An In vitro Model for Bacterial Growth on Human Stratum Corneum.

PubMed

van der Krieken, Danique A; Ederveen, Thomas H A; van Hijum, Sacha A F T; Jansen, Patrick A M; Melchers, Willem J G; Scheepers, Paul T J; Schalkwijk, Joost; Zeeuwen, Patrick L J M

2016-11-02

The diversity and dynamics of the skin microbiome in health and disease have been studied recently, but adequate model systems to study skin microbiotas in vitro are largely lacking. We developed an in vitro system that mimics human stratum corneum, using human callus as substrate and nutrient source for bacterial growth. The growth of several commensal and pathogenic bacterial strains was measured for up to one week by counting colony-forming units or by quantitative PCR with strain-specific primers. Human skin pathogens were found to survive amidst a minimal microbiome consisting of 2 major skin commensals: Staphylococcus epidermidis and Propionibacterium acnes. In addition, complete microbiomes, taken from the backs of healthy volunteers, were inoculated and maintained using this system. This model may enable the modulation of skin microbiomes in vitro and allow testing of pathogens, biological agents and antibiotics in a medium-throughput format.

Measuring bacterial growth by refractive index tapered fiber optic biosensor.

PubMed

Zibaii, Mohammad Ismail; Kazemi, Alireza; Latifi, Hamid; Azar, Mahmoud Karimi; Hosseini, Seyed Masoud; Ghezelaiagh, Mohammad Hossein

2010-12-02

A single-mode tapered fiber optic biosensor was utilized for real-time monitoring of the Escherichia coli (E. coli K-12) growth in an aqueous medium. The applied fiber tapers were fabricated using heat-pulling method with waist diameter and length of 6-7μm and 3mm, respectively. The bacteria were immobilized on the tapered surface using Poly-l-Lysine. By providing the proper condition, bacterial population growth on the tapered surface increases the average surface density of the cells and consequently the refractive index (RI) of the tapered region would increase. The adsorption of the cells on the tapered fiber leads to changes in the optical characteristics of the taper. This affects the evanescent field leading to changes in optical throughput. The bacterial growth rate was monitored at room temperature by transmission of a 1558.17nm distributed feedback (DFB) laser through the tapered fiber. At the same condition, after determining the growth rate of E. coli by means of colony counting method, we compared the results with that obtained from the fiber sensor measurements. This novel sensing method, promises new application such as rapid analysis of the presence of bacteria. Copyright © 2010 Elsevier B.V. All rights reserved.

A uniform bacterial growth potential assay for different water types.

PubMed

Farhat, Nadia; Hammes, Frederik; Prest, Emmanuelle; Vrouwenvelder, Johannes

2018-06-06

The bacterial growth potential is important to understand and manage bacterial regrowth-related water quality concerns. Bacterial growth potential depends on growth promoting/limiting compounds, therefore, nutrient availability is the key factor governing bacterial growth potential. Selecting proper tools for bacterial growth measurement is essential for routine implementation of the growth potential measurement. This study proposes a growth potential assay that is universal and can be used for different water types and soil extract without restrictions of pure culture or cultivability of the bacterial strain. The proposed assay measures the sample bacterial growth potential by using the indigenous community as inocula. Flow cytometry (FCM) and adenosine tri-phosphate (ATP) were used to evaluate the growth potential of six different microbial communities indigenous to the sample being analyzed, with increasing carbon concentrations. Bottled mineral water, non-chlorinated tap water, seawater, river water, wastewater effluent and a soil organic carbon extract were analyzed. Results showed that indigenous bacterial communities followed normal batch growth kinetics when grown on naturally present organic carbon. Indigenous bacterial growth could detect spiked organic carbon concentrations as low as 10 μg/L. The indigenous community in all samples responded proportionally to the increase in acetate-carbon and proportional growth could be measured with both FCM and ATP. Bacterial growth was proportional to the carbon concentration but not the same proportion factor for the different water samples tested. The effect of inoculating the same water with different indigenous microbial communities on the growth potential was also examined. The FCM results showed that the highest increase in total bacterial cell concentration was obtained with bacteria indigenous to the water sample. The growth potential assay using indigenous bacterial community revealed consistent results

Bacterial Growth on Chitosan-Coated Polypropylene Textile

PubMed Central

Erben, D.; Hola, V.; Jaros, J.; Rahel, J.

2012-01-01

Biofouling is a problem common in all systems where microorganisms and aqueous environment meet. Prevention of biofouling is therefore important in many industrial processes. The aim of this study was to develop a method to evaluate the ability of material coating to inhibit biofilm formation. Chitosan-coated polypropylene nonwoven textile was prepared using dielectric barrier discharge plasma activation. Resistance of the textile to biofouling was then tested. First, the textile was submerged into a growth medium inoculated with green fluorescein protein labelled Pseudomonas aeruginosa. After overnight incubation at 33°C, the textile was observed using confocal laser scanning microscopy for bacterial enumeration and biofilm structure characterisation. In the second stage, the textile was used as a filter medium for prefiltered river water, and the pressure development on the in-flow side was measured to quantify the overall level of biofouling. In both cases, nontreated textile samples were used as a control. The results indicate that the chitosan coating exhibits antibacterial properties. The developed method is applicable for the evaluation of the ability to inhibit biofilm formation. PMID:23724330

Analysis of bacterial growth by UV/Vis spectroscopy and laser reflectometry

NASA Astrophysics Data System (ADS)

Peña-Gomar, Mary Carmen; Viramontes-Gamboa, Gonzalo; Peña-Gomar, Grethel; Ortiz Gutiérrez, Mauricio; Hernández Ramírez, Mariano

2012-10-01

This work presents a preliminary study on an experimental analysis of the lactobacillus bacterial growth in liquid medium with and without the presence of silver nanoparticles. The study aims to quantify the bactericidal effect of nanoparticles. Quantification of bacterial growth at different times was analyzed by spectroscopy UV/visible and laser reflectometry near the critical angle. From these two techniques the best results were obtained by spectroscopy, showing that as the concentration of silver nanoparticles increases, it inhibits the growth of bacteria, it only grows 63% of the population. Regarding Laser Reflectometry, the variation of reflectance near the critical angle is measured in real time. The observed results at short times are reasonable, since they indicate a gradual growth of the bacteria and the stabilization stage of the population. But at long time, the observed results show abrupt changes caused by temperature effects. The bacteria were isolated from samples taken from commercial yougurth, and cultured in MRS broth at pH 6.5, and controlled with citric acid and constant temperature of 32 °C. Separately, silver nanoparticles were synthesized at 3 °C from aqueous solutions of 1.0 mM silver nitrate and chemically reduced with sodium borohydride to 2.0 mM, with magnetic stirring.

Procedures involving lipid media for detection of bacterial contamination in breweries.

PubMed

Van Vuuren, H J; Louw, H A; Loos, M A; Meisel, R

1977-02-01

The liquid equivalent of universal beer agar, designated universal beer liquid medium, and its beer-free equivalent, universal liquid medium (UL), were equally effective in demonstrating bacterial contamination in 120 of 200 samples from different stages of commercial brewing process. Growth of the contaminants after 3 days was consistently more luxuriant in the UL medium. A yeast-water substrate medium failed to reveal many contaminants detected with UL in 392 samples from three breweries and revealed only a few not detected with UL. The use of UL and a lactose-peptone medium, with microscope examination of the media for bacterial growth, permitted detection of 93% of the known contaminants compared to 87%, detected with UL alone; this combination or universal beer liquid medium plus lactose-peptone medium can therefore be recommended for the detection of bacterial contaminants in brewery samples. Bacterial contamination of pitching yeasts appeared to be a particular problem in the breweries investigated.

Coupled effects of chemotaxis and growth on traveling bacterial waves.

PubMed

Yan, Zhifeng; Bouwer, Edward J; Hilpert, Markus

2014-08-01

Traveling bacterial waves are capable of improving contaminant remediation in the subsurface. It is fairly well understood how bacterial chemotaxis and growth separately affect the formation and propagation of such waves. However, their interaction is not well understood. We therefore perform a modeling study to investigate the coupled effects of chemotaxis and growth on bacterial migration, and examine their effects on contaminant remediation. We study the waves by using different initial electron acceptor concentrations for different bacteria and substrate systems. Three types of traveling waves can occur: a chemotactic wave due to the biased movement of chemotactic bacteria resulting from metabolism-generated substrate concentration gradients; a growth/decay/motility wave due to a dynamic equilibrium between bacterial growth, decay and random motility; and an integrated wave due to the interaction between bacterial chemotaxis and growth. Chemotaxis hardly enhances the bacterial propagation if it is too weak to form a chemotactic wave or its wave speed is less than half of the growth/decay/motility wave speed. However, chemotaxis significantly accelerates bacterial propagation once its wave speed exceeds the growth/decay/motility wave speed. When convection occurs, it speeds up the growth/decay/motility wave but slows down or even eliminates the chemotactic wave due to the dispersion. Bacterial survival proves particularly important for bacterial propagation. Therefore we develop a conceptual model to estimate the speed of growth/decay/motility waves. Copyright © 2014 Elsevier B.V. All rights reserved.

A Computer Simulation of Bacterial Growth During Food-Processing

DTIC Science & Technology

1974-11-01

1 AD A TECHNICAL REPORT A COMPUTER SIMULATION OF BACTERIAL GROWTH DURING FOOD PROCESSING =r= by Edward W. Ross, Jr. Approved for public...COMPUTER SIMULATION OF BACTERIAL GROWTH DURING FOOD - PROCESSING Edward W. Ross, Jr. Army Natick Laboratories Natick, Massachusetts Novembe...CATALOG NUMBER 4. TITLE fand SubtKUJ "A Computer Sinulatlon of Bacterial Growth During Food - Processing " 5. TYPE OF REPORT A PERIOD COVERED 6

Diagnostic medium containing inositol, urea, and caffeic acid for selective growth of Cryptococcus neoformans.

PubMed Central

Healy, M E; Dillavou, C L; Taylor, G E

1977-01-01

An agar medium containing inositol and urea as sole carbon and nitrogen sources, caffeic acid and ferric citrate as agents for the selective pigmentation of Cryptococcus neoformans, gentamicin as a broad-spectrum bacterial antibiotic, and yeast nitrogen base without amino acids and ammonium sulfate (Difco) was tested against 137 clinical isolates, 4 survey specimens, and 11 ATCC yeast and yeast-like strains. All 28 strains of C. neoformans showed heavy growth and dark brown pigmentation after 36 h. All other tested species of Cryptococcus showed heavy growth after 36 h but only light brown pigmentation after 48 h. No growth was observed in any tested strains of Geotrichum, Pityrosporum, Rhodotorula, Saccharomyces, and Torulopsis. Only the Cryptococcus-like Candida humicola grew of the 8 species and 62 strains of Candida tested. Six of 15 strains of Trichosporon cutaneum and 1 of 2 strains of Trichosporon pullulans showed moderate growth after 48 h. Very different colonial and microscopic morphology and/or the absence of brown pigmentation easily differentiated these strains of T. cutaneum, T. pullulans, and C. humicola from C. neoformans. The growth- and pigmentation-providing characteristics of the medium were unaffected by 2 h of exposure to 254 nm of ultraviolet light. PMID:334795

Aerobic biological treatment of low-strength synthetic wastewater in membrane-coupled bioreactors: the structure and function of bacterial enrichment cultures as the net growth rate approaches zero.

PubMed

Chen, Ruoyu; LaPara, Timothy M

2006-01-01

The goal of the current research was to determine if the stringent nutrient limitation imposed by membrane-coupled bioreactors (MBRs) could be used to force mixed bacterial communities to exhibit a zero net growth rate over an extended time period. Mechanistically, this zero net growth rate could be achieved when the amount of energy available for growth is balanced by the maintenance requirements of the bacterial community. Bench-scale MBRs were fed synthetic feed medium containing gelatin as the major organic substrate. Biomass concentrations initially increased rapidly, but subsequently declined until an asymptote was reached. Leucine aminopeptidase activities concomitantly increased by at least 10-fold, suggesting that bacterial catabolic activity remained high even while growth rates became negligible. In contrast, alpha-glucosidase and heptanoate esterase activities decreased, indicating that the bacterial community specifically adapted to the carbon source in the feed medium. Bacterial community analysis by denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments (PCR-DGGE) suggested that the bacterial community structure completely changed from the beginning to the end of each MBR. Excision and nucleotide sequence analysis of prominent PCR-DGGE bands suggested that many of the dominant populations were similar to novel bacterial strains that were previously uncultivated or recently cultivated during studies specifically targeting these novel populations. This research demonstrates that MBRs have substantial practical applications for biological wastewater treatment; in addition, MBRs are a useful tool to study the ecology of slow-growing bacteria.

High density growth of T7 expression strains with auto-induction option

DOEpatents

Studier, F. William

2010-07-20

A bacterial growth medium for promoting auto-induction of transcription of cloned DNA in cultures of bacterial cells grown batchwise is disclosed. The transcription is under the control of a lac repressor. Also disclosed is a bacterial growth medium for improving the production of a selenomethionine-containing protein or polypeptide in a bacterial cell, the protein or polypeptide being produced by recombinant DNA techniques from a lac or T7lac promoter, the bacterial cell encoding a vitamin B12-dependent homocysteine methylase. Finally, disclosed is a bacterial growth medium for suppressing auto-induction of expression in cultures of bacterial cells grown batchwise, said transcription being under the control of lac repressor.

Visual Estimation of Bacterial Growth Level in Microfluidic Culture Systems.

PubMed

Kim, Kyukwang; Kim, Seunggyu; Jeon, Jessie S

2018-02-03

Microfluidic devices are an emerging platform for a variety of experiments involving bacterial cell culture, and has advantages including cost and convenience. One inevitable step during bacterial cell culture is the measurement of cell concentration in the channel. The optical density measurement technique is generally used for bacterial growth estimation, but it is not applicable to microfluidic devices due to the small sample volumes in microfluidics. Alternately, cell counting or colony-forming unit methods may be applied, but these do not work in situ; nor do these methods show measurement results immediately. To this end, we present a new vision-based method to estimate the growth level of the bacteria in microfluidic channels. We use Fast Fourier transform (FFT) to detect the frequency level change of the microscopic image, focusing on the fact that the microscopic image becomes rough as the number of cells in the field of view increases, adding high frequencies to the spectrum of the image. Two types of microfluidic devices are used to culture bacteria in liquid and agar gel medium, and time-lapsed images are captured. The images obtained are analyzed using FFT, resulting in an increase in high-frequency noise proportional to the time passed. Furthermore, we apply the developed method in the microfluidic antibiotics susceptibility test by recognizing the regional concentration change of the bacteria that are cultured in the antibiotics gradient. Finally, a deep learning-based data regression is performed on the data obtained by the proposed vision-based method for robust reporting of data.

Study of Bacterial Response to Antibiotics in Low Magnetic Fields

NASA Astrophysics Data System (ADS)

Abdul-Moqueet, Mohammad; Albalawi, Abdullah; Masood, Samina

Effect of low magnetic fields on bacterial growth has been well established. Current study shows how different magnetic fields effect the bacterial response to antibiotics shows that the bacterial infections treatment and disease cure is changed in the presence of weak fields. This study has focused on understanding how different types of low magnetic fields change the response the bacterium to antibiotics in a liquid medium. This low magnetic field coupled with the introduction of antibiotics to the growth medium shows a drop in the growth curve. The most significant effect of low magnetic fields was seen with the uniform electromagnetic field as compared to the similar strength of constant static magnetic field produced by a bar magnets.

The Bacterial Growth Curve.

ERIC Educational Resources Information Center

Paulton, Richard J. L.

1991-01-01

A procedure that allows students to view an entire bacterial growth curve during a two- to three-hour student laboratory period is described. Observations of the lag phase, logarithmic phase, maximum stationary phase, and phase of decline are possible. A nonpathogenic, marine bacterium is used in the investigation. (KR)

Bacterial and fungal growth for monitoring the impact of wildfire combined or not with different soil stabilization treatments

NASA Astrophysics Data System (ADS)

Barreiro, Ana; Baath, Erland; Díaz-Raviña, Montserrat

2015-04-01

Soil stabilization techniques are rapidly gaining acceptance as efficient tool for reducing post-fire erosion. However, despite its interest, information concerning their impact on soil biota is scarce. We examined, under field conditions, the bacterial and fungal medium-term responses in a hillslope area located in Laza (NW Spain) affected by a high severity wildfire with the following treatments established by triplicate (4 x 20 m plots): unburnt control soil, burnt control soil, burnt soil with rye seeding and burnt soil with straw mulch. The bacterial and fungal growth, as well as respiration, were measured 4 years after fire and application of treatments using leucine incorporation for bacterial growth and acetate-in-ergosterol incorporation for fungal growth. The results showed that soil respiration and fungal biomass were negatively affected by fire, in the top layer (0-5 cm), while bacterial and fungal growth was stimulated. These microbial changes induced by fire were associated with modifications in organic matter (50% reduction in C content) and soil pH (increase of 0.5-0.9 units). Thus, the results suggested that under acid environment (pH in water 3.5) post-fire conditions might have favoured both microbial groups, which is supported by the fact that estimated bacterial and fungal growth were positive and significant correlated with soil pH (range of 3.5-4.5). This contrast with the well-known reported investigations showing that bacteria rather than fungi proliferation occurred after prescribed fire or wildfire; it should be noticed, however, that soils with a higher pH than that in the present study were used. Our data also indicated that bacterial and fungal communities were not significantly affected by seeding and mulching treatments. The results highlighted the importance of pre-fire soil pH as key factor in determining the microbial response after fire. Acknowledgements. A. Barreiro is recipient of FPU grant from Spanish Ministry of Education

Modeling of scale-dependent bacterial growth by chemical kinetics approach.

PubMed

Martínez, Haydee; Sánchez, Joaquín; Cruz, José-Manuel; Ayala, Guadalupe; Rivera, Marco; Buhse, Thomas

2014-01-01

We applied the so-called chemical kinetics approach to complex bacterial growth patterns that were dependent on the liquid-surface-area-to-volume ratio (SA/V) of the bacterial cultures. The kinetic modeling was based on current experimental knowledge in terms of autocatalytic bacterial growth, its inhibition by the metabolite CO2, and the relief of inhibition through the physical escape of the inhibitor. The model quantitatively reproduces kinetic data of SA/V-dependent bacterial growth and can discriminate between differences in the growth dynamics of enteropathogenic E. coli, E. coli JM83, and Salmonella typhimurium on one hand and Vibrio cholerae on the other hand. Furthermore, the data fitting procedures allowed predictions about the velocities of the involved key processes and the potential behavior in an open-flow bacterial chemostat, revealing an oscillatory approach to the stationary states.

Bacterial Associates Modify Growth Dynamics of the Dinoflagellate Gymnodinium catenatum

PubMed Central

Bolch, Christopher J. S.; Bejoy, Thaila A.; Green, David H.

2017-01-01

Marine phytoplankton cells grow in close association with a complex microbial associate community known to affect the growth, behavior, and physiology of the algal host. The relative scale and importance these effects compared to other major factors governing algal cell growth remain unclear. Using algal-bacteria co-culture models based on the toxic dinoflagellate Gymnodinium catenatum, we tested the hypothesis that associate bacteria exert an independent effect on host algal cell growth. Batch co-cultures of G. catenatum were grown under identical environmental conditions with simplified bacterial communities composed of one-, two-, or three-bacterial associates. Modification of the associate community membership and complexity induced up to four-fold changes in dinoflagellate growth rate, equivalent to the effect of a 5°C change in temperature or an almost six-fold change in light intensity (20–115 moles photons PAR m-2 s-1). Almost three-fold changes in both stationary phase cell concentration and death rate were also observed. Co-culture with Roseobacter sp. DG874 reduced dinoflagellate exponential growth rate and led to a more rapid death rate compared with mixed associate community controls or co-culture with either Marinobacter sp. DG879, Alcanivorax sp. DG881. In contrast, associate bacteria concentration was positively correlated with dinoflagellate cell concentration during the exponential growth phase, indicating growth was limited by supply of dinoflagellate-derived carbon. Bacterial growth increased rapidly at the onset of declining and stationary phases due to either increasing availability of algal-derived carbon induced by nutrient stress and autolysis, or at mid-log phase in Roseobacter co-cultures potentially due to the onset of bacterial-mediated cell lysis. Co-cultures with the three bacterial associates resulted in dinoflagellate and bacterial growth dynamics very similar to more complex mixed bacterial community controls, suggesting that

Glycerol as an additional carbon source for bacterial cellulose synthesis

NASA Astrophysics Data System (ADS)

Agustin, Y. E.; Padmawijaya, K. S.; Rixwari, H. F.; Yuniharto, V. A. S.

2018-03-01

Bacterial cellulose, the fermentation result of Acetobacter xylinus can be produced when glycerol was used as an additional carbon source. In this research, bacterial cellulose produced in two different fermentation medium, Hestrin and Scharmm (HS) medium and HS medium with additional MgSO4. Concentration of glycerol that used in this research were 0%; 5%; 10%; and 15% (v/v). The optimum conditions of bacterial cellulose production on each experiment variations determined by characterization of the mechanical properties, including thickness, tensile strength and elongation. Fourier Transform Infra Red Spectroscopy (FTIR) revealed the characterization of bacterial cellulose. Results showed that the growth rate of bacterial cellulose in HS-MgSO4-glycerol medium was faster than in HS-glycerol medium. Increasing concentrations of glycerol will lower the value of tensile strength and elongation. Elongation test showed that the elongation bacterial cellulose (BC) with the addition of 4.95% (v/v) glycerol in the HS-MgSO4 medium is the highest elongation value. The optimum bacterial cellulose production was achieved when 4.95% (v/v) of glycerol added into HS-MgSO4 medium with stress at break of 116.885 MPa and 4.214% elongation.

Correlation between genome reduction and bacterial growth.

PubMed

Kurokawa, Masaomi; Seno, Shigeto; Matsuda, Hideo; Ying, Bei-Wen

2016-12-01

Genome reduction by removing dispensable genomic sequences in bacteria is commonly used in both fundamental and applied studies to determine the minimal genetic requirements for a living system or to develop highly efficient bioreactors. Nevertheless, whether and how the accumulative loss of dispensable genomic sequences disturbs bacterial growth remains unclear. To investigate the relationship between genome reduction and growth, a series of Escherichia coli strains carrying genomes reduced in a stepwise manner were used. Intensive growth analyses revealed that the accumulation of multiple genomic deletions caused decreases in the exponential growth rate and the saturated cell density in a deletion-length-dependent manner as well as gradual changes in the patterns of growth dynamics, regardless of the growth media. Accordingly, a perspective growth model linking genome evolution to genome engineering was proposed. This study provides the first demonstration of a quantitative connection between genomic sequence and bacterial growth, indicating that growth rate is potentially associated with dispensable genomic sequences. © The Author 2016. Published by Oxford University Press on behalf of Kazusa DNA Research Institute.

Effect of Weak Magnetic Field on Bacterial Growth

NASA Astrophysics Data System (ADS)

Masood, Samina

Effects of weak magnetic fields are observed on the growth of various bacterial strains. Different sources of a constant magnetic field are used to demonstrate that ion transport in the nutrient broth and bacterial cellular dynamics is perturbed in the presence of weak magnetic field which affects the mobility and absorption of nutrients in cells and hence their doubling rate. The change is obvious after a few hours of exposure and keeps on increasing with time for all the observed species. The growth rate depends on the field strength and the nature of the magnetic field. The field effect varies with the shape and the structure of the bacterial cell wall as well as the concentration of nutrient broth. We closely study the growth of three species Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis with the same initial concentrations at the same temperature in the same laboratory environment. Our results indicate that the weak static field of a few gauss after a few hours gives a measurable change in the growth rates of all bacterial species. This shows that the same magnetic field has different effects on different species in the same environment.

Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth.

PubMed

Molina-Romero, Dalia; Baez, Antonino; Quintero-Hernández, Verónica; Castañeda-Lucio, Miguel; Fuentes-Ramírez, Luis Ernesto; Bustillos-Cristales, María Del Rocío; Rodríguez-Andrade, Osvaldo; Morales-García, Yolanda Elizabeth; Munive, Antonio; Muñoz-Rojas, Jesús

2017-01-01

Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications.

Compatible bacterial mixture, tolerant to desiccation, improves maize plant growth

PubMed Central

Molina-Romero, Dalia; Baez, Antonino; Quintero-Hernández, Verónica; Castañeda-Lucio, Miguel; Fuentes-Ramírez, Luis Ernesto; Bustillos-Cristales, María del Rocío; Rodríguez-Andrade, Osvaldo; Morales-García, Yolanda Elizabeth; Munive, Antonio

2017-01-01

Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desiccation-tolerant strains with potential as PGPR. The formulation had one moderately (Pseudomonas putida KT2440) and three highly desiccation-tolerant (Sphingomonas sp. OF178, Azospirillum brasilense Sp7 and Acinetobacter sp. EMM02) strains. The four bacterial strains were able to adhere to seeds and colonize the rhizosphere of plants when applied in both mono-inoculation and multi-inoculation treatments, showing that they can also coexist without antagonistic effects in association with plants. The effects of the bacterial consortium on the growth of blue maize were evaluated. Seeds inoculated with either individual bacterial strains or the bacterial consortium were subjected to two experimental conditions before sowing: normal hydration or desiccation. In general, inoculation with the bacterial consortium increased the shoot and root dry weight, plant height and plant diameter compared to the non-inoculated control or mono-inoculation treatments. The bacterial consortium formulated in this work had greater benefits for blue maize plants even when the inoculated seeds underwent desiccation stress before germination, making this formulation attractive for future field applications. PMID:29117218

Adaptive self-organization during growth of bacterial colonies

NASA Astrophysics Data System (ADS)

Ben-Jacob, Eshel; Shmueli, Haim; Shochet, Ofer; Tenenbaum, Adam

1992-09-01

We present a study of interfacial pattern formation during diffusion-limited growth of Bacillus subtilis. It is demonstrated that bacterial colonies can develop patterns similar to morphologies observed during diffusion-limited growth in non-living (azoic) systems such as solidification and electro-chemical deposition. The various growth morphologies, that is the global structure of the colony, are observed as we vary the growth conditions. These include fractal growth, dense-branching growth, compact growth, dendritic growth and chiral growth. The results demonstrate the action of a singular interplay between the micro-level (individual bacterium) and macro-level (the colony) in selecting the observed morphologies as is understood for non-living systems. Furthermore, the observed morphologies can be organized within a morphology diagram indicating the existence of a morphology selection principle similar to the one proposed for azoic systems. We propose a phase-field-like model (the phase being the bacterial concentration and the field being the nutrient concentration) to describe the growth. The bacteria-bacteria interaction is manifested as a phase dependent diffusion constant. Growth of a bacterial colony presents an inherent additional level of complexity compared to azoic systems, since the building blocks themselves are living systems. Thus, our studies also focus on the transition between morphologies. We have observed extended morphology transitions due to phenotypic changes of the bacteria, as well as bursts of new morphologies resulting from genotypic changes. In addition, we have observed extended and heritable transitions (mainly between dense branching growth and chiral growth) as well as phenotypic transitions that turn genotypic over time. We discuss the implications of our results in the context of the evolving picture of genome cybernetics. Diffusion limited growth of bacterial colonies combined with new understanding of pattern formation in azoic

Global dynamics of the Escherichia coli proteome and phosphoproteome during growth in minimal medium.

PubMed

Soares, Nelson C; Spät, Philipp; Krug, Karsten; Macek, Boris

2013-06-07

Recent phosphoproteomics studies have generated relatively large data sets of bacterial proteins phosphorylated on serine, threonine, and tyrosine, implicating this type of phosphorylation in the regulation of vital processes of a bacterial cell; however, most phosphoproteomics studies in bacteria were so far qualitative. Here we applied stable isotope labeling by amino acids in cell culture (SILAC) to perform a quantitative analysis of proteome and phosphoproteome dynamics of Escherichia coli during five distinct phases of growth in the minimal medium. Combining two triple-SILAC experiments, we detected a total of 2118 proteins and quantified relative dynamics of 1984 proteins in all measured phases of growth, including 570 proteins associated with cell wall and membrane. In the phosphoproteomic experiment, we detected 150 Ser/Thr/Tyr phosphorylation events, of which 108 were localized to a specific amino acid residue and 76 were quantified in all phases of growth. Clustering analysis of SILAC ratios revealed distinct sets of coregulated proteins for each analyzed phase of growth and overrepresentation of membrane proteins in transition between exponential and stationary phases. The proteomics data indicated that proteins related to stress response typically associated with the stationary phase, including RpoS-dependent proteins, had increasing levels already during earlier phases of growth. Application of SILAC enabled us to measure median occupancies of phosphorylation sites, which were generally low (<12%). Interestingly, the phosphoproteome analysis showed a global increase of protein phosphorylation levels in the late stationary phase, pointing to a likely role of this modification in later phases of growth.

Effects of Fe nanoparticles on bacterial growth and biosurfactant production

NASA Astrophysics Data System (ADS)

Liu, Jia; Vipulanandan, Cumaraswamy; Cooper, Tim F.; Vipulanandan, Geethanjali

2013-01-01

Environmental conditions can have a major impact on bacterial growth and production of secondary products. In this study, the effect of different concentrations of Fe nanoparticles on the growth of Serratia sp. and on its production of a specific biosurfactant was investigated. The Fe nanoparticles were produced using the foam method, and the needle-shaped nanoparticles were about 30 nm in diameter. It was found that Fe nanoparticles can have either a positive or a negative impact on the bacterial growth and biosurfactant production, depending on their concentration. At 1 mg/L of Fe nanoparticle concentration the bacterial growth increased by 57 % and biosurfactant production increased by 63 %. When the Fe nanoparticle concentration was increased to 1 g/L, the bacterial growth decreased by 77 % and biosurfactant activity was undetectable. The biosurfactant itself was not directly affected by Fe nanoparticles over the range of concentrations studied, indicating that the observed changes in biosurfactant activity resulted indirectly from the effect of nanoparticles on the bacteria. These negative effects with nanoparticle exposures were temporary, demonstrated by the restoration of biosurfactant activity when the bacteria initially exposed to Fe nanoparticles were allowed to regrow in the absence of nanoparticles. Finally, the kinetics of bacterial growth and biosurfactant production were modeled. The model's predictions agreed with the experimental results.

Biological consequences and advantages of asymmetric bacterial growth.

PubMed

Kysela, David T; Brown, Pamela J B; Huang, Kerwyn Casey; Brun, Yves V

2013-01-01

Asymmetries in cell growth and division occur in eukaryotes and prokaryotes alike. Even seemingly simple and morphologically symmetric cell division processes belie inherent underlying asymmetries in the composition of the resulting daughter cells. We consider the types of asymmetry that arise in various bacterial cell growth and division processes, which include both conditionally activated mechanisms and constitutive, hardwired aspects of bacterial life histories. Although asymmetry disposes some cells to the deleterious effects of aging, it may also benefit populations by efficiently purging accumulated damage and rejuvenating newborn cells. Asymmetries may also generate phenotypic variation required for successful exploitation of variable environments, even when extrinsic changes outpace the capacity of cells to sense and respond to challenges. We propose specific experimental approaches to further develop our understanding of the prevalence and the ultimate importance of asymmetric bacterial growth.

Cow dung extract: a medium for the growth of pseudomonads enhancing their efficiency as biofertilizer and biocontrol agent in rice.

PubMed

Srivastava, Rashmi; Aragno, Michel; Sharma, A K

2010-09-01

Some pseudomands are being utilized as biofertilizers and biopesticides because of their role in plant growth promotion and plant protection against root parasites, respectively. Two strains of Pseudomonas, P. jessenii LHRE62 and P. synxantha HHRE81, recovered from wheat rhizosphere, have shown their potential in field bioinoculation tests under rice-wheat and pulse-wheat rotation systems. Normally, pseudomonads are cultivated on synthetic media-like King's B and used for inoculation on seeds/soil drench with talcum or charcoal as carrier material. Cow dung is being used for different purposes from the ancient time and has a significant role in crop growth because of the content in humic compounds and fertilizing bioelements available in it. Here, cow dung extract was tested as a growth medium for strains LHRE62 and HHRE81, in comparison with growth in King's B medium. The log phase was delayed by 2 h as compared to growth in King's B medium. The bacterial growth yield, lower in plain cow dung extract as compared to King's B medium, was improved upon addition of different carbon substrates. Growth of rice var. Pant Dhan 4 in pot cultures was increased using liquid formulation of cow dung extract and bacteria as foliar spray, compared to their respective controls. Biocontrol efficacy of the bioagents was assessed by challenging rice crop with Rhizoctonia solani, a sheath blight pathogen. The growth promotion and biocontrol efficiencies were more pronounced in the case of mixed inocula of strains LHRE62 and HHRE81.

Effect of Vibration on Bacterial Growth and Antibiotic Resistance

NASA Technical Reports Server (NTRS)

Juergensmeyer, Elizabeth A.; Juergensmeyer, Margaret A.

2004-01-01

The purpose of this research grant was to provide a fundamental, systematic investigation of the effects of oscillatory acceleration on bacterial proliferation and their responses to antibiotics in a liquid medium.

Lime-amended growing medium causes seedling growth distortions

Treesearch

R. Kasten Dumroese; Gale Thompson; David L. Wenny

1990-01-01

Although a commercial growing medium with incorporated agricultural lime had been successfully used for years, it caused growth distortion of coniferous and deciduous seedlings during 1988. Seedlings grown in the amended medium were stunted and chlorotic, often with disfigured needles and multiple tops. Seedlings grown in the same medium without incorporated lime grew...

[TMOSKOVHE COMPARATIVE CHARACTERISTIC OF GROWTH MEDIUMS FOR SEPARATION OF CORYNEBACTERIA].

PubMed

Shepelin, A P; Polosenko, O V; Borisova, O Yu; Pimenova, A S; Gadua, N T

2016-01-01

The comparative tests of growth mediums for isolation and accumulation of diphtheria bacteria were implemented. The testing consisted of six series of growth medium "Corynebacagar" produced by the state research center of applied microbiology and biotechnology and three series of blood tellurite agar. The concluding results of identification of biological indicators of all series of growth nutrient mediums are presented The "Corynebacagar" is recommended for application in health care practice for primary inoculation of pathological material during implementation of cultural analysis on diphtheria.

Growth of bacterial phytopathogens in animal manures.

PubMed

Sledz, Wojciech; Zoledowska, Sabina; Motyka, Agata; Kadziński, Leszek; Banecki, Bogdan

2017-01-01

Animal manures are routinely applied to agricultural lands to improve crop yield, but the possibility to spread bacterial phytopathogens through field fertilization has not been considered yet. We monitored 49 cattle, horse, swine, sheep or chicken manure samples collected in 14 Polish voivodeships for the most important plant pathogenic bacteria - Ralstonia solanacearum (Rsol), Xanthomonas campestris pv. campestris (Xcc), Pectobacterium carotovorum subsp. carotovorum (Pcc), Pectobacterium atrosepticum (Pba), Erwinia amylovora (Eam), Clavibacter michiganensis subsp. sepedonicus (Cms) and Dickeya sp. (Dsp). All of the tested animal fertilizers were free of these pathogens. Subsequently, the growth dynamics of Pba, Pcc, Rsol, and Xcc in cattle, horse, swine, sheep and chicken manures sterilized either by autoclaving or filtration was evaluated. The investigated phytopathogens did not exhibit any growth in the poultry manure. However, the manure filtrates originating from other animals were suitable for microbial growth, which resulted in the optical density change of 0.03-0.22 reached within 26 h (48 h Rsol, 120 h Xcc), depending on bacterial species and the manure source. Pcc and Pba multiplied most efficiently in the cattle manure filtrate. These bacteria grew faster than Rsol and Xcc in all the tested manure samples, both the filtrates and the autoclaved semi-solid ones. Though the growth dynamics of investigated strains in different animal fertilizers was unequal, all of the tested bacterial plant pathogens were proven to use cattle, horse, swine and sheep manures as the sources of nutrients. These findings may contribute to further research on the alternative routes of spread of bacterial phytopathogens, especially because of the fact that the control of pectionolytic bacteria is only based on preventive methods.

Limitation of Bacterial Growth by Dissolved Organic Matter and Iron in the Southern Ocean†

PubMed Central

Church, Matthew J.; Hutchins, David A.; Ducklow, Hugh W.

2000-01-01

The importance of resource limitation in controlling bacterial growth in the high-nutrient, low-chlorophyll (HNLC) region of the Southern Ocean was experimentally determined during February and March 1998. Organic- and inorganic-nutrient enrichment experiments were performed between 42°S and 55°S along 141°E. Bacterial abundance, mean cell volume, and [3H]thymidine and [3H]leucine incorporation were measured during 4- to 5-day incubations. Bacterial biomass, production, and rates of growth all responded to organic enrichments in three of the four experiments. These results indicate that bacterial growth was constrained primarily by the availability of dissolved organic matter. Bacterial growth in the subtropical front, subantarctic zone, and subantarctic front responded most favorably to additions of dissolved free amino acids or glucose plus ammonium. Bacterial growth in these regions may be limited by input of both organic matter and reduced nitrogen. Unlike similar experimental results in other HNLC regions (subarctic and equatorial Pacific), growth stimulation of bacteria in the Southern Ocean resulted in significant biomass accumulation, apparently by stimulating bacterial growth in excess of removal processes. Bacterial growth was relatively unchanged by additions of iron alone; however, additions of glucose plus iron resulted in substantial increases in rates of bacterial growth and biomass accumulation. These results imply that bacterial growth efficiency and nitrogen utilization may be partly constrained by iron availability in the HNLC Southern Ocean. PMID:10653704

Studies on Batch Production of Bacterial Concentrates from Mixed Species Lactic Starters

PubMed Central

Pettersson, H. E.

1975-01-01

Optimum growth conditions for mixed species starter FDs 0172 at constant pH in skim milk, whey, and tryptone medium were investigated. Growth rate and maximum population were optimal at 30 C. pH values between 5.5 and 7.0 did not influence the growth rate and maximum population obtainable. Lactic acid-producing activity declined rapidly after reaching the end of the exponential growth phase. The bacterial balance was found to be influenced by the growth parameters: media, pH, temperature, and neutralizer. Skim milk or whey medium at 25 C, pH 6.5, and neutralized with 20% (vol/vol) NH4OH kept the bacterial balance almost constant throughout the cultivation. Grown in tryptone medium at constant pH, the changes in bacterial balance and other metabolic activities were striking compared to the other two media tested. The effect of lactate as an inhibitor was found to be complex, changing with the growth conditions. Concentrates made from mixed species starters FDs 0172, FD 0570, CH 0170, CHs 0170, and T 27 were comparable to controls when cultivated at the optimum conditions found and thereafter centrifuged. Aroma production, proteolytic activity, and CO2 production did not change significantly compared to controls when cultivated at optimum conditions in skim milk or whey medium. PMID:16350009

PEROXOTITANATE- AND MONOSODIUM METAL-TITANATE COMPOUNDS AS INHIBITORS OF BACTERIAL GROWTH

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

Hobbs, D.

2011-01-19

Sodium titanates are ion-exchange materials that effectively bind a variety of metal ions over a wide pH range. Sodium titanates alone have no known adverse biological effects but metal-exchanged titanates (or metal titanates) can deliver metal ions to mammalian cells to alter cell processes in vitro. In this work, we test a hypothesis that metal-titanate compounds inhibit bacterial growth; demonstration of this principle is one prerequisite to developing metal-based, titanate-delivered antibacterial agents. Focusing initially on oral diseases, we exposed five species of oral bacteria to titanates for 24 h, with or without loading of Au(III), Pd(II), Pt(II), and Pt(IV), andmore » measuring bacterial growth in planktonic assays through increases in optical density. In each experiment, bacterial growth was compared with control cultures of titanates or bacteria alone. We observed no suppression of bacterial growth by the sodium titanates alone, but significant (p < 0.05, two-sided t-tests) suppression was observed with metal-titanate compounds, particularly Au(III)-titanates, but with other metal titanates as well. Growth inhibition ranged from 15 to 100% depending on the metal ion and bacterial species involved. Furthermore, in specific cases, the titanates inhibited bacterial growth 5- to 375-fold versus metal ions alone, suggesting that titanates enhanced metal-bacteria interactions. This work supports further development of metal titanates as a novel class of antibacterials.« less

Evaluation of the in vitro growth of urinary tract infection-causing gram-negative and gram-positive bacteria in a proposed synthetic human urine (SHU) medium.

PubMed

Ipe, Deepak S; Ulett, Glen C

2016-08-01

Bacteriuria is a hallmark of urinary tract infection (UTI) and asymptomatic bacteriuria (ABU), which are among the most frequent infections in humans. A variety of gram-negative and gram-positive bacteria are associated with these infections but Escherichia coli contributes up to 80% of cases. Multiple bacterial species including E. coli can grow in human urine as a means to maintain colonization during infections. In vitro bacteriuria studies aimed at modeling microbial growth in urine have utilized various compositions of synthetic human urine (SHU) and a Composite SHU formulation was recently proposed. In this study, we sought to validate the recently proposed Composite SHU as a medium that supports the growth of several bacterial species that are known to grow in normal human urine and/or artificial urine. Comparative growth assays of gram-negative and gram-positive bacteria E. coli, Pseudomonas aeruginosa, Proteus mirabilis, Streptococcus agalactiae, Staphylococcus saprophyticus and Enterococcus faecalis were undertaken using viable bacterial count and optical density measurements over a 48h culture period. Three different SHU formulations were tested in various culture vessels, shaking conditions and volumes and showed that Composite SHU can support the robust growth of gram-negative bacteria but requires supplementation with 0.2% yeast extract to support the growth of gram-positive bacteria. Experiments are also presented that show an unexpected but major influence of P. mirabilis towards the ability to measure bacterial growth in generally accepted multiwell assays using absorbance readings, predicted to have a basis in the release of volatile organic compound(s) from P. mirabilis during growth in Composite SHU medium. This study represents an essential methodological validation of a more chemically defined type of synthetic urine that can be applied to study mechanisms of bacteriuria and we conclude will offer a useful in vitro model to investigate the

Application of Low cost Spirulina growth medium using Deep sea water

NASA Astrophysics Data System (ADS)

Lim, Dae-hack; Kim, Bong-ju; Lee, Sung-jae; Choi, Nag-chul; Park, Cheon-young

2017-04-01

Deep-sea water has a relatively constant temperature, abundant nutrients such as calcium, magnesium, nitrates, and phosphates, etc., and stable water quality, even though there might be some variations of their compositions according to collection places. Thus, deep-sea water would be a good substrate for algal growth and biomass production since it contains various nutrients, including a fluorescent red pigment, and β-carotene, etc. The aim of this study was to investigate the economics of a culture condition through comparative analysis to Spirulina platensis growth characteristic under various medium conditions for cost-effective production of Spirulina sp.. Growth experiments were performed with S. platensis under various culture medium conditions (deep sea water + SP medium). Growth tests for culture medium demonstrated that the deep sea water to SP medium ratio of 50:50(W/W) was effective in S. platensis with the maximum biomass (1.35g/L) and minimum medium making cost per production mass (133.28 KRW/g). Parameter estimation of bio-kinetics (maximum growth rate and yield) for low cost medium results showed that the maximum growth rate and yield of N, P, K were obtained under deep sea water to SP medium ratio of 50:50(W/W) of 0.057 1/day and 0.151, 0.076, 0.123, respectively. Acknowledgment : "This research was a part of the project titled 'Development of microalgae culture technique for cosmetic materials based on ocean deep sea water(20160297)', funded by the Ministry of Oceans and Fisheries, Korea."

Bacterial Growth as a Practical Indicator of Extensive Biodegradability of Organic Compounds

PubMed Central

Prochazka, G. J.; Payne, W. J.

1965-01-01

The proportionality of growth, as indicated by turbidity of cultures of Pseudomonas C12B, to the initial concentration of sodium dodecyl sulfate, dodecanol, or a mixture of C10-C20 secondary alcohol sulfates, each provided as sole carbon source in basal mineral salts medium, was demonstrated. Subsequently, the direct correlation of culture turbidity as a growth indicator and degradation of sodium dodecyl sulfate and the C10-C20 compounds was established. Degradation of these detergents was measured by the rise in surface tension and the decrease in methylene blue values, respectively. Turbidimetry was found to be a poor indicator of degradation of dodecanol in the early hours of culture, however, and did not correlate over a significant range with degradation of substrate. Viable cell counts did parallel dodecanol degradation as measured by gas-liquid chromatography. The use of bacterial growth as a reliable, quantitative, and easily measured parameter indicating biodegradability was suggested for those organic compounds which can be shown to serve as a carbon source for a bacterium. PMID:5867651

A size-structured model of bacterial growth and reproduction.

PubMed

Ellermeyer, S F; Pilyugin, S S

2012-01-01

We consider a size-structured bacterial population model in which the rate of cell growth is both size- and time-dependent and the average per capita reproduction rate is specified as a model parameter. It is shown that the model admits classical solutions. The population-level and distribution-level behaviours of these solutions are then determined in terms of the model parameters. The distribution-level behaviour is found to be different from that found in similar models of bacterial population dynamics. Rather than convergence to a stable size distribution, we find that size distributions repeat in cycles. This phenomenon is observed in similar models only under special assumptions on the functional form of the size-dependent growth rate factor. Our main results are illustrated with examples, and we also provide an introductory study of the bacterial growth in a chemostat within the framework of our model.

Chitosan inhibits enterotoxigenic Clostridium perfringens type A in growth medium and chicken meat.

PubMed

Alnoman, Maryam; Udompijitkul, Pathima; Sarker, Mahfuzur R

2017-06-01

Clostridium perfringens is a spore-forming bacterium and a major cause of bacterial food-borne illness. In this study, we evaluated the inhibitory effects of chitosan against spore germination, spore outgrowth and vegetative growth of C. perfringens food poisoning (FP) isolates. Chitosan of differing molecular weights inhibited germination of spores of all tested FP isolates in a KCl germinant solution containing 0.1 mg/ml chitosan at pH 4.5. However, higher level (0.25 mg/ml) of chitosan was required to effectively arrest outgrowth of the germinated C. perfringens spores in Tripticase-yeast extract-glucose (TGY) medium. Furthermore, chitosan (1.0 mg/ml) was bacteriostatic against vegetative cells of C. perfringens in TGY medium. Although chitosan showed strong inhibitory activities against C. perfringens in laboratory medium, higher levels (2.0 mg/g) were required to achieve similar inhibition of spores inoculated into chicken meat. In summary, the inhibitory effects of chitosan against C. perfringens FP isolates was concentration dependent, and no major difference was observed when using different molecule weight chitosan as an inhibitor. Our results contribute to a better understanding on the potential application of chitosan in cooked meat products to control C. perfringens-associated disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rapid Method of Determining Factors Limiting Bacterial Growth in Soil

PubMed Central

Aldén, L.; Demoling, F.; Bååth, E.

