in a lower total workload at maximal intensities. Aerobic dance may therefore not be as suitable as running during maximal intensities in well-trained females.

  6. Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes

    PubMed Central

    Oswald, Kirsten; Milucka, Jana; Brand, Andreas; Littmann, Sten; Wehrli, Bernhard; Kuypers, Marcel M. M.; Schubert, Carsten J.

    2015-01-01

    Lakes are a natural source of methane to the atmosphere and contribute significantly to total emissions compared to the oceans. Controls on methane emissions from lake surfaces, particularly biotic processes within anoxic hypolimnia, are only partially understood. Here we investigated biological methane oxidation in the water column of the seasonally stratified Lake Rotsee. A zone of methane oxidation extending from the oxic/anoxic interface into anoxic waters was identified by chemical profiling of oxygen, methane and δ13C of methane. Incubation experiments with 13C-methane yielded highest oxidation rates within the oxycline, and comparable rates were measured in anoxic waters. Despite predominantly anoxic conditions within the zone of methane oxidation, known groups of anaerobic methanotrophic archaea were conspicuously absent. Instead, aerobic gammaproteobacterial methanotrophs were identified as the active methane oxidizers. In addition, continuous oxidation and maximum rates always occurred under light conditions. These findings, along with the detection of chlorophyll a, suggest that aerobic methane oxidation is tightly coupled to light-dependent photosynthetic oxygen production both at the oxycline and in the anoxic bottom layer. It is likely that this interaction between oxygenic phototrophs and aerobic methanotrophs represents a widespread mechanism by which methane is oxidized in lake water, thus diminishing its release into the atmosphere. PMID:26193458

  7. Coral bleaching independent of photosynthetic activity.

    PubMed

    Tolleter, Dimitri; Seneca, François O; DeNofrio, Jan C; Krediet, Cory J; Palumbi, Stephen R; Pringle, John R; Grossman, Arthur R

    2013-09-23

    The global decline of reef-building corals is due in part to the loss of algal symbionts, or "bleaching," during the increasingly frequent periods of high seawater temperatures. During bleaching, endosymbiotic dinoflagellate algae (Symbiodinium spp.) either are lost from the animal tissue or lose their photosynthetic pigments, resulting in host mortality if the Symbiodinium populations fail to recover. The >1,000 studies of the causes of heat-induced bleaching have focused overwhelmingly on the consequences of damage to algal photosynthetic processes, and the prevailing model for bleaching invokes a light-dependent generation of toxic reactive oxygen species (ROS) by heat-damaged chloroplasts as the primary trigger. However, the precise mechanisms of bleaching remain unknown, and there is evidence for involvement of multiple cellular processes. In this study, we asked the simple question of whether bleaching can be triggered by heat in the dark, in the absence of photosynthetically derived ROS. We used both the sea anemone model system Aiptasia and several species of reef-building corals to demonstrate that symbiont loss can occur rapidly during heat stress in complete darkness. Furthermore, we observed damage to the photosynthetic apparatus under these conditions in both Aiptasia endosymbionts and cultured Symbiodinium. These results do not directly contradict the view that light-stimulated ROS production is important in bleaching, but they do show that there must be another pathway leading to bleaching. Elucidation of this pathway should help to clarify bleaching mechanisms under the more usual conditions of heat stress in the light.

  8. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

    Gregory Kremer; David J. Bayless; Morgan Vis; Michael Prudich; Keith Cooksey; Jeff Muhs

    2004-07-15

    This report highlights significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation Project for the period ending 06/30/2004. The major accomplishment was the modification of the header and harvesting work, with a system designed to distribute algae at startup, sustain operations and harvest in one unit.

  9. Longitudinal photosynthetic gradient in crust lichens' thalli.

    PubMed

    Wu, Li; Zhang, Gaoke; Lan, Shubin; Zhang, Delu; Hu, Chunxiang

    2014-05-01

    In order to evaluate the self-shading protection for inner photobionts, the photosynthetic activities of three crust lichens were detected using Microscope-Imaging-PAM. The false color images showed that longitudinal photosynthetic gradient was found in both the green algal lichen Placidium sp. and the cyanolichen Peltula sp. In longitudinal direction, all the four chlorophyll fluorescence parameters Fv/Fm, Yield, qP, and rETR gradually decreased with depth in the thalli of both of these two lichens. In Placidium sp., qN values decreased with depth, whereas an opposite trend was found in Peltula sp. However, no such photosynthetic heterogeneity was found in the thalli of Collema sp. in longitudinal direction. Microscope observation showed that photobiont cells are compactly arranged in Placidium sp. and Peltula sp. while loosely distributed in Collema sp. It was considered that the longitudinal photosynthetic heterogeneity was ascribed to the result of gradual decrease of incidence caused by the compact arrangement of photobiont cells in the thalli. The results indicate a good protection from the self-shading for the inner photobionts against high radiation in crust lichens.

  10. Photosynthetic strategies of two Mojave Desert shrubs

    SciTech Connect

    Kleinkopf, G.E.; Hartsock, T.L.; Wallace, A.; Romney, E.M.

    1980-01-01

    Photosynthetic production of two Mojave Desert shrubs was measured under natural growing conditions. Measurements of photosynthesis, transpiration, resistances to water vapor flux, soil moisture potential, and tissue water potential were made. Atriplex canescens (Pursh) Nutt., a member of the C/sub 4/ biochemical carbon dioxide fixation group was highly competitive in growth rate and production during conditions of adequate soil moisture. As soil moisture conditions declined to minus 40 bars, the net photosynthetic rate of Atriplex decreased to zero. However, the C/sub 3/ shrub species Larrea tridentata (Sesse and Moc. ex DC.) Cov. was able to maintain positive net photosynthetic production during conditions of high temperature and extreme low soil moisture through the major part of the season. The comparative advantages of the C/sub 4/ versus the C/sub 3/ pathway of carbon fixation was lost between these two species as the soil moisture potential declined to minus 40 bars. Desert plants have diffferent strategies for survival, one of the strategies being the C/sub 4/ biochemical carbon fixation pathway. However, many of the plants are members of the C/sub 3/ group. In this instance, the C/sub 4/ fixation pathway does not confer an added advantage to the productivity of the species in the Mojave Desert. Species distribution based on comparative photosynthetic production is discussed

  11. On the evolution of the photosynthetic pigments.

    PubMed

    Evstigneev, V B

    1975-07-01

    During the course of terrestrial evolution, some organisms developed the capability of capturing and utilizing solar radiation. Colored compounds were undoubtedly incorporated within living forms from the earliest times, but during the transition from heterotrophic to a photoautotrophic metabolism only those pigments were selected that were components of the evolving photosynthetic apparatus and were able to catalyze reactions involving storage of light energy in chemical bonds. In this communication, some properties of tetrapyrroles with a closed porphyrin ring containing a metal ion in the center are discussed. These compounds are present in all principal contemporary photosynthetic pigments, and their synthesis has been demonstrated from simpler compounds under prebiotic conditions. It is probable that during intermediate stages in the evolution of photosynthesis, pigments with oxidizing potentials lower than that of chlorophyll were utilized to store light energy although they were not capable of removing electrons from water. The evolution and function of multiple forms of a given photosynthetic pigment in vivo are discussed. 'Accessory' pigments may be regarded as rudiments of the evolutionary development of the photosynthetic apparatus.

  12. Aerobic microorganisms associated with alfalfa leafcutter bees (megachile rotundata).

    PubMed

    Inglis, G D; Sigler, L; Goette, M S

    1993-09-01

    Characterization of microorganisms associated with alfalfa leaf-cutter bee (Megachile rotundata) nectar, pollen, provisions, larval guts, and frass (excreta) in Alberta demonstrated a varied aerobic microflora. Yeasts were isolated frequently from nectar, pollen, and provisions but rarely from guts or frass. The most prevalent yeast taxa were: Candida bombicola, Cryptococcus albidus, Metschnikowia reukaufii, and Rhodotorula glutinis. Although few filamentous fungi were found in nectar, they were frequently isolated from pollen and provisions; the predominant taxa were Alternaria alternata, Cladosporium cladosporioides, C. herbarum, Epicoccum nigrum, and Penicillium chrysogenum. Bacteria, including species of Bacillus, Corynebacterium, Micrococcus, and the actinomycete Streptomyces, also were prevalent in provisions and/or on pollen. In general, the diversity of microorganisms isolated from alimentary canals and frass was lower than from nectar, pollen, and provisions. Bacillus firmus, B. licheniformis, B. megaterium, B. pumilus, and Streptomyces spp. were the most frequently isolated bacteria, whereas Trichosporonoides megachiliensis was the most common filamentous fungus isolated from larval guts and/or frass. These taxa may be part of the resident microflora of the alimentary canal. Populations of bacteria and filamentous fungi, but not yeasts, were larger from Ascosphaera aggregata-infected larvae than from healthy larvae. However, with the exception of Aspergillus niger and T. megachiliensis in frass from healthy larvae, no taxon of filamentous fungi was conspicuously present or absent in infected larvae, healthy larvae, or their frass. PMID:24190009

  13. Phototrophic bacteria and their role in the biogeochemical sulfur cycle

    NASA Technical Reports Server (NTRS)

    Trueper, H. G.

    1985-01-01

    An essential step that cannot be bypassed in the biogeochemical cycle of sulfur today is dissimilatory sulfate reduction by anaerobic bacteria. The enormous amounts of sulfides produced by these are oxidized again either anaerobically by phototrophic bacteria or aerobically by thiobacilli and large chemotrophic bacteria (Beggiatoa, Thiovulum, etc.). Phototrophic bacteria use sulfide, sulfur, thiosulfate, and sulfite as electron donors for photosynthesis. The most obvious intermediate in their oxidative sulfur metabolism is a long chain polysulfide that appears as so called sulfur globules either inside (Chromatiaceae) or outside (Ectothiorhodospiraceae, Chlorobiaceae, and some of the Rhodospirillaceae) the cells. The assimilation of sulfur compounds in phototrophic bacteria is in principle identical with that of nonphototrophic bacteria. However, the Chlorobiaceae and some of the Chromatiaceae and Rhodospirillaceae, unable to reduce sulfate, rely upon reduced sulfur for biosynthetic purposes.

  14. Growth, photosynthetic acclimation and yield quality in legumes under climate change simulations: an updated survey.

    PubMed

    Irigoyen, J J; Goicoechea, N; Antolín, M C; Pascual, I; Sánchez-Díaz, M; Aguirreolea, J; Morales, F

    2014-09-01

    Continued emissions of CO2, derived from human activities, increase atmospheric CO2 concentration. The CO2 rise stimulates plant growth and affects yield quality. Effects of elevated CO2 on legume quality depend on interactions with N2-fixing bacteria and mycorrhizal fungi. Growth at elevated CO2 increases photosynthesis under short-term exposures in C3 species. Under long-term exposures, however, plants generally acclimate to elevated CO2 decreasing their photosynthetic capacity. An updated survey of the literature indicates that a key factor, perhaps the most important, that characteristically influences this phenomenon, its occurrence and extent, is the plant source-sink balance. In legumes, the ability of exchanging C for N at nodule level with the N2-fixing symbionts creates an extra C sink that avoids the occurrence of photosynthetic acclimation. Arbuscular mycorrhizal fungi colonizing roots may also result in increased C sink, preventing photosynthetic acclimation. Defoliation (Anthyllis vulneraria, simulated grazing) or shoot cutting (alfalfa, usual management as forage) largely increases root/shoot ratio. During re-growth at elevated CO2, new shoots growth and nodule respiration function as strong C sinks that counteracts photosynthetic acclimation. In the presence of some limiting factor, the legumes response to elevated CO2 is weakened showing photosynthetic acclimation. This survey has identified limiting factors that include an insufficient N supply from bacterial strains, nutrient-poor soils, low P supply, excess temperature affecting photosynthesis and/or nodule activity, a genetically determined low nodulation capacity, an inability of species or varieties to increase growth (and therefore C sink) at elevated CO2 and a plant phenological state or season when plant growth is stopped. PMID:25113447

  15. Aerobic bacterial microbiota isolated from the cloaca of the European pond turtle (Emys orbicularis) in Poland.

    PubMed

    Nowakiewicz, Aneta; Ziółkowska, Grażyna; Zięba, Przemysław; Dziedzic, Barbara Majer; Gnat, Sebastian; Wójcik, Mariusz; Dziedzic, Roman; Kostruba, Anna

    2015-01-01

    We conducted a comparative analysis of the aerobic cloacal bacteria of European pond turtles (Emys orbicularis) living in their natural environment and juvenile turtles reared under controlled conditions in a breeding center. We included 130 turtles in the study. The aerobic bacteria isolated from the cloaca of the juvenile turtles were less diverse and more prevalent than the bacteria isolated from free-living adults. We isolated 17 bacterial species from juvenile captive turtles, among which the dominant species were Cellulomonas flavigena (77/96), Enterococcus faecalis (96/96), Escherichia coli (58/96), and Proteus mirabilis (41/96). From the adult, free-living turtles, we isolated 36 bacterial species, some of which are a potential threat to public health (e.g., Salmonella enterica serovars Newport, Daytona, and Braenderup; Listeria monocytogenes; Yersinia enterocolitica; Yersinia ruckeri; Klebsiella pneumoniae; Vibrio fluvialis; and Serratia marcescens), and pathogens that are etiologic agents of diseases of ectothermic animals (e.g., Aeromonas sobria, Aeromonas caviae, Hafnia alvei, Edwardsiella tarda, and Citrobacter braakii; the last two species were isolated from both groups of animals). The cloacal bacterial biota of the European pond turtle was characterized by numerous species of bacteria, and its composition varied with turtle age and environmental conditions. The small number of isolated bacteria that are potential human pathogens may indicate that the European pond turtle is of relatively minor importance as a threat to public health.

  16. Aerobic bacterial microbiota isolated from the cloaca of the European pond turtle (Emys orbicularis) in Poland.

    PubMed

    Nowakiewicz, Aneta; Ziółkowska, Grażyna; Zięba, Przemysław; Dziedzic, Barbara Majer; Gnat, Sebastian; Wójcik, Mariusz; Dziedzic, Roman; Kostruba, Anna

    2015-01-01

    We conducted a comparative analysis of the aerobic cloacal bacteria of European pond turtles (Emys orbicularis) living in their natural environment and juvenile turtles reared under controlled conditions in a breeding center. We included 130 turtles in the study. The aerobic bacteria isolated from the cloaca of the juvenile turtles were less diverse and more prevalent than the bacteria isolated from free-living adults. We isolated 17 bacterial species from juvenile captive turtles, among which the dominant species were Cellulomonas flavigena (77/96), Enterococcus faecalis (96/96), Escherichia coli (58/96), and Proteus mirabilis (41/96). From the adult, free-living turtles, we isolated 36 bacterial species, some of which are a potential threat to public health (e.g., Salmonella enterica serovars Newport, Daytona, and Braenderup; Listeria monocytogenes; Yersinia enterocolitica; Yersinia ruckeri; Klebsiella pneumoniae; Vibrio fluvialis; and Serratia marcescens), and pathogens that are etiologic agents of diseases of ectothermic animals (e.g., Aeromonas sobria, Aeromonas caviae, Hafnia alvei, Edwardsiella tarda, and Citrobacter braakii; the last two species were isolated from both groups of animals). The cloacal bacterial biota of the European pond turtle was characterized by numerous species of bacteria, and its composition varied with turtle age and environmental conditions. The small number of isolated bacteria that are potential human pathogens may indicate that the European pond turtle is of relatively minor importance as a threat to public health. PMID:25380369

  17. Copper tolerance and virulence in bacteria.

    PubMed

    Ladomersky, Erik; Petris, Michael J

    2015-06-01

    Copper (Cu) is an essential trace element for all aerobic organisms. It functions as a cofactor in enzymes that catalyze a wide variety of redox reactions due to its ability to cycle between two oxidation states, Cu(I) and Cu(II). This same redox property of copper has the potential to cause toxicity if copper homeostasis is not maintained. Studies suggest that the toxic properties of copper are harnessed by the innate immune system of the host to kill bacteria. To counter such defenses, bacteria rely on copper tolerance genes for virulence within the host. These discoveries suggest bacterial copper intoxication is a component of host nutritional immunity, thus expanding our knowledge of the roles of copper in biology. This review summarizes our current understanding of copper tolerance in bacteria, and the extent to which these pathways contribute to bacterial virulence within the host.