2001-01-01

A technique to determine which nutrients limit bacterial growth in soil was developed. The method was based on measuring the thymidine incorporation rate of bacteria after the addition of C, N, and P in different combinations to soil samples. First, the thymidine incorporation method was tested in two different soils: an agricultural soil and a forest humus soil. Carbon (as glucose) was found to be the limiting substance for bacterial growth in both of these soils. The effect of adding different amounts of nutrients was studied, and tests were performed to determine whether the additions affected the soil pH and subsequent bacterial activity. The incubation time required to detect bacterial growth after adding substrate to the soil was also evaluated. Second, the method was used in experiments in which three different size fractions of straw (1 to 2, 0.25 to 1, and <0.25 mm) were mixed into the agricultural soil in order to induce N limitation for bacterial growth. When the straw fraction was small enough (<0.25 mm), N became the limiting nutrient for bacterial growth after about 3 weeks. After the addition of the larger straw fractions (1 to 2 and 0.25 to 1 mm), the soil bacteria were C limited throughout the incubation period (10 weeks), although an increase in the thymidine incorporation rate after the addition of C and N together compared with adding them separately was seen in the sample containing the size fraction from 0.25 to 1 mm. Third, soils from high-pH, limestone-rich areas were examined. P limitation was observed in one of these soils, while tendencies toward P limitation were seen in some of the other soils. PMID:11282640

Bacterial community changes in an industrial algae production system.

PubMed

Fulbright, Scott P; Robbins-Pianka, Adam; Berg-Lyons, Donna; Knight, Rob; Reardon, Kenneth F; Chisholm, Stephen T

2018-04-01

While microalgae are a promising feedstock for production of fuels and other chemicals, a challenge for the algal bioproducts industry is obtaining consistent, robust algae growth. Algal cultures include complex bacterial communities and can be difficult to manage because specific bacteria can promote or reduce algae growth. To overcome bacterial contamination, algae growers may use closed photobioreactors designed to reduce the number of contaminant organisms. Even with closed systems, bacteria are known to enter and cohabitate, but little is known about these communities. Therefore, the richness, structure, and composition of bacterial communities were characterized in closed photobioreactor cultivations of Nannochloropsis salina in F/2 medium at different scales, across nine months spanning late summer-early spring, and during a sequence of serially inoculated cultivations. Using 16S rRNA sequence data from 275 samples, bacterial communities in small, medium, and large cultures were shown to be significantly different. Larger systems contained richer bacterial communities compared to smaller systems. Relationships between bacterial communities and algae growth were complex. On one hand, blooms of a specific bacterial type were observed in three abnormal, poorly performing replicate cultivations, while on the other, notable changes in the bacterial community structures were observed in a series of serial large-scale batch cultivations that had similar growth rates. Bacteria common to the majority of samples were identified, including a single OTU within the class Saprospirae that was found in all samples. This study contributes important information for crop protection in algae systems, and demonstrates the complex ecosystems that need to be understood for consistent, successful industrial algae cultivation. This is the first study to profile bacterial communities during the scale-up process of industrial algae systems.

Modification of the technical properties of Lactobacillus johnsonii NCC 533 by supplementing the growth medium with unsaturated fatty acids.

PubMed

Muller, J A; Ross, R P; Sybesma, W F H; Fitzgerald, G F; Stanton, C

2011-10-01

The aim of this study was to investigate the influence of supplementing growth medium with unsaturated fatty acids on the technical properties of the probiotic strain Lactobacillus johnsonii NCC 533, such as heat and acid tolerance, and inhibition of Salmonella enterica serovar Typhimurium infection. Our results showed that the membrane composition and morphology of L. johnsonii NCC 533 were significantly changed by supplementing a minimal Lactobacillus medium with oleic, linoleic, and linolenic acids. The ratio of saturated to unsaturated plus cyclic fatty acids in the bacterial membrane decreased by almost 2-fold when minimal medium was supplemented with unsaturated fatty acids (10 μg/ml). The subsequent acid and heat tolerance of L. johnsonii decreased by 6- and 20-fold when the strain was grown in the presence of linoleic and linolenic acids, respectively, compared with growth in oleic acid (all at 10 μg/ml). Following acid exposure, significantly higher (P < 0.05) oleic acid content was detected in the membrane when growth medium was supplemented with linoleic or linolenic acid, indicating that saturation of the membrane fatty acids occurred during acid stress. Cell integrity was determined in real time during stressed conditions using a fluorescent viability kit in combination with flow cytometric analysis. Following heat shock (at 62.5°C for 5 min), L. johnsonii was unable to form colonies; however, 60% of the bacteria showed no cell integrity loss, which could indicate that the elevated heat inactivated vital processes within the cell, rendering it incapable of replication. Furthermore, L. johnsonii grown in fatty acid-enriched minimal medium had different adhesion properties and caused a 2-fold decrease in S. enterica serovar Typhimurium UK1-lux invasion of HT-29 epithelial cells compared with bacteria grown in minimal medium alone. This could be related to changes in the hydrophobicity and fluidity of the membrane. Our study shows that technical

The growth of Paracoccus halodenitrificans in a defined medium

NASA Technical Reports Server (NTRS)

Hochstein, L. I.; Tomlinson, G. A.

1984-01-01

A synthetic medium, consisting of inorganic salts and any of a number of carbon sources, supported the aerobic growth of Paracoccus halodenitrificans when supplemented with thiamine. The same medium plus a nitrogenous oxide supported anaerobic growth when additionally supplemented with methionine. The observation that vitamin B12 or betaine replaced methionine suggested that P. halodenitrificans had a defect in the cobalamin dependent pathway for methionine biosynthesis, as well as the inability to synthesize betanine when growing anaerobically.

The growth of paracoccus halodenitrificans in a defined medium

NASA Technical Reports Server (NTRS)

Hochstein, L. I.; Tomlinson, G. A.

1983-01-01

A synthetic medium, consisting of inorganic salts and any of a number of carbon sources, supported the aerobic growth of Paracoccus halodenitrificans when supplemented with thiamine. The same medium plus a nitrogenous oxide supported anaerobic growth when additionally supplemented with methionine. The observation that vitamin B12 or betaine replaced methionine suggested that P. halodenitrificans had a defect in the cobalamin dependent pathway for methionine biosynthesis, as well as the inability to synthesize betaine when growing anaerobically.

Changes in the bacterial community of soybean rhizospheres during growth in the field.

PubMed

Sugiyama, Akifumi; Ueda, Yoshikatsu; Zushi, Takahiro; Takase, Hisabumi; Yazaki, Kazufumi

2014-01-01

Highly diverse communities of bacteria inhabiting soybean rhizospheres play pivotal roles in plant growth and crop production; however, little is known about the changes that occur in these communities during growth. We used both culture-dependent physiological profiling and culture independent DNA-based approaches to characterize the bacterial communities of the soybean rhizosphere during growth in the field. The physiological properties of the bacterial communities were analyzed by a community-level substrate utilization assay with BioLog Eco plates, and the composition of the communities was assessed by gene pyrosequencing. Higher metabolic capabilities were found in rhizosphere soil than in bulk soil during all stages of the BioLog assay. Pyrosequencing analysis revealed that differences between the bacterial communities of rhizosphere and bulk soils at the phylum level; i.e., Proteobacteria were increased, while Acidobacteria and Firmicutes were decreased in rhizosphere soil during growth. Analysis of operational taxonomic units showed that the bacterial communities of the rhizosphere changed significantly during growth, with a higher abundance of potential plant growth promoting rhizobacteria, including Bacillus, Bradyrhizobium, and Rhizobium, in a stage-specific manner. These findings demonstrated that rhizosphere bacterial communities were changed during soybean growth in the field.

Bacterial growth laws and their applications.

PubMed

Scott, Matthew; Hwa, Terence

2011-08-01

Quantitative empirical relationships between cell composition and growth rate played an important role in the early days of microbiology. Gradually, the focus of the field began to shift from growth physiology to the ever more elaborate molecular mechanisms of regulation employed by the organisms. Advances in systems biology and biotechnology have renewed interest in the physiology of the cell as a whole. Furthermore, gene expression is known to be intimately coupled to the growth state of the cell. Here, we review recent efforts in characterizing such couplings, particularly the quantitative phenomenological approaches exploiting bacterial 'growth laws.' These approaches point toward underlying design principles that can guide the predictive manipulation of cell behavior in the absence of molecular details. Copyright © 2011 Elsevier Ltd. All rights reserved.

Bacterial growth laws and their applications

PubMed Central

SCOTT, Matthew; HWA, Terence

2011-01-01

Quantitative empirical relationships between cell composition and growth rate played an important role in the early days of microbiology. Gradually, the focus of the field began to shift from growth physiology to the ever more elaborate molecular mechanisms of regulation employed by the organisms. Advances in systems biology and biotechnology have renewed interest in the physiology of the cell as a whole. Furthermore, gene expression is known to be intimately coupled to the growth state of the cell. Here, we review recent efforts in characterizing such couplings, particularly the quantitative phenomenological approaches exploiting bacterial `growth laws.' These approaches point toward underlying design principles that can guide the predictive manipulation of cell behavior in the absence of molecular details. PMID:21592775

New plant-growth medium for increased power output of the Plant-Microbial Fuel Cell.

PubMed

Helder, M; Strik, D P B T B; Hamelers, H V M; Kuijken, R C P; Buisman, C J N

2012-01-01

In a Plant-Microbial Fuel Cell anode-conditions must be created that are favorable for plant growth and electricity production. One of the major aspects in this is the composition of the plant-growth medium. Hoagland medium has been used until now, with added phosphate buffer to reduce potential losses over the membrane because of differences in pH between anode and cathode. We developed a new, improved plant-growth medium that improves current production, while the plant keeps growing. This medium is a nitrate-less, ammonium-rich medium that contains all macro- and micro-nutrients necessary for plant growth, with a balanced amount of bicarbonate buffer. Sulphate presence in the plant-growth medium helps to keep a low anode-potential. With the new plant-growth medium the maximum current production of the Plant-Microbial Fuel Cell increased from 186 mA/m(2) to 469 mA/m(2). Copyright © 2011 Elsevier Ltd. All rights reserved.

An improved medium for the anaerobic growth of Paracoccus denitrificans Pd1222

PubMed Central

Hahnke, Stefanie M.; Moosmann, Philipp; Erb, Tobias J.; Strous, Marc

2014-01-01

Paracoccus denitrificans is a well studied model organism with respect to its aerobic and anaerobic respiratory enzymes. However, until now, the growth medium for this organism has not been optimized for anaerobic growth. In particular, the requirements of P. denitrificans for trace elements (TEs) are not well known. In the present study we aimed to improve growth rates of P. denitrificans Pd1222 on a defined medium under anoxic conditions. We designed media containing different combinations of TEs at various concentrations, and tested their performance against previously reported media. Our results suggest that growth rate and yield depend on the availability and concentration of TEs in the medium. A chelated TE solution was more suitable than an acidified TE solution. Highest growth rates were achieved with medium comprising the TEs iron, manganese, molybdenum, copper and zinc ranging from 0.1 to 9 μM. On this medium, P. denitrificans Pd1222 grew with a generation time of 4.4 h under anoxic conditions and 2.8 h under oxic conditions. Diauxic growth was clearly shown with respect to nitrate and nitrite reduction under anoxic conditions. PMID:24550891

An improved medium for the anaerobic growth of Paracoccus denitrificans Pd1222.

PubMed

Hahnke, Stefanie M; Moosmann, Philipp; Erb, Tobias J; Strous, Marc

2014-01-01

Paracoccus denitrificans is a well studied model organism with respect to its aerobic and anaerobic respiratory enzymes. However, until now, the growth medium for this organism has not been optimized for anaerobic growth. In particular, the requirements of P. denitrificans for trace elements (TEs) are not well known. In the present study we aimed to improve growth rates of P. denitrificans Pd1222 on a defined medium under anoxic conditions. We designed media containing different combinations of TEs at various concentrations, and tested their performance against previously reported media. Our results suggest that growth rate and yield depend on the availability and concentration of TEs in the medium. A chelated TE solution was more suitable than an acidified TE solution. Highest growth rates were achieved with medium comprising the TEs iron, manganese, molybdenum, copper and zinc ranging from 0.1 to 9 μM. On this medium, P. denitrificans Pd1222 grew with a generation time of 4.4 h under anoxic conditions and 2.8 h under oxic conditions. Diauxic growth was clearly shown with respect to nitrate and nitrite reduction under anoxic conditions.

Effect of human milk fortifiers on bacterial growth in human milk.

PubMed

Santiago, Myla S; Codipilly, Champa N; Potak, Debra C; Schanler, Richard J

2005-10-01

As a component in human milk fortifiers (HMF), iron may equilibrate with human milk for as long as 24 hours, bind important bacteriostatic proteins, and potentially affect the host defense properties of human milk. We compared bacterial growth in human milk prepared with each of two HMF differing in their content of iron. Samples of human milk obtained from mothers of premature infants were divided and mixed with one of two HMF and maintained at refrigerator temperature. Refrigerated milk samples were removed at 0, 24, and 72 hours for determination of total bacterial colony counts (TBCC). TBCC did not differ between groups but declined from 0 to 72 hours, p<0.001. These data suggest that differences in iron content, or other nutrients in HMF, do not affect bacterial growth in human milk. Storage of fortified human milk at refrigerator temperature for 72 hours results in decreased bacterial growth. As a component in human milk fortifiers (HMF), iron may equilibrate with human milk for as long as 24 hours, bind important bacteriostatic proteins, and potentially affect the host defense properties of human milk. We compared bacterial growth in human milk prepared with each of two HMF differing in their content of iron. Samples of human milk obtained from mothers of premature infants were divided and mixed with one of two HMF and maintained at refrigerator temperature. Refrigerated milk samples were removed at 0, 24, and 72 hours for determination of total bacterial colony counts (TBCC).

In vitro bacterial growth and in vivo ruminal microbiota populations associated with bloat in steers grazing wheat forage.

PubMed

Min, B R; Pinchak, W E; Anderson, R C; Hume, M E

2006-10-01

The role of ruminal bacteria in the frothy bloat complex common to cattle grazing winter wheat has not been previously determined. Two experiments, one in vitro and another in vivo, were designed to elucidate the effects of fresh wheat forage on bacterial growth, biofilm complexes, rumen fermentation end products, rumen bacterial diversity, and bloat potential. In Exp. 1, 6 strains of ruminal bacteria (Streptococcus bovis strain 26, Prevotella ruminicola strain 23, Eubacterium ruminantium B1C23, Ruminococcus albus SY3, Fibrobacter succinogenes ssp. S85, and Ruminococcus flavefaciens C94) were used in vitro to determine the effect of soluble plant protein from winter wheat forage on specific bacterial growth rate, biofilm complexes, VFA, and ruminal H2 and CH4 in mono or coculture with Methanobrevibacter smithii. The specific growth rate in plant protein medium containing soluble plant protein (3.27% nitrogen) was measured during a 24-h incubation at 39 degrees C in Hungate tubes under a CO2 gas phase. A monoculture of M. smithii was grown similarly, except under H2:CO2 (1:1), in a basal methanogen growth medium supplemented likewise with soluble plant protein. In Exp. 2, 6 ruminally cannulated steers grazing wheat forage were used to evaluate the influence of bloat on the production of biofilm complexes, ruminal microbial biodiversity patterns, and ruminal fluid protein fractions. In Exp. 1, cultures of R. albus (P < 0.01) and R. flavefaciens (P < 0.05) produced the most H2 among strains and resulted in greater (P < 0.01) CH4 production when cocultured with M. smithii than other coculture combinations. Cultures of S. bovis and E. ruminantium + M. smithii produced the most biofilm mass among strains. In Exp. 2, when diets changed from bermudagrass hay to wheat forage, biofilm production increased (P < 0.01). Biofilm production, concentrations of whole ruminal content (P < 0.01), and cheesecloth filtrate protein fractions (P < 0.05) in the ruminal fluid were greater

Analytic derivation of bacterial growth laws from a simple model of intracellular chemical dynamics.

PubMed

Pandey, Parth Pratim; Jain, Sanjay

2016-09-01

Experiments have found that the growth rate and certain other macroscopic properties of bacterial cells in steady-state cultures depend upon the medium in a surprisingly simple manner; these dependencies are referred to as 'growth laws'. Here we construct a dynamical model of interacting intracellular populations to understand some of the growth laws. The model has only three population variables: an amino acid pool, a pool of enzymes that transport an external nutrient and produce the amino acids, and ribosomes that catalyze their own and the enzymes' production from the amino acids. We assume that the cell allocates its resources between the enzyme sector and the ribosomal sector to maximize its growth rate. We show that the empirical growth laws follow from this assumption and derive analytic expressions for the phenomenological parameters in terms of the more basic model parameters. Interestingly, the maximization of the growth rate of the cell as a whole implies that the cell allocates resources to the enzyme and ribosomal sectors in inverse proportion to their respective 'efficiencies'. The work introduces a mathematical scheme in which the cellular growth rate can be explicitly determined and shows that two large parameters, the number of amino acid residues per enzyme and per ribosome, are useful for making approximations.

Effect of flow and active mixing on bacterial growth in a colon-like geometry

NASA Astrophysics Data System (ADS)

Cremer, Jonas; Segota, Igor; Arnoldini, Markus; Groisman, Alex; Hwa, Terence

The large intestine harbors bacteria from hundreds of species, with bacterial densities reaching up to 1012 cells per gram. Many different factors influence bacterial growth dynamics and thus bacterial density and microbiota composition. One dominant force is flow which can in principle lead to a washout of bacteria from the proximal colon. Active mixing by Contractions of the colonic wall together with bacterial growth might counteract such flow-forces and allow high bacterial densities to occur. As a step towards understanding bacterial growth in the presence of mixing and flow, we constructed an in-vitro setup where controlled wall-deformations of a channel emulate Contractions. We investigate growth along the channel under a steady nutrient inflow. In the limits of no or very frequent Contractions, the device behaves like a plug-flow reactor and a chemostat respectively. Depending on mixing and flow, we observe varying spatial gradients in bacterial density along the channel. Active mixing by deformations of the channel wall is shown to be crucial in maintaining a steady-state bacterial population in the presence of flow. The growth-dynamics is quantitatively captured by a simple mathematical model, with the effect of mixing described by an effective diffusion term.

Modification of the Technical Properties of Lactobacillus johnsonii NCC 533 by Supplementing the Growth Medium with Unsaturated Fatty Acids ▿

PubMed Central

Muller, J. A.; Ross, R. P.; Sybesma, W. F. H.; Fitzgerald, G. F.; Stanton, C.

2011-01-01

The aim of this study was to investigate the influence of supplementing growth medium with unsaturated fatty acids on the technical properties of the probiotic strain Lactobacillus johnsonii NCC 533, such as heat and acid tolerance, and inhibition of Salmonella enterica serovar Typhimurium infection. Our results showed that the membrane composition and morphology of L. johnsonii NCC 533 were significantly changed by supplementing a minimal Lactobacillus medium with oleic, linoleic, and linolenic acids. The ratio of saturated to unsaturated plus cyclic fatty acids in the bacterial membrane decreased by almost 2-fold when minimal medium was supplemented with unsaturated fatty acids (10 μg/ml). The subsequent acid and heat tolerance of L. johnsonii decreased by 6- and 20-fold when the strain was grown in the presence of linoleic and linolenic acids, respectively, compared with growth in oleic acid (all at 10 μg/ml). Following acid exposure, significantly higher (P < 0.05) oleic acid content was detected in the membrane when growth medium was supplemented with linoleic or linolenic acid, indicating that saturation of the membrane fatty acids occurred during acid stress. Cell integrity was determined in real time during stressed conditions using a fluorescent viability kit in combination with flow cytometric analysis. Following heat shock (at 62.5°C for 5 min), L. johnsonii was unable to form colonies; however, 60% of the bacteria showed no cell integrity loss, which could indicate that the elevated heat inactivated vital processes within the cell, rendering it incapable of replication. Furthermore, L. johnsonii grown in fatty acid-enriched minimal medium had different adhesion properties and caused a 2-fold decrease in S. enterica serovar Typhimurium UK1-lux invasion of HT-29 epithelial cells compared with bacteria grown in minimal medium alone. This could be related to changes in the hydrophobicity and fluidity of the membrane. Our study shows that technical

Human Milk Oligosaccharides Promote the Growth of Staphylococci

PubMed Central

Hunt, K. M.; Preuss, J.; Nissan, C.; Davlin, C. A.; Williams, J. E.; Shafii, B.; Richardson, A. D.; McGuire, M. K.; Bode, L.

2012-01-01

Human milk oligosaccharides (HMO), which constitute a major component of human milk, promote the growth of particular bacterial species in the infant's gastrointestinal tract. We hypothesized that HMO also interact with the bacterial communities present in human milk. To test this hypothesis, two experiments were conducted. First, milk samples were collected from healthy women (n = 16); culture-independent analysis of the bacterial communities was performed, HMO content was analyzed, and the relation between these factors was investigated. A positive correlation was observed between the relative abundance of Staphylococcus and total HMO content (r = 0.66). In a follow-up study, we conducted a series of in vitro growth curve experiments utilizing Staphylococcus aureus or Staphylococcus epidermidis and HMO isolated from human milk. HMO exhibited stimulatory effects on bacterial growth under various nutritional conditions. Analysis of culture supernatants from these experiments revealed that HMO did not measurably disappear from the culture medium, indicating that the growth-enhancing effects were not a result of bacterial metabolism of the HMO. Instead, stimulation of growth caused greater utilization of amino acids in minimal medium. Collectively, the data provide evidence that HMO may promote the growth of Staphylococcus species in the lactating mammary gland. PMID:22562995

No bacterial growth found in spiked intravenous fluids over an 8-hour period.

PubMed

Haas, Richard E; Beitz, Edwin; Reed, Amy; Burtnett, Howard; Lowe, Jason; Crist, Arthur E; Stierer, Kevin A; Birenberg, Allan M

2017-04-01

Protocol changes prompted by the Joint Commission mandating intravenous (IV) fluid bags to be used within 1 hour of spiking because of possible bacterial contamination have sparked clinical and economic concerns. This study investigated the degree of bacterial growth in which samples were obtained from spiked IV fluid bags at the time of spiking and 1, 2, 4, and 8 hours after spiking. No bacterial growth occurred in any of the 80 bags of Lactated Ringer's (LR) IV solutions sampled. This study demonstrated that LR IV bags do not support any bacterial growth for up to 8 hours after spiking. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Vision Marker-Based In Situ Examination of Bacterial Growth in Liquid Culture Media.

PubMed

Kim, Kyukwang; Choi, Duckyu; Lim, Hwijoon; Kim, Hyeongkeun; Jeon, Jessie S

2016-12-18

The detection of bacterial growth in liquid media is an essential process in determining antibiotic susceptibility or the level of bacterial presence for clinical or research purposes. We have developed a system, which enables simplified and automated detection using a camera and a striped pattern marker. The quantification of bacterial growth is possible as the bacterial growth in the culturing vessel blurs the marker image, which is placed on the back of the vessel, and the blurring results in a decrease in the high-frequency spectrum region of the marker image. The experiment results show that the FFT (fast Fourier transform)-based growth detection method is robust to the variations in the type of bacterial carrier and vessels ranging from the culture tubes to the microfluidic devices. Moreover, the automated incubator and image acquisition system are developed to be used as a comprehensive in situ detection system. We expect that this result can be applied in the automation of biological experiments, such as the Antibiotics Susceptibility Test or toxicity measurement. Furthermore, the simple framework of the proposed growth measurement method may be further utilized as an effective and convenient method for building point-of-care devices for developing countries.

Determination of optimized growth medium and cryoprotective additives to enhance the growth and survival of Lactobacillus salivarius.