  18. Copper tolerance and virulence in bacteria

    PubMed Central

    Ladomersky, Erik; Petris, Michael J.

    2015-01-01

    Copper (Cu) is an essential trace element for all aerobic organisms. It functions as a cofactor in enzymes that catalyze a wide variety of redox reactions due to its ability to cycle between two oxidation states, Cu(I) and Cu(II). This same redox property of copper has the potential to cause toxicity if copper homeostasis is not maintained. Studies suggest that the toxic properties of copper are harnessed by the innate immune system of the host to kill bacteria. To counter such defenses, bacteria rely on copper tolerance genes for virulence within the host. These discoveries suggest bacterial copper intoxication is a component of host nutritional immunity, thus expanding our knowledge of the roles of copper in biology. This review summarizes our current understanding of copper tolerance in bacteria, and the extent to which these pathways contribute to bacterial virulence within the host. PMID:25652326

  19. Comparative analysis of plastid genomes of non-photosynthetic Ericaceae and their photosynthetic relatives.

    PubMed

    Logacheva, Maria D; Schelkunov, Mikhail I; Shtratnikova, Victoria Y; Matveeva, Maria V; Penin, Aleksey A

    2016-07-25

    Although plastid genomes of flowering plants are typically highly conserved regarding their size, gene content and order, there are some exceptions. Ericaceae, a large and diverse family of flowering plants, warrants special attention within the context of plastid genome evolution because it includes both non-photosynthetic and photosynthetic species with rearranged plastomes and putative losses of "essential" genes. We characterized plastid genomes of three species of Ericaceae, non-photosynthetic Monotropa uniflora and Hypopitys monotropa and photosynthetic Pyrola rotundifolia, using high-throughput sequencing. As expected for non-photosynthetic plants, M. uniflora and H. monotropa have small plastid genomes (46 kb and 35 kb, respectively) lacking genes related to photosynthesis, whereas P. rotundifolia has a larger genome (169 kb) with a gene set similar to other photosynthetic plants. The examined genomes contain an unusually high number of repeats and translocations. Comparative analysis of the expanded set of Ericaceae plastomes suggests that the genes clpP and accD that are present in the plastid genomes of almost all plants have not been lost in this family (as was previously thought) but rather persist in these genomes in unusual forms. Also we found a new gene in P. rotundifolia that emerged as a result of duplication of rps4 gene.

  20. Characterisation of antioxidants in photosynthetic and non-photosynthetic leaf tissues of variegated Pelargonium zonale plants.

    PubMed

    Vidović, M; Morina, F; Milić-Komić, S; Vuleta, A; Zechmann, B; Prokić, Lj; Veljović Jovanović, S

    2016-07-01

    Hydrogen peroxide is an important signalling molecule, involved in regulation of numerous metabolic processes in plants. The most important sources of H2 O2 in photosynthetically active cells are chloroplasts and peroxisomes. Here we employed variegated Pelargonium zonale to characterise and compare enzymatic and non-enzymatic components of the antioxidative system in autotrophic and heterotrophic leaf tissues at (sub)cellular level under optimal growth conditions. The results revealed that both leaf tissues had specific strategies to regulate H2 O2 levels. In photosynthetic cells, the redox regulatory system was based on ascorbate, and on the activities of thylakoid-bound ascorbate peroxidase (tAPX) and catalase. In this leaf tissue, ascorbate was predominantly localised in the nucleus, peroxisomes, plastids and mitochondria. On the other hand, non-photosynthetic cells contained higher glutathione content, mostly located in mitochondria. The enzymatic antioxidative system in non-photosynthetic cells relied on the ascorbate-glutathione cycle and both Mn and Cu/Zn superoxide dismutase. Interestingly, higher content of ascorbate and glutathione, and higher activities of APX in the cytosol of non-photosynthetic leaf cells compared to the photosynthetic ones, suggest the importance of this compartment in H2 O2 regulation. Together, these results imply different regulation of processes linked with H2 O2 signalling at subcellular level. Thus, we propose green-white variegated leaves as an excellent system for examination of redox signal transduction and redox communication between two cell types, autotrophic and heterotrophic, within the same organ.

  1. Comparative analysis of plastid genomes of non-photosynthetic Ericaceae and their photosynthetic relatives.

    PubMed

    Logacheva, Maria D; Schelkunov, Mikhail I; Shtratnikova, Victoria Y; Matveeva, Maria V; Penin, Aleksey A

    2016-01-01

    Although plastid genomes of flowering plants are typically highly conserved regarding their size, gene content and order, there are some exceptions. Ericaceae, a large and diverse family of flowering plants, warrants special attention within the context of plastid genome evolution because it includes both non-photosynthetic and photosynthetic species with rearranged plastomes and putative losses of "essential" genes. We characterized plastid genomes of three species of Ericaceae, non-photosynthetic Monotropa uniflora and Hypopitys monotropa and photosynthetic Pyrola rotundifolia, using high-throughput sequencing. As expected for non-photosynthetic plants, M. uniflora and H. monotropa have small plastid genomes (46 kb and 35 kb, respectively) lacking genes related to photosynthesis, whereas P. rotundifolia has a larger genome (169 kb) with a gene set similar to other photosynthetic plants. The examined genomes contain an unusually high number of repeats and translocations. Comparative analysis of the expanded set of Ericaceae plastomes suggests that the genes clpP and accD that are present in the plastid genomes of almost all plants have not been lost in this family (as was previously thought) but rather persist in these genomes in unusual forms. Also we found a new gene in P. rotundifolia that emerged as a result of duplication of rps4 gene. PMID:27452401

  2. Comparative analysis of plastid genomes of non-photosynthetic Ericaceae and their photosynthetic relatives

    PubMed Central

    Logacheva, Maria D.; Schelkunov, Mikhail I.; Shtratnikova, Victoria Y.; Matveeva, Maria V.; Penin, Aleksey A.

    2016-01-01

    Although plastid genomes of flowering plants are typically highly conserved regarding their size, gene content and order, there are some exceptions. Ericaceae, a large and diverse family of flowering plants, warrants special attention within the context of plastid genome evolution because it includes both non-photosynthetic and photosynthetic species with rearranged plastomes and putative losses of “essential” genes. We characterized plastid genomes of three species of Ericaceae, non-photosynthetic Monotropa uniflora and Hypopitys monotropa and photosynthetic Pyrola rotundifolia, using high-throughput sequencing. As expected for non-photosynthetic plants, M. uniflora and H. monotropa have small plastid genomes (46 kb and 35 kb, respectively) lacking genes related to photosynthesis, whereas P. rotundifolia has a larger genome (169 kb) with a gene set similar to other photosynthetic plants. The examined genomes contain an unusually high number of repeats and translocations. Comparative analysis of the expanded set of Ericaceae plastomes suggests that the genes clpP and accD that are present in the plastid genomes of almost all plants have not been lost in this family (as was previously thought) but rather persist in these genomes in unusual forms. Also we found a new gene in P. rotundifolia that emerged as a result of duplication of rps4 gene. PMID:27452401

  3. Aerobic biotransformation of polybrominated diphenyl ethers (PBDEs) by bacterial isolates.

    PubMed

    Robrock, Kristin R; Coelhan, Mehmet; Sedlak, David L; Alvarez-Cohent, Lisa

    2009-08-01

    Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been used in consumer products and furniture for three decades. Currently, very little is known about their fate in the environment and specifically about their susceptibility to aerobic biotransformation. Here, we investigated the ability of the polychlorinated biphenyl (PCB) degrading bacteria Rhodococcus jostii RHA1 and Burkholderia xenovorans LB400 to transform mono- through hexa-BDEs at ppb levels. We also tested the PBDE transforming abilities of the related strain Rhodococcus sp. RR1 and the ether-degrading Pseudonocardia dioxanivorans CB1190. The two PCB-degrading strains transformed all of the mono- through penta-BDEs and strain LB400 transformed one of the hexa-BDEs. The extent of transformation was inversely proportional to the degree of bromination. Strains RR1 and CB1190 were only able to transform the less brominated mono- and di-BDE congeners. RHA1 released stoichiometric quantities of bromide while transforming mono- and tetra-BDE congeners. LB400 instead converted most of a mono-BDE to a hydroxylated mono-BDE. This is the first report of aerobic transformation of tetra-, penta,- and hexa-BDEs as well as the first report of stoichiometric release of bromide during PBDE transformation.

  4. Comparison of sidestream treatment technologies: post aerobic digestion and Anammox.

    PubMed

    Bauer, Heidi; Johnson, Thomas D; Johnson, Bruce R; Oerke, David; Graziano, Steven

    2016-01-01

    Post aerobic digestion (PAD) and anaerobic ammonium oxidation (Anammox) are sidestream treatment technologies which are both excellent options for the reduction of nitrogen recycled back to the liquid stream without the need for supplemental carbon or alkalinity. However, the achievement of this goal is where the similarities between the two technologies end. PAD is an advanced digestion process where aerobic digestion is designed to follow anaerobic digestion. Other benefits of PAD include volatile solids reduction, odor reduction, and struvite formation reduction. Anammox harnesses a specific species of autotrophic bacteria that can help achieve partial nitritation/deammonification. Other benefits of Anammox include lower energy consumption due to requiring less oxygen compared with conventional nitrification. This manuscript describes the unique benefits and challenges of each technology. Example installations are presented with a narrative of how and why the technology was selected. A whole plant simulator is used to compare and contrast the mass balances and net present value costs on an 'apples to apples' basis. The discussion includes descriptions of conditions under which each technology would potentially be the most beneficial and cost-effective against a baseline facility without sidestream treatment. PMID:27232417

  5. Aerobic biotransformation of polybrominated diphenyl ethers (PBDEs) by bacterial isolates

    PubMed Central

    Robrock, Kristin R.; Coelhan, Mehmet; Sedlak, David; Alvarez-Cohen, Lisa

    2009-01-01

    Polybrominated diphenyl ethers (PBDEs) are flame retardants that have been used in consumer products and furniture for three decades. Currently, very little is known about their fate in the environment and specifically about their susceptibility to aerobic biotransformation. Here, we investigated the ability of the polychlorinated biphenyl (PCB) degrading bacteria Rhodococcus jostii RHA1 and Burkholderia xenovorans LB400 to transform mono- through hexa-BDEs at ppb levels. We also tested the PBDE transforming abilities of related strain Rhodococcus sp. RR1 and the ether-degrading Pseudonocardia dioxanivorans CB1190. The two PCB-degrading strains transformed all of the mono- through penta-BDEs and strain LB400 transformed one of the hexa-BDEs. The extent of transformation was inversely proportional to the degree of bromination. Strains RR1 and CB1190 were only able to transform the less brominated mono- and di- BDE congeners. RHA1 released stoichiometric quantities of bromide while transforming mono- and tetra-BDE congeners. LB400 instead converted most of a mono-BDE to a hydroxylated mono-BDE. This is the first report of aerobic transformation of tetra-, penta- and hexa-BDEs as well as the first report of stoichiometric release of bromide during PBDE transformation. PMID:19731666

  6. Comparison of sidestream treatment technologies: post aerobic digestion and Anammox.

    PubMed

    Bauer, Heidi; Johnson, Thomas D; Johnson, Bruce R; Oerke, David; Graziano, Steven

    2016-01-01

    Post aerobic digestion (PAD) and anaerobic ammonium oxidation (Anammox) are sidestream treatment technologies which are both excellent options for the reduction of nitrogen recycled back to the liquid stream without the need for supplemental carbon or alkalinity. However, the achievement of this goal is where the similarities between the two technologies end. PAD is an advanced digestion process where aerobic digestion is designed to follow anaerobic digestion. Other benefits of PAD include volatile solids reduction, odor reduction, and struvite formation reduction. Anammox harnesses a specific species of autotrophic bacteria that can help achieve partial nitritation/deammonification. Other benefits of Anammox include lower energy consumption due to requiring less oxygen compared with conventional nitrification. This manuscript describes the unique benefits and challenges of each technology. Example installations are presented with a narrative of how and why the technology was selected. A whole plant simulator is used to compare and contrast the mass balances and net present value costs on an 'apples to apples' basis. The discussion includes descriptions of conditions under which each technology would potentially be the most beneficial and cost-effective against a baseline facility without sidestream treatment.

  7. Aerobic and anaerobic PCB biodegradation in the environment

    SciTech Connect

    Abramowicz, D.A.

    1995-06-01

    Studies have identified two distinct biological processes capable of biotransforming polychlorinated biphenyls (PCBs): aerobic oxidative processes and anaerobic reductive processes. It is now known that these two complementary activities are occurring naturally in the environment. Anaerobic PCB dechlorination, responsible for the conversion of highly chlorinated PCBs to lightly chlorinated ortho-enriched congeners, has been documented extensively in the Hudson River and has been observed at many other sites throughout the world. The products from this anaerobic process are readily degradable by a wide range of aerobic bacteria, and it has now been shown that this process is occurring in surficial sediments in the Hudson River. The widespread anaerobic dechlorination of PCBs that has been observed in many river and marine sediments results in reduction of both the potential risk from and potential exposure to PCBs. The reductions in potential risk include reduced dioxin like toxicity and reduced carcinogenicity. The reduced PCB exposure realized upon dechlorination is manifested by reduced bioaccumulation in the food chain and by the increased anaerobic degradability of these products. 27 refs., 1 fig., 1 tab.

  8. [Aerobic methanotrophic communities in the bottom sediments of Lake Baikal].

    PubMed

    Gaĭnutdinova, E A; Eshinimaev, B Ts; Tsyrenzhapova, I S; Dagurova, O P; Suzina, N E; Khmelenina, V N; Namsaraev, B B; Trotsenko, Iu A

    2005-01-01

    The results of the first methodical investigation into the aerobic methanotrophic communities inhabiting the bottom sediments of Lake Baikal are reported. Use of the radioisotopic method revealed methane consumption in 12 10- to 50-cm-long sediment cores. The maximum methane consumption rates (495-737 microl/(dm3 day) were recorded in sediments in the regions of hydrothermal vents and oil and gas occurrence. Methane consumption was most active in the surface layers of the sediments (0-4 cm); it decreased with the sediment depth and became negligible or absent at depths below 20 cm. The number of methanotrophic bacteria usually ranged from 100 to 1000 cells/cm3 of sediment and reached 1 million cells/cm3 in the regions of oil and gas occurrence. The 17 enrichment cultures obtained were represented mainly by morphotype II methanotrophs. Phylogenetic analysis of the enrichment cultures in terms of the amino acid sequence of the alpha subunit of the membrane-bound methane monooxygenase revealed the predominance of methanotrophs of the genus Methylocystis. The results obtained suggest the presence of an active aerobic methanotrophic community in Lake Baikal. PMID:16211862

  9. Enzymes and genes involved in aerobic alkane degradation

    PubMed Central

    Wang, Wanpeng; Shao, Zongze

    2013-01-01

    Alkanes are major constituents of crude oil. They are also present at low concentrations in diverse non-contaminated because many living organisms produce them as chemo-attractants or as protecting agents against water loss. Alkane degradation is a widespread phenomenon in nature. The numerous microorganisms, both prokaryotic and eukaryotic, capable of utilizing alkanes as a carbon and energy source, have been isolated and characterized. This review summarizes the current knowledge of how bacteria metabolize alkanes aerobically, with a particular emphasis on the oxidation of long-chain alkanes, including factors that are responsible for chemotaxis to alkanes, transport across cell membrane of alkanes, the regulation of alkane degradation gene and initial oxidation. PMID:23755043

  10. The Energetics of Aerobic versus Anaerobic Respiration.

    ERIC Educational Resources Information Center

    Champion, Timothy D.; Schwenz, Richard W.

    1990-01-01

    Background information, laboratory procedures, and a discussion of the results of an experiment designed to investigate the difference in energy gained from the aerobic and anaerobic oxidation of glucose are presented. Sample experimental and calculated data are included. (CW)

  11. Neuromodulation of Aerobic Exercise—A Review

    PubMed Central

    Heijnen, Saskia; Hommel, Bernhard; Kibele, Armin; Colzato, Lorenza S.

    2016-01-01

    Running, and aerobic exercise in general, is a physical activity that increasingly many people engage in but that also has become popular as a topic for scientific research. Here we review the available studies investigating whether and to which degree aerobic exercise modulates hormones, amino acids, and neurotransmitters levels. In general, it seems that factors such as genes, gender, training status, and hormonal status need to be taken into account to gain a better understanding of the neuromodular underpinnings of aerobic exercise. More research using longitudinal studies and considering individual differences is necessary to determine actual benefits. We suggest that, in order to succeed, aerobic exercise programs should include optimal periodization, prevent overtraining and be tailored to interindividual differences, including neuro-developmental and genetically-based factors. PMID:26779053

  12. Neuromodulation of Aerobic Exercise-A Review.

    PubMed

    Heijnen, Saskia; Hommel, Bernhard; Kibele, Armin; Colzato, Lorenza S

    2015-01-01

    Running, and aerobic exercise in general, is a physical activity that increasingly many people engage in but that also has become popular as a topic for scientific research. Here we review the available studies investigating whether and to which degree aerobic exercise modulates hormones, amino acids, and neurotransmitters levels. In general, it seems that factors such as genes, gender, training status, and hormonal status need to be taken into account to gain a better understanding of the neuromodular underpinnings of aerobic exercise. More research using longitudinal studies and considering individual differences is necessary to determine actual benefits. We suggest that, in order to succeed, aerobic exercise programs should include optimal periodization, prevent overtraining and be tailored to interindividual differences, including neuro-developmental and genetically-based factors. PMID:26779053

  13. Conditioning and Aerobics for Older Americans.

    ERIC Educational Resources Information Center

    Hansen, Joyce

    1980-01-01

    A class designed for the maintenance and gradual improvement of senior citizens' physical fitness includes relaxation training, flexibility and stretching exercises, interval training activities (designed as a link between less strenuous exercise and more strenuous activities), and aerobic exercises. (CJ)

  14. Enrichments for phototrophic bacteria and characterization by morphology and pigment analysis

    NASA Technical Reports Server (NTRS)

    Brune, D.

    1985-01-01

    The purpose of this investigation was to examine several sulfide containing environments for the presence of phototrophic bacteria and to obtain enriched cultures of some of the bacteria present. The field sites were Alum Rock State Park, the Palo Alto salt marsh, the bay area salt ponds, and Big Soda Lake (near Fallon, Nevada). Bacteria from these sites were characterized by microscopic examination, measurement of in vitro absorption spectra, and analysis of carotenoid pigments. Field observations at one of the bay area salt ponds, in which the salt concentration was saturating (about 30 percent NaCl) and the sediments along the shore of the pond covered with a gypsum crust, revealed a layer of purple photosynthetic bacteria under a green layer in the gypsum crust. Samples of this gypsum crust were taken to the laboratory to measure light transmission through the crust and to try to identify the purple photosynthetic bacteria present in this extremely saline environment.

  15. Enzymatic systems of inorganic pyrophosphate bioenergetics in photosynthetic and heterotrophic protists: remnants or metabolic cornerstones?

    PubMed

    Pérez-Castiñeira, J R; Gómez-García, R; López-Marqués, R L; Losada, M; Serrano, A

    2001-09-01

    An increasing body of biochemical and genetic evidence suggests that inorganic pyrophosphate (PPi) plays an important role in protist bioenergetics. In these organisms, two types of inorganic pyrophosphatases [EC 3.6.1.1, namely soluble PPases (sPPases) and proton-translocating PPases (H+-PPases)] that hydrolyse the PPi generated by cell anabolism, thereby replenishing the orthophosphate pool needed for phosphorylation reactions, are present in different cellular compartments. Photosynthetic and heterotrophic protists possess sPPases located in cellular organelles (plastids and mitochondria), where many anabolic and biosynthetic reactions take place, in addition to H+-PPases, which are integral membrane proteins of the vacuolysosomal membranes and use the chemical energy of PPi to generate an electrochemical proton gradient useful in cell bioenergetics. This last category of proton pumps was considered to be restricted to higher plants and some primitive photosynthetic bacteria, but it has been found recently in many protists (microalgae and protozoa) and bacteria, thus indicating that H+-PPases are much more widespread than previously thought. No cytosolic sPPase (in bacteria, fungi and animal cells) has been shown to occur in these lower eukaryotes. The widespread occurrence of these key enzymes of PPi metabolism among evolutionarily divergent protists strongly supports the ancestral character of the bioenergetics based on this simple energy-rich compound, which may play an important role in survival under different biotic and abiotic stress conditions.

  16. Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions

    PubMed Central

    Amachawadi, Raghavendra G.; Renter, David G.; Volkova, Victoriya V.

    2016-01-01

    Antimicrobial treatments result in the host’s enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-Test® following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: β-lactams (specifically, ampicillin and ceftriaxone E-Test®), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n≥30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment

  17. Antimicrobial Susceptibility of Enteric Gram Negative Facultative Anaerobe Bacilli in Aerobic versus Anaerobic Conditions.

    PubMed

    DeMars, Zachary; Biswas, Silpak; Amachawadi, Raghavendra G; Renter, David G; Volkova, Victoriya V

    2016-01-01

    Antimicrobial treatments result in the host's enteric bacteria being exposed to the antimicrobials. Pharmacodynamic models can describe how this exposure affects the enteric bacteria and their antimicrobial resistance. The models utilize measurements of bacterial antimicrobial susceptibility traditionally obtained in vitro in aerobic conditions. However, in vivo enteric bacteria are exposed to antimicrobials in anaerobic conditions of the lower intestine. Some of enteric bacteria of food animals are potential foodborne pathogens, e.g., Gram-negative bacilli Escherichia coli and Salmonella enterica. These are facultative anaerobes; their physiology and growth rates change in anaerobic conditions. We hypothesized that their antimicrobial susceptibility also changes, and evaluated differences in the susceptibility in aerobic vs. anaerobic conditions of generic E. coli and Salmonella enterica of diverse serovars isolated from cattle feces. Susceptibility of an isolate was evaluated as its minimum inhibitory concentration (MIC) measured by E-Test® following 24 hours of adaptation to the conditions on Mueller-Hinton agar, and on a more complex tryptic soy agar with 5% sheep blood (BAP) media. We considered all major antimicrobial drug classes used in the U.S. to treat cattle: β-lactams (specifically, ampicillin and ceftriaxone E-Test®), aminoglycosides (gentamicin and kanamycin), fluoroquinolones (enrofloxacin), classical macrolides (erythromycin), azalides (azithromycin), sulfanomides (sulfamethoxazole/trimethoprim), and tetracyclines (tetracycline). Statistical analyses were conducted for the isolates (n≥30) interpreted as susceptible to the antimicrobials based on the clinical breakpoint interpretation for human infection. Bacterial susceptibility to every antimicrobial tested was statistically significantly different in anaerobic vs. aerobic conditions on both media, except for no difference in susceptibility to ceftriaxone on BAP agar. A satellite experiment

  18. Up-converted fluorescence from photosynthetic light-harvesting complexes linearly dependent on excitation intensity.

    PubMed

    Leiger, Kristjan; Freiberg, Arvi

    2016-01-01

    Weak up-converted fluorescence related to bacteriochlorophyll a was recorded from various detergent-isolated and membrane-embedded light-harvesting pigment-protein complexes as well as from the functional membranes of photosynthetic purple bacteria under continuous-wave infrared laser excitation at 1064 nm, far outside the optically allowed singlet absorption bands of the chromophore. The fluorescence increases linearly with the excitation power, distinguishing it from the previously observed two-photon excited fluorescence upon femtosecond pulse excitation. Possible mechanisms of this excitation are discussed.

  19. [Biological activity of lipids and photosynthetic pigments of Sargassum pallidum C. Agardh].

    PubMed

    Gerasimenko, N I; Martyias, E A; Logvinov, S V; Busarova, N G

    2014-01-01

    The biological activity of lipids and photosynthetic pigments of the kelp Sargassum pallidum (Turner) C. Agardh has been studied. Free fatty acids and their esters demonstrated considerable antimicrobial activity against bacteria (Staphylococcus aureus[ital] and Escherichia coli), yeast-like fungi (Candida albicans), and opportunistic pathogenic (Aspergilius niger) and phytopathogenic (Fusarium oxysporum, and Septoria glycines) fungi. Glyceroglycolipids and neutral lipids demonstrated moderate activity. Fucoxanthin and chlorophylls weakly suppressed the growth of microorganisms. None of the studied substances demonstrated activity against Ehrlich's carcinoma. It was shown that the season of weed harvesting affected both antimicrobial and hemolytic activities of different lipids due to changes in their fatty acid composition. PMID:25272757

  20. Enteric bacteria: friend or foe?

    PubMed

    Batt, R M; Rutgers, H C; Sancak, A A

    1996-06-01

    The normal gastrointestinal tract contains an enormous number of aerobic and anaerobic bacteria which normally enjoy a symbiotic relationship with the host but can have adverse effects with local and systemic consequences. The small intestine constitutes a zone of transition between the sparsely populated stomach and the luxuriant bacterial flora of the colon. Regulation of the intestinal flora depends on complex interactions between many factors including secretion of gastric acid, intestinal motility, biliary and pancreatic secretions, local immunity, the surface glycocalyx and mucus layer, and diet. Microbial interactions are also important, and can involve alterations in redox potential, substrate depletion and production of substances such as bacteriocins that inhibit bacterial growth. The beneficial effect of the normal enteric flora include the competitive exclusion of potentially pathogenic organisms, and the production of nutrients such as short-chain fatty acids (which represent an important energy source for the colonic mucosa) and vitamins. Detrimental effects of the enteric flora include competition for calories and essential nutrients, particularly by bacteria located in the small intestine, and a capacity to damage the mucosa, in some circumstances causing or contributing to inflammatory bowel disease. These problems can be accentuated by interference with the physiological regulation of intraluminal bacteria allowing overgrowth by a normal resident, or colonisation by transient pathogens. The pathophysiological consequences may involve direct damage to the intestinal mucosa, and bacterial metabolism of intraluminal constituents, for example forming deconjugated bile acids and hydroxylated fatty acids which stimulate fluid secretion. Additional problems arise if there is interference with the mucosal barrier since this can result in increased passage of bacteria and bacterial products stimulating mucosal inflammation, while bacterial translocation

  1. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

    Gregory Kremer; David J. Bayless; Morgan Vis; Michael Prudich; Keith Cooksey; Jeff Muhs

    2004-10-13

    This report highlights significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation Project for the period ending 09/30/2004. The primary effort of this quarter was focused on mass transfer of carbon dioxide into the water film to study the potential effects on the photosynthetic organisms that depend on the carbon. Testing of the carbon dioxide scrubbing capability (mass transfer capability) of flowing water film appears to be relatively high and largely unaffected by transport of the gas through the bioreactor. The implications are that the transfer of carbon dioxide into the film is nearly at maximum and that it is sufficient to sustain photosynthesis at whatever rate the organisms can sustain. This finding is key to assuming that the process is an energy (photon) limited reaction and not a nutrient limited reaction.

  2. [Engineering photosynthetic cyanobacterial chassis: a review].

    PubMed

    Wu, Qin; Chen, Lei; Wang, Jiangxin; Zhang, Weiwen

    2013-08-01

    Photosynthetic cyanobacteria possess a series of good properties, such as their abilities to capture solar energy for CO2 fixation, low nutritional requirements for growth, high growth rate, and relatively simple genetic background. Due to the high oil price and increased concern of the global warming in recent years, cyanobacteria have attracted widespread attention because they can serve as an 'autotrophic microbial factory' for producing renewable biofuels and fine chemicals directly from CO2. Particularly, significant progress has been made in applying synthetic biology techniques and strategies to construct and optimize cyanobacteria chassis. In this article, we critically summarized recent advances in developing new methods to optimize cyanobacteria chassis, improving cyanobacteria photosynthetic efficiency, and in constructing cyanobacteria chassis tolerant to products or environmental stresses. In addition, various industrial applications of cyanobacteria chassis are also discussed.

  3. BOREAS TE-9 NSA Photosynthetic Response Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G.; Curd, Shelaine (Editor); Dang, Qinglai; Margolis, Hank; Coyea, Marie

    2000-01-01

    The Boreal Ecosystem-Atmospheric Study (BOREAS) TE-9 (Terrestrial Ecology) team collected several data sets related to chemical and photosynthetic properties of leaves. This data set describes: (1) the response of leaf and shoot-level photosynthesis to ambient and intercellular CO2 concentration, temperature, and incident photosynthetically active radiation (PAR) for black spruce, jack pine, and aspen during the three intensive field campaigns (IFCs) in 1994 in the Northern Study Area (NSA); (2) the response of stomatal conductance to vapor pressure difference throughout the growing season of 1994; and (3) a range of shoot water potentials (controlled in the laboratory) for black spruce and jack pine. The data are stored in tabular ASCII files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  4. Photosynthetic hydrogen and oxygen production - Kinetic studies

    NASA Astrophysics Data System (ADS)

    Greenbaum, E.

    1982-01-01

    The simultaneous photoproduction of hydrogen and oxygen was measured in a study of the steady-state turnover times of two biological systems, by driving them into the steady state with repetitive, single-turnover flash illumination. The systems were: (1) in vitro, isolated chloroplasts, ferredoxin and hydrogenase; and (2) the anaerobically-adapted green alga Chlamydomonas reinhardtii. It is found that the turnover times for production of both oxygen and hydrogen in photosynthetic water splitting are in milliseconds, and either equal to, or less than, the turnover time for carbon dioxide reduction in intact algal cells. There is therefore mutual compatibility between hydrogen and oxygen turnover times, and partial compatibility with the excitation rate of the photosynthetic reaction centers under solar irradiation conditions.

  5. Nanowire-bacteria hybrids for unassisted solar carbon dioxide fixation to value-added chemicals.

    PubMed

    Liu, Chong; Gallagher, Joseph J; Sakimoto, Kelsey K; Nichols, Eva M; Chang, Christopher J; Chang, Michelle C Y; Yang, Peidong

    2015-05-13

    Direct solar-powered production of value-added chemicals from CO2 and H2O, a process that mimics natural photosynthesis, is of fundamental and practical interest. In natural photosynthesis, CO2 is first reduced to common biochemical building blocks using solar energy, which are subsequently used for the synthesis of the complex mixture of molecular products that form biomass. Here we report an artificial photosynthetic scheme that functions via a similar two-step process by developing a biocompatible light-capturing nanowire array that enables a direct interface with microbial systems. As a proof of principle, we demonstrate that a hybrid semiconductor nanowire-bacteria system can reduce CO2 at neutral pH to a wide array of chemical targets, such as fuels, polymers, and complex pharmaceutical precursors, using only solar energy input. The high-surface-area silicon nanowire array harvests light energy to provide reducing equivalents to the anaerobic bacterium, Sporomusa ovata, for the photoelectrochemical production of acetic acid under aerobic conditions (21% O2) with low overpotential (η < 200 mV), high Faradaic efficiency (up to 90%), and long-term stability (up to 200 h). The resulting acetate (∼6 g/L) can be activated to acetyl coenzyme A (acetyl-CoA) by genetically engineered Escherichia coli and used as a building block for a variety of value-added chemicals, such as n-butanol, polyhydroxybutyrate (PHB) polymer, and three different isoprenoid natural products. As such, interfacing biocompatible solid-state nanodevices with living systems provides a starting point for developing a programmable system of chemical synthesis entirely powered by sunlight.

  6. Nitric oxide in marine photosynthetic organisms.

    PubMed

    Kumar, Amit; Castellano, Immacolata; Patti, Francesco Paolo; Palumbo, Anna; Buia, Maria Cristina

    2015-05-01

    Nitric oxide is a versatile and powerful signaling molecule in plants. However, most of our understanding stems from studies on terrestrial plants and very little is known about marine autotrophs. This review summarizes current knowledge about the source of nitric oxide synthesis in marine photosynthetic organisms and its role in various physiological processes under normal and stress conditions. The interactions of nitric oxide with other stress signals and cross talk among secondary messengers are also highlighted.