PubMed

Yeo, Soyoung; Shin, Hee Sung; Lee, Hye Won; Hong, Doseon; Park, Hyunjoon; Holzapfel, Wilhelm; Kim, Eun Bae; Huh, Chul Sung

2018-03-16

Beneficial effects of lactic acid bacteria (LAB) have been intensively investigated in recent decades with special focus on modulation of the host intestinal microbiota. Numerous discoveries of effective probiotics are driven by a significantly increasing demand for dietary supplements. Consequently, technological advances in the large-scale production and lyophilization are needed by probiotic-related industries for producing probiotic LAB for commercial use. Our study had a dual objective, i.e., to determine the optimum growth medium composition and to investigate appropriate cryoprotective additives (CPAs) for Lactobacillus salivarius , and compare its responses with other Lactobacillus species. The one-factor-at-a-time method and central composite design were applied to determine the optimal medium composition for L. salivarius cultivation. The following composition of the medium was established (per liter): 21.64 g maltose, 85 g yeast extract, 1.21 ml Tween 80, 6 g sodium acetate, 0.2 g MgSO 4 ∙7H 2 O, 0.02 g MnSO 4 ∙H 2 O, 1 g K 2 HPO 4 , 1.5 g KH 2 PO 4 , 0.01 g FeSO 4 ∙7H 2 O and 1 g sodium citrate. A cryoprotective additive combination comprising 10% ( w/v ) skim milk and 10% ( w/v ) sucrose supplemented with 2.5% ( w/v ) sodium glutamate was selected for L. salivarius , and its effectiveness was confirmed using culture-independent methods in the freeze-dried cells of the Lactobacillus strains. In conclusion, the optimized medium enhanced the species-specific cultivation of L. salivarius . On the other hand, the cryoprotective effects of the selected CPA mixture may also be dependent on the bacterial strain. This study highlights the necessity for precise and advanced processing techniques for large-scale production of probiotics in the food and feed industries.

Predicting the dynamics of bacterial growth inhibition by ribosome-targeting antibiotics

NASA Astrophysics Data System (ADS)

Greulich, Philip; Doležal, Jakub; Scott, Matthew; Evans, Martin R.; Allen, Rosalind J.

2017-12-01

Understanding how antibiotics inhibit bacteria can help to reduce antibiotic use and hence avoid antimicrobial resistance—yet few theoretical models exist for bacterial growth inhibition by a clinically relevant antibiotic treatment regimen. In particular, in the clinic, antibiotic treatment is time-dependent. Here, we use a theoretical model, previously applied to steady-state bacterial growth, to predict the dynamical response of a bacterial cell to a time-dependent dose of ribosome-targeting antibiotic. Our results depend strongly on whether the antibiotic shows reversible transport and/or low-affinity ribosome binding (‘low-affinity antibiotic’) or, in contrast, irreversible transport and/or high affinity ribosome binding (‘high-affinity antibiotic’). For low-affinity antibiotics, our model predicts that growth inhibition depends on the duration of the antibiotic pulse, and can show a transient period of very fast growth following removal of the antibiotic. For high-affinity antibiotics, growth inhibition depends on peak dosage rather than dose duration, and the model predicts a pronounced post-antibiotic effect, due to hysteresis, in which growth can be suppressed for long times after the antibiotic dose has ended. These predictions are experimentally testable and may be of clinical significance.

Predicting the dynamics of bacterial growth inhibition by ribosome-targeting antibiotics

PubMed Central

Greulich, Philip; Doležal, Jakub; Scott, Matthew; Evans, Martin R; Allen, Rosalind J

2017-01-01

Understanding how antibiotics inhibit bacteria can help to reduce antibiotic use and hence avoid antimicrobial resistance—yet few theoretical models exist for bacterial growth inhibition by a clinically relevant antibiotic treatment regimen. In particular, in the clinic, antibiotic treatment is time-dependent. Here, we use a theoretical model, previously applied to steady-state bacterial growth, to predict the dynamical response of a bacterial cell to a time-dependent dose of ribosome-targeting antibiotic. Our results depend strongly on whether the antibiotic shows reversible transport and/or low-affinity ribosome binding (‘low-affinity antibiotic’) or, in contrast, irreversible transport and/or high affinity ribosome binding (‘high-affinity antibiotic’). For low-affinity antibiotics, our model predicts that growth inhibition depends on the duration of the antibiotic pulse, and can show a transient period of very fast growth following removal of the antibiotic. For high-affinity antibiotics, growth inhibition depends on peak dosage rather than dose duration, and the model predicts a pronounced post-antibiotic effect, due to hysteresis, in which growth can be suppressed for long times after the antibiotic dose has ended. These predictions are experimentally testable and may be of clinical significance. PMID:28714461

Microbial dynamics during harmful dinoflagellate Ostreopsis cf. ovata growth: Bacterial succession and viral abundance pattern.

PubMed

Guidi, Flavio; Pezzolesi, Laura; Vanucci, Silvana

2018-02-27

Algal-bacterial interactions play a major role in shaping diversity of algal associated bacterial communities. Temporal variation in bacterial phylogenetic composition reflects changes of these complex interactions which occur during the algal growth cycle as well as throughout the lifetime of algal blooms. Viruses are also known to cause shifts in bacterial community diversity which could affect algal bloom phases. This study investigated on changes of bacterial and viral abundances, bacterial physiological status, and on bacterial successional pattern associated with the harmful benthic dinoflagellate Ostreopsis cf. ovata in batch cultures over the algal growth cycle. Bacterial community phylogenetic structure was assessed by 16S rRNA gene ION torrent sequencing. A comparison between bacterial community retrieved in cultures and that one co-occurring in situ during the development of the O. cf. ovata bloom from where the algal strain was isolated was also reported. Bacterial community growth was characterized by a biphasic pattern with the highest contributions (~60%) of highly active bacteria found at the two bacterial exponential growth steps. An alphaproteobacterial consortium composed by the Rhodobacteraceae Dinoroseobacter (22.2%-35.4%) and Roseovarius (5.7%-18.3%), together with Oceanicaulis (14.2-40.3%), was strongly associated with O. cf. ovata over the algal growth. The Rhodobacteraceae members encompassed phylotypes with an assessed mutualistic-pathogenic bimodal behavior. Fabibacter (0.7%-25.2%), Labrenzia (5.6%-24.3%), and Dietzia (0.04%-1.7%) were relevant at the stationary phase. Overall, the successional pattern and the metabolic and functional traits of the bacterial community retrieved in culture mirror those ones underpinning O. cf. ovata bloom dynamics in field. Viral abundances increased synoptically with bacterial abundances during the first bacterial exponential growth step while being stationary during the second step. Microbial trends

Morphomechanics of bacterial biofilms undergoing anisotropic differential growth

NASA Astrophysics Data System (ADS)

Zhang, Cheng; Li, Bo; Huang, Xiao; Ni, Yong; Feng, Xi-Qiao

2016-10-01

Growing bacterial biofilms exhibit a number of surface morphologies, e.g., concentric wrinkles, radial ridges, and labyrinthine networks, depending on their physiological status and nutrient access. We explore the mechanisms underlying the emergence of these greatly different morphologies. Ginzburg-Landau kinetic method and Fourier spectral method are integrated to simulate the morphological evolution of bacterial biofilms. It is shown that the morphological instability of biofilms is triggered by the stresses induced by anisotropic and heterogeneous bacterial expansion, and involves the competition between membrane energy and bending energy. Local interfacial delamination further enriches the morphologies of biofilms. Phase diagrams are established to reveal how the anisotropy and spatial heterogeneity of growth modulate the surface patterns. The mechanics of three-dimensional microbial morphogenesis may also underpin self-organization in other development systems and provide a potential strategy for engineering microscopic structures from bacterial aggregates.

Dynamic succession of substrate-associated bacterial composition and function during Ganoderma lucidum growth

PubMed Central

Li, Qiang; Zou, Jie; Tan, Hao; Tan, Wei; Peng, Weihong

2018-01-01

Background Ganoderma lucidum, a valuable medicinal fungus, is widely distributed in China. It grows alongside with a complex microbial ecosystem in the substrate. As sequencing technology advances, it is possible to reveal the composition and functions of substrate-associated bacterial communities. Methods We analyzed the bacterial community dynamics in the substrate during the four typical growth stages of G. lucidum using next-generation sequencing. Results The physicochemical properties of the substrate (e.g. acidity, moisture, total nitrogen, total phosphorus and total potassium) changed between different growth stages. A total of 598,771 sequences from 12 samples were obtained and assigned to 22 bacterial phyla. Proteobacteria and Firmicutes were the dominant phyla. Bacterial community composition and diversity significantly differed between the elongation stage and the other three growth stages. LEfSe analysis revealed a large number of bacterial taxa (e.g. Bacteroidetes, Acidobacteria and Nitrospirae) with significantly higher abundance at the elongation stage. Functional pathway prediction uncovered significant abundance changes of a number of bacterial functional pathways between the elongation stage and other growth stages. At the elongation stage, the abundance of the environmental information processing pathway (mainly membrane transport) decreased, whereas that of the metabolism-related pathways increased. Discussion The changes in bacterial community composition, diversity and predicted functions were most likely related to the changes in the moisture and nutrient conditions in the substrate with the growth of G. lucidum, particularly at the elongation stage. Our findings shed light on the G. lucidum-bacteria-substrate relationships, which should facilitate the industrial cultivation of G. lucidum. PMID:29915697

Use of an insect cell culture growth medium to isolate bacteria from horses with effusive, fibrinous pericarditis: a preliminary study.

PubMed

Jones, Samuel L; Valenzisi, Amy; Sontakke, Sushama; Sprayberry, Kimberly A; Maggi, Ricardo; Hegarty, Barbara; Breitschwerdt, Edward

2007-03-31

Effusive, fibrinous pericarditis is an uncommon disease entity in horses. In 2001, pericarditis occurred in conjunction with an epizootic in central Kentucky that was associated with exposure to eastern tent caterpillars (ETCs). Bacterial isolation from equine pericardial fluid samples was attempted using an insect cell culture growth medium (ICCGM). Using previously cultured, stored frozen samples from four horses with fibrinous pericarditis, inoculation of 10% blood agar plates yielded no growth, whereas simultaneous inoculation of ICCGM resulted in the isolation of Proprionibacterium acnes, Staphylococcus equorum, a Streptococcus sp. and Pseudomonas rhodesiae from pericardial fluid samples. A similar or novel caterpillar-associated bacteria was not identified; however, use of an ICCGM might enhance isolation of bacteria from equine pericardial fluid.

Aptamer-functionalized capacitance sensors for real-time monitoring of bacterial growth and antibiotic susceptibility.

PubMed

Jo, Namgyeong; Kim, Bongjun; Lee, Sun-Mi; Oh, Jeseung; Park, In Ho; Jin Lim, Kook; Shin, Jeon-Soo; Yoo, Kyung-Hwa

2018-04-15

To prevent spread of infection and antibiotic resistance, fast and accurate diagnosis of bacterial infection and subsequent administration of antimicrobial agents are important. However, conventional methods for bacterial detection and antibiotic susceptibility testing (AST) require more than two days, leading to delays that have contributed to an increase in antibiotic-resistant bacteria. Here, we report an aptamer-functionalized capacitance sensor array that can monitor bacterial growth and antibiotic susceptibility in real-time. While E. coli and S. aureus were cultured, the capacitance increased over time, and apparent bacterial growth curves were observed even when 10 CFU/mL bacteria was inoculated. Furthermore, because of the selectivity of aptamers, bacteria could be identified within 1h using the capacitance sensor array functionalized with aptamers. In addition to bacterial growth, antibiotic susceptibility could be monitored in real-time. When bacteria were treated with antibiotics above the minimum inhibitory concentration (MIC), the capacitance decreased because the bacterial growth was inhibited. These results demonstrate that the aptamer-functionalized capacitance sensor array might be applied for rapid ASTs. Copyright © 2017 Elsevier B.V. All rights reserved.

A selective medium for the enumeration and differentiation of Lactobacillus delbrueckii ssp. bulgaricus.

PubMed

Nwamaioha, Nwadiuto O; Ibrahim, Salam A

2018-06-01

Modified reinforced clostridial medium (mRCM) was developed and evaluated for the differential enumeration of Lactobacillus delbrueckii ssp. bulgaricus. Lactobacillus bulgaricus, an important species of lactic acid bacteria with health benefits, is used in the production of yogurt and other fermented foods. Our results showed that supplementing reinforced clostridial medium with 0.025% CaCl 2 , 0.01% uracil, and 0.2% Tween 80 (mRCM) significantly enhanced the growth rate of L. bulgaricus RR and ATCC 11842 strains as measured by the optical densities of these strains after 12 h of incubation at 42°C. The bacterial populations (plate count) of the RR and ATCC 11842 strains were 0.76 and 0.77 log cfu/g higher in mRCM than in de Man, Rogosa, and Sharpe and reinforced clostridial medium media, respectively. Conversely, the population counts for other bacterial species (Bifidobacterium, Lactobacillus rhamnosus, and Lactobacillus reuteri) were significantly inhibited in the mRCM medium. The addition of aniline blue dye to mRCM (mRCM-blue) improved the selectivity of L. bulgaricus in mixed lactic bacterial cultures compared with de Man, Rogosa, and Sharpe medium and lactic agar with regard to colony appearance and morphology. The mRCM-blue performed better than the conventional medium in culturing, enumerating, and differentiating L. bulgaricus. Therefore, mRCM-blue could be used as a selective medium to enhance the growth and differentiation of L. bulgaricus in order to meet the increasing demand for this beneficial species of bacteria. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Analysis of Factors Limiting Bacterial Growth in PDMS Mother Machine Devices.

PubMed

Yang, Da; Jennings, Anna D; Borrego, Evalynn; Retterer, Scott T; Männik, Jaan

2018-01-01

The microfluidic mother machine platform has attracted much interest for its potential in studies of bacterial physiology, cellular organization, and cell mechanics. Despite numerous experiments and development of dedicated analysis software, differences in bacterial growth and morphology in narrow mother machine channels compared to typical liquid media conditions have not been systematically characterized. Here we determine changes in E. coli growth rates and cell dimensions in different sized dead-end microfluidic channels using high resolution optical microscopy. We find that E. coli adapt to the confined channel environment by becoming narrower and longer compared to the same strain grown in liquid culture. Cell dimensions decrease as the channel length increases and width decreases. These changes are accompanied by increases in doubling times in agreement with the universal growth law. In channels 100 μm and longer, cell doublings can completely stop as a result of frictional forces that oppose cell elongation. Before complete cessation of elongation, mechanical stresses lead to substantial deformation of cells and changes in their morphology. Our work shows that mechanical forces rather than nutrient limitation are the main growth limiting factor for bacterial growth in long and narrow channels.

Analysis of Factors Limiting Bacterial Growth in PDMS Mother Machine Devices

DOE PAGES

Yang, Da; Jennings, Anna D.; Borrego, Evalynn; ...

2018-05-01

The microfluidic mother machine platform has attracted much interest for its potential in studies of bacterial physiology, cellular organization, and cell mechanics. Despite numerous experiments and development of dedicated analysis software, differences in bacterial growth and morphology in narrow mother machine channels compared to typical liquid media conditions have not been systematically characterized. Here we determine changes in E. coli growth rates and cell dimensions in different sized dead-end microfluidic channels using high resolution optical microscopy. We find that E. coli adapt to the confined channel environment by becoming narrower and longer compared to the same strain grown in liquidmore » culture. Cell dimensions decrease as the channel length increases and width decreases. These changes are accompanied by increases in doubling times in agreement with the universal growth law. In channels 100 μm and longer, cell doublings can completely stop as a result of frictional forces that oppose cell elongation. Before complete cessation of elongation, mechanical stresses lead to substantial deformation of cells and changes in their morphology. Lastly, our work shows that mechanical forces rather than nutrient limitation are the main growth limiting factor for bacterial growth in long and narrow channels.« less

Analysis of Factors Limiting Bacterial Growth in PDMS Mother Machine Devices

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

Yang, Da; Jennings, Anna D.; Borrego, Evalynn

The microfluidic mother machine platform has attracted much interest for its potential in studies of bacterial physiology, cellular organization, and cell mechanics. Despite numerous experiments and development of dedicated analysis software, differences in bacterial growth and morphology in narrow mother machine channels compared to typical liquid media conditions have not been systematically characterized. Here we determine changes in E. coli growth rates and cell dimensions in different sized dead-end microfluidic channels using high resolution optical microscopy. We find that E. coli adapt to the confined channel environment by becoming narrower and longer compared to the same strain grown in liquidmore » culture. Cell dimensions decrease as the channel length increases and width decreases. These changes are accompanied by increases in doubling times in agreement with the universal growth law. In channels 100 μm and longer, cell doublings can completely stop as a result of frictional forces that oppose cell elongation. Before complete cessation of elongation, mechanical stresses lead to substantial deformation of cells and changes in their morphology. Lastly, our work shows that mechanical forces rather than nutrient limitation are the main growth limiting factor for bacterial growth in long and narrow channels.« less

Theoretical and Experimental Study of Bacterial Colony Growth in 3D

NASA Astrophysics Data System (ADS)

Shao, Xinxian; Mugler, Andrew; Nemenman, Ilya

2014-03-01

Bacterial cells growing in liquid culture have been well studied and modeled. However, in nature, bacteria often grow as biofilms or colonies in physically structured habitats. A comprehensive model for population growth in such conditions has not yet been developed. Based on the well-established theory for bacterial growth in liquid culture, we develop a model for colony growth in 3D in which a homogeneous colony of cells locally consume a diffusing nutrient. We predict that colony growth is initially exponential, as in liquid culture, but quickly slows to sub-exponential after nutrient is locally depleted. This prediction is consistent with our experiments performed with E. coli in soft agar. Our model provides a baseline to which studies of complex growth process, such as such as spatially and phenotypically heterogeneous colonies, must be compared.

PMAnalyzer: a new web interface for bacterial growth curve analysis.

PubMed

Cuevas, Daniel A; Edwards, Robert A

2017-06-15

Bacterial growth curves are essential representations for characterizing bacteria metabolism within a variety of media compositions. Using high-throughput, spectrophotometers capable of processing tens of 96-well plates, quantitative phenotypic information can be easily integrated into the current data structures that describe a bacterial organism. The PMAnalyzer pipeline performs a growth curve analysis to parameterize the unique features occurring within microtiter wells containing specific growth media sources. We have expanded the pipeline capabilities and provide a user-friendly, online implementation of this automated pipeline. PMAnalyzer version 2.0 provides fast automatic growth curve parameter analysis, growth identification and high resolution figures of sample-replicate growth curves and several statistical analyses. PMAnalyzer v2.0 can be found at https://edwards.sdsu.edu/pmanalyzer/ . Source code for the pipeline can be found on GitHub at https://github.com/dacuevas/PMAnalyzer . Source code for the online implementation can be found on GitHub at https://github.com/dacuevas/PMAnalyzerWeb . dcuevas08@gmail.com. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press.

Effect of surgical hand scrub time on subsequent bacterial growth.

PubMed

Wheelock, S M; Lookinland, S

1997-06-01

In this experimental study, the researchers evaluated the effect of surgical hand scrub time on subsequent bacterial growth and assessed the effectiveness of the glove juice technique in a clinical setting. In a randomized crossover design, 25 perioperative staff members scrubbed for two or three minutes in the first trial and vice versa in the second trial, after which the wore sterile surgical gloves for one hour under clinical conditions. The researchers then sampled the subjects' nondominant hands for bacterial growth, cultured aliquots from the sampling solution, and counted microorganisms. Scrubbing for three minutes produced lower mean log bacterial counts than scrubbing for two minutes. Although the mean bacterial count differed significantly (P = .02) between the two-minute and three-minute surgical hand scrub times, it fell below 0.5 log, which is the threshold for practical and clinical significance. This finding suggests that a two-minute surgical hand scrub is clinically as effective as a three-minute surgical had scrub. The glove juice technique demonstrated sensitivity and reliability in enumerating bacteria on the hands of perioperative staff members in a clinical setting.

The effect of growth medium on B. anthracis Sterne spore carbohydrate content.

PubMed

Colburn, Heather A; Wunschel, David S; Antolick, Kathryn C; Melville, Angela M; Valentine, Nancy B

2011-06-01

The expressed characteristics of biothreat agents may be impacted by variations in the culture environment, including growth medium formulation. The carbohydrate composition of B. anthracis spores has been well studied, particularly for the exosporium, which is the outermost spore structure. The carbohydrate composition of the exosporium has been demonstrated to be distinct from the vegetative form containing unique monosaccharides. We have investigated the carbohydrate composition of B. anthracis Sterne spores produced using four different medium types formulated with different sources of medium components. The amount of rhamnose, 3-O-methyl rhamnose and galactosamine was found to vary significantly between spores cultured using different medium formulations. The relative abundance of these monosaccharides compared to other monosaccharides such as mannosamine was also found to vary with medium type. Specific medium components were also found to impact the carbohydrate profile. Xylose has not been previously described in B. anthracis spores but was detected at low levels in two media. This may represent residual material from the brewery yeast extract used to formulate these two media. These results illustrate the utility of this method to capture the impact of growth medium on carbohydrate variation in spores. Detecting carbohydrate profiles in B. anthracis evidentiary material may provide useful forensic information on the growth medium used for sporulation. Copyright © 2011 Elsevier B.V. All rights reserved.

Optimization of medium components and physicochemical parameters to simultaneously enhance microbial growth and production of lypolitic enzymes by Stenotrophomonas sp.

PubMed

Mazzucotelli, Cintia Anabela; Agüero, María Victoria; Del Rosario Moreira, María; Ansorena, María Roberta

2016-05-01

The optimization of lipase and esterase production (LP and EP) and bacterial growth (BG) of a Stenotrophomonas sp. strain was developed. For this purpose, the effect of five different medium components and three physicochemical parameters were evaluated using a Plackett-Burman statistical design. Among eight variables, stirring speed, pH, and peptone concentration were found to be the most effective factors on the three responses under evaluation. An optimization study applying Box-Behnken response surface methodology was used to study the interactive effects of the three selected variables on LP/EP and microorganism growth. Predicted models were found to be significant with high regression coefficients (90%-99%). By using the desirability function approach, the optimum condition applying simultaneous optimization of the three responses under study resulted to be: stirring speed of 100 rpm, pH of 7.5, and a peptone concentration of 10 g/L, with a desirability value of 0.977. Under these optimal conditions, it is possible to achieve in the optimized medium a 15-fold increase in esterase productivity, a 117-fold increase in lipase production, and a 9-log CFU/mL increase in BG, compared with the basal medium without agitation. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

Effect of DSS on Bacterial Growth in Gastrointestinal Tract.

PubMed

Hlinková, J; Svobodová, H; Brachtlová, T; Gardlík, R

2016-01-01

Inflammatory bowel disease is an idiopathic autoimmune disorder that is mainly divided into ulcerative colitis and Crohn's disease. Probiotics are known for their beneficial effect and used as a treatment option in different gastrointestinal problems. The aim of our study was to find suitable bacterial vectors for gene therapy of inflammatory bowel disease. Salmonella enterica serovar Typhimurium SL7207 and Escherichia coli Nissle 1917 were investigated as potential vectors. Our results show that the growth of Escherichia coli Nissle 1917 was inhibited in the majority of samples collected from dextran sodium sulphate-treated animals compared with control growth in phosphate-buffered saline. The growth of Salmonella enterica serovar Typhimurium SL7207 in all investigated samples was enhanced or unaffected in comparison with phosphate-buffered saline; however, it did not reach the growth rates of Escherichia coli Nissle 1917. Dextran sodium sulphate treatment had a stimulating effect on the growth of both strains in homogenates of distant small intestine and proximal colon samples. The gastrointestinal tract contents and tissue homogenates did not inhibit growth of Salmonella enterica serovar Typhimurium SL7207 in comparison with the negative control, and provided more suitable environment for growth compared to Escherichia coli Nissle 1917. We therefore conclude that Salmonella enterica serovar Typhimurium SL7207 is a more suitable candidate for a potential bacterial vector, even though it has no known probiotic properties.