  7. ENHANCED PRACTICAL PHOTOSYNTHETIC CO2 MITIGATION

    SciTech Connect

    Dr. Gregory Kremer; Dr. David J. Bayless; Dr. Morgan Vis; Dr. Michael Prudich; Dr. Keith Cooksey; Dr. Jeff Muhs

    2003-04-15

    This quarterly report documents significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation project during the period from 1/2/2003 through 4/01/2003. As indicated in the list of accomplishments below we are progressing with long-term model scale bioreactor tests and are completing final preparations for pilot scale bioreactor testing. Specific results and accomplishments for the first quarter of 2003 are included.

  8. Enhanced Practical Photosynthetic CO2 Mitigation

    SciTech Connect

    Gregory Kremer; David J. Bayless; Morgan Vis; Michael Prudich; Keith Cooksey; Jeff Muhs

    2005-01-13

    This report highlights significant achievements in the Enhanced Practical Photosynthetic CO{sub 2} Mitigation Project during the ending 12/31/2004. Specific results and accomplishments for the program include review of pilot scale testing and design of a new bioreactor. Testing confirmed that algae can be grown in a sustainable fashion in the pilot bioreactor, even with intermittent availability of sunlight. The pilot-scale tests indicated that algal growth rate followed photon delivery during productivity testing.

  9. Thioredoxin Is Involved in Oxygen-Regulated Formation of the Photosynthetic Apparatus of Rhodobacter sphaeroides

    PubMed Central

    Pasternak, Cecile; Haberzettl, Kerstin; Klug, Gabriele

    1999-01-01

    Thioredoxin, a redox active protein, has been previously demonstrated to be essential for growth of the anoxygenic photosynthetic bacterium Rhodobacter sphaeroides. In the present study, the involvement of thioredoxin in the formation of the photosynthetic apparatus of R. sphaeroides WS8 was investigated by construction and analysis of a mutant strain disrupted for the chromosomal trxA copy and carrying a plasmid-borne copy of trxA under the control of the hybrid ptrc promoter inducible by IPTG (isopropyl-β-d-thiogalactopyranoside). This strain was viable in the absence of IPTG but was affected in pigmentation. When shifted from high to low oxygen tension conditions, the trxA mutant showed a reduced bacteriochlorophyll content in comparison to that of the wild type. Although thioredoxin is able to regulate aminolevulinic acid (ALA) synthase (the first enzyme of the tetrapyrrole biosynthetic pathway) activity by a dithiol-disulfide exchange, our mutant strain exhibited a level of ALA synthase activity identical to that of the wild type, suggesting that thioredoxin is involved in other steps to regulate the synthesis of the photosynthetic apparatus. Accordingly, we showed that the trxA mutation affects the oxygen-regulated expression of the puf operon encoding the pigment-binding proteins of the light-harvesting and reaction center complexes. Upon transition from aerobic to semiaerobic growth conditions, the maximal puf mRNA level was found to be 40 to 50% lower in the mutant strain than in the wild type. The stability of the puf transcripts was identical in both strains grown under low oxygen tension, indicating that the role of thioredoxin in regulating puf expression occurs at the transcriptional level. PMID:9864318

  10. Photosynthetic carbon metabolism in Enteromorpha compressa (Chlorophyta)

    SciTech Connect

    Beer, S.; Shragge, B.

    1987-12-01

    The intertidal macroalga Enteromorpha compressa showed the ability to use HCO/sub 3//sup -/, as an exogenous inorganic carbon (Ci) source for photosynthesis. However, although the natural sea water concentration of this carbon form was saturating, additional CO/sub 2/ above ambient Ci levels doubled net photosynthetic rates. Therefore, the productivity of this alga, when submerged, is likely to be limited by Ci. When plants were exposed to air, photosynthetic rates saturated at air-levels of CO/sub 2/ during mild desiccation. Based on carbon fixing enzyme activities and Ci pulse-chase incorporation patterns, it was found that Enteromorpha is a C/sub 3/ plant. However, this alga did not show O/sub 2/ inhibited photosynthetic rates at natural sea water Ci conditions. It is suggested that such a C/sub 4/-like gas exchange response is due to the HCO/sub 3//sup -/ utilization system concentrating CO/sub 2/ intracellularly, thus alleviating apparent photorespiration.

  11. Improving photosynthetic efficiency for greater yield.

    PubMed

    Zhu, Xin-Guang; Long, Stephen P; Ort, Donald R

    2010-01-01

    Increasing the yield potential of the major food grain crops has contributed very significantly to a rising food supply over the past 50 years, which has until recently more than kept pace with rising global demand. Whereas improved photosynthetic efficiency has played only a minor role in the remarkable increases in productivity achieved in the last half century, further increases in yield potential will rely in large part on improved photosynthesis. Here we examine inefficiencies in photosynthetic energy transduction in crops from light interception to carbohydrate synthesis, and how classical breeding, systems biology, and synthetic biology are providing new opportunities to develop more productive germplasm. Near-term opportunities include improving the display of leaves in crop canopies to avoid light saturation of individual leaves and further investigation of a photorespiratory bypass that has already improved the productivity of model species. Longer-term opportunities include engineering into plants carboxylases that are better adapted to current and forthcoming CO(2) concentrations, and the use of modeling to guide molecular optimization of resource investment among the components of the photosynthetic apparatus, to maximize carbon gain without increasing crop inputs. Collectively, these changes have the potential to more than double the yield potential of our major crops. PMID:20192734

  12. Aerobic Excercise and Research Opportunities to Benefit Impaired Children. (Project AEROBIC). Final Report.

    ERIC Educational Resources Information Center

    Idaho Univ., Moscow.

    The final report summarizes accomplishments of Project AEROBIC (Aerobic Exercise and Research Opportunities to Benefit Impaired Children), which provided a physical education exercise program for severely, profoundly, and multiply handicapped children aged 10-21. Activities are outlined for the 3 year period and include modification of exercise…

  13. Distribution and identification of luminous bacteria from the sargasso sea.

    PubMed

    Orndorff, S A; Colwell, R R

    1980-05-01

    Vibrio fischeri and Lucibacterium harveyi constituted 75 of the 83 luminous bacteria isolated from Sargasso Sea surface waters. Photobacterium leiognathi and Photobacterium phosphoreum constituted the remainder of the isolates. Luminescent bacteria were recovered at concentrations of 1 to 63 cells per 100 ml from water samples collected at depths of 160 to 320 m. Two water samples collected at the thermocline yielded larger numbers of viable, aerobic heterotrophic and luminous bacteria. Luminescent bacteria were not recovered from surface microlayer samples. The species distribution of the luminous bacteria reflected previously recognized growth patterns; i.e., L. harveyi and V. fischeri were predominant in the upper, warm waters (only one isolate of P. phosphoreum was obtained from surface tropical waters).

  14. Tectonics and the photosynthetic habitable zone (Invited)

    NASA Astrophysics Data System (ADS)

    Sleep, N. H.

    2009-12-01

    The traditional habitable zone lies between an inner stellar radius where the surface of the planet becomes too hot for liquid water carbon-based life and on outer radius, where the surface freezes. It is effectively the zone where photosynthesis is feasible. The concept extends to putative life on objects with liquid methane at the surface, like Titan. As a practical matter, photosynthesis leaves detectable biosignatures in the geological record; black shale on the Earth indicates that sulfide and probably FeO based photosynthesis existed by 3.8 Ga. The hard crustal rocks and the mantle sequester numerous photosynthetic biosignatures. Photosynthesis can produce detectable free oxygen with ozone in the atmosphere of extrasolar planets. In contrast, there is no outer limit for subsurface life in large silicate objects. Pre-photosynthetic niches are dependable but meager and not very detectable at great antiquity or great distance, with global productivity less than 1e-3 of the photosynthetic ones. Photosynthetic organisms have bountiful energy that modifies their surface environment and even tectonics. For example, metamorphic rocks formed at the expense of thick black shale are highly radioactive and hence self-fluxing. Active tectonics with volcanism and metamorphism prevents volatiles from being sequestered in the subsurface as on Mars. A heat-pipe object, like a larger Io, differs from the Earth in that the volatiles return to the deep interior distributed within massive volcanic deposits rather than concentrated in the shallow oceanic crust. One the Earth, the return of water to the surface by arc volcanoes controls its mantle abundance at the transition between behaving as a trace element and behaving as a major element that affects melting. The ocean accumulates the water that the mantle and crust do not take. The Earth has the “right” amount of water that erosion/deposition and tectonics both tend to maintain near sea level surfaces. The mantle contains

  15. Structure-function investigations of bacterial photosynthetic reaction centers.

    PubMed

    Leonova, M M; Fufina, T Yu; Vasilieva, L G; Shuvalov, V A

    2011-12-01

    During photosynthesis light energy is converted into energy of chemical bonds through a series of electron and proton transfer reactions. Over the first ultrafast steps of photosynthesis that take place in the reaction center (RC) the quantum efficiency of the light energy transduction is nearly 100%. Compared to the plant and cyanobacterial photosystems, bacterial RCs are well studied and have relatively simple structure. Therefore they represent a useful model system both for manipulating of the electron transfer parameters to study detailed mechanisms of its separate steps as well as to investigate the common principles of the photosynthetic RC structure, function, and evolution. This review is focused on the research papers devoted to chemical and genetic modifications of the RCs of purple bacteria in order to study principles and mechanisms of their functioning. Investigations of the last two decades show that the maximal rates of the electron transfer reactions in the RC depend on a number of parameters. Chemical structure of the cofactors, distances between them, their relative orientation, and interactions to each other are of great importance for this process. By means of genetic and spectral methods, it was demonstrated that RC protein is also an essential factor affecting the efficiency of the photochemical charge separation. Finally, some of conservative water molecules found in RC not only contribute to stability of the protein structure, but are directly involved in the functioning of the complex.

  16. A multi-pathway model for photosynthetic reaction center.

    PubMed

    Qin, M; Shen, H Z; Yi, X X

    2016-03-28

    Charge separation occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine. Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem II reaction center (PSII RC) to describe the charge separation. Our model mainly considers two charge-separation pathways which is more than that typically considered in the published literature. We explore how these cross-couplings increase the current and power of the charge separation and discuss the effects of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PSII RC and dephasing induced by environments is also explored, and extension from two pathways to multiple pathways is made. These results suggest that noise-induced quantum coherence helps to suppress the influence of acceptor-to-donor charge recombination, and besides, nature-mimicking architectures with engineered multiple pathways for charge separations might be better for artificial solar energy devices considering the influence of environments. PMID:27036480

  17. A multi-pathway model for photosynthetic reaction center

    NASA Astrophysics Data System (ADS)

    Qin, M.; Shen, H. Z.; Yi, X. X.

    2016-03-01

    Charge separation occurs in a pair of tightly coupled chlorophylls at the heart of photosynthetic reaction centers of both plants and bacteria. Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell, working like a quantum heat engine. Here, we propose a biological quantum heat engine (BQHE) motivated by Photosystem II reaction center (PSII RC) to describe the charge separation. Our model mainly considers two charge-separation pathways which is more than that typically considered in the published literature. We explore how these cross-couplings increase the current and power of the charge separation and discuss the effects of multiple pathways in terms of current and power. The robustness of the BQHE against the charge recombination in natural PSII RC and dephasing induced by environments is also explored, and extension from two pathways to multiple pathways is made. These results suggest that noise-induced quantum coherence helps to suppress the influence of acceptor-to-donor charge recombination, and besides, nature-mimicking architectures with engineered multiple pathways for charge separations might be better for artificial solar energy devices considering the influence of environments.

  18. Thermal Quantum Correlations in Photosynthetic Light-Harvesting Complexes

    NASA Astrophysics Data System (ADS)

    Mahdian, M.; Kouhestani, H.

    2015-08-01

    Photosynthesis is one of the ancient biological processes, playing crucial role converting solar energy to cellular usable currency. Environmental factors and external perturbations has forced nature to choose systems with the highest efficiency and performance. Recent theoretical and experimental studies have proved the presence of quantum properties in biological systems. Energy transfer systems like Fenna-Matthews-Olson (FMO) complex shows quantum entanglement between sites of Bacteriophylla molecules in protein environment and presence of decoherence. Complex biological systems implement more truthful mechanisms beside chemical-quantum correlations to assure system's efficiency. In this study we investigate thermal quantum correlations in FMO protein of the photosynthetic apparatus of green sulfur bacteria by quantum discord measure. The results confirmed existence of remarkable quantum correlations of of BChla pigments in room temperature. This results approve involvement of quantum correlation mechanisms for information storage and retention in living organisms that could be useful for further evolutionary studies. Inspired idea of this study is potentially interesting to practice by the same procedure in genetic data transfer mechanisms.

  19. Photosynthetic vesicle architecture and constraints on efficient energy harvesting.

    PubMed

    Sener, Melih; Strümpfer, Johan; Timney, John A; Freiberg, Arvi; Hunter, C Neil; Schulten, Klaus

    2010-07-01

    Photosynthetic chromatophore vesicles found in some purple bacteria constitute one of the simplest light-harvesting systems in nature. The overall architecture of chromatophore vesicles and the structural integration of vesicle function remain poorly understood despite structural information being available on individual constituent proteins. An all-atom structural model for an entire chromatophore vesicle is presented, which improves upon earlier models by taking into account the stoichiometry of core and antenna complexes determined by the absorption spectrum of intact vesicles in Rhodobacter sphaeroides, as well as the well-established curvature-inducing properties of the dimeric core complex. The absorption spectrum of low-light-adapted vesicles is shown to correspond to a light-harvesting-complex 2 to reaction center ratio of 3:1. A structural model for a vesicle consistent with this stoichiometry is developed and used in the computation of excitonic properties. Considered also is the packing density of antenna and core complexes that is high enough for efficient energy transfer and low enough for quinone diffusion from reaction centers to cytochrome bc(1) complexes.

  20. Kinetics of the biodegradation pathway of endosulfan in the aerobic and anaerobic environments.

    PubMed

    Tiwari, Manoj K; Guha, Saumyen

    2013-09-01

    The enriched mixed culture aerobic and anaerobic bacteria from agricultural soils were used to study the degradation of endosulfan (ES) in aqueous and soil slurry environments. The extent of biodegradation was ∼95% in aqueous and ∼65% in soil slurry during 15 d in aerobic studies and, ∼80% in aqueous and ∼60% in soil slurry during 60 d in anaerobic studies. The pathways of aerobic and anaerobic degradation of ES were modeled using combination of Monod no growth model and first order kinetics. The rate of biodegradation of β-isomer was faster compared to α-isomer. Conversion of ES to endosulfan sulfate (ESS) and endosulfan diol (ESD) were the rate limiting steps in aerobic medium and, the hydrolysis of ES to ESD was the rate limiting step in anaerobic medium. The mass balance indicated further degradation of endosulfan ether (ESE) and endosulfan lactone (ESL), but no end-products were identified. In the soil slurries, the rates of degradation of sorbed contaminants were slower. As a result, net rate of degradation reduced, increasing the persistence of the compounds. The soil phase degradation rate of β-isomer was slowed down more compared with α-isomer, which was attributed to its higher partition coefficient on the soil.

  1. Characterisation of antioxidants in photosynthetic and non-photosynthetic leaf tissues of variegated Pelargonium zonale plants.