Development of a novel artificial medium based on utilization of algal photosynthetic metabolites by symbiotic heterotrophs.

PubMed

Watanabe, K; Imase, M; Aoyagi, H; Ohmura, N; Saiki, H; Tanaka, H

2008-09-01

(i) Quantitative and qualitative analyses of photosynthetic metabolites of Chlorella sorokiniana and elucidation of the mechanism of their utilization by algal symbionts. (ii) Development of artificial medium that imitates photoautotroph-heterotroph interaction and investigation of its suitability for isolation of novel microbes from the environment. Various components, including free dissolved carbohydrates, nitrogenous compounds and vitamin, were detected and together contributed 11.1% (as carbon content) of the total photosynthetic metabolites in the medium. Utilization of these photosynthetic metabolites in algal culture broth by algal symbionts was studied. Many symbionts showed specific utilization patterns. A novel artificial extracellular released organic carbon medium, which imitated the nutritional conditions surrounding algae, was developed based on the pattern of utilization of the algal metabolites by the symbiotic heterotrophs. About 42.9% of the isolates were closely related to photoautotrophic-dependent and oligotrophic bacteria. With the novel artificial medium, it was possible to selectively isolate some bacterial strains. Synthetic bacterial growth medium is an important and basic tool for bacterial isolation from environmental samples. The current study shows that preferential separation of typical bacterial subset can be achieved by using artificial medium that mimics photosynthetic metabolites.

A Novel Biocontainment Strategy Makes Bacterial Growth and Survival Dependent on Phosphite.

PubMed

Hirota, Ryuichi; Abe, Kenji; Katsuura, Zen-Ichiro; Noguchi, Reiji; Moribe, Shigeaki; Motomura, Kei; Ishida, Takenori; Alexandrov, Maxym; Funabashi, Hisakage; Ikeda, Takeshi; Kuroda, Akio

2017-03-20

There is a growing demand to develop biocontainment strategies that prevent unintended proliferation of genetically modified organisms in the open environment. We found that the hypophosphite (H 3 PO 2 , HPt) transporter HtxBCDE from Pseudomonas stutzeri WM88 was also capable of transporting phosphite (H 3 PO 3 , Pt) but not phosphate (H 3 PO 4 , Pi), suggesting the potential for engineering a Pt/HPt-dependent bacterial strain as a biocontainment strategy. We disrupted all Pi and organic Pi transporters in an Escherichia coli strain expressing HtxABCDE and a Pt dehydrogenase, leaving Pt/HPt uptake and oxidation as the only means to obtain Pi. Challenge on non-permissive growth medium revealed that no escape mutants appeared for at least 21 days with a detection limit of 1.94 × 10 -13 per colony forming unit. This represents, to the best of our knowledge, the lowest escape frequency among reported strategies. Since Pt/HPt are ecologically rare and not available in amounts sufficient for the growth of the Pt/HPt-dependent bacteria, this strategy offers a reliable and practical method for biocontainment.

Modulation of Medium pH by Caulobacter crescentus Facilitates Recovery from Uranium-Induced Growth Arrest

PubMed Central

Park, Dan M.

2014-01-01

The oxidized form of uranium [U(VI)] predominates in oxic environments and poses a major threat to ecosystems. Due to its ability to mineralize U(VI), the oligotroph Caulobacter crescentus is an attractive candidate for U(VI) bioremediation. However, the physiological basis for U(VI) tolerance is unclear. Here we demonstrated that U(VI) caused a temporary growth arrest in C. crescentus and three other bacterial species, although the duration of growth arrest was significantly shorter for C. crescentus. During the majority of the growth arrest period, cell morphology was unaltered and DNA replication initiation was inhibited. However, during the transition from growth arrest to exponential phase, cells with shorter stalks were observed, suggesting a decoupling between stalk development and the cell cycle. Upon recovery from growth arrest, C. crescentus proliferated with a growth rate comparable to that of a control without U(VI), although a fraction of these cells appeared filamentous with multiple replication start sites. Normal cell morphology was restored by the end of exponential phase. Cells did not accumulate U(VI) resistance mutations during the prolonged growth arrest, but rather, a reduction in U(VI) toxicity occurred concomitantly with an increase in medium pH. Together, these data suggest that C. crescentus recovers from U(VI)-induced growth arrest by reducing U(VI) toxicity through pH modulation. Our finding represents a unique U(VI) detoxification strategy and provides insight into how microbes cope with U(VI) under nongrowing conditions, a metabolic state that is prevalent in natural environments. PMID:25002429

Growth medium for the rapid isolation and identification of anthrax

NASA Astrophysics Data System (ADS)

Kiel, Johnathan L.; Parker, Jill E.; Grubbs, Teri R.; Alls, John L.

2000-07-01

Anthrax has been recognized as a highly likely biological warfare or terrorist agent. The purpose of this work was to design a culture technique to rapidly isolate and identify `live' anthrax. In liquid or solid media form, 3AT medium (3-amino-L-tyrosine, the main ingredient) accelerated germination and growth of anthrax spores in 5 to 6 hours to a point expected at 18 to 24 hours with ordinary medium. During accelerated growth, standard definitive diagnostic tests such as sensitivity to lysis by penicillin or bacteriophage can be run. During this time, the bacteria synthesized a fluorescent and thermochemiluminescent polymer. Bacteria captured by specific antibody are, therefore, already labeled. Because living bacteria are required to generate the polymer, the test converts immunoassays for anthrax into viability assays. Furthermore, the polymer formation leads to the death of the vegetative form and non-viability of the spores produced in the medium. By altering the formulation of the medium, other microbes and even animal and human cells can be grown in it and labeled (including viruses grown in the animal or human cells).

Escherichia coli growth changes by the mediated effects after low-intensity electromagnetic irradiation of extremely high frequencies.

PubMed

Torgomyan, Heghine; Hovnanyan, Karlen; Trchounian, Armen

2013-04-01

Water is the major constituent of environmental medium and biological systems. The effects occurring in water as a result of low-intensity electromagnetic irradiation (EMI) in extremely high frequencies are supposed to be the primary mechanism to create conditions for biological responses. The EMI effects on Escherichia coli, after irradiation of their suspension, are most probably water-mediated. Indirect effects of EMI at 51.8, 53, 70.6, and 73 GHz frequencies on bacteria, through water, assay buffer (Tris-phosphate buffer with inorganic salts at low or moderate concentrations), or peptone growth medium were studied. The mediated effects of 70.6 and 73 GHz irradiated water, assay buffer, and growth medium on E. coli growth characteristics were insignificant. But the results were different for 51.8 and 53 GHz. EMI mediated effects on bacterial growth were clearly demonstrated. The effects were more strongly expressed with 53 GHz. Moreover, it was shown that 70.6 and 73 GHz similarly suppressed the cell growth after direct irradiation of E. coli in water or on solid medium. Interestingly, for 51.8 and 53 GHz the bacterial growth decreases after suspension irradiation was less, compared to the direct irradiation of bacteria on solid medium. Especially, it was also more expressed in case of 53 GHz. Also with electron microscopy, EMI-induced bacterial cell sizes and structure different changes were detected. In addition, the distinguished changes in surface tension, oxidation-reduction potential and pH of water, assay buffer, growth medium, and bacterial suspension were determined. They depended on EMI frequency used. The differences could be associated with the partial absorbance of EMI energy by the surrounding medium, which depends on a specific frequency. The results are crucial to understand biophysical mechanisms of EMI effects on bacteria.

Spatial Patterning of Newly-Inserted Material during Bacterial Cell Growth

NASA Astrophysics Data System (ADS)

Ursell, Tristan

2012-02-01

In the life cycle of a bacterium, rudimentary microscopy demonstrates that cell growth and elongation are essential characteristics of cellular reproduction. The peptidoglycan cell wall is the main load-bearing structure that determines both cell shape and overall size. However, simple imaging of cellular growth gives no indication of the spatial patterning nor mechanism by which material is being incorporated into the pre-existing cell wall. We employ a combination of high-resolution pulse-chase fluorescence microscopy, 3D computational microscopy, and detailed mechanistic simulations to explore how spatial patterning results in uniform growth and maintenance of cell shape. We show that growth is happening in discrete bursts randomly distributed over the cell surface, with a well-defined mean size and average rate. We further use these techniques to explore the effects of division and cell wall disrupting antibiotics, like cephalexin and A22, respectively, on the patterning of cell wall growth in E. coli. Finally, we explore the spatial correlation between presence of the bacterial actin-like cytoskeletal protein, MreB, and local cell wall growth. Together these techniques form a powerful method for exploring the detailed dynamics and involvement of antibiotics and cell wall-associated proteins in bacterial cell growth.[4pt] In collaboration with Kerwyn Huang, Stanford University.

Accelerating bacterial growth detection and antimicrobial susceptibility assessment in integrated picoliter droplet platform.

PubMed

Kaushik, Aniruddha M; Hsieh, Kuangwen; Chen, Liben; Shin, Dong Jin; Liao, Joseph C; Wang, Tza-Huei

2017-11-15

There remains an urgent need for rapid diagnostic methods that can evaluate antibiotic resistance for pathogenic bacteria in order to deliver targeted antibiotic treatments. Toward this end, we present a rapid and integrated single-cell biosensing platform, termed dropFAST, for bacterial growth detection and antimicrobial susceptibility assessment. DropFAST utilizes a rapid resazurin-based fluorescent growth assay coupled with stochastic confinement of bacteria in 20 pL droplets to detect signal from growing bacteria after 1h incubation, equivalent to 2-3 bacterial replications. Full integration of droplet generation, incubation, and detection into a single, uninterrupted stream also renders this platform uniquely suitable for in-line bacterial phenotypic growth assessment. To illustrate the concept of rapid digital antimicrobial susceptibility assessment, we employ the dropFAST platform to evaluate the antibacterial effect of gentamicin on E. coli growth. Copyright © 2017 Elsevier B.V. All rights reserved.

Bacterial growth on stream insects: potential for use in bioassessment

Treesearch

A. Dennis Lemly

1998-01-01

Growth of filamentous bacteria (Sphaerotilus sp., Leptothrix sp.) on aquatic insects was evaluated for its usefulness as a bioindicator of detrimental nutrient levels in streams. Field measurements of insect abundance, nutrient concentrations, and incidence/ degree of bacterial growth on insects upstream and downstream of livestock pastures were made in 2 Virginia, USA...

Revisiting the host as a growth medium

PubMed Central

Brown, Stacie A.; Palmer, Kelli L.; Whiteley, Marvin

2011-01-01

The ability of the human body to play host to bacterial pathogens has been studied for more than 200 years. Successful pathogenesis relies on the ability to acquire the nutrients that are necessary for growth and survival, yet relatively little is understood about the in vivo physiology and metabolism of most human pathogens. This Review discusses how in vivo carbon sources can affect disease and highlights the concept that carbon metabolic pathways provide viable targets for antibiotic development. PMID:18679171

Malt-yeast extract-sucrose agar, a suitable medium for enumeration and isolation of fungi from silage.

PubMed Central

Skaar, I; Stenwig, H

1996-01-01

A general medium named malt-yeast extract-sucrose agar (MYSA) containing oxgall was designed. The medium was intended for the enumeration and isolation of molds and yeasts in routine examinations of animal feed stuffs. In this study MYSA was tested as a general medium for mycological examination of silage. The medium was compared with dichloran-rose bengal medium (DRBC) in an examination of more than 500 specimens of big bale grass silage. Selected characteristics of known fungal species commonly isolated from feeds were examined after growth on MYSA and DRBC and on malt extract agar, used as a noninhibitory control medium. MYSA suppressed bacterial growth, without affecting the growth of fungi common in feeds. The fungi growing on MYSA were easily recognized, and the medium seemed to slow radial growth of fungal colonies, which permitted, easy counting. The number of species found was higher on MYSA than on DRBC. When we compared MYSA with DRBC for mycological examination of grass silage samples, MYSA was found to be the medium of choice. PMID:8837416

Flow and active mixing have a strong impact on bacterial growth dynamics in the proximal large intestine

NASA Astrophysics Data System (ADS)

Cremer, Jonas; Segota, Igor; Yang, Chih-Yu; Arnoldini, Markus; Groisman, Alex; Hwa, Terence

2016-11-01

More than half of fecal dry weight is bacterial mass with bacterial densities reaching up to 1012 cells per gram. Mostly, these bacteria grow in the proximal large intestine where lateral flow along the intestine is strong: flow can in principal lead to a washout of bacteria from the proximal large intestine. Active mixing by contractions of the intestinal wall together with bacterial growth might counteract such a washout and allow high bacterial densities to occur. As a step towards understanding bacterial growth in the presence of mixing and flow, we constructed an in-vitro setup where controlled wall-deformations of a channel emulate contractions. We investigate growth along the channel under a steady nutrient inflow. Depending on mixing and flow, we observe varying spatial gradients in bacterial density along the channel. Active mixing by deformations of the channel wall is shown to be crucial in maintaining a steady-state bacterial population in the presence of flow. The growth-dynamics is quantitatively captured by a simple mathematical model, with the effect of mixing described by an effective diffusion term. Based on this model, we discuss bacterial growth dynamics in the human large intestine using flow- and mixing-behavior having been observed for humans.

Cooperative Bacterial Growth Dynamics Predict the Evolution of Antibiotic Resistance

NASA Astrophysics Data System (ADS)

Artemova, Tatiana; Gerardin, Ylaine; Hsin-Jung Li, Sophia; Gore, Jeff

2011-03-01

Since the discovery of penicillin, antibiotics have been our primary weapon against bacterial infections. Unfortunately, bacteria can gain resistance to penicillin by acquiring the gene that encodes beta-lactamase, which inactivates the antibiotic. However, mutations in this gene are necessary to degrade the modern antibiotic cefotaxime. Understanding the conditions that favor the spread of these mutations is a challenge. Here we show that bacterial growth in beta-lactam antibiotics is cooperative and that the nature of this growth determines the conditions in which resistance evolves. Quantitative analysis of the growth dynamics predicts a peak in selection at very low antibiotic concentrations; competition between strains confirms this prediction. We also find significant selection at higher antibiotic concentrations, close to the minimum inhibitory concentrations of the strains. Our results argue that an understanding of the evolutionary forces that lead to antibiotic resistance requires a quantitative understanding of the evolution of cooperation in bacteria.

Evaluation of environmental bacterial communities as a factor affecting the growth of duckweed Lemna minor.

PubMed

Ishizawa, Hidehiro; Kuroda, Masashi; Morikawa, Masaaki; Ike, Michihiko

2017-01-01

Duckweed (family Lemnaceae ) has recently been recognized as an ideal biomass feedstock for biofuel production due to its rapid growth and high starch content, which inspired interest in improving their productivity. Since microbes that co-exist with plants are known to have significant effects on their growth according to the previous studies for terrestrial plants, this study has attempted to understand the plant-microbial interactions of a duckweed, Lemna minor , focusing on the growth promotion/inhibition effects so as to assess the possibility of accelerated duckweed production by modifying co-existing bacterial community. Co-cultivation of aseptic L. minor and bacterial communities collected from various aquatic environments resulted in changes in duckweed growth ranging from -24 to +14% compared to aseptic control. A number of bacterial strains were isolated from both growth-promoting and growth-inhibitory communities, and examined for their co-existing effects on duckweed growth. Irrespective of the source, each strain showed promotive, inhibitory, or neutral effects when individually co-cultured with L. minor . To further analyze the interactions among these bacterial strains in a community, binary combinations of promotive and inhibitory strains were co-cultured with aseptic L. minor , resulting in that combinations of promotive-promotive or inhibitory-inhibitory strains generally showed effects similar to those of individual strains. However, combinations of promotive-inhibitory strains tended to show inhibitory effects while only Aquitalea magnusonii H3 exerted its plant growth-promoting effect in all combinations tested. Significant change in biomass production was observed when duckweed was co-cultivated with environmental bacterial communities. Promotive, neutral, and inhibitory bacteria in the community would synergistically determine the effects. The results indicate the possibility of improving duckweed biomass production via regulation of co

Supplemental oxygen attenuates the increase in wound bacterial growth during simulated aeromedical evacuation in goats.

PubMed

Earnest, Ryan E; Sonnier, Dennis I; Makley, Amy T; Campion, Eric M; Wenke, Joseph C; Bailey, Stephanie R; Dorlac, Warren C; Lentsch, Alex B; Pritts, Timothy A

2012-07-01

Bacterial growth in soft tissue and open fractures is a known risk factor for tissue loss and complications in contaminated musculoskeletal wounds. Current care for battlefield casualties with soft tissue and musculoskeletal wounds includes tactical and strategic aeromedical evacuation (AE). This exposes patients to a hypobaric, hypoxic environment. In this study, we sought to determine whether exposure to AE alters bacterial growth in contaminated complex musculoskeletal wounds and whether supplemental oxygen had any effect on wound infections during simulated AE. A caprine model of a contaminated complex musculoskeletal wound was used. Complex musculoskeletal wounds were created and inoculated with bioluminescent Pseudomonas aeruginosa. Goats were divided into three experimental groups: ground control, simulated AE, and simulated AE with supplemental oxygen. Simulated AE was induced in a hypobaric chamber pressurized to 8,800 feet for 7 hours. Bacterial luminescence was measured using a photon counting camera at three time points: preflight (20 hours postsurgery), postflight (7 hours from preflight and 27 hours postsurgery), and necropsy (24 hours from preflight and 44 hours postsurgery). There was a significant increase in bacterial growth in the AE group compared with the ground control group measured postflight and at necropsy. Simulated AE induced hypoxia with oxygen saturation less than 93%. Supplemental oxygen corrected the hypoxia and significantly reduced bacterial growth in wounds at necropsy. Hypoxia induced during simulated AE enhances bacterial growth in complex musculoskeletal wounds which can be prevented with the application of supplemental oxygen to the host.

Induction of gram-negative bacterial growth by neurochemical containing banana (Musa x paradisiaca) extracts.

PubMed

Lyte, M

1997-09-15

Bananas contain large quantities of neurochemicals. Extracts from the peel and pulp of bananas in increasing stages of ripening were prepared and evaluated for their ability to modulate the growth of non-pathogenic and pathogenic bacteria. Extracts from the peel, and to a much lesser degree the pulp, increased the growth of Gram-negative bacterial strains Escherichia coli O157:H7, Shigella flexneri, Enterobacter cloacae and Salmonella typhimurium, as well as two non-pathogenic E. coli strains, in direct relation to the content of norepinephrine and dopamine, but not serotonin. The growth of Gram-positive bacteria was not altered by any of the extracts. Supplementation of vehicle and pulp cultures with norepinephrine or dopamine yielded growth equivalent to peel cultures. Total organic analysis of extracts further demonstrated that the differential effects of peel and pulp on bacterial growth was not nutritionally based, but due to norepinephrine and dopamine. These results suggest that neurochemicals contained within foodstuffs may influence the growth of pathogenic and indigenous bacteria through direct neurochemical-bacterial interactions.

Universality in Bacterial Colonies

NASA Astrophysics Data System (ADS)

Bonachela, Juan A.; Nadell, Carey D.; Xavier, João B.; Levin, Simon A.

2011-07-01

The emergent spatial patterns generated by growing bacterial colonies have been the focus of intense study in physics during the last twenty years. Both experimental and theoretical investigations have made possible a clear qualitative picture of the different structures that such colonies can exhibit, depending on the medium on which they are growing. However, there are relatively few quantitative descriptions of these patterns. In this paper, we use a mechanistically detailed simulation framework to measure the scaling exponents associated with the advancing fronts of bacterial colonies on hard agar substrata, aiming to discern the universality class to which the system belongs. We show that the universal behavior exhibited by the colonies can be much richer than previously reported, and we propose the possibility of up to four different sub-phases within the medium-to-high nutrient concentration regime. We hypothesize that the quenched disorder that characterizes one of these sub-phases is an emergent property of the growth and division of bacteria competing for limited space and nutrients.

A dynamic regression analysis tool for quantitative assessment of bacterial growth written in Python.

PubMed

Hoeflinger, Jennifer L; Hoeflinger, Daniel E; Miller, Michael J

2017-01-01

Herein, an open-source method to generate quantitative bacterial growth data from high-throughput microplate assays is described. The bacterial lag time, maximum specific growth rate, doubling time and delta OD are reported. Our method was validated by carbohydrate utilization of lactobacilli, and visual inspection revealed 94% of regressions were deemed excellent. Copyright © 2016 Elsevier B.V. All rights reserved.

Ellipsometric Measurement of Bacterial Films at Metal-Electrolyte Interfaces

PubMed Central

Busalmen, J. P.; de Sánchez, S. R.; Schiffrin, D. J.

1998-01-01

Ellipsometric measurements were used to monitor the formation of a bacterial cell film on polarized metal surfaces (Al-brass and Ti). Under cathodic polarization bacterial attachment was measured from changes in the ellipsometric angles. These were fitted to an effective medium model for a nonabsorbing bacterial film with an effective refractive index (nf) of 1.38 and a thickness (df) of 160 ± 10 nm. From the optical measurements a surface coverage of 17% was estimated, in agreement with direct microscopic observations. The influence of bacteria on the formation of oxide films was monitored by ellipsometry following the film growth in situ. A strong inhibition of metal oxide film formation was observed, which was assigned to the decrease in oxygen concentration due to the presence of bacteria. It is shown that the irreversible adhesion of bacteria to the surface can be monitored ellipsometrically. Electrophoretic mobility is proposed as one of the factors determining bacterial attachment. The high sensitivity of ellipsometry and its usefulness for the determination of growth of interfacial bacterial films is demonstrated. PMID:9758786

Wall Teichoic Acids Are Involved in the Medium-Induced Loss of Function of the Autolysin CD11 against Clostridium difficile

PubMed Central

Wu, Xia; Paskaleva, Elena E.; Mehta, Krunal K.; Dordick, Jonathan S.; Kane, Ravi S.

2016-01-01

Bacterial lysins are potent antibacterial enzymes with potential applications in the treatment of bacterial infections. Some lysins lose activity in the growth media of target bacteria, and the underlying mechanism remains unclear. Here we use CD11, an autolysin of Clostridium difficile, as a model lysin to demonstrate that the inability of this enzyme to kill C. difficile in growth medium is not associated with inhibition of the enzyme activity by medium, or the modification of the cell wall peptidoglycan. Rather, wall teichoic acids (WTAs) appear to prevent the enzyme from binding to the cells and cleaving the cell wall peptidoglycan. By partially blocking the biosynthetic pathway of WTAs with tunicamycin, cell binding improved and the lytic efficacy of CD11 was significantly enhanced. This is the first report of the mechanism of lysin inactivation in growth medium, and provides insights into understanding the behavior of lysins in complex environments, including the gastrointestinal tract. PMID:27759081

The effect of temperature and bacterial growth phase on protein extraction by means of electroporation.

PubMed

Haberl-Meglič, Saša; Levičnik, Eva; Luengo, Elisa; Raso, Javier; Miklavčič, Damijan

2016-12-01

Different chemical and physical methods are used for extraction of proteins from bacteria, which are used in variety of fields. But on a large scale, many methods have severe drawbacks. Recently, extraction by means of electroporation showed a great potential to quickly obtain proteins from bacteria. Since many parameters are affecting the yield of extracted proteins, our aim was to investigate the effect of temperature and bacterial growth phase on the yield of extracted proteins. At the same time bacterial viability was tested. Our results showed that the temperature has a great effect on protein extraction, the best temperature post treatment being 4°C. No effect on bacterial viability was observed for all temperatures tested. Also bacterial growth phase did not affect the yield of extracted proteins or bacterial viability. Nevertheless, further experiments may need to be performed to confirm this observation, since only one incubation temperature (4°C) and one incubation time before and after electroporation (0.5 and 1h) were tested for bacterial growth phase. Based on our results we conclude that temperature is a key element for bacterial membrane to stay in a permeabilized state, so more proteins flow out of bacteria into surrounding media. Copyright © 2016 Elsevier B.V. All rights reserved.

Consequences of packaging on bacterial growth. Meat is an ecological niche.

PubMed

Labadie, J

1999-07-01

Meat is a good support for bacterial growth and particularly for bacteria which are specific of meat and meat products. Little is known about the physiological and biochemical factors which could explain why some bacterial species are only isolated from meat. This review tentatively points out, from an ecological point of view, some of these factors in Gram negative and Gram positive micro-organisms influencing storage life.

Gradient microfluidics enables rapid bacterial growth inhibition testing.

PubMed

Li, Bing; Qiu, Yong; Glidle, Andrew; McIlvenna, David; Luo, Qian; Cooper, Jon; Shi, Han-Chang; Yin, Huabing

2014-03-18

Bacterial growth inhibition tests have become a standard measure of the adverse effects of inhibitors for a wide range of applications, such as toxicity testing in the medical and environmental sciences. However, conventional well-plate formats for these tests are laborious and provide limited information (often being restricted to an end-point assay). In this study, we have developed a microfluidic system that enables fast quantification of the effect of an inhibitor on bacteria growth and survival, within a single experiment. This format offers a unique combination of advantages, including long-term continuous flow culture, generation of concentration gradients, and single cell morphology tracking. Using Escherichia coli and the inhibitor amoxicillin as one model system, we show excellent agreement between an on-chip single cell-based assay and conventional methods to obtain quantitative measures of antibiotic inhibition (for example, minimum inhibition concentration). Furthermore, we show that our methods can provide additional information, over and above that of the standard well-plate assay, including kinetic information on growth inhibition and measurements of bacterial morphological dynamics over a wide range of inhibitor concentrations. Finally, using a second model system, we show that this chip-based systems does not require the bacteria to be labeled and is well suited for the study of naturally occurring species. We illustrate this using Nitrosomonas europaea, an environmentally important bacteria, and show that the chip system can lead to a significant reduction in the period required for growth and inhibition measurements (<4 days, compared to weeks in a culture flask).

Using Bacterial Growth on Insects to Assess Nutrient Impacts in Streams

Treesearch

A. Dennis Lemly

2000-01-01

A combination field and laboratory study was conducted to evaluate the ability of a recently developed bioindicator to detect detrimental nutrient conditions in streams. The method utilizes bacterial growth on aquatic insects to determine nutrient impacts. Field investigations indicated that elevated concentrations of nitrate and phosphate were associated with growth...

Growth mechanics of bacterial cell wall and morphology of bacteria

NASA Astrophysics Data System (ADS)

Jiang, Hongyuan; Sun, Sean

2010-03-01

The peptidoglycan cell wall of bacteria is responsible for maintaining the cell shape and integrity. During the bacterial life cycle, the growth of the cell wall is affected by mechanical stress and osmotic pressure internal to the cell. We develop a theory to describe cell shape changes under the influence of mechanical forces. We find that the theory predicts a steady state size and shape for bacterial cells ranging from cocci to spirillum. Moreover, the theory suggest a mechanism by which bacterial cytoskeletal proteins such as MreB and crescentin can maintain the shape of the cell. The theory can also explain the several recent experiments on growing bacteria in micro-environments.

Diamagnetic levitation enhances growth of liquid bacterial cultures by increasing oxygen availability

PubMed Central

Dijkstra, Camelia E.; Larkin, Oliver J.; Anthony, Paul; Davey, Michael R.; Eaves, Laurence; Rees, Catherine E. D.; Hill, Richard J. A.

2011-01-01

Diamagnetic levitation is a technique that uses a strong, spatially varying magnetic field to reproduce aspects of weightlessness, on the Earth. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 h, to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture and reduces the sedimentation rate of the cells. Further experiments and microarray gene analysis show that the increase in growth rate is owing to enhanced oxygen availability. We also demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause convection during the aerobic phases of bacterial growth. We propose that this convection enhances oxygen availability by transporting oxygen around the liquid culture. Since this process results from the strong magnetic field, it is not present in other weightless environments, e.g. in Earth orbit. Hence, these results are of significance and timely to researchers considering the use of diamagnetic levitation to explore effects of weightlessness on living organisms and on physical phenomena. PMID:20667843

Diamagnetic levitation enhances growth of liquid bacterial cultures by increasing oxygen availability.

PubMed

Dijkstra, Camelia E; Larkin, Oliver J; Anthony, Paul; Davey, Michael R; Eaves, Laurence; Rees, Catherine E D; Hill, Richard J A

2011-03-06

Diamagnetic levitation is a technique that uses a strong, spatially varying magnetic field to reproduce aspects of weightlessness, on the Earth. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 h, to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture and reduces the sedimentation rate of the cells. Further experiments and microarray gene analysis show that the increase in growth rate is owing to enhanced oxygen availability. We also demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause convection during the aerobic phases of bacterial growth. We propose that this convection enhances oxygen availability by transporting oxygen around the liquid culture. Since this process results from the strong magnetic field, it is not present in other weightless environments, e.g. in Earth orbit. Hence, these results are of significance and timely to researchers considering the use of diamagnetic levitation to explore effects of weightlessness on living organisms and on physical phenomena.

Chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of animal bacterial pathogens.

PubMed

Ebrahimi, Azizollah; Hemati, Majid; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Khoshnood, Sheida; Khubani, Shahin; Dokht Faraj, Mahdi; Hakimi Alni, Reza

2014-05-01

To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals. The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens. Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus. aureus and Streptococcus agalactiae (10 isolates for each) were examined for chlorhexidine digluconate effects on biofilm formation and planktonic growth using microtiter plates. In all of the examined strains in the presence of chlorhexidine digluconate, biofilm development and planktonic growth were affected at the same concentrations of the disinfectant. Chlorhexidine digluconate inhibited the planktonic growth of different bacterial species at sub-MICs. But they were able to induce biofilm development of the E. coli, Salmonella spp., S. aureus and Str. agalactiae strains. Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains.

Chemical interference with iron transport systems to suppress bacterial growth of Streptococcus pneumoniae.

PubMed

Yang, Xiao-Yan; Sun, Bin; Zhang, Liang; Li, Nan; Han, Junlong; Zhang, Jing; Sun, Xuesong; He, Qing-Yu

2014-01-01

Iron is an essential nutrient for the growth of most bacteria. To obtain iron, bacteria have developed specific iron-transport systems located on the membrane surface to uptake iron and iron complexes such as ferrichrome. Interference with the iron-acquisition systems should be therefore an efficient strategy to suppress bacterial growth and infection. Based on the chemical similarity of iron and ruthenium, we used a Ru(II) complex R-825 to compete with ferrichrome for the ferrichrome-transport pathway in Streptococcus pneumoniae. R-825 inhibited the bacterial growth of S. pneumoniae and stimulated the expression of PiuA, the iron-binding protein in the ferrichrome-uptake system on the cell surface. R-825 treatment decreased the cellular content of iron, accompanying with the increase of Ru(II) level in the bacterium. When the piuA gene (SPD_0915) was deleted in the bacterium, the mutant strain became resistant to R-825 treatment, with decreased content of Ru(II). Addition of ferrichrome can rescue the bacterial growth that was suppressed by R-825. Fluorescence spectral quenching showed that R-825 can bind with PiuA in a similar pattern to the ferrichrome-PiuA interaction in vitro. These observations demonstrated that Ru(II) complex R-825 can compete with ferrichrome for the ferrichrome-transport system to enter S. pneumoniae, reduce the cellular iron supply, and thus suppress the bacterial growth. This finding suggests a novel antimicrobial approach by interfering with iron-uptake pathways, which is different from the mechanisms used by current antibiotics.

Impact assessment of silver nanoparticles on plant growth and soil bacterial diversity.

PubMed

Pallavi; Mehta, C M; Srivastava, Rashmi; Arora, Sandeep; Sharma, A K

2016-12-01

The present study was carried out to investigate the impact of silver nanoparticles (AgNPs) on the growth of three different crop species, wheat (Triticum aestivum, var. UP2338), cowpea (Vigna sinensis, var. Pusa Komal), and Brassica (Brassica juncea, var. Pusa Jai Kisan), along with their impact on the rhizospheric bacterial diversity. Three different concentrations (0, 50 and 75 ppm) of AgNPs were applied through foliar spray. After harvesting, shoot and root parameters were compared, and it was observed that wheat was relatively unaffected by all AgNP treatments. The optimum growth promotion and increased root nodulation were observed at 50 ppm treatment in cowpea, while improved shoot parameters were recorded at 75 ppm in Brassica. To observe the impact of AgNPs on soil bacterial community, sampling was carried out from the rhizosphere of these crops at 20 and 40 days after the spraying of AgNPS. The bacterial diversity of these samples was analyzed by both cultural and molecular techniques (denaturing gradient gel electrophoresis). It is clearly evident from the results that application of AgNPs changes the soil bacterial diversity and this is further influenced by the plant species grown in that soil. Also, the functional bacterial diversity differed with different concentrations of AgNPs.

Cost-effective production of bacterial cellulose using acidic food industry by-products.

PubMed

Revin, Victor; Liyaskina, Elena; Nazarkina, Maria; Bogatyreva, Alena; Shchankin, Mikhail

2018-03-13

To reduce the cost of obtaining bacterial cellulose, acidic by-products of the alcohol and dairy industries were used without any pretreatment or addition of other nitrogen sources. Studies have shown that the greatest accumulation of bacterial cellulose (6.19g/L) occurs on wheat thin stillage for 3 days of cultivation under dynamic conditions, which is almost 3 times higher than on standard Hestrin and Schramm medium (2.14g/L). The use of whey as a nutrient medium makes it possible to obtain 5.45g/L bacterial cellulose under similar conditions of cultivation. It is established that the pH of the medium during the growth of Gluconacetobacter sucrofermentans B-11267 depends on the feedstock used and its initial value. By culturing the bacterium on thin stillage and whey, there is a decrease in the acidity of the waste. It is shown that the infrared spectra of bacterial cellulose obtained in a variety of environments have a similar character, but we found differences in the micromorphology and crystallinity of the resulting biopolymer. Copyright © 2018 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Chlorhexidine Digluconate Effects on Planktonic Growth and Biofilm Formation in Some Field Isolates of Animal Bacterial Pathogens

PubMed Central

Ebrahimi, Azizollah; Hemati, Majid; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Khoshnood, Sheida; Khubani, Shahin; Dokht Faraj, Mahdi; Hakimi Alni, Reza

2014-01-01

Background: To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals. Objectives: The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens. Materials and Methods: Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus. aureus and Streptococcus agalactiae (10 isolates for each) were examined for chlorhexidine digluconate effects on biofilm formation and planktonic growth using microtiter plates. In all of the examined strains in the presence of chlorhexidine digluconate, biofilm development and planktonic growth were affected at the same concentrations of the disinfectant. Results: Chlorhexidine digluconate inhibited the planktonic growth of different bacterial species at sub-MICs. But they were able to induce biofilm development of the E. coli, Salmonella spp., S. aureus and Str. agalactiae strains. Conclusions: Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains. PMID:24872940

Bacterial growth and the decomposition of particulate organic carbon collected in sediment traps

NASA Astrophysics Data System (ADS)

Ducklow, Hugh W.; Hill, Suzanne M.; Gardner, Wilford D.

We have studied bacterial abundance and production in samples from sediment traps deployed for 1 and 100 days in several areas of the shelf and slope regions of the Middle Atlantic Bight, U.S.A. By making a series of assumptions about bacterial growth at the expense of POC in traps, we have estimated that the turnover time of organic particles collected in traps during long deployments is slow (mean 1500 ± 300 days), if only bacterial activity is considered. However the abundance and biomass of bacteria in traps is very high, ranging from 3 to 30 × 10 11 cells gC -1, i.e., 0.3 to 3% of the POC is bacterial carbon. Fifteen to 88% of the particles in traps were colonized by bacteria, but usually about half the particles had only 0 to 1 cell attached. Growth of bacteria was observed at all scales relevant to these trap deployments; over periods ranging from hours to weeks, at rates of 0.01 to 0.3 d -1. In spite of slow growth, bacteria appeared to be physiologically active in that [ 3H]adenine and [ 3H]thymidine were incorporated more rapidly into RNA and protein than into DNA. Total incorporation rates were high. We conclude that even relatively old (ca. 1 y) POC in sediment traps supports high levels of active bacterial biomass, but that POC decomposition is slow, so that bacteria may not be the principal agents of POC turnover following collection.

Bacterial Cell Growth Inhibitors Targeting Undecaprenyl Diphosphate Synthase and Undecaprenyl Diphosphate Phosphatase.

PubMed

Wang, Yang; Desai, Janish; Zhang, Yonghui; Malwal, Satish R; Shin, Christopher J; Feng, Xinxin; Sun, Hong; Liu, Guizhi; Guo, Rey-Ting; Oldfield, Eric

2016-10-19

We synthesized a series of benzoic acids and phenylphosphonic acids and investigated their effects on the growth of Staphylococcus aureus and Bacillus subtilis. One of the most active compounds, 5-fluoro-2-(3-(octyloxy)benzamido)benzoic acid (7, ED 50 ∼0.15 μg mL -1 ) acted synergistically with seven antibiotics known to target bacterial cell-wall biosynthesis (a fractional inhibitory concentration index (FICI) of ∼0.35, on average) but had indifferent effects in combinations with six non-cell-wall biosynthesis inhibitors (average FICI∼1.45). The most active compounds were found to inhibit two enzymes involved in isoprenoid/bacterial cell-wall biosynthesis: undecaprenyl diphosphate synthase (UPPS) and undecaprenyl diphosphate phosphatase (UPPP), but not farnesyl diphosphate synthase, and there were good correlations between bacterial cell growth inhibition, UPPS inhibition, and UPPP inhibition. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Growth yields and fermentation balance of Bacteroides fragilis cultured in glucose-enriched medium.

PubMed

Frantz, J C; McCallum, R E

1979-03-01

Bacteroides fragilis is an obligate anaerobic bacterium classified with the gram-negative, non-sporeforming bacilli and is the Bacteroides species most frequently isolated from human infections. In the present study, experiments were designed to investigate growth characteristics of B. fragilis in a complex medium. In a minimal defined medium, which was employed for comparison purposes, B. fragilis grew with a generation time of 2 h. Growth of the organism in glucose-enriched medium used in the present study was superior. Maximum generation time was 60 min. Total and viable cells (colony-forming units) were 8.9 x 10(9) and 2.1 x 10(9), respectively, at maximum measurable growth. The molar growth yield (Ym) was 51.5. Growth yields were found to reach a maximum 2 to 3 h before maximum growth and to vary with respect to the phase of growth. Estimates of the fermentation products indicated that glucose was the sole energy substrate. Major products included acetic acid, propionic acid, lactic acid, and succinic acid. Other products included ethyl alcohol, pyruvic acid, and fumaric acid. No attempt was made to recover CO2 or formic acid. The OR balances from two experiments were 0.013 and -0.093 and the respective carbon recoveries were 6.268 and 6.241. The results of the present study show that B. fragilis is capable of rapid rates of growth in vitro by using glucose as the sole energy source.

Differentiation of bacterial colonies and temporal growth patterns using hyperspectral imaging

NASA Astrophysics Data System (ADS)

Mehrübeoglu, Mehrube; Buck, Gregory W.; Livingston, Daniel W.

2014-09-01

Detection and identification of bacteria are important for health and safety. Hyperspectral imaging offers the potential to capture unique spectral patterns and spatial information from bacteria which can then be used to detect and differentiate bacterial species. Here, hyperspectral imaging has been used to characterize different bacterial colonies and investigate their growth over time. Six bacterial species (Pseudomonas fluorescens, Escherichia coli, Serratia marcescens, Salmonella enterica, Staphylococcus aureus, Enterobacter aerogenes) were grown on tryptic soy agar plates. Hyperspectral data were acquired immediately after, 24 hours after, and 96 hours after incubation. Spectral signatures from bacterial colonies demonstrated repeatable measurements for five out of six species. Spatial variations as well as changes in spectral signatures were observed across temporal measurements within and among species at multiple wavelengths due to strengthening or weakening reflectance signals from growing bacterial colonies based on their pigmentation. Between-class differences and within-class similarities were the most prominent in hyperspectral data collected 96 hours after incubation.

Metal-tolerant PAH-degrading bacteria: development of suitable test medium and effect of cadmium and its availability on PAH biodegradation.

PubMed

Thavamani, Palanisami; Megharaj, Mallavarapu; Naidu, Ravi

2015-06-01

The use of metal-tolerant polyaromatic hydrocarbon (PAH)-degrading bacteria is viable for mitigating metal inhibition of organic compound biodegradation in the remediation of mixed contaminated sites. Many microbial growth media used for toxicity testing contain high concentrations of metal-binding components such as phosphates that can reduce solution-phase metal concentrations thereby underestimate the real toxicity. In this study, we isolated two PAHs-degrading bacterial consortia from long-term mixed contaminated soils. We have developed a new mineral medium by optimising the concentrations of medium components to allow the bacterial growth and at the same time maintain high bioavailable metal (Cd(2+) as a model metal) in the medium. This medium has more than 60 % Cd as Cd(2+) at pH 6.5 as measured by an ion selective electrode and visual MINTEQ model. The Cd-tolerant patterns of the consortia were tested and minimum inhibitory concentration (MIC) derived. The consortium-5 had the highest MIC of 5 mg l(-1) Cd followed by consortium-9. Both cultures were able to completely metabolise 200 mg l(-1) phenanthrene in less than 4 days in the presence of 5 mg l(-1) Cd. The isolated metal-tolerant PAH-degrading bacterial cultures have great potential for bioremediation of mixed contaminated soils.

Development of a restricted state space stochastic differential equation model for bacterial growth in rich media.

PubMed

Møller, Jan Kloppenborg; Bergmann, Kirsten Riber; Christiansen, Lasse Engbo; Madsen, Henrik

2012-07-21

In the present study, bacterial growth in a rich media is analysed in a Stochastic Differential Equation (SDE) framework. It is demonstrated that the SDE formulation and smoothened state estimates provide a systematic framework for data driven model improvements, using random walk hidden states. Bacterial growth is limited by the available substrate and the inclusion of diffusion must obey this natural restriction. By inclusion of a modified logistic diffusion term it is possible to introduce a diffusion term flexible enough to capture both the growth phase and the stationary phase, while concentration is restricted to the natural state space (substrate and bacteria non-negative). The case considered is the growth of Salmonella and Enterococcus in a rich media. It is found that a hidden state is necessary to capture the lag phase of growth, and that a flexible logistic diffusion term is needed to capture the random behaviour of the growth model. Further, it is concluded that the Monod effect is not needed to capture the dynamics of bacterial growth in the data presented. Copyright © 2012 Elsevier Ltd. All rights reserved.

Primordial soup was edible: abiotically produced Miller-Urey mixture supports bacterial growth.

PubMed

Xie, Xueshu; Backman, Daniel; Lebedev, Albert T; Artaev, Viatcheslav B; Jiang, Liying; Ilag, Leopold L; Zubarev, Roman A

2015-09-28

Sixty years after the seminal Miller-Urey experiment that abiotically produced a mixture of racemized amino acids, we provide a definite proof that this primordial soup, when properly cooked, was edible for primitive organisms. Direct admixture of even small amounts of Miller-Urey mixture strongly inhibits E. coli bacteria growth due to the toxicity of abundant components, such as cyanides. However, these toxic compounds are both volatile and extremely reactive, while bacteria are highly capable of adaptation. Consequently, after bacterial adaptation to a mixture of the two most abundant abiotic amino acids, glycine and racemized alanine, dried and reconstituted MU soup was found to support bacterial growth and even accelerate it compared to a simple mixture of the two amino acids. Therefore, primordial Miller-Urey soup was perfectly suitable as a growth media for early life forms.

Isoprenoid Biosynthesis Inhibitors Targeting Bacterial Cell Growth.

PubMed

Desai, Janish; Wang, Yang; Wang, Ke; Malwal, Satish R; Oldfield, Eric

2016-10-06

We synthesized potential inhibitors of farnesyl diphosphate synthase (FPPS), undecaprenyl diphosphate synthase (UPPS), or undecaprenyl diphosphate phosphatase (UPPP), and tested them in bacterial cell growth and enzyme inhibition assays. The most active compounds were found to be bisphosphonates with electron-withdrawing aryl-alkyl side chains which inhibited the growth of Gram-negative bacteria (Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa) at ∼1-4 μg mL -1 levels. They were found to be potent inhibitors of FPPS; cell growth was partially "rescued" by the addition of farnesol or overexpression of FPPS, and there was synergistic activity with known isoprenoid biosynthesis pathway inhibitors. Lipophilic hydroxyalkyl phosphonic acids inhibited UPPS and UPPP at micromolar levels; they were active (∼2-6 μg mL -1 ) against Gram-positive but not Gram-negative organisms, and again exhibited synergistic activity with cell wall biosynthesis inhibitors, but only indifferent effects with other inhibitors. The results are of interest because they describe novel inhibitors of FPPS, UPPS, and UPPP with cell growth inhibitory activities as low as ∼1-2 μg mL -1 . © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Menaquinone analogs inhibit growth of bacterial pathogens.

PubMed

Schlievert, Patrick M; Merriman, Joseph A; Salgado-Pabón, Wilmara; Mueller, Elizabeth A; Spaulding, Adam R; Vu, Bao G; Chuang-Smith, Olivia N; Kohler, Petra L; Kirby, John R

2013-11-01

Gram-positive bacteria cause serious human illnesses through combinations of cell surface and secreted virulence factors. We initiated studies with four of these organisms to develop novel topical antibacterial agents that interfere with growth and exotoxin production, focusing on menaquinone analogs. Menadione, 1,4-naphthoquinone, and coenzymes Q1 to Q3 but not menaquinone, phylloquinone, or coenzyme Q10 inhibited the growth and to a greater extent exotoxin production of Staphylococcus aureus, Bacillus anthracis, Streptococcus pyogenes, and Streptococcus agalactiae at concentrations of 10 to 200 μg/ml. Coenzyme Q1 reduced the ability of S. aureus to cause toxic shock syndrome in a rabbit model, inhibited the growth of four Gram-negative bacteria, and synergized with another antimicrobial agent, glycerol monolaurate, to inhibit S. aureus growth. The staphylococcal two-component system SrrA/B was shown to be an antibacterial target of coenzyme Q1. We hypothesize that menaquinone analogs both induce toxic reactive oxygen species and affect bacterial plasma membranes and biosynthetic machinery to interfere with two-component systems, respiration, and macromolecular synthesis. These compounds represent a novel class of potential topical therapeutic agents.

Insulin and heparin-binding epidermal growth factor-like growth factor synergistically promote astrocyte survival and proliferation in serum-free medium.

PubMed

Jia, Mei; Shi, Zhongfang; Yan, Xu; Xu, Lixin; Dong, Liping; Li, Jiaxin; Wang, Yujiao; Yang, Shaohua; Yuan, Fang

2018-06-08

In vitro systems allowing maintenance and experimentation on primary astrocyte cultures have been used for decades. Astrocyte cultures are most maintained in serum-containing medium which has been found to alter the morphology and gene profiles of astrocytes. Here, we reported a new serum-free medium for astrocyte culture, which consisted of DMEM and NB media supplemented with insulin and heparin-binding epidermal growth factor-like growth factor (HB-EGF) (SF-I-H medium). Meanwhile FBS-containing (FBS) medium composed of DMEM medium containing 10% FBS were used for comparison study. Cerebral cortex was harvested from postnatal day 1 Wistar rats and brain cells were isolated and seeded to poly-L-lysine coated culture dishes after 15 min differential velocity adherence. Compared with FBS medium, astrocytes in SF-I-H medium are smaller and exhibited process bearing morphologies. MTT assays showed that cell density and proliferation rate were higher in SF-I-H medium than in FBS medium all the time, and flow cytometry analysis revealed that SF-I-H medium promoted cell mitosis in a manner comparable to FBS medium. Consistently, western blot analysis further revealed that insulin and HB-EGF synergistically activated the PI3K-AKT and MAPK-ERK1/2 signaling cascades as FBS. Astrocytes cultured in SF-I-H medium grow faster than FBS medium. Taken together, our results indicated that SF-I-H medium, in which cell morphology was similar with astrocytes in brain, was more effective for astrocyte survival and proliferation than FBS medium, providing a new cell model to study astrocyte functions without the interference of serum. Copyright © 2018. Published by Elsevier B.V.