    PubMed

    Vidović, M; Morina, F; Milić-Komić, S; Vuleta, A; Zechmann, B; Prokić, Lj; Veljović Jovanović, S

    2016-07-01

    Hydrogen peroxide is an important signalling molecule, involved in regulation of numerous metabolic processes in plants. The most important sources of H2 O2 in photosynthetically active cells are chloroplasts and peroxisomes. Here we employed variegated Pelargonium zonale to characterise and compare enzymatic and non-enzymatic components of the antioxidative system in autotrophic and heterotrophic leaf tissues at (sub)cellular level under optimal growth conditions. The results revealed that both leaf tissues had specific strategies to regulate H2 O2 levels. In photosynthetic cells, the redox regulatory system was based on ascorbate, and on the activities of thylakoid-bound ascorbate peroxidase (tAPX) and catalase. In this leaf tissue, ascorbate was predominantly localised in the nucleus, peroxisomes, plastids and mitochondria. On the other hand, non-photosynthetic cells contained higher glutathione content, mostly located in mitochondria. The enzymatic antioxidative system in non-photosynthetic cells relied on the ascorbate-glutathione cycle and both Mn and Cu/Zn superoxide dismutase. Interestingly, higher content of ascorbate and glutathione, and higher activities of APX in the cytosol of non-photosynthetic leaf cells compared to the photosynthetic ones, suggest the importance of this compartment in H2 O2 regulation. Together, these results imply different regulation of processes linked with H2 O2 signalling at subcellular level. Thus, we propose green-white variegated leaves as an excellent system for examination of redox signal transduction and redox communication between two cell types, autotrophic and heterotrophic, within the same organ. PMID:26712503

  2. Accelerating Aerobic Sludge Granulation by Adding Dry Sewage Sludge Micropowder in Sequencing Batch Reactors.

    PubMed

    Li, Jun; Liu, Jun; Wang, Danjun; Chen, Tao; Ma, Ting; Wang, Zhihong; Zhuo, Weilong

    2015-08-01

    Micropowder (20-250 µm) made from ground dry waste sludge from a municipal sewage treatment plant was added in a sequencing batch reactor (R2), which was fed by synthetic wastewater with acetate as carbon source. Compared with the traditional SBR (R1), aerobic sludge granulation time was shortened 15 days in R2. Furthermore, filamentous bacteria in bulking sludge were controlled to accelerate aerobic granulation and form large granules. Correspondingly, the SVI decreased from 225 mL/g to 37 mL/g. X-ray Fluorescence (XRF) analysis demonstrated that Al and Si from the micropowder were accumulated in granules. A mechanism hypotheses for the acceleration of aerobic granulation by adding dry sludge micropowder is proposed: added micropowder acts as nuclei to induce bacterial attachment; dissolved matters from the micropowder increase abruptly the organic load for starved sludge to control overgrown filamentous bacteria as a framework for aggregation; increased friction from the movement of micropowder forces the filaments which extend outwards to shrink for shaping granules. PMID:26308025

  3. Supramolecular organization of bacterial aerobic respiratory chains: From cells and back.

    PubMed

    Melo, Ana M P; Teixeira, Miguel

    2016-03-01

    Aerobic respiratory chains from all life kingdoms are composed by several complexes that have been deeply characterized in their isolated form. These membranous complexes link the oxidation of reducing substrates to the reduction of molecular oxygen, in a process that conserves energy by ion translocation between both sides of the mitochondrial or prokaryotic cytoplasmatic membranes. In recent years there has been increasing evidence that those complexes are organized as supramolecular structures, the so-called supercomplexes and respirasomes, being available for eukaryotes strong data namely obtained by electron microscopy and single particle analysis. A parallel study has been developed for prokaryotes, based on blue native gels and mass spectrometry analysis, showing that in these more simple unicellular organisms such supercomplexes also exist, involving not only typical aerobic-respiration associated complexes, but also anaerobic-linked enzymes. After a short overview of the data on eukaryotic supercomplexes, we will analyse comprehensively the different types of prokaryotic aerobic respiratory supercomplexes that have been thus far suggested, in both bacteria and archaea. This article is part of a Special Issue entitled Organization and dynamics of bioenergetic systems in bacteria, edited by Prof Conrad Mullineaux. PMID:26546715

  4. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling.

    PubMed

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-09-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis-Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species' climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species' growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species' thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized

  5. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling.

    PubMed

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-09-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis-Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species' climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species' growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species' thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized

  6. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling

    PubMed Central

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-01-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis–Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species’ climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species’ growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species’ thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to

  7. Aerobic hydrogen production by the heterocystous cyanobacteria Anabaena spp. strains CA and 1F.

    PubMed Central

    Zhang, X K; Haskell, J B; Tabita, F R; Van Baalen, C

    1983-01-01

    Aerobic photoproduction of H2 was demonstrated in Anabaena spp. strains CA and 1F when cells were growing under nitrogen-fixing conditions. The rates of production, measured either by the hydrogen electrode or in a flow system by gas chromatography, were 10 to 15% of the rate of photosynthetic O2 evolution or 50 to 80% of the rates of acetylene reduction. Strains CA and 1F differed in several respects. In strain CA, H2 production was immediately partially sensitive to 3-(3,4-dichlorophenyl)-1,1-dimethylurea, whereas strain 1F was not immediately affected. Strain CA also showed a consistently higher rate of H2 production than did strain 1F. H2 production in strain CA was also markedly influenced by the light intensity used for growth, although the growth rates indicated that the light intensities used were essentially saturating. PMID:6417109

  8. Silicification-induced cell aggregation for the sustainable production of H2 under aerobic conditions.

    PubMed

    Xiong, Wei; Zhao, Xiaohong; Zhu, Genxing; Shao, Changyu; Li, Yaling; Ma, Weimin; Xu, Xurong; Tang, Ruikang

    2015-10-01

    Photobiological hydrogen production is of great importance because of its promise for generating clean renewable energy. In nature, green algae cannot produce hydrogen as a result of the extreme sensitivity of hydrogenase to oxygen. However, we find that silicification-induced green algae aggregates can achieve sustainable photobiological hydrogen production even under natural aerobic conditions. The core-shell structure of the green algae aggregates creates a balance between photosynthetic electron generation and hydrogenase activity, thus allowing the production of hydrogen. This finding provides a viable pathway for the solar-driven splitting of water into hydrogen and oxygen to develop green energy alternatives by using rationally designed cell-material complexes. PMID:26302695

  9. Reduced bacterial colony count of anaerobic bacteria is associated with a worsening in lung clearance index and inflammation in cystic fibrosis.

    PubMed

    O'Neill, Katherine; Bradley, Judy M; Johnston, Elinor; McGrath, Stephanie; McIlreavey, Leanne; Rowan, Stephen; Reid, Alastair; Bradbury, Ian; Einarsson, Gisli; Elborn, J Stuart; Tunney, Michael M

    2015-01-01

    Anaerobic bacteria have been identified in abundance in the airways of cystic fibrosis (CF) subjects. The impact their presence and abundance has on lung function and inflammation is unclear. The aim of this study was to investigate the relationship between the colony count of aerobic and anaerobic bacteria, lung clearance index (LCI), spirometry and C-Reactive Protein (CRP) in patients with CF. Sputum and blood were collected from CF patients at a single cross-sectional visit when clinically stable. Community composition and bacterial colony counts were analysed using extended aerobic and anaerobic culture. Patients completed spirometry and a multiple breath washout (MBW) test to obtain LCI. An inverse correlation between colony count of aerobic bacteria (n = 41, r = -0.35; p = 0.02), anaerobic bacteria (n = 41, r = -0.44, p = 0.004) and LCI was observed. There was an inverse correlation between colony count of anaerobic bacteria and CRP (n = 25, r = -0.44, p = 0.03) only. The results of this study demonstrate that a lower colony count of aerobic and anaerobic bacteria correlated with a worse LCI. A lower colony count of anaerobic bacteria also correlated with higher CRP levels. These results indicate that lower abundance of aerobic and anaerobic bacteria may reflect microbiota disruption and disease progression in the CF lung.

  10. [Photosynthetic characteristics of five arbor species in Shenyang urban area].

    PubMed

    Li, Hai-Me; He, Xing-Yuan; Wang, Kui-Ling; Chen, Wei

    2007-08-01

    By using LI-6400 infrared gas analyzer, this paper studied the diurnal and seasonal variations of the photosynthetic rate of main arbor species (Populus alba x P. berolinensis, Salix matsudana, Ulmus pumila, Robinia pseudoacacia and Prunus davidiana) in Shenyang urban area. The correlations between net photosynthetic rate and environmental factors (photosynthetic active radiation, temperature, and stomatal conductance) were assessed by multivariate regression analysis, and related equations were constructed. The results showed that for test arbor species, the diurnal variation of photosynthetic rate mainly presented a single peak curve, and the seasonal variation was in the order of summer > autumn > spring. The major factors affecting the photosynthetic rate were photosynthetic active radiation, stomatal conductance, and intercellular CO2 concentration.

  11. Anaerobic biodegradation of explosives and related compounds by sulfate-reducing and methanogenic bacteria : a review.

    SciTech Connect

    Boopathy, R.; Kulpa, C. F.; Manning, J.; Environmental Research; Univ. of Notre Dame

    1998-01-01

    In recent years, research on microbial degradation of explosives and nitroaromatic compounds has increased. Most studies of the microbial metabolism of nitroaromatic compounds have used aerobic microorganisms. Ecological observations suggest that sulfate-reducing and methanogenic bacteria might metabolize nitroaromatic compounds under anaerobic conditions if appropriate electron donors and electron acceptors are present in the environment, but this ability had not been demonstrated until recently. Few review papers exist, and those deal mainly with aerobic bacterial degradation of explosives; none deals with anaerobic bacteria. In this paper, we review the anaerobic metabolic processes in the degradation of explosives and nitroaromatic compounds under sulfate-reducing and methanogenic conditions.

  12. Controlling the catalytic aerobic oxidation of phenols.

    PubMed

    Esguerra, Kenneth Virgel N; Fall, Yacoub; Petitjean, Laurène; Lumb, Jean-Philip

    2014-05-28

    The oxidation of phenols is the subject of extensive investigation, but there are few catalytic aerobic examples that are chemo- and regioselective. Here we describe conditions for the ortho-oxygenation or oxidative coupling of phenols under copper (Cu)-catalyzed aerobic conditions that give rise to ortho-quinones, biphenols or benzoxepines. We demonstrate that each product class can be accessed selectively by the appropriate choice of Cu(I) salt, amine ligand, desiccant and reaction temperature. In addition, we evaluate the effects of substituents on the phenol and demonstrate their influence on selectivity between ortho-oxygenation and oxidative coupling pathways. These results create an important precedent of catalyst control in the catalytic aerobic oxidation of phenols and set the stage for future development of catalytic systems and mechanistic investigations. PMID:24784319

  13. Drying and recovery of aerobic granules.

    PubMed

    Hu, Jianjun; Zhang, Quanguo; Chen, Yu-You; Lee, Duu-Jong

    2016-10-01

    To dehydrate aerobic granules to bone-dry form was proposed as a promising option for long-term storage of aerobic granules. This study cultivated aerobic granules with high proteins/polysaccharide ratio and then dried these granules using seven protocols: drying at 37°C, 60°C, 4°C, under sunlight, in dark, in a flowing air stream or in concentrated acetone solutions. All dried granules experienced volume shrinkage of over 80% without major structural breakdown. After three recovery batches, although with loss of part of the volatile suspended solids, all dried granules were restored most of their original size and organic matter degradation capabilities. The strains that can survive over the drying and storage periods were also identified. Once the granules were dried, they can be stored over long period of time, with minimal impact yielded by the applied drying protocols. PMID:27392096

  14. Energy Transfer Dynamics in an RC-LH1-PufX Tubular Photosynthetic Membrane

    PubMed Central

    Hsin, Jen; Strümpfer, Johan; Sener, Melih; Qian, Pu; Hunter, C. Neil; Schulten, Klaus

    2010-01-01

    Light absorption and the subsequent transfer of excitation energy are the first two steps of the photosynthetic process, carried out by protein-bound pigments, mainly bacteriochlorophylls (BChls), in photosynthetic bacteria. BChls are anchored in light-harvesting (LH) complexes, such as light-harvesting complex I (LH1), which directly associates with the reaction center (RC), forming the RC-LH1 core complex. In Rhodobacter sphaeroides, RC-LH1 core complexes contain an additional protein, PufX, and assemble into dimeric RC-LH1-PufX core complexes. In the absence of light-harvesting complexes II, the former complexes can aggregate into a helically ordered tubular photosynthetic membrane. We examined the excitation transfer dynamics in a single RC-LH1-PufX core complex dimer using the hierarchical equations of motion for dissipative quantum dynamics that accurately, yet computationally costly, treat the coupling between BChls and their protein environment. A widely employed description, generalized Förster theory, was also used to calculate the transfer rates of the same excitonic system in order to verify the accuracy of this computationally cheap method. Additionally, in light of the structural uncertainties in the Rhodobacter sphaeroides RC-LH1-PufX core complex, geometrical alterations were introduced in the BChl organization. It is shown that the energy transfer dynamics is not affected by the considered changes in the BChl organization, and that generalized Förster theory provides accurate transfer rates. An all-atom model for a tubular photosynthetic membrane is then constructed on the basis of electron microscopy data, and the overall energy transfer properties of this membrane are computed. PMID:21152381

  15. Magnetic bacteria against MIC

    SciTech Connect

    Javaherdashti, R.

    1997-12-01

    In this article, it is suggested to use the sensitivity of magnetotactic bacteria to changes of magnetic field direction and the natural ability of this bacteria in rapid growth during relatively short time intervals against corrosion-enhancing bacteria and especially sulfate-reducing bacteria. If colonies of sulfate-reducing bacteria could be packed among magnetotactic bacteria, then, by applying sufficiently powerful magnetic field (about 0.5 gauss), all of these bacteria (magnetic and non-magnetic) will be oriented towards an Anti-bacteria agent (oxygen or biocide). So, Microbiologically-Influenced Corrosion in the system would be controlled to a large extent.

  16. Back To Bacteria.

    ERIC Educational Resources Information Center

    Flannery, Maura C.

    1997-01-01

    Explores new research about bacteria. Discusses bacterial genomes, archaea, unusual environments, evolution, pathogens, bacterial movement, biofilms, bacteria in the body, and a bacterial obsession. Contains 29 references. (JRH)

  17. Molecular Factors Controlling Photosynthetic Light-Harvesting by Carotenoids

    PubMed Central

    Polívka, Tomáš; Frank, Harry A.

    2010-01-01

    Carotenoids are naturally-occurring pigments that absorb light in the spectral region in which the sun irradiates maximally. These molecules transfer this energy to chlorophylls, initiating the primary photochemical events of photosynthesis. Carotenoids also regulate the flow of energy within the photosynthetic apparatus and protect it from photo-induced damage caused by excess light absorption. To carry out these functions in nature, carotenoids are bound in discrete pigment-protein complexes in close proximity to chlorophylls. A few 3D structures of these carotenoid complexes have been determined by X-ray crystallography. Thus, the stage is set for attempting to correlate the structural information with the spectroscopic properties of carotenoids to understand the molecular mechanism(s) of their function in photosynthetic systems. In this Account, we summarize current spectroscopic data describing the excited state energies and ultrafast dynamics of purified carotenoids in solution and bound in light-harvesting complexes from purple bacteria, marine algae, and green plants. Many of these complexes can be modified using mutagenesis or pigment exchange which facilitates making the correlations between structure and function. We describe the structural and electronic factors controlling the function of carotenoids as energy donors. We also discuss unresolved issues related to the nature of spectroscopically dark excited states, which could play a role in light-harvesting. To illustrate the interplay between structural determinations and spectroscopic investigations that exemplifies work in the field, we describe the spectroscopic properties of four light-harvesting complexes whose structures have been determined to atomic resolution. The first, the LH2 complex from the purple bacterium Rhodopseudomonas acidophila, contains the carotenoid, rhodopin glucoside. The second is the LHCII trimeric complex from higher plants which uses the carotenoids, lutein, neoxanthin

  18. Functional type 2 photosynthetic reaction centers found in the rare bacterial phylum Gemmatimonadetes.

    PubMed

    Zeng, Yonghui; Feng, Fuying; Medová, Hana; Dean, Jason; Koblížek, Michal

    2014-05-27

    Photosynthetic bacteria emerged on Earth more than 3 Gyr ago. To date, despite a long evolutionary history, species containing (bacterio)chlorophyll-based reaction centers have been reported in only 6 out of more than 30 formally described bacterial phyla: Cyanobacteria, Proteobacteria, Chlorobi, Chloroflexi, Firmicutes, and Acidobacteria. Here we describe a bacteriochlorophyll a-producing isolate AP64 that belongs to the poorly characterized phylum Gemmatimonadetes. This red-pigmented semiaerobic strain was isolated from a freshwater lake in the western Gobi Desert. It contains fully functional type 2 (pheophytin-quinone) photosynthetic reaction centers but does not assimilate inorganic carbon, suggesting that it performs a photoheterotrophic lifestyle. Full genome sequencing revealed the presence of a 42.3-kb-long photosynthesis gene cluster (PGC) in its genome. The organization and phylogeny of its photosynthesis genes suggests an ancient acquisition of PGC via horizontal transfer from purple phototrophic bacteria. The data presented here document that Gemmatimonadetes is the seventh bacterial phylum containing (bacterio)chlorophyll-based phototrophic species. To our knowledge, these data provide the first evidence that (bacterio)chlorophyll-based phototrophy can be transferred between distant bacterial phyla, providing new insights into the evolution of bacterial photosynthesis. PMID:24821787

  19. Functional type 2 photosynthetic reaction centers found in the rare bacterial phylum Gemmatimonadetes

    PubMed Central

    Zeng, Yonghui; Feng, Fuying; Medová, Hana; Dean, Jason; Koblížek, Michal

    2014-01-01

    Photosynthetic bacteria emerged on Earth more than 3 Gyr ago. To date, despite a long evolutionary history, species containing (bacterio)chlorophyll-based reaction centers have been reported in only 6 out of more than 30 formally described bacterial phyla: Cyanobacteria, Proteobacteria, Chlorobi, Chloroflexi, Firmicutes, and Acidobacteria. Here we describe a bacteriochlorophyll a-producing isolate AP64 that belongs to the poorly characterized phylum Gemmatimonadetes. This red-pigmented semiaerobic strain was isolated from a freshwater lake in the western Gobi Desert. It contains fully functional type 2 (pheophytin-quinone) photosynthetic reaction centers but does not assimilate inorganic carbon, suggesting that it performs a photoheterotrophic lifestyle. Full genome sequencing revealed the presence of a 42.3-kb–long photosynthesis gene cluster (PGC) in its genome. The organization and phylogeny of its photosynthesis genes suggests an ancient acquisition of PGC via horizontal transfer from purple phototrophic bacteria. The data presented here document that Gemmatimonadetes is the seventh bacterial phylum containing (bacterio)chlorophyll-based phototrophic species. To our knowledge, these data provide the first evidence that (bacterio)chlorophyll-based phototrophy can be transferred between distant bacterial phyla, providing new insights into the evolution of bacterial photosynthesis. PMID:24821787

  20. Denitrification and nitric oxide reduction in an aerobic toluene-treating biofilter

    SciTech Connect

    Plessis, C.A. du; Kinney, K.A.; Schroeder, E.D.; Chang, D.P.Y.; Scow, K.M.

    1998-05-20

    The presence of significant denitrification activity in an aerobic toluene-treating biofilter was demonstrated under batch and flow-through conditions. N{sub 2}O concentrations of 9.2 ppm{sub v} were produced by denitrifying bacteria in the presence of 15% acetylene, in a flow-through system with a bulk gas phase O{sub 2} concentration of >17%. The carbon source for denitrification was not toluene but a byproduct or metabolite of toluene catabolism. Denitrification conditions were successfully used for the reduction of 60 ppm{sub v} nitric oxide to 15 ppm{sub v} at a flow rate of 3 L/min (EBRT of 3 min) in a fully aerated, 17%/v/v O{sub 2} (superficially aerobic) biofilter. Higher NO removal efficiency (97%) was obtained by increasing the toluene supply to the biofilter.

  1. Isolation of an aerobic sulfur oxidizer from the SUP05/Arctic96BD-19 clade.

    PubMed

    Marshall, Katharine T; Morris, Robert M

    2013-02-01

    Bacteria from the uncultured SUP05/Arctic96BD-19 clade of gamma proteobacterial sulfur oxidizers (GSOs) have the genetic potential to oxidize reduced sulfur and fix carbon in the tissues of clams and mussels, in oxygen minimum zones and throughout the deep ocean (>200 m). Here, we report isolation of the first cultured representative from this GSO clade. Closely related cultures were obtained from surface waters in Puget Sound and from the deep chlorophyll maximum in the North Pacific gyre. Pure cultures grow aerobically on natural seawater media, oxidize sulfur, and reach higher final cell densities when glucose and thiosulfate are added to the media. This suggests that aerobic sulfur oxidation enhances organic carbon utilization in the oceans. The first isolate from the SUP05/Arctic96BD-19 clade was given the provisional taxonomic assignment 'Candidatus: Thioglobus singularis', alluding to the clade's known role in sulfur oxidation and the isolate's planktonic lifestyle. PMID:22875135

  2. Temperature response of Antarctic cryptoendolithic photosynthetic microorganisms

    NASA Technical Reports Server (NTRS)

    Ocampo-Friedmann, R.; Meyer, M. A.; Chen, M.; Friedmann, E. I.

    1988-01-01

    Growth responses to temperatures between 12.5 [degrees] C and 25 degrees C were determined for five photosynthetic microorganisms isolated from the Ross Desert cryptoendolithic community. Among eukaryotic algae, two strains of Trebouxia sp. have an upper temperature limit of 20 degrees C, and two strains of Hemichloris antarctica of 25 degrees C. The cyanobacterium Chroococcidiopsis sp., in contrast, grows at temperatures above 25 degrees C. These and earlier studies suggest that the eukaryotic algae of the Antarctic cryptoendolithic community have an upper temperature limit near 25 degrees C.

  3. Engineering cyanobacteria as photosynthetic feedstock factories.

    PubMed

    Hays, Stephanie G; Ducat, Daniel C

    2015-03-01

    Carbohydrate feedstocks are at the root of bioindustrial production and are needed in greater quantities than ever due to increased prioritization of renewable fuels with reduced carbon footprints. Cyanobacteria possess a number of features that make them well suited as an alternative feedstock crop in comparison to traditional terrestrial plant species. Recent advances in genetic engineering, as well as promising preliminary investigations of cyanobacteria in a number of distinct production regimes have illustrated the potential of these aquatic phototrophs as biosynthetic chassis. Further improvements in strain productivities and design, along with enhanced understanding of photosynthetic metabolism in cyanobacteria may pave the way to translate cyanobacterial theoretical potential into realized application.

  4. Microspectroscopy of the photosynthetic compartment of algae.

    PubMed

    Evangelista, Valtere; Frassanito, Anna Maria; Passarelli, Vincenzo; Barsanti, Laura; Gualtieri, Paolo

    2006-01-01

    We performed microspectroscopic evaluation of the pigment composition of the photosynthetic compartments of algae belonging to different taxonomic divisions and higher plants. The feasibility of microspectroscopy for discriminating among species and/or phylogenetic groups was tested on laboratory cultures. Gaussian bands decompositions and a fitting algorithm, together with fourth-derivative transformation of absorbance spectra, provided a reliable discrimination among chlorophylls a, b and c, phycobiliproteins and carotenoids. Comparative analysis of absorption spectra highlighted the evolutionary grouping of the algae into three main lineages in accordance with the most recent endosymbiotic theories.

  5. Temperature response of Antarctic cryptoendolithic photosynthetic microorganisms.

    PubMed

    Ocampo-Friedmann, R; Meyer, M A; Chen, M; Friedmann, E I

    1988-01-01

    Growth responses to temperatures between 12.5 [degrees] C and 25 degrees C were determined for five photosynthetic microorganisms isolated from the Ross Desert cryptoendolithic community. Among eukaryotic algae, two strains of Trebouxia sp. have an upper temperature limit of 20 degrees C, and two strains of Hemichloris antarctica of 25 degrees C. The cyanobacterium Chroococcidiopsis sp., in contrast, grows at temperatures above 25 degrees C. These and earlier studies suggest that the eukaryotic algae of the Antarctic cryptoendolithic community have an upper temperature limit near 25 degrees C.

  6. ANAEROBIC AND AEROBIC TREATMENT OF CHLORINATED ALIPHATIC COMPOUNDS

    EPA Science Inventory

    Biological degradation of 12 chlorinated aliphatic compounds (CACs) was assessed in bench-top reactors and in serum bottle tests. Three continuously mixed daily batch-fed reactor systems were evaluated: anaerobic, aerobic, and sequential-anaerobic-aerobic (sequential). Glucose,...

  7. Parallel pathways of ethoxylated alcohol biodegradation under aerobic conditions.

    PubMed

    Zembrzuska, Joanna; Budnik, Irena; Lukaszewski, Zenon

    2016-07-01

    Non-ionic surfactants (NS) are a major component of the surfactant flux discharged into surface water, and alcohol ethoxylates (AE) are the major component of this flux. Therefore, biodegradation pathways of AE deserve more thorough investigation. The aim of this work was to investigate the stages of biodegradation of homogeneous oxyethylated dodecanol C12E9 having 9 oxyethylene subunits, under aerobic conditions. Enterobacter strain Z3 bacteria were chosen as biodegrading organisms under conditions with C12E9 as the sole source of organic carbon. Bacterial consortia of river water were used in a parallel test as an inoculum for comparison. The LC-MS technique was used to identify the products of biodegradation. Liquid-liquid extraction with ethyl acetate was selected for the isolation of C12E9 and metabolites from the biodegradation broth. The LC-MS/MS technique operating in the multiple reaction monitoring (MRM) mode was used for quantitative determination of C12E9, C12E8, C12E7 and C12E6. Apart from the substrate, the homologues C12E8, C12E7 and C12E6, being metabolites of C12E9 biodegradation by shortening of the oxyethylene chain, as well as intermediate metabolites having a carboxyl end group in the oxyethylene chain (C12E8COOH, C12E7COOH, C12E6COOH and C12E5COOH), were identified. Poly(ethylene glycols) (E) having 9, 8 and 7 oxyethylene subunits were also identified, indicating parallel central fission of C12E9 and its metabolites. Similar results were obtained with river water as inoculum. It is concluded that AE, under aerobic conditions, are biodegraded via two parallel pathways: by central fission with the formation of PEG, and by Ω-oxidation of the oxyethylene chain with the formation of carboxylated AE and subsequent shortening of the oxyethylene chain by a single unit. PMID:27037882

  8. Aerobic degradation of sulfanilic acid using activated sludge.

    PubMed

    Chen, Gang; Cheng, Ka Yu; Ginige, Maneesha P; Kaksonen, Anna H

    2012-01-01

    This paper evaluates the aerobic degradation of sulfanilic acid (SA) by an acclimatized activated sludge. The sludge was enriched for over three months with SA (>500 mg/L) as the sole carbon and energy source and dissolved oxygen (DO, >5mg/L) as the primary electron acceptor. Effects of aeration rate (0-1.74 L/min), DO concentration (0-7 mg/L) and initial SA concentration (104-1085 mg/L) on SA biodegradation were quantified. A modified Haldane substrate inhibition model was used to obtain kinetic parameters of SA biodegradation and oxygen uptake rate (OUR). Positive linear correlations were obtained between OUR and SA degradation rate (R(2)≥ 0.91). Over time, the culture consumed more oxygen per SA degraded, signifying a gradual improvement in SA mineralization (mass ratio of O(2): SA at day 30, 60 and 120 were 0.44, 0.51 and 0.78, respectively). The concomitant release of near stoichiometric quantity of sulphate (3.2 mmol SO(4)(2-) released from 3.3 mmol SA) and the high chemical oxygen demand (COD) removal efficacy (97.1%) indicated that the enriched microbial consortia could drive the overall SA oxidation close to a complete mineralization. In contrast to other pure-culture systems, the ammonium released from the SA oxidation was predominately converted into nitrate, revealing the presence of ammonium-oxidizing bacteria (AOB) in the mixed culture. No apparent inhibitory effect of SA on the nitrification was noted. This work also indicates that aerobic SA biodegradation could be monitored by real-time DO measurement.

  9. [Enhanced Resistance of Pea Plants to Oxidative: Stress Caused by Paraquat during Colonization by Aerobic Methylobacteria].

    PubMed

    Agafonova, N V; Doronina, N Y; Trotsenko, Yu A

    2016-01-01

    The influence of colonization of the pea (Pisum sativum L.) by aerobic methylobacteria of five different species (Methylophilus flavus Ship, Methylobacterium extorquens G10, Methylobacillus arboreus Iva, Methylopila musalis MUSA, Methylopila turkiensis Sidel) on plant resistance to paraquat-induced stresses has been studied. The normal conditions of pea colonization by methylobacteria were characterized by a decrease in the activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidases) and in the concentrations of endogenous H2O2, proline, and malonic dialdehyde, which is a product of lipid peroxidation and indicator of damage to plant cell membranes, and an increase in the activity of the photosynthetic apparatus (the content of chlorophylls a, b and carotenoids). In the presence of paraquat, the colonized plants had higher activities of antioxidant enzymes, stable photosynthetic indices, and a less intensive accumulation of the products of lipid peroxidation as compared to noncolonized plants. Thus, colonization by methylobacteria considerably increased the adaptive protection of pea plants to the paraquat-induced oxidative stress.

  10. [Enhanced Resistance of Pea Plants to Oxidative: Stress Caused by Paraquat during Colonization by Aerobic Methylobacteria].

    PubMed

    Agafonova, N V; Doronina, N Y; Trotsenko, Yu A

    2016-01-01

    The influence of colonization of the pea (Pisum sativum L.) by aerobic methylobacteria of five different species (Methylophilus flavus Ship, Methylobacterium extorquens G10, Methylobacillus arboreus Iva, Methylopila musalis MUSA, Methylopila turkiensis Sidel) on plant resistance to paraquat-induced stresses has been studied. The normal conditions of pea colonization by methylobacteria were characterized by a decrease in the activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidases) and in the concentrations of endogenous H2O2, proline, and malonic dialdehyde, which is a product of lipid peroxidation and indicator of damage to plant cell membranes, and an increase in the activity of the photosynthetic apparatus (the content of chlorophylls a, b and carotenoids). In the presence of paraquat, the colonized plants had higher activities of antioxidant enzymes, stable photosynthetic indices, and a less intensive accumulation of the products of lipid peroxidation as compared to noncolonized plants. Thus, colonization by methylobacteria considerably increased the adaptive protection of pea plants to the paraquat-induced oxidative stress. PMID:27266250

  11. Fate of aerobic bacterial granules with fungal contamination under different organic loading conditions.

    PubMed

    Li, An-jie; Zhang, Tong; Li, Xiao-yan

    2010-01-01

    Aerobic sludge granulation is an attractive new technology for biological wastewater treatment. However, the instability of aerobic granules caused by fungal growth is still one of the main problems encountered in granular bioreactors. In this study, laboratory experiments were conducted to investigate the fate and transformation of aerobic granules under different organic loading conditions. Bacterial granules (2-3mm) in a poor condition with fungi-like black filamentous growth were seeded into two 1L batch reactors. After more than 100d of cultivation, the small seed granules in the two reactors had grown into two different types of large granules (>20mm) with different and unique morphological features. In reactor R1 with a high organic loading rate of 2.0g COD L(-1)d(-1), the black filaments mostly disappeared from the granules, and the dominance of rod-shaped bacteria was recovered. In contrast, at a low loading of 0.5g COD L(-1)d(-1) in reactor R2, the filaments eventually became dominant in the black fungal granules. The bacteria in R1 granules had a unique web-like structure with large pores of a few hundred microm in size, which would allow for effective substrate and oxygen transport into the interior of the granules. DNA-based molecular analysis indicated the evolution of the bacterial population in R1 and that of the eukaryal community in R2. The experimental results suggest that a high loading rate can be an effective means of helping to control fungal bloom, recover bacterial domination and restore the stability of aerobic granules that suffer from fungal contamination.

  12. The Lomagundi Event Marks Post-Pasteur Point Evolution of Aerobic Respiration: A Hypothesis

    NASA Astrophysics Data System (ADS)

    Raub, T. D.; Kirschvink, J. L.; Nash, C. Z.; Raub, T. M.; Kopp, R. E.; Hilburn, I. A.