Temporal changes in species interactions in simple aquatic bacterial communities

PubMed Central

2012-01-01

Background Organisms modify their environment and in doing so change the quantity and possibly the quality of available resources. Due to the two-way relationship between organisms and their resource environment, and the complexity it brings to biological communities, measuring species interactions reliably in any biological system is a challenging task. As the resource environment changes, the intensity and even the sign of interactions may vary in time. We used Serratia marcescens and Novosphingobium capsulatum bacteria to study how the interaction between resource environment and organisms influence the growth of the bacterial species during circa 200 generations. We used a sterile-filtering method to measure how changes in resource environment are reflected in growth rates of the two species. Results Changes in the resource environment caused complex time and species composition-dependent effects on bacterial growth performance. Variation in the quality of the growth medium indicated existence of temporally fluctuating within-species facilitation and inhibition, and between-species asymmetric facilitation. Conclusions The interactions between the community members could not be fully predicted based only on the knowledge of the growth performance of each member in isolation. Growth dynamics in sterile-filtered samples of the conditioned growth medium can reveal both biologically meaningful changes in resource availability and temporally changing facilitative resource-mediated interactions between study species. This is the first study we are aware of where the filter-sterilization – growth assay method is applied to study the effect of long-term changes in the environment on species interactions. PMID:22984961

The papain inhibitor (SPI) of Streptomyces mobaraensis inhibits bacterial cysteine proteases and is an antagonist of bacterial growth.

PubMed

Zindel, Stephan; Kaman, Wendy E; Fröls, Sabrina; Pfeifer, Felicitas; Peters, Anna; Hays, John P; Fuchsbauer, Hans-Lothar

2013-07-01

A novel papain inhibitory protein (SPI) from Streptomyces mobaraensis was studied to measure its inhibitory effect on bacterial cysteine protease activity (Staphylococcus aureus SspB) and culture supernatants (Porphyromonas gingivalis, Bacillus anthracis). Further, growth of Bacillus anthracis, Staphylococcus aureus, Pseudomonas aeruginosa, and Vibrio cholerae was completely inhibited by 10 μM SPI. At this concentration of SPI, no cytotoxicity was observed. We conclude that SPI inhibits bacterial virulence factors and has the potential to become a novel therapeutic treatment against a range of unrelated pathogenic bacteria.

Bacterial diversity, community structure and potential growth rates along an estuarine salinity gradient

PubMed Central

Campbell, Barbara J; Kirchman, David L

2013-01-01

Very little is known about growth rates of individual bacterial taxa and how they respond to environmental flux. Here, we characterized bacterial community diversity, structure and the relative abundance of 16S rRNA and 16S rRNA genes (rDNA) using pyrosequencing along the salinity gradient in the Delaware Bay. Indices of diversity, evenness, structure and growth rates of the surface bacterial community significantly varied along the transect, reflecting active mixing between the freshwater and marine ends of the estuary. There was no positive correlation between relative abundances of 16S rRNA and rDNA for the entire bacterial community, suggesting that abundance of bacteria does not necessarily reflect potential growth rate or activity. However, for almost half of the individual taxa, 16S rRNA positively correlated with rDNA, suggesting that activity did follow abundance in these cases. The positive relationship between 16S rRNA and rDNA was less in the whole water community than for free-living taxa, indicating that the two communities differed in activity. The 16S rRNA:rDNA ratios of some typically marine taxa reflected differences in light, nutrient concentrations and other environmental factors along the estuarine gradient. The ratios of individual freshwater taxa declined as salinity increased, whereas the 16S rRNA:rDNA ratios of only some typical marine bacteria increased as salinity increased. These data suggest that physical and other bottom-up factors differentially affect growth rates, but not necessarily abundance of individual taxa in this highly variable environment. PMID:22895159

Development and validation of a minimal growth medium for recycling Chlorella vulgaris culture.

PubMed

Hadj-Romdhane, F; Jaouen, P; Pruvost, J; Grizeau, D; Van Vooren, G; Bourseau, P

2012-11-01

When microalgae culture medium is recycled, ions (e.g. Na(+), K(+), Ca(2+)) that were not assimilated by the microalgae accumulate in the medium. Therefore, a growth medium (HAMGM) was developed that included ions that were more easily assimilated by Chlorella vulgaris, such as ammonium one (NH(4)(+)). Recycling performance was studied by carrying out 8-week continuous cultivation of C. vulgaris with recycled HAMGM medium. No loss of biomass productivity was observed compared to culture in a conventional medium, and accumulation of ions over time was negligible. Copyright © 2012 Elsevier Ltd. All rights reserved.

The effect of medium structure complexity on the growth of Saccharomyces cerevisiae in gelatin-dextran systems.

PubMed

Boons, Kathleen; Noriega, Estefanía; Verherstraeten, Niels; David, Charlotte C; Hofkens, Johan; Van Impe, Jan F

2015-04-16

As most food systems are (semi-)solid, the effect of food structure on bacterial growth has been widely acknowledged. However, studies on the growth dynamics of yeasts have neglected the effect of food structure. In this paper, the growth dynamics of the spoilage yeast Saccharomyces cerevisiae was investigated at 23.5 °C in broth, singular, homogeneous biopolymer systems and binary biopolymer systems with a heterogeneous microstructure. The biopolymers gelatin and dextran were used to introduce the different levels of structure. The metabolizing ability of gelatin and dextran by S. cerevisiae was examined. To study microbial behavior in the binary systems at the micro level, mixtures were imaged with confocal laser scanning microscopy (CLSM). Growth dynamics and microscopic images of S. cerevisiae were compared with those obtained for Escherichia coli in the same model system (Boons et al., 2014). Different phase-separated, heterogeneous microstructures were obtained by changing the amount of added gelatin and dextran. Regardless of the microstructure, S. cerevisiae was preferentially located in the dextran phase. Metabolizing ability-tests indicated that gelatin could be consumed by S. cerevisiae but in the presence of glucose, no change in gelatin concentration was observed. No indication of dextran metabolizing ability was observed. When supplementing broth with gelatin or dextran alone, an enhanced growth rate and maximum cell density were observed. This enhancement was further increased by adding a second biopolymer, introducing a heterogeneous microstructure and hence increasing the medium structure complexity. The results obtained indicate that food structure complexity plays a significant role in the growth dynamics of S. cerevisiae, an important food spoiler. Copyright © 2014. Published by Elsevier B.V.

New Medium for Isolation of Bacteria From Cement Kiln Dust with a Potential to Apply in Bio-Concrete

NASA Astrophysics Data System (ADS)

Alshalif, A. F.; Irwan, J. M.; Othman, N.; Al-Gheethi, A.

2018-04-01

The present study aimed to introduce a new isolation medium named kiln dust medium (KDM) for recovering of bacteria from cement kiln dust with high pH (>pH 11) without the need for nutrients additives. The cement kiln dust samples were collected from five different areas of Cement Industries of Malaysia Berhad (CIMA). The bacterial isolates were recovered on KDM by direct plating technique. The chemical components for all collected samples were identified using X-ray fluorescence (XRF). The primary identification for the bacterial isolates indicated that these bacteria belongs to Bacillus spp. Based on the morphological characteristics. The growth curve of the bacterial strains was monitored using the optical density (OD) with 650 nm wavelength, which in role confirmed that all isolated bacteria had the ability to grow successfully in the proposed medium. The ability of the bacterial strains to grow at high pH reflects their potential in the bio-concrete applications (aerated and non-aerated concrete). These findings indicated that the cement kiln dust samples from Cement Industries represent the most appropriate source for bacteria used in the bioconcrete.

The growth of Treponema hyodysenteriae and other porcine intestinal spirochaetes in a liquid medium.

PubMed

Lemcke, R M; Bew, J; Burrows, M R; Lysons, R J

1979-05-01

A new simple method for the preparation of a liquid medium containing rabbit serum for the propagation of Treponema hyodysenteriae and other porcine intestinal spirochaetes is described. The medium, when dispensed in shallow layers and sealed under 10 per cent CO2 in nitrogen, had a redox potential not greater than -125mV and an initial pH of about 6.9 when buffered with bicarbonate. Growth of T hyodysenteriae developed more rapidly and viable counts reached higher levels at 42 degrees C than at 37 degrees C. Viable counts increased at least 10,000-fold after two to five days' incubation, depending on the temperature. Growth could be initiated from small inocula that failed to produce colonies on blood agar. Using a 1 per cent inoculum, the medium supported the growth of two strains of T hyodysenteriae through 10 serial passages.

[The Influence of New Medium with RGD on Cell Growth,Cell Fusion and Expression of Exogenous Gene].

PubMed

Wang, Pei-Pei; Wei, Da-Peng; Zhu, Tong-Bo

2018-03-01

To investigate the influence of a new culture medium added with RGD on cell growth,cell fusion and expression of exogenous gene. A new medium was prepared by adding different concentrations of RGD to ordinary culture medium. The optimum concentration of RGD was determined by observation of the growth of human pancreatic epithelial cell line HPDE6-C7. After determining the optimum concentration of RGD,different concentrations of cells HPDE6-C7 (5×10 4 ,10 5 ,5×10 5 mL －1 ) were inoculated in the two mediums. The morphology,adherence,growth and density of the cells were observed by inverted microscope; The ratio of clone formation and the positive rate of cloning were compared between the two cultures after fusion; The fluorescence intensity after the transfection of plasmid with green fluorescent protein ( GFP ) and the protein expression after transfection of plasmid with KRAS were observed to campare the expression of exogenous genes between the new medium with ordinary medium. Firstly,the optimal concentration of RGD was 10 ng/mL. Compared with the normal medium,the cultured cells with RGD had better morphology,adhesion and faster proliferation. In addition,both of the number and positive rate of clones formed in the new medium were significantly higher than that in the ordinary medium ( P <0.05);The fluorescence intensity after transfection of exogenous gene GFP in the new medium was significantly higher than that in normal medium ( P <0.05); Expression level of exogenous gene KRAS of the new medium was also significantly higher than that in normal medium. The new culture medium has highlighted advantages in cell growth,cell fusion and expression of exogenous genes. RGD peptide has widely prospect and potential value in the cell culture. Copyright© by Editorial Board of Journal of Sichuan University (Medical Science Edition).

Role of the gut microbiota in host appetite control: bacterial growth to animal feeding behaviour.

PubMed

Fetissov, Sergueï O

2017-01-01

The life of all animals is dominated by alternating feelings of hunger and satiety - the main involuntary motivations for feeding-related behaviour. Gut bacteria depend fully on their host for providing the nutrients necessary for their growth. The intrinsic ability of bacteria to regulate their growth and to maintain their population within the gut suggests that gut bacteria can interfere with molecular pathways controlling energy balance in the host. The current model of appetite control is based mainly on gut-brain signalling and the animal's own needs to maintain energy homeostasis; an alternative model might also involve bacteria-host communications. Several bacterial components and metabolites have been shown to stimulate intestinal satiety pathways; at the same time, their production depends on bacterial growth cycles. This short-term bacterial growth-linked modulation of intestinal satiety can be coupled with long-term regulation of appetite, controlled by the neuropeptidergic circuitry in the hypothalamus. Indeed, several bacterial products are detected in the systemic circulation, which might act directly on hypothalamic neurons. This Review analyses the data relevant to possible involvement of the gut bacteria in the regulation of host appetite and proposes an integrative homeostatic model of appetite control that includes energy needs of both the host and its gut bacteria.

Atropine and glycopyrrolate do not support bacterial growth-safety and economic considerations.

PubMed

Ittzes, Balazs; Weiling, Zsolt; Batai, Istvan Zoard; Kerenyi, Monika; Batai, Istvan

2016-12-01

Evaluation of bacterial growth in atropine and glycopyrrolate. Laboratory investigation. Standard microbiological methods were used to evaluate the impact of atropine and glycopyrrolate on the growth of Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. Bacterial count was checked at 0, 1, 2, 3, 4, 6, and 24 hours. Atropine or glycopyrrolate did not support the growth of the above bacteria at any examined time at room temperature. Glycopyrrolate killed all of the examined strains (P < .05), whereas in atropine, only the clinical isolates of Staphylococcus and Acinetobacter were killed (P < .05). Drawing up atropine or glycopyrrolate at the beginning of the operating list and use within 24 hours if needed are a safe practice and do not pose infection hazard. We can also reduce hospital costs if we do not throw away these unused syringes following each case. Copyright © 2016 Elsevier Inc. All rights reserved.

Impact of ZnO and Ag Nanoparticles on Bacterial Growth and Viability

NASA Astrophysics Data System (ADS)

Olson, M. S.; Digiovanni, K. A.

2007-12-01

Hundreds of consumer products containing nanomaterials are currently available in the U.S., including computers, clothing, cosmetics, sports equipment, medical devices and product packaging. Metallic nanoparticles can be embedded in or coated on product surfaces to provide antimicrobial, deodorizing, and stain- resistant properties. Although these products have the potential to provide significant benefit to the user, the impact of these products on the environment remains largely unknown. The purpose of this project is to study the effect of metallic nanoparticles released to the environment on bacterial growth and viability. Inhibition of bacterial growth was tested by adding doses of suspended ZnO and Ag nanoparticles into luria broth prior to inoculation of Escherichia coli cells. ZnO particles (approximately 40 nm) were obtained commercially and Ag particles (12-14 nm) were fabricated by reduction of silver nitrate with sodium borohydride. Toxicity assays were performed to test the viability of E. coli cells exposed to both ZnO and Ag nanoparticles using the LIVE/DEAD BacLight bacterial viability kit (Invitrogen). Live cells stain green whereas cells with compromised membranes that are considered dead or dying stain red. Cells were first grown, stained, and exposed to varying doses of metallic nanoparticles, and then bacterial viability was measured hourly using fluorescence microscopy. Results indicate that both ZnO and Ag nanoparticles inhibit the growth of E. coli in liquid media. Preliminary results from toxicity assays confirm the toxic effect of ZnO and Ag nanoparticles on active cell cultures. Calculated death rates resulting from analyses of toxicity studies will be presented.

Effects of Benzalkonium Chloride on Planktonic Growth and Biofilm Formation by Animal Bacterial Pathogens

PubMed Central

Ebrahimi, Azizollah; Hemati, Majid; Shabanpour, Ziba; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Lotfalian, Sharareh; Khubani, Shahin

2015-01-01

Background: Resistance toward quaternary ammonium compounds (QACs) is widespread among a diverse range of microorganisms and is facilitated by several mechanisms such as biofilm formation. Objectives: In this study, the effects of benzalkonium chloride on planktonic growth and biofilm formation by some field isolates of animal bacterial pathogens were investigated. Materials and Methods: Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus aureus and Streptococcus agalactiae (10 isolates of each) were examined for effects of benzalkonium chloride on biofilm formation and planktonic growth using microtiter plates. For all the examined strains in the presence of benzalkonium chloride, biofilm development and planktonic growth were affected at the same concentrations of disinfectant. Results: The means of strains growth increase after the minimal inhibitory concentration (MIC) were significant in all the bacteria (except for E. coli in 1/32 and S. agalactiae in of 1/8 MIC). Biofilm formation increased with decrease of antiseptics concentration; a significant increase was found in all the samples. The most turbidity related to S. aureus and the least to Salmonella. Conclusions: Bacterial resistance against quaternary ammonium compounds is increasing which can increase the bacterial biofilm formation. PMID:25793094

[THE ACTUAL APPROACHES TO PROBLEM OF IMPORT SUBSTITUTION IN TH FIELD OF PRODUCTION GROWTH MEDIUM].

PubMed

Shepelin, A P; Domotenko, L V; Diatlov, I A; Mironov, A Yu; Aleshkin, V A

2015-06-01

The import substitution becomes one of strategic tasks of Russian economy as a result of imposition of economic sanctions on part of the USA, EU countries, Japan and number of other states. The development of structure and technology of production of national import substituted growth mediums permits satisfying needs of laboratory service of Russia inactive storage and to secure appropriate response to occurring challenges and new biological menaces and support bio-security of state at proper level. The presented data concerning substantiation of nomenclature of growth mediums and transport system permit satisfying in fullness the needs of clinical and sanitary microbiology in growth mediums of national production and to give up of import deliveries without decreasing of quality of microbiological studies.

Plant growth promotion properties of bacterial strains isolated from the rhizosphere of the Jerusalem artichoke (Helianthus tuberosus L.) adapted to saline-alkaline soils and their effect on wheat growth.

PubMed

Liu, Xiaolin; Li, Xiangyue; Li, Yan; Li, Runzhi; Xie, Zhihong

2017-03-01

The Jerusalem artichoke (JA; Helianthus tuberosus), known to be tolerant to saline-alkaline soil conditions, has been cultivated for many years in the Yellow River delta, Shandong Province coastal zone, in China. The aim of our study was to isolate nitrogen-fixing bacteria colonizing the rhizosphere of JA and to characterize other plant growth promotion properties. The ultimate goal was to identify isolates that could be used as inoculants benefiting an economic crop, in particular for improving wheat growth production in the Yellow River delta. Bacterial strains were isolated from the rhizosphere soil of JA on the basis of growth on nitrogen-free Ashby medium. Identification and phylogenetic analysis was performed after nucleotide sequencing of 16S rRNA gene. Plant-growth-promoting traits, such as nitrogen fixation activity, phosphate solubilization activity, indole-3-acetic acid production, were determined using conventional methods. Eleven strains were isolated and 6 of them were further examined for their level of salt tolerance and their effect on plant growth promotion. Inoculation of Enterobacter sp. strain N10 on JA and wheat led to significant increases in both root and shoot dry mass and shoot height. Enterobacter sp. strain N10 appeared to be the best plant-growth-promoting rhizobacteria to increase wheat productivity in future field applications.

Effect of flow and peristaltic mixing on bacterial growth in a gut-like channel

PubMed Central

Cremer, Jonas; Segota, Igor; Yang, Chih-yu; Arnoldini, Markus; Sauls, John T.; Zhang, Zhongge; Gutierrez, Edgar; Groisman, Alex; Hwa, Terence

2016-01-01

The ecology of microbes in the gut has been shown to play important roles in the health of the host. To better understand microbial growth and population dynamics in the proximal colon, the primary region of bacterial growth in the gut, we built and applied a fluidic channel that we call the “minigut.” This is a channel with an array of membrane valves along its length, which allows mimicking active contractions of the colonic wall. Repeated contraction is shown to be crucial in maintaining a steady-state bacterial population in the device despite strong flow along the channel that would otherwise cause bacterial washout. Depending on the flow rate and the frequency of contractions, the bacterial density profile exhibits varying spatial dependencies. For a synthetic cross-feeding community, the species abundance ratio is also strongly affected by mixing and flow along the length of the device. Complex mixing dynamics due to contractions is described well by an effective diffusion term. Bacterial dynamics is captured by a simple reaction–diffusion model without adjustable parameters. Our results suggest that flow and mixing play a major role in shaping the microbiota of the colon. PMID:27681630

BACTERIAL GROWTH AND MULTIPLICATION AS DISCLOSED BY MICRO MOTION PICTURES

PubMed Central

Wyckoff, Ralph W. G.

1934-01-01

Using a micro motion picture technique for making records, studies covering several thousand hours of observation have been made of the growth of a number of bacteria. On the basis of these experiments a discussion is offered of bacterial division and its influence on gross colony appearance, of different kinds of pleomorphism that have been observed, and of the nature of the internal structure that is seen in some bacteria. Several of the microorganisms chosen for examination are ones that have been thought to give evidence of life cycle phenomena. The present pictures, however, contain no evidence of a bacterial cycle in the commonly accepted meaning of the term. PMID:19870252

Dislocation-mediated growth of bacterial cell walls

PubMed Central

Amir, Ariel; Nelson, David R.

2012-01-01

Recent experiments have illuminated a remarkable growth mechanism of rod-shaped bacteria: proteins associated with cell wall extension move at constant velocity in circles oriented approximately along the cell circumference [Garner EC, et al., (2011) Science 333:222–225], [Domínguez-Escobar J, et al. (2011) Science 333:225–228], [van Teeffelen S, et al. (2011) PNAS 108:15822–15827]. We view these as dislocations in the partially ordered peptidoglycan structure, activated by glycan strand extension machinery, and study theoretically the dynamics of these interacting defects on the surface of a cylinder. Generation and motion of these interacting defects lead to surprising effects arising from the cylindrical geometry, with important implications for growth. We also discuss how long range elastic interactions and turgor pressure affect the dynamics of the fraction of actively moving dislocations in the bacterial cell wall. PMID:22660931

Bacterial growth laws reflect the evolutionary importance of energy efficiency.

PubMed

Maitra, Arijit; Dill, Ken A

2015-01-13

We are interested in the balance of energy and protein synthesis in bacterial growth. How has evolution optimized this balance? We describe an analytical model that leverages extensive literature data on growth laws to infer the underlying fitness landscape and to draw inferences about what evolution has optimized in Escherichia coli. Is E. coli optimized for growth speed, energy efficiency, or some other property? Experimental data show that at its replication speed limit, E. coli produces about four mass equivalents of nonribosomal proteins for every mass equivalent of ribosomes. This ratio can be explained if the cell's fitness function is the the energy efficiency of cells under fast growth conditions, indicating a tradeoff between the high energy costs of ribosomes under fast growth and the high energy costs of turning over nonribosomal proteins under slow growth. This model gives insight into some of the complex nonlinear relationships between energy utilization and ribosomal and nonribosomal production as a function of cell growth conditions.

Quantitative spectral light scattering polarimetry for monitoring fractal growth pattern of Bacillus thuringiensis bacterial colonies

NASA Astrophysics Data System (ADS)

Banerjee, Paromita; Soni, Jalpa; Ghosh, Nirmalya; Sengupta, Tapas K.

2013-02-01

It is of considerable current interest to develop various methods which help to understand and quantify the cellular association in growing bacterial colonies and is also important in terms of detection and identification of a bacterial species. A novel approach is used here to probe the morphological structural changes occurring during the growth of the bacterial colony of Bacillus thuringiensis under different environmental conditions (in normal nutrient agar, in presence of glucose - acting as additional nutrient and additional 3mM arsenate as additional toxic material). This approach combines the quantitative Mueller matrix polarimetry to extract intrinsic polarization properties and inverse analysis of the polarization preserving part of the light scattering spectra to determine the fractal parameter H (Hurst exponent) using Born approximation. Interesting differences are observed in the intrinsic polarization parameters and also in the Hurst exponent, which is a measurement of the fractality of a pattern formed by bacteria while growing as a colony. These findings are further confirmed with optical microscopic studies of the same sample and the results indicate a very strong and distinct dependence on the environmental conditions during growth, which can be exploited to quantify different bacterial species and their growth patterns.