    2009-05-01

    All published early Earth carbon cycle models assume that aerobic respiration is as ancient as oxygenic photosynthesis. However, aerobic respiration shuts down at oxygen concentrations below the Pasteur Point, (.01 of the present atmospheric level, PAL). As geochemical processes are unable to produce even local oxygen concentrations above .001 PAL, it follows that aerobic respiration could only have evolved after oxygenic photosynthesis, implying a time gap. The evolution of oxygen reductase-utilizing metabolisms presumably would have occupied this interval. During this time the PS-II-generated free oxygen would have been largely unavailable for remineralization of dissolved organic carbon and so would have profoundly shifted the burial ratio of organic/inorganic carbon. We argue that the sequential geological record of the Makganyene (Snowball?) glaciation (2.3-2.22), the exessively aerobic Hekpoort and coeval paleosols, the Lomagundi-Jatuli carbon isotopic excursion (ending 2.056 Ga), and the deposition of concentrated, sedimentary organic carbon (shungite) mark this period of a profoundly unbalanced global carbon cycle. The Kopp et al. (2005) model for oxyatmoversion agrees with phylogenetic evidence for the radiation of cyanobacteria followed closely by the radiation of gram-negative lineages containing magnetotactic bacteria, which depend upon vertical oxygen gradients. These organisms include delta-Proteobacteria from which the mitochondrial ancestor originated. The Precambrian carbon cycle was rebalanced after a series of biological innovations allowed utilization of the high redox potential of free oxygen. Aerobic respiration in mitochondria required the evolution of a unique family of Fe-Cu oxidases, one of many factors contributing to the >210 Myr delay between the Makganyene deglaciation and the end of the Lomagundi-Jatuli event. We speculate that metalliferious fluids associated with the eruption of the Bushveld complex facilitated evolution of these

  13. [Aerobic bacterial flora from the digestive tract of the common vampire bat, Desmodus rotundus (Chiroptera: Phyllostomidae)].

    PubMed

    Chaverri, Gloriana

    2006-09-01

    This study addresses the composition of microbial flora in the vampire bat (Desmodus rotundus) primarily because all available data are outdated, and because of the economical significance of this bat species. Twenty-one bats were collected and their aerobic bacteria documented separately for stomach and intestine. Bacteria were identified through the Analytical Profile Index (API), and results analyzed with the APILAB software. A total of thirty bacterial species were isolated from sixteen females and five males. The most common species were Escherichia coli and Staphylococcus aureus, although other bacteria, such as Acinetobacterjohnsonii, Enterobacter sakazakii, Staphylococcus chromogenes, S. hyicus and S. xylosus were also common. The number of species found in the stomach and intestine was significantly different, and the intestine presented a higher diversity compared to the stomach. This has previously been found in other mammals and it is attributed to a reduction of acidity. Most of the species found in this study are considered normal components of the digestive tract of mammals, although other bacteria common in the skin of mammals and from aquatic environments were found. Bacteria from the skin may invade the vampire's stomach and/or intestine when the bat has contact with its prey, and may suggest that the vampire's feeding habit facilitates the invasion of other microbes not common in its digestive tract. The fact that bacteria from aquatic environments were also found suggests that D. rotundus, as previously found by other researchers, drinks free water when available, and water may be another source of microbial invasion.

  14. Effect of Diquat (1,1′-Ethylene-2,2′-Dipyridylium Dibromide) on the Photosynthetic Growth of Rhodospirillum rubrum

    PubMed Central

    Kaneshiro, Tsuneo; Zweig, Gunter

    1965-01-01

    Diquat (2 × 10-4m) inhibited both aerobic and anaerobic growth of Rhodospirillum rubrum. With photosynthetic cultures, diquat affected the synthesis of bacteriochlorophyll more readily than cell mass (turbidity). Diquat retarded the synthesis of bacteriochlorophyll and some protein more readily than that of other cellular constituents such as ribonucleic acid, deoxyribonucleic acid, and cell mass. With cells deficient in phosphate, diquat inhibited the uptake-conversion of inorganic phosphate completely only when 3-(3,4-dichlorophenyl)-1,1′-dimethyl urea and ascorbate were also present. PMID:5866040

  15. The making of a photosynthetic animal

    PubMed Central

    Rumpho, Mary E.; Pelletreau, Karen N.; Moustafa, Ahmed; Bhattacharya, Debashish

    2011-01-01

    Symbiotic animals containing green photobionts challenge the common perception that only plants are capable of capturing the sun's rays and converting them into biological energy through photoautotrophic CO2 fixation (photosynthesis). ‘Solar-powered’ sacoglossan molluscs, or sea slugs, have taken this type of symbiotic association one step further by solely harboring the photosynthetic organelle, the plastid (=chloroplast). One such sea slug, Elysia chlorotica, lives as a ‘plant’ when provided with only light and air as a result of acquiring plastids during feeding on its algal prey Vaucheria litorea. The captured plastids (kleptoplasts) are retained intracellularly in cells lining the digestive diverticula of the sea slug, a phenomenon sometimes referred to as kleptoplasty. Photosynthesis by the plastids provides E. chlorotica with energy and fixed carbon for its entire lifespan of ∼10 months. The plastids are not transmitted vertically (i.e. are absent in eggs) and do not undergo division in the sea slug. However, de novo protein synthesis continues, including plastid- and nuclear-encoded plastid-targeted proteins, despite the apparent absence of algal nuclei. Here we discuss current data and provide hypotheses to explain how long-term photosynthetic activity is maintained by the kleptoplasts. This fascinating ‘green animal’ provides a unique model to study the evolution of photosynthesis in a multicellular heterotrophic organism. PMID:21177950

  16. Phosphofructokinase Activities in Photosynthetic Organisms 1

    PubMed Central

    Carnal, Nancy Wieland; Black, Clanton C.

    1983-01-01

    A pyrophosphate-dependent phosphofructokinase (PPi-PFK) activity is detectable in extracts of a wide variety of primitive and advanced plants, the Charalean algae, and in the photosynthetic bacterium, Rhodospirillum rubrum. Angiosperms with extractable PPi-PFK activities 4- to 70-fold higher than the respective ATP-PFK activities tend to be succulent and to exhibit CAM. Even though PPi-PFK activity is not detected in crude extracts of some well known CAM plants, e.g. plants in the Crassulaceae, gel filtration of the extract and/or inclusion of the PPi-PFK activator, fructose 2,6-bisphosphate, in the assay reveals that a PPi-PFK activity is present in these species. Fructose 2,6-bisphosphate likewise activates PPi-PFK activities in extracts of C3 and C4 plants. C3 and C4 plant PPi-PFK activities are roughly equivalent to ATP-PFK activities in the same species. PPi-PFK activity is also detected in some bryophytes, lower vascular plants, ferns, and gymnosperms. The Charophytes, advanced algae presumed to be similar to species ancestral to vascular plants, exhibit at least 4-fold higher PPi-PFK than ATP-PFK activities. R. rubrum also exhibits a much higher PPi-PFK activity than ATP-PFK activity. These data indicate that PPi-PFK may serve as an alternate enzyme to ATP-PFK in glycolysis in a wide range of photosynthetic organisms. PMID:16662776

  17. Thermal responses of Symbiodinium photosynthetic carbon assimilation

    NASA Astrophysics Data System (ADS)

    Oakley, Clinton A.; Schmidt, Gregory W.; Hopkinson, Brian M.

    2014-06-01

    The symbiosis between hermatypic corals and their dinoflagellate endosymbionts, genus Symbiodinium, is based on carbon exchange. This symbiosis is disrupted by thermally induced coral bleaching, a stress response in which the coral host expels its algal symbionts as they become physiologically impaired. The disruption of the dissolved inorganic carbon (DIC) supply or the thermal inactivation of Rubisco have been proposed as sites of initial thermal damage that leads to the bleaching response. Symbiodinium possesses a highly unusual Form II ribulose bisphosphate carboxylase/oxygenase (Rubisco), which exhibits a lower CO2:O2 specificity and may be more thermally unstable than the Form I Rubiscos of other algae and land plants. Components of the CO2 concentrating mechanism (CCM), which supplies inorganic carbon for photosynthesis, may also be temperature sensitive. Here, we examine the ability of four cultured Symbiodinium strains to acquire and fix DIC across a temperature gradient. Surprisingly, the half-saturation constant of photosynthesis with respect to DIC concentration ( K P), an index of CCM function, declined with increasing temperature in three of the four strains, indicating a greater potential for photosynthetic carbon acquisition at elevated temperatures. In the fourth strain, there was no effect of temperature on K P. Finding no evidence for thermal inhibition of the CCM, we conclude that CCM components are not likely to be the primary sites of thermal damage. Reduced photosynthetic quantum yields, a hallmark of thermal bleaching, were observed at low DIC concentrations, leaving open the possibility that reduced inorganic carbon availability is involved in bleaching.

  18. Laser remote monitoring of plant photosynthetic activity

    NASA Astrophysics Data System (ADS)

    Barbini, Roberto; Colao, Francesco; Fantoni, Roberta; Palucci, Antonio; Ribezzo, Sergio

    1995-11-01

    Laboratory measurements of laser induced chlorophyll fluorescence kinetics (Kautsky effect) on dark-adapted vegetation targets (maize, pine-tree) have been performed with a lidar fluorosensor by superimposing probe pulses upon an actinic light. The collected induction curves (fast rise and slow decline) have been used to reveal the occurrence of stresses and the damage produced by a pine-tree parasite. A new two-pulse LIF (laser induced fluorescence) methodology has been investigated both theoretically and experimentally, in view of remotely monitoring the plant photosynthetic activity. This technique may yield information upon the in-vivo photosynthetic processes of plants, revealing a possible stress status (nutrients depletion, presence of herbicides, photoinhibition, etc.). The lidar apparatus used contains two laser sources in order to differentially measure the chlorophyll fluorescence by means of a laser pump-and-probe technique. In fact LIF signals in the red chlorophyll band 690 nm may provide in-vivo information upon photosynthesis process in high order plants and algae. Laser pump-and-probe experimental tests, with excitation 355 nm or 532 nm, already detect the presence of herbicides, and the effects of plant exposure to thermal stresses and to low levels of gaseous pollutants. Laser measured fluorescence yields (Y) have been found to be consistent with those obtained by an in-situ fluorimeter (PAM). With proper choices of experimental parameters (pump and probe laser intensities), Y approaches the theoretical value expected for a healthy dark-adapted plant.

  19. Non-photosynthetic pigments as potential biosignatures

    NASA Astrophysics Data System (ADS)

    Schwieterman, E. W.; Cockell, C. S.; Meadows, V. S.

    2014-03-01

    Photosynthetic organisms on Earth produce potentially detectable surface reflectance biosignatures due in part to the spectral location and strength of pigment absorption. However, life on Earth uses pigments for a multitude of purposes other than photosynthesis, including coping with extreme environments. Macroscopic environments exist on Earth where the surface reflectance is significantly altered by a nonphotosynthetic pigment, such as the case of hypersaline lakes and ponds (Oren et al. 1992). Here we explore the nature and potential detectability of non-photosynthetic pigments in disk-averaged planetary observations using a combination of laboratory measurements and archival reflectance spectra, along with simulated broadband photometry and spectra. The in vivo visible reflectance spectra of a cross section of pigmented microorganisms are presented to illustrate the spectral diversity of biologically produced pigments. Synthetic broadband colors are generated to show a significant spread in color space. A 1D radiative transfer model (Meadows & Crisp 1996; Crisp 1997) is used to approximate the spectra of scenarios where pigmented organisms are widespread on planets with Earth-like atmospheres. Broadband colors are revisited to show that colors due to surface reflectivity are not robust to the addition of scattering and absorption effects from the atmosphere. We consider a èbest case' plausible scenario for the detection of nonphotosynthetic pigments by using the Virtual Planetary Laboratory's 3D spectral Earth model (Robinson et al. 2011) to explore the detectability of the surface biosignature produced by pigmented halophiles that are widespread on an Earth-analog planet.

  20. Redox regulation of photosynthetic gene expression

    PubMed Central

    Queval, Guillaume; Foyer, Christine H.

    2012-01-01

    Redox chemistry and redox regulation are central to the operation of photosynthesis and respiration. However, the roles of different oxidants and antioxidants in the regulation of photosynthetic or respiratory gene expression remain poorly understood. Leaf transcriptome profiles of a range of Arabidopsis thaliana genotypes that are deficient in either hydrogen peroxide processing enzymes or in low molecular weight antioxidant were therefore compared to determine how different antioxidant systems that process hydrogen peroxide influence transcripts encoding proteins targeted to the chloroplasts or mitochondria. Less than 10 per cent overlap was observed in the transcriptome patterns of leaves that are deficient in either photorespiratory (catalase (cat)2) or chloroplastic (thylakoid ascorbate peroxidase (tapx)) hydrogen peroxide processing. Transcripts encoding photosystem II (PSII) repair cycle components were lower in glutathione-deficient leaves, as were the thylakoid NAD(P)H (nicotinamide adenine dinucleotide (phosphate)) dehydrogenases (NDH) mRNAs. Some thylakoid NDH mRNAs were also less abundant in tAPX-deficient and ascorbate-deficient leaves. Transcripts encoding the external and internal respiratory NDHs were increased by low glutathione and low ascorbate. Regulation of transcripts encoding specific components of the photosynthetic and respiratory electron transport chains by hydrogen peroxide, ascorbate and glutathione may serve to balance non-cyclic and cyclic electron flow pathways in relation to oxidant production and reductant availability. PMID:23148274

  1. Respiratory processes in non-photosynthetic plastids

    PubMed Central

    Renato, Marta; Boronat, Albert; Azcón-Bieto, Joaquín

    2015-01-01

    Chlororespiration is a respiratory process located in chloroplast thylakoids which consists in an electron transport chain from NAD(P)H to oxygen. This respiratory chain involves the NAD(P)H dehydrogenase complex, the plastoquinone pool and the plastid terminal oxidase (PTOX), and it probably acts as a safety valve to prevent the over-reduction of the photosynthetic machinery in stress conditions. The existence of a similar respiratory activity in non-photosynthetic plastids has been less studied. Recently, it has been reported that tomato fruit chromoplasts present an oxygen consumption activity linked to ATP synthesis. Etioplasts and amyloplasts contain several electron carriers and some subunits of the ATP synthase, so they could harbor a similar respiratory process. This review provides an update on the study about respiratory processes in chromoplasts, identifying the major gaps that need to be addressed in future research. It also reviews the proteomic data of etioplasts and amyloplasts, which suggest the presence of a respiratory electron transport chain in these plastids. PMID:26236317

  2. Photosynthetic water splitting: 1987 annual report

    SciTech Connect

    Greenbaum, E.

    1988-01-01

    This document is an annual report of photosynthetic water splitting for the production of hydrogen and oxygen. Unicellular green algae are capable of evolving molecular hydrogen in the presence of carbon dioxide. Controlling factors that determine hydrogen evolution are either temperature or light intensity. Also, mutants of the green alga Chlamydomonas are capable of evolving hydrogen in the presence of carbon dioxide. The significance of these discoveries is that the presence of carbon dioxide (or bicarbonate) is a key factor in determining the activity of the Photosystem II water splitting complex. Second, a new advance in oxygen sensor technology has been made that, for the first time, allows the absolute measurement of photosynthetically evolved oxygen from a single colony of microalgae growing on a solidified agar medium. The key aspect of this electrochemical sensor is the utilization of ultra-pure potassium hydroxide as the electrolyte and a recognition of the role that electrolyte impurities play in contributing to base line noise. 9 refs., 8 figs., 2 tabs.

  3. Micromachined microbial and photosynthetic fuel cells

    NASA Astrophysics Data System (ADS)

    Chiao, Mu; Lam, Kien B.; Lin, Liwei

    2006-12-01

    This paper presents two types of fuel cells: a miniature microbial fuel cell (µMFC) and a miniature photosynthetic electrochemical cell (µPEC). A bulk micromachining process is used to fabricate the fuel cells, and the prototype has an active proton exchange membrane area of 1 cm2. Two different micro-organisms are used as biocatalysts in the anode: (1) Saccharomyces cerevisiae (baker's yeast) is used to catalyze glucose and (2) Phylum Cyanophyta (blue-green algae) is used to produce electrons by a photosynthetic reaction under light. In the dark, the µPEC continues to generate power using the glucose produced under light. In the cathode, potassium ferricyanide is used to accept electrons and electric power is produced by the overall redox reactions. The bio-electrical responses of µMFCs and µPECs are characterized with the open-circuit potential measured at an average value of 300-500 mV. Under a 10 ohm load, the power density is measured as 2.3 nW cm-2 and 0.04 nW cm-2 for µMFCs and µPECs, respectively.

  4. Respiratory processes in non-photosynthetic plastids.

    PubMed

    Renato, Marta; Boronat, Albert; Azcón-Bieto, Joaquín

    2015-01-01

    Chlororespiration is a respiratory process located in chloroplast thylakoids which consists in an electron transport chain from NAD(P)H to oxygen. This respiratory chain involves the NAD(P)H dehydrogenase complex, the plastoquinone pool and the plastid terminal oxidase (PTOX), and it probably acts as a safety valve to prevent the over-reduction of the photosynthetic machinery in stress conditions. The existence of a similar respiratory activity in non-photosynthetic plastids has been less studied. Recently, it has been reported that tomato fruit chromoplasts present an oxygen consumption activity linked to ATP synthesis. Etioplasts and amyloplasts contain several electron carriers and some subunits of the ATP synthase, so they could harbor a similar respiratory process. This review provides an update on the study about respiratory processes in chromoplasts, identifying the major gaps that need to be addressed in future research. It also reviews the proteomic data of etioplasts and amyloplasts, which suggest the presence of a respiratory electron transport chain in these plastids.

  5. Peroxide-Sensing Transcriptional Regulators in Bacteria

    PubMed Central

    Mongkolsuk, Skorn

    2012-01-01

    The ability to maintain intracellular concentrations of toxic reactive oxygen species (ROS) within safe limits is essential for all aerobic life forms. In bacteria, as well as other organisms, ROS are produced during the normal course of aerobic metabolism, necessitating the constitutive expression of ROS scavenging systems. However, bacteria can also experience transient high-level exposure to ROS derived either from external sources, such as the host defense response, or as a secondary effect of other seemingly unrelated environmental stresses. Consequently, transcriptional regulators have evolved to sense the levels of ROS and coordinate the appropriate oxidative stress response. Three well-studied examples of these are the peroxide responsive regulators OxyR, PerR, and OhrR. OxyR and PerR are sensors of primarily H2O2, while OhrR senses organic peroxide (ROOH) and sodium hypochlorite (NaOCl). OxyR and OhrR sense oxidants by means of the reversible oxidation of specific cysteine residues. In contrast, PerR senses H2O2 via the Fe-catalyzed oxidation of histidine residues. These transcription regulators also influence complex biological phenomena, such as biofilm formation, the evasion of host immune responses, and antibiotic resistance via the direct regulation of specific proteins. PMID:22797754

  6. Aerobic Exercise Prescription for Rheumatoid Arthritics.

    ERIC Educational Resources Information Center

    Evans, Blanche W.; Williams, Hilda L.

    The use of exercise as a general treatment for rheumatoid arthritics (RA) has included range of motion, muscular strength, water exercise and rest therapy while virtually ignoring possible benefits of aerobic exercise. The purposes of this project were to examine the guidelines for exercise prescription in relation to this special population and…

  7. Response of aerobic rice to Piriformospora indica.

    PubMed

    Das, Joy; Ramesh, K V; Maithri, U; Mutangana, D; Suresh, C K

    2014-03-01

    Rice cultivation under aerobic condition not only saves water but also opens up a splendid scope for effective application of beneficial root symbionts in rice crop unlike conventional puddled rice cultivation where water logged condition acts as constraint for easy proliferation of various beneficial soil microorganisms like arbuscular mycorrhizal (AM) fungi. Keeping these in view, an in silico investigation were carried out to explore the interaction of hydrogen phosphate with phosphate transporter protein (PTP) from P. indica. This was followed by greenhouse investigation to study the response of aerobic rice to Glomusfasciculatum, a conventional P biofertilizer and P. indica, an alternative to AM fungi. Computational studies using ClustalW tool revealed several conserved motifs between the phosphate transporters from Piriformospora indica and 8 other Glomus species. The 3D model of PTP from P. indica resembling "Mayan temple" was successfully docked onto hydrogen phosphate, indicating the affinity of this protein for inorganic phosphorus. Greenhouse studies revealed inoculation of aerobic rice either with P. indica, G. fasciculatum or both significantly enhanced the plant growth, biomass and yield with higher NPK, chlorophyll and sugar compared to uninoculated ones, P. indica inoculated plants being superior. A significantly enhanced activity of acid phosphatase and alkaline phosphatase were noticed in the rhizosphere soil of rice plants inoculated either with P. indica, G. fasciculatum or both, contributing to higher P uptake. Further, inoculation of aerobic rice plants with P. indica proved to be a better choice as a potential biofertilizer over mycorrhiza. PMID:24669667

  8. AEROBIC DENITRIFICATION: IMPLICATIONS FOR NITROGEN FATE MODELING

    EPA Science Inventory

    In the Mississippi, as well as most nitrogen-degraded rivers and streams, NO3- is the dominant N species and therefore understanding its biogeochemical behavior is critical for accurate nitrogen fate modeling. To our knowledge this is the first work to report aerobic denitrificat...

  9. Media for the aerobic growth of campylobacter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of agar and sodium bicarbonate (NaHCO3) concentration on aerobic growth of Campylobacter in a fumarate-pyruvate medium was examined. The broth medium was supplemented with 0.0 to 0.2% agar and inoculated with 106 CFU/ml of Campylobacter coli 33559, Campylobacter fetus 27349, Campylobacter...

  10. Reflections on Psychotherapy and Aerobic Exercise.

    ERIC Educational Resources Information Center

    Silverman, Wade

    This document provides a series of reflections by a practicing psychologist on the uses of aerobic workouts in psychotherapy. Two case histories are cited to illustrate the contention that the mode of exercise, rather than simply its presence or absence, is the significant indicator of a patient's emotional well-being or psychopathology. The first…

  11. A proposed aerobic granules size development scheme for aerobic granulation process.

    PubMed

    Dahalan, Farrah Aini; Abdullah, Norhayati; Yuzir, Ali; Olsson, Gustaf; Salmiati; Hamdzah, Myzairah; Din, Mohd Fadhil Mohd; Ahmad, Siti Aqlima; Khalil, Khalilah Abdul; Anuar, Aznah Nor; Noor, Zainura Zainon; Ujang, Zaini

    2015-04-01

    Aerobic granulation is increasingly used in wastewater treatment due to its unique physical properties and microbial functionalities. Granule size defines the physical properties of granules based on biomass accumulation. This study aims to determine the profile of size development under two physicochemical conditions. Two identical bioreactors namely Rnp and Rp were operated under non-phototrophic and phototrophic conditions, respectively. An illustrative scheme was developed to comprehend the mechanism of size development that delineates the granular size throughout the granulation. Observations on granules' size variation have shown that activated sludge revolutionised into the form of aerobic granules through the increase of biomass concentration in bioreactors which also determined the changes of granule size. Both reactors demonstrated that size transformed in a similar trend when tested with and without illumination. Thus, different types of aerobic granules may increase in size in the same way as recommended in the aerobic granule size development scheme.

  12. The inhibition of Clostridium botulinum type C by other bacteria in wetland sediments

    USGS Publications Warehouse

    Sandler, Renee J.; Rocke, Tonie E.; Yuill, Thomas M.

    1998-01-01

    Bacteria with inhibitory activity against Clostridium botulinum type C were isolated from 32% of sediment samples (n = 1600) collected from 10 marshes in a northern California wetland over a 12 mo period. Aerobic and anaerobic bacteria with inhibitory activity were isolated from 12% and 23% of the samples, respectively. Bacteria with inhibitory activity were isolated from all 10 study sites and throughout the year. This study demonstrates that bacteria with inhibitory activity against C. botulinum type C occur naturally in wetland sediments.

  13. Ventilation and Speech Characteristics during Submaximal Aerobic Exercise

    ERIC Educational Resources Information Center

    Baker, Susan E.; Hipp, Jenny; Alessio, Helaine

    2008-01-01

    Purpose: This study examined alterations in ventilation and speech characteristics as well as perceived dyspnea during submaximal aerobic exercise tasks. Method: Twelve healthy participants completed aerobic exercise-only and simultaneous speaking and aerobic exercise tasks at 50% and 75% of their maximum oxygen consumption (VO[subscript 2] max).…

  14. Adolescents' Interest and Performances in Aerobic Fitness Testing

    ERIC Educational Resources Information Center

    Zhu, Xihe; Chen, Senlin; Parrott, James

    2014-01-01

    This study examined adolescents' interest in aerobic fitness testing and its relation to the test performances. Adolescents (N = 356) from three middle schools participated in the study. The participants took two aerobic fitness tests: the Progressive Aerobic Cardiovascular Endurance Run (PACER) and One-Mile Run (1MR) with a two-day interval,…

  15. Sulfur cycling and metabolism of phototrophic and filamentous sulfur bacteria

    NASA Technical Reports Server (NTRS)

    Guerrero, R.; Brune, D.; Poplawski, R.; Schmidt, T. M.

    1985-01-01

    Phototrophic sulfur bacteria taken from different habitate (Alum Rock State Park, Palo Alto salt marsh, and Big Soda Lake) were grown on selective media, characterized by morphological and pigment analysis, and compared with bacteria maintained in pure culture. A study was made of the anaerobic reduction of intracellular sulfur globules by a phototrophic sulfur bacterium (Chromatium vinosum) and a filamentous aerobic sulfur bacterium (Beggiatoa alba). Buoyant densities of different bacteria were measured in Percoll gradients. This method was also used to separate different chlorobia in mixed cultures and to assess the relative homogeneity of cultures taken directly or enriched from natural samples (including the purple bacterial layer found at a depth of 20 meters at Big Soda Lake.) Interactions between sulfide oxidizing bacteria were studied.

  16. Tetracycline as a selector for resistant bacteria in activated sludge.

    PubMed

    Kim, Sungpyo; Jensen, James N; Aga, Diana S; Weber, A Scott

    2007-01-01

    Tetracycline, one of the most widely used antibiotics, is excreted into wastewater after consumption by humans and animals. The focus of this research was to evaluate the fate of tetracycline resistant bacteria in the activated sludge process as a function of tetracycline loading. The studies were conducted with aerobic biological sequencing batch reactors (SBRs). When comparing 250 microgl(-1) tetracycline fed SBRs with parallel SBRs having a background influent wastewater tetracycline concentration of approximately 1 microgl(-1), tetracycline fed reactors were found to have increased concentrations and production rates of tetracycline resistant bacteria, higher net growth rates of resistant bacteria, and higher percentages of tetracycline resistant bacteria, which were amplified by increase in organic loading and growth rates.

  17. A Carbon-Neutral Photosynthetic Microbial Fuel Cell Powered by Microcystis aeruginosa.

    PubMed

    Ma, Meirong; Cao, Limin; Chen, Li; Ying, Xiaofang; Deng, Zongwu

    2015-07-01

    A photosynthetic microbial fuel cell (m-PMFC) is developed for generating electricity by harnessing solar energy using Microcystis aeruginosa. In this m-PMFC, commensal bacteria can consume the nutrients that Microcystis aeruginosa produces to generate electricity so that no net CO₂production occurs. A b-MFC is constructed to confirm the role of commensal bacteria in electric generation. An s-PMFC is constructed to confirm the contribution of Microcystis aeruginosa as substrates. The power outputs of m-PMFCs exhibit no significant difference in terms of different inoculation amount of Microcystis aeruginosa or light/dark cycles. The power density of m-PMFC exhibits similar response to bubbling of N₂and O₂as that of b-MFC, as confirmed by cyclic voltammetry analysis of m-PMFC and b-MFC. Scanning electron microscope images demonstrate that the biofilm of m-PMFC consists mainly of commensal bacteria. These results suggest that commensal bacteria act as the main biocatalysts and Microcystis aeruginosa as the anode substrates in the m-PMFC.

  18. Selecting anti-microbial treatment of aerobic vaginitis.

    PubMed

    Donders, Gilbert G G; Ruban, Katerina; Bellen, Gert

    2015-05-01

    Aerobic vaginitis (AV) is a vaginal infectious condition which is often confused with bacterial vaginosis (BV) or with the intermediate microflora as diagnosed by Nugent's method to detect BV on Gram-stained specimens. However, although both conditions reflect a state of lactobacillary disruption in the vagina, leading to an increase in pH, BV and AV differ profoundly. While BV is a noninflammatory condition composed of a multiplex array of different anaerobic bacteria in high quantities, AV is rather sparely populated by one or two enteric commensal flora bacteria, like Streptococcus agalactiae, Staphylocuccus aureus, or Escherichia coli. AV is typically marked by either an increased inflammatory response or by prominent signs of epithelial atrophy or both. The latter condition, if severe, is also called desquamative inflammatory vaginitis. As AV is per exclusionem diagnosed by wet mount microscopy, it is a mistake to treat just vaginal culture results. Vaginal cultures only serve as follow-up data in clinical research projects and are at most used in clinical practice to confirm the diagnosis or exclude Candida infection. AV requires treatment based on microscopy findings and a combined local treatment with any of the following which may yield the best results: antibiotic (infectious component), steroids (inflammatory component), and/or estrogen (atrophy component). In cases with Candida present on microscopy or culture, antifungals must be tried first in order to see if other treatment is still needed. Vaginal rinsing with povidone iodine can provide rapid relief of symptoms but does not provide long-term reduction of bacterial loads. Local antibiotics most suitable are preferably non-absorbed and broad spectrum, especially those covering enteric gram-positive and gram-negative aerobes, like kanamycin. To achieve rapid and short-term improvement of severe symptoms, oral therapy with amoxyclav or moxifloxacin can be used, especially in deep dermal vulvitis and

  19. Evolution of Molybdenum Nitrogenase during the Transition from Anaerobic to Aerobic Metabolism

    PubMed Central

    Boyd, Eric S.; Costas, Amaya M. Garcia; Hamilton, Trinity L.; Mus, Florence

    2015-01-01

    ABSTRACT Molybdenum nitrogenase (Nif), which catalyzes the reduction of dinitrogen to ammonium, has modulated the availability of fixed nitrogen in the biosphere since early in Earth's history. Phylogenetic evidence indicates that oxygen (O2)-sensitive Nif emerged in an anaerobic archaeon and later diversified into an aerobic bacterium. Aerobic bacteria that fix N2 have adapted a number of strategies to protect Nif from inactivation by O2, including spatial and temporal segregation of Nif from O2 and respiratory consumption of O2. Here we report the complement of Nif-encoding genes in 189 diazotrophic genomes. We show that the evolution of Nif during the transition from anaerobic to aerobic metabolism was accompanied by both gene recruitment and loss, resulting in a substantial increase in the number of nif genes. While the observed increase in the number of nif genes and their phylogenetic distribution are strongly correlated with adaptation to utilize O2 in metabolism, the increase is not correlated with any of the known O2 protection mechanisms. Rather, gene recruitment appears to have been in response to selective pressure to optimize Nif synthesis to meet fixed N demands associated with aerobic productivity and to more efficiently regulate Nif under oxic conditions that favor protein turnover. Consistent with this hypothesis, the transition of Nif from anoxic to oxic environments is associated with a shift from posttranslational regulation in anaerobes to transcriptional regulation in obligate aerobes and facultative anaerobes. Given that fixed nitrogen typically limits ecosystem productivity, our observations further underscore the dynamic interplay between the evolution of Earth's oxygen, nitrogen, and carbon biogeochemical cycles. IMPORTANCE Molybdenum nitrogenase (Nif), which catalyzes the reduction of dinitrogen to ammonium, has modulated the availability of fixed nitrogen in the biosphere since early in Earth's history. Nif emerged in an anaerobe and

  20. Determination of photosynthetic parameters in two seawater-tolerant vegetables

    NASA Astrophysics Data System (ADS)

    Qiu, Nianwei; Zhou, Feng; Liu, Qian; Zhao, Wenqian

    2016-03-01

    It is difficult to determine the photosynthetic parameters of non-flat leaves/green stems using photosynthetic instruments, due to the unusual morphology of both organs, especially for Suaeda salsa and Salicornia bigelovii as two seawater-tolerant vegetables. To solve the problem, we developed a simple, practical, and effective method to measure and calculate the photosynthetic parameters (such as P N, g s, E) based on unit fresh mass, instead of leaf area. The light/CO2/temperature response curves of the plants can also be measured by this method. This new method is more effective, stable, and reliable than conventional methods for plants with non-flat leaves. In addition, the relative notes on measurements and calculation of photosynthetic parameters were discussed in this paper. This method solves technical difficulties in photosynthetic parameter determination of the two seawater-tolerant vegetables and similar plants.