The Adc/Lmb System Mediates Zinc Acquisition in Streptococcus agalactiae and Contributes to Bacterial Growth and Survival

PubMed Central

Moulin, Pauline; Patron, Kévin; Cano, Camille; Zorgani, Mohamed Amine; Camiade, Emilie; Borezée-Durant, Elise; Rosenau, Agnès; Mereghetti, Laurent

2016-01-01

ABSTRACT The Lmb protein of Streptococcus agalactiae is described as an adhesin that binds laminin, a component of the human extracellular matrix. In this study, we revealed a new role for this protein in zinc uptake. We also identified two Lmb homologs, AdcA and AdcAII, redundant binding proteins that combine with the AdcCB translocon to form a zinc-ABC transporter. Expression of this transporter is controlled by the zinc concentration in the medium through the zinc-dependent regulator AdcR. Triple deletion of lmb, adcA, and adcAII, or that of the adcCB genes, impaired growth and cell separation in a zinc-restricted environment. Moreover, we found that this Adc zinc-ABC transporter promotes S. agalactiae growth and survival in some human biological fluids, suggesting that it contributes to the infection process. These results indicated that zinc has biologically vital functions in S. agalactiae and that, under the conditions tested, the Adc/Lmb transporter constitutes the main zinc acquisition system of the bacterium. IMPORTANCE A zinc transporter, composed of three redundant binding proteins (Lmb, AdcA, and AdcAII), was characterized in Streptococcus agalactiae. This system was shown to be essential for bacterial growth and morphology in zinc-restricted environments, including human biological fluids. PMID:27672194

Bacterial Community Associated with Healthy and Diseased Pacific White Shrimp (Litopenaeus vannamei) Larvae and Rearing Water across Different Growth Stages.

PubMed

Zheng, Yanfen; Yu, Min; Liu, Jiwen; Qiao, Yanlu; Wang, Long; Li, Zhitao; Zhang, Xiao-Hua; Yu, Mingchao

2017-01-01

Bacterial communities are called another "organ" for aquatic animals and their important influence on the health of host has drawn increasing attention. Thus, it is important to study the relationships between aquatic animals and bacterial communities. Here, bacterial communities associated with Litopenaeus vannamei larvae at different healthy statuses (diseased and healthy) and growth stages (i.e., zoea, mysis, and early postlarvae periods) were examined using 454-pyrosequencing of the 16S rRNA gene. Bacterial communities with significant difference were observed between healthy and diseased rearing water, and several bacterial groups, such as genera Nautella and Kordiimonas could also distinguish healthy and diseased shrimp. Rhodobacteraceae was widely distributed in rearing water at all growth stages but there were several stage-specific groups, indicating that bacterial members in rearing water assembled into distinct communities throughout the larval development. However, Gammaproteobacteria , mainly family Enterobacteriaceae , was the most abundant group (accounting for more than 85%) in shrimp larvae at all growth stages. This study compared bacterial communities associated with healthy and diseased L . vannamei larvae and rearing water, and identified several health- and growth stage-specific bacterial groups, which might be provided as indicators for monitoring the healthy status of shrimp larvae in hatchery.

Bacterial Community Associated with Healthy and Diseased Pacific White Shrimp (Litopenaeus vannamei) Larvae and Rearing Water across Different Growth Stages

PubMed Central

Zheng, Yanfen; Yu, Min; Liu, Jiwen; Qiao, Yanlu; Wang, Long; Li, Zhitao; Zhang, Xiao-Hua; Yu, Mingchao

2017-01-01

Bacterial communities are called another “organ” for aquatic animals and their important influence on the health of host has drawn increasing attention. Thus, it is important to study the relationships between aquatic animals and bacterial communities. Here, bacterial communities associated with Litopenaeus vannamei larvae at different healthy statuses (diseased and healthy) and growth stages (i.e., zoea, mysis, and early postlarvae periods) were examined using 454-pyrosequencing of the 16S rRNA gene. Bacterial communities with significant difference were observed between healthy and diseased rearing water, and several bacterial groups, such as genera Nautella and Kordiimonas could also distinguish healthy and diseased shrimp. Rhodobacteraceae was widely distributed in rearing water at all growth stages but there were several stage-specific groups, indicating that bacterial members in rearing water assembled into distinct communities throughout the larval development. However, Gammaproteobacteria, mainly family Enterobacteriaceae, was the most abundant group (accounting for more than 85%) in shrimp larvae at all growth stages. This study compared bacterial communities associated with healthy and diseased L. vannamei larvae and rearing water, and identified several health- and growth stage-specific bacterial groups, which might be provided as indicators for monitoring the healthy status of shrimp larvae in hatchery. PMID:28769916

Effect of bacterial growth rate on bacteriophage population growth rate.

PubMed

Nabergoj, Dominik; Modic, Petra; Podgornik, Aleš

2018-04-01

It is important to understand how physiological state of the host influence propagation of bacteriophages (phages), due to the potential higher phage production needs in the future. In our study, we tried to elucidate the effect of bacterial growth rate on adsorption constant (δ), latent period (L), burst size (b), and bacteriophage population growth rate (λ). As a model system, a well-studied phage T4 and Escherichia coli K-12 as a host was used. Bacteria were grown in a continuous culture operating at dilution rates in the range between 0.06 and 0.98 hr -1 . It was found that the burst size increases linearly from 8 PFU·cell -1 to 89 PFU·cell -1 with increase in bacteria growth rate. On the other hand, adsorption constant and latent period were both decreasing from 2.6∙10 -9  ml·min -1 and 80 min to reach limiting values of 0.5 × 10 -9  ml·min -1 and 27 min at higher growth rates, respectively. Both trends were mathematically described with Michaelis-Menten based type of equation and reasons for such form are discussed. By applying selected equations, a mathematical equation for prediction of bacteriophage population growth rate as a function of dilution rate was derived, reaching values around 8 hr -1 at highest dilution rate. Interestingly, almost identical description can be obtained using much simpler Monod type equation and possible reasons for this finding are discussed. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Trophosome of the Deep-Sea Tubeworm Riftia pachyptila Inhibits Bacterial Growth.

PubMed

Klose, Julia; Aistleitner, Karin; Horn, Matthias; Krenn, Liselotte; Dirsch, Verena; Zehl, Martin; Bright, Monika

2016-01-01

The giant tubeworm Riftia pachyptila lives in symbiosis with the chemoautotrophic gammaproteobacterium Cand. Endoriftia persephone. Symbionts are released back into the environment upon host death in high-pressure experiments, while microbial fouling is not involved in trophosome degradation. Therefore, we examined the antimicrobial effect of the tubeworm's trophosome and skin. The growth of all four tested Gram-positive, but only of one of the tested Gram-negative bacterial strains was inhibited by freshly fixed and degrading trophosome (incubated up to ten days at either warm or cold temperature), while no effect on Saccharomyces cerevisiae was observed. The skin did not show antimicrobial effects. A liquid chromatography-mass spectrometric analysis of the ethanol supernatant of fixed trophosomes lead to the tentative identification of the phospholipids 1-palmitoleyl-2-lyso-phosphatidylethanolamine, 2-palmitoleyl-1-lyso-phosphatidylethanolamine and the free fatty acids palmitoleic, palmitic and oleic acid, which are known to have an antimicrobial effect. As a result of tissue autolysis, the abundance of the free fatty acids increased with longer incubation time of trophosome samples. This correlated with an increasing growth inhibition of Bacillus subtilis and Listeria welshimeri, but not of the other bacterial strains. Therefore, the free fatty acids produced upon host degradation could be the cause of inhibition of at least these two bacterial strains.

Spatial and temporal features of the growth of a bacterial species colonizing the zebrafish gut.

PubMed

Jemielita, Matthew; Taormina, Michael J; Burns, Adam R; Hampton, Jennifer S; Rolig, Annah S; Guillemin, Karen; Parthasarathy, Raghuveer

2014-12-16

The vertebrate intestine is home to microbial ecosystems that play key roles in host development and health. Little is known about the spatial and temporal dynamics of these microbial communities, limiting our understanding of fundamental properties, such as their mechanisms of growth, propagation, and persistence. To address this, we inoculated initially germ-free zebrafish larvae with fluorescently labeled strains of an Aeromonas species, representing an abundant genus in the zebrafish gut. Using light sheet fluorescence microscopy to obtain three-dimensional images spanning the gut, we quantified the entire bacterial load, as founding populations grew from tens to tens of thousands of cells over several hours. The data yield the first ever measurements of the growth kinetics of a microbial species inside a live vertebrate intestine and show dynamics that robustly fit a logistic growth model. Intriguingly, bacteria were nonuniformly distributed throughout the gut, and bacterial aggregates showed considerably higher growth rates than did discrete individuals. The form of aggregate growth indicates intrinsically higher division rates for clustered bacteria, rather than surface-mediated agglomeration onto clusters. Thus, the spatial organization of gut bacteria both relative to the host and to each other impacts overall growth kinetics, suggesting that spatial characterizations will be an important input to predictive models of host-associated microbial community assembly. Our intestines are home to vast numbers of microbes that influence many aspects of health and disease. Though we now know a great deal about the constituents of the gut microbiota, we understand very little about their spatial structure and temporal dynamics in humans or in any animal: how microbial populations establish themselves, grow, fluctuate, and persist. To address this, we made use of a model organism, the zebrafish, and a new optical imaging technique, light sheet fluorescence microscopy

N-Glycosylation of Campylobacter jejuni Surface Proteins Promotes Bacterial Fitness

PubMed Central

Nothaft, Harald; Zheng, Jing

2013-01-01

Campylobacter jejuni is the etiologic agent of human bacterial gastroenteritis worldwide. In contrast, despite heavy colonization, C. jejuni maintains a commensal mode of existence in chickens. The consumption of contaminated chicken products is thought to be the principal mode of C. jejuni transmission to the human population. C. jejuni harbors a system for N-linked protein glycosylation that has been well characterized and modifies more than 60 periplasmic and membrane-bound proteins. However, the precise role of this modification in the biology of C. jejuni remains unexplored. We hypothesized that the N-glycans protect C. jejuni surface proteins from the action of gut proteases. The C. jejuni pglB mutant, deficient in the expression of the oligosaccharyltransferase, exhibited reduced growth in medium supplemented with chicken cecal contents (CCC) compared with that of wild-type (WT) cells. Inactivation of the cecal proteases by heat treatment or with protease inhibitors completely restored bacterial viability and partially rescued bacterial growth. Physiological concentrations of trypsin, but not chymotrypsin, also reduced C. jejuni pglB mutant CFU. Live or dead staining indicated that CCC preferentially influenced C. jejuni growth as opposed to bacterial viability. We identified multiple chicken cecal proteases by mass fingerprinting. The use of protease inhibitors that target specific classes indicated that both metalloproteases and serine proteases were involved in the attenuated growth of the oligosaccharyltransferase mutant. In conclusion, protein N-linked glycosylation of surface proteins may enhance C. jejuni fitness by protecting bacterial proteins from cleavage due to gut proteases. PMID:23460522

Quantitative Characterization of the Growth of Deinococcus geothermalis DSM-11302: Effect of Inoculum Size, Growth Medium and Culture Conditions.

PubMed

Bornot, Julie; Molina-Jouve, Carole; Uribelarrea, Jean-Louis; Gorret, Nathalie

2015-08-20

Due to their remarkable resistance to extreme conditions, Deinococcaceae strains are of great interest to biotechnological prospects. However, the physiology of the extremophile strain Deinococcus geothermalis has scarcely been studied and is not well understood. The physiological behaviour was then studied in well-controlled conditions in flask and bioreactor cultures. The growth of D. geothermalis type strains was compared. Among the strains tested, the strain from the German Collection of Microorganisms (Deutsche Sammlung von Mikroorganismen DSM) DSM-11302 was found to give the highest biomass concentration and growth rate: in a complex medium with glucose, the growth rate reached 0.75 h(-1) at 45 °C. Yeast extract concentration in the medium had significant constitutive and catalytic effects. Furthermore, the results showed that the physiological descriptors were not affected by the inoculum preparation steps. A batch culture of D. geothermalis DSM-11302 on defined medium was carried out: cells grew exponentially with a maximal growth rate of 0.28 h(-1) and D. geothermalis DSM-11302 biomass reached 1.4 g·L(-1) in 20 h. Then, 1.4 gDryCellWeight of biomass (X) was obtained from 5.6 g glucose (Glc) consumed as carbon source, corresponding to a yield of 0.3 CmolX·CmolGlc(-1); cell specific oxygen uptake and carbon dioxide production rates reached 216 and 226 mmol.CmolX(-1)·h(-1), respectively, and the respiratory quotient (QR) value varied from 1.1 to 1.7. This is the first time that kinetic parameters and yields are reported for D. geothermalis DSM-11302 grown on a mineral medium in well-controlled batch culture.

Quantitative Characterization of the Growth of Deinococcus geothermalis DSM-11302: Effect of Inoculum Size, Growth Medium and Culture Conditions

PubMed Central

Bornot, Julie; Molina-Jouve, Carole; Uribelarrea, Jean-Louis; Gorret, Nathalie

2015-01-01

Due to their remarkable resistance to extreme conditions, Deinococcaceae strains are of great interest to biotechnological prospects. However, the physiology of the extremophile strain Deinococcus geothermalis has scarcely been studied and is not well understood. The physiological behaviour was then studied in well-controlled conditions in flask and bioreactor cultures. The growth of D. geothermalis type strains was compared. Among the strains tested, the strain from the German Collection of Microorganisms (Deutsche Sammlung von Mikroorganismen DSM) DSM-11302 was found to give the highest biomass concentration and growth rate: in a complex medium with glucose, the growth rate reached 0.75 h−1 at 45 °C. Yeast extract concentration in the medium had significant constitutive and catalytic effects. Furthermore, the results showed that the physiological descriptors were not affected by the inoculum preparation steps. A batch culture of D. geothermalis DSM-11302 on defined medium was carried out: cells grew exponentially with a maximal growth rate of 0.28 h−1 and D. geothermalis DSM-11302 biomass reached 1.4 g·L−1 in 20 h. Then, 1.4 gDryCellWeight of biomass (X) was obtained from 5.6 g glucose (Glc) consumed as carbon source, corresponding to a yield of 0.3 CmolX·CmolGlc−1; cell specific oxygen uptake and carbon dioxide production rates reached 216 and 226 mmol.CmolX−1·h−1, respectively, and the respiratory quotient (QR) value varied from 1.1 to 1.7. This is the first time that kinetic parameters and yields are reported for D. geothermalis DSM-11302 grown on a mineral medium in well-controlled batch culture. PMID:27682099

A critical synopsis: Continuous growth of proximal tubular kidney epithelial cells in hormone-supplemented serum-free medium

NASA Technical Reports Server (NTRS)

Chuman, L. M.; FINE; COHEN; Saier, M. H.

1985-01-01

The kidney forms urine and reabsorbs electrolytes and water. Kidney cell lines and hormone supplemented serum free medium were used for growth. The hormones were insulin, transferrin, vasopressin, cholesterol, prostaglandins, hydrocortisone, and triidothyronine. Epithelial cell lines are polar and form hemicysts. The Madin-Darby canine kidney(MDCK) cell line used is distal tubulelike. LLC-PK sub 1 cells are derived from pig kidneys and have the properties of different kidney segments. The LLC-PK sub 1 cells with proximal tubule properties were maintained in hormone-supplemented serum free medium. Seven factors (the aforementioned homrones and selenium) were needed for growth. Hormone-defined medium supported LLC-PK sub 1 cell growth, allowed transport (as seen by hemicyst formation), and influenced cell morphology. Vasopressin (used for growth and morphology) could be partially replaced by isobutylmethylxanthine or dibutyryl cAMP. The defined medium was used to isolate rabbit proximal tubule kidney epithelial cells free of fibroblasts.

Periodic growth of bacterial colonies

NASA Astrophysics Data System (ADS)

Yamazaki, Yoshihiro; Ikeda, Takemasa; Shimada, Hirotoshi; Hiramatsu, Fumiko; Kobayashi, Naoki; Wakita, Jun-ichi; Itoh, Hiroto; Kurosu, Sayuri; Nakatsuchi, Michio; Matsuyama, Tohey; Matsushita, Mitsugu

2005-06-01

The formation of concentric ring colonies by bacterial species Bacillus subtilis and Proteus mirabilis has been investigated experimentally, focusing our attention on the dependence of local cell density upon the bacterial motility. It has been confirmed that these concentric ring colonies reflect the periodic change of the bacterial motility between motile cell state and immotile cell state. We conclude that this periodic change is macroscopically determined neither by biological factors (i.e., biological clock) nor by chemical factors (chemotaxis as inhibitor). And our experimental results strongly suggest that the essential factor for the change of the bacterial motility during concentric ring formation is the local cell density.

Differential growth responses of soil bacterial taxa to carbon substrates of varying chemical recalcitrance

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

Goldfarb, K.C.; Karaoz, U.; Hanson, C.A.

2011-04-18

Soils are immensely diverse microbial habitats with thousands of co-existing bacterial, archaeal, and fungal species. Across broad spatial scales, factors such as pH and soil moisture appear to determine the diversity and structure of soil bacterial communities. Within any one site however, bacterial taxon diversity is high and factors maintaining this diversity are poorly resolved. Candidate factors include organic substrate availability and chemical recalcitrance, and given that they appear to structure bacterial communities at the phylum level, we examine whether these factors might structure bacterial communities at finer levels of taxonomic resolution. Analyzing 16S rRNA gene composition of nucleotide analog-labeledmore » DNA by PhyloChip microarrays, we compare relative growth rates on organic substrates of increasing chemical recalcitrance of >2,200 bacterial taxa across 43 divisions/phyla. Taxa that increase in relative abundance with labile organic substrates (i.e., glycine, sucrose) are numerous (>500), phylogenetically clustered, and occur predominantly in two phyla (Proteobacteria and Actinobacteria) including orders Actinomycetales, Enterobacteriales, Burkholderiales, Rhodocyclales, Alteromonadales, and Pseudomonadales. Taxa increasing in relative abundance with more chemically recalcitrant substrates (i.e., cellulose, lignin, or tannin-protein) are fewer (168) but more phylogenetically dispersed, occurring across eight phyla and including Clostridiales, Sphingomonadalaes, Desulfovibrionales. Just over 6% of detected taxa, including many Burkholderiales increase in relative abundance with both labile and chemically recalcitrant substrates. Estimates of median rRNA copy number per genome of responding taxa demonstrate that these patterns are broadly consistent with bacterial growth strategies. Taken together, these data suggest that changes in availability of intrinsically labile substrates may result in predictable shifts in soil bacterial

Effects of storage temperature on bacterial growth rates and community structure in fresh retail sushi.

PubMed

Hoel, S; Jakobsen, A N; Vadstein, O

2017-09-01

This study was conducted to assess the effects of different storage temperatures (4-20°C), on bacterial concentrations, growth rates and community structure in fresh retail sushi, a popular retail product with a claimed shelf life of 2-3 days. The maximum specific growth rate based on aerobic plate count (APC) at 4°C was 0·06 h -1 and displayed a sixfold increase (0·37 h -1 ) at 20°C. Refrigeration resulted in no growth of hydrogen sulphide (H 2 S)-producing bacteria, but this group had the strongest temperature response. The bacterial community structure was determined by PCR/DGGE (denaturing gradient gel electrophoresis). Multivariate analysis based on Bray-Curtis similarities demonstrated that temperature alone was not the major determinant for the bacterial community structure. The total concentration of aerobic bacteria was the variable that most successfully explained the differences between the communities. The dominating organisms, detected by sequencing of DNA bands excised from the DGGE gel, were Brochothrix thermosphacta and genera of lactic acid bacteria (LAB). The relationship between growth rates and storage temperatures clearly demonstrates that these products are sensitive to deviations from optimal storage temperature, possibly resulting in loss of quality during shelf life. Regardless of the storage temperature, the bacterial communities converged towards a similar structure and density, but the storage temperature determined how fast the community reached its carrying capacity. Little information is available on the microbial composition of ready-to-eat food that are prepared with raw fish, subjected to contamination during handling, and susceptible to microbial growth during cold storage. Moreover, the data are a good first possibility to simulate growth of APC, H 2 S-producing bacteria and LAB under different temperature scenarios that might occur during production, distribution or storage. © 2017 The Society for Applied Microbiology.

Culturable bacterial endophytes isolated from Mangrove tree (Rhizophora apiculata Blume) enhance seedling growth in Rice.

PubMed

Deivanai, Subramanian; Bindusara, Amitraghata Santhanam; Prabhakaran, Guruswamy; Bhore, Subhash Janardhan

2014-07-01

Endophytic bacteria do have several potential applications in medicine and in other various sectors of biotechnology including agriculture. Bacterial endophytes need to be explored for their potential applications in agricultural biotechnology. One of the potential applications of bacterial endophytes in agricultural is to enhance the growth of the agricultural crops. Hence, this study was undertaken to explore the plant growth promoting potential application of bacterial endophytes. The objective of this study was to examine the effect of endophytic bacteria from mangrove tree (Rhizophora apiculata Blume) for their efficacy in promoting seedling growth in rice. Eight endophytic bacterial isolates (EBIs) isolated from twig and petiole tissues of the mangrove were identified based on their 16S ribosomal ribonucleic acid (rRNA) gene sequence homology. Separately, surface sterilized paddy seeds were treated with cell-free broth and cell suspension of the EBIs. Rice seedlings were analyzed by various bioassays and data was recorded. The gene sequences of the isolates were closely related to two genera namely, Bacillus and Pantoea. Inoculation of EBIs from R. apiculata with rice seeds resulted in accelerated root and shoot growth with significant increase in chlorophyll content. Among the isolates, Pantoea ananatis (1MSE1) and Bacillus amyloliquefaciens (3MPE1) had shown predominance of activity. Endophytic invasion was recognized by the non-host by rapid accumulation of reactive oxygen species (ROS) and was counteracted by the production of hydrogen peroxide (H2O2) and lipid peroxide. The results demonstrated that EBIs from mangrove tree can increase the fitness of the rice seedlings under controlled conditions. These research findings could be useful to enhance the seedling growth and could serve as foundation in further research on enhancing the growth of the rice crop using endophytic bacteria.

Molecular Mechanisms of Enhanced Bacterial Growth on Hexadecane with Red Clay.

PubMed

Jung, Jaejoon; Jang, In-Ae; Ahn, Sungeun; Shin, Bora; Kim, Jisun; Park, Chulwoo; Jee, Seung Cheol; Sung, Jung-Suk; Park, Woojun

2015-11-01

Red clay was previously used to enhance bioremediation of diesel-contaminated soil. It was speculated that the enhanced degradation of diesel was due to increased bacterial growth. In this study, we selected Acinetobacter oleivorans DR1, a soil-borne degrader of diesel and alkanes, as a model bacterium and performed transcriptional analysis using RNA sequencing to investigate the cellular response during hexadecane utilization and the mechanism by which red clay promotes hexadecane degradation. We confirmed that red clay promotes the growth of A. oleivorans DR1 on hexadecane, a major component of diesel, as a sole carbon source. Addition of red clay to hexadecane-utilizing DR1 cells highly upregulated β-oxidation, while genes related to alkane oxidation were highly expressed with and without red clay. Red clay also upregulated genes related to oxidative stress defense, such as superoxide dismutase, catalase, and glutaredoxin genes, suggesting that red clay supports the response of DR1 cells to oxidative stress generated during hexadecane utilization. Increased membrane fluidity in the presence of red clay was confirmed by fatty acid methyl ester analysis at different growth phases, suggesting that enhanced growth on hexadecane could be due to increased uptake of hexadecane coupled with upregulation of downstream metabolism and oxidative stress defense. The monitoring of the bacterial community in soil with red clay for a year revealed that red clay stabilized the community structure.

A cost effective cultivation medium for biocalcification of Bacillus pasteurii KCTC 3558 and its effect on cement cubes properties.

PubMed

Yoosathaporn, S; Tiangburanatham, P; Bovonsombut, S; Chaipanich, A; Pathom-Aree, W

2016-01-01

Application of carbonate precipitation induced by Bacillus pasteurii for improving some properties of cement has been reported. However, it is not yet successful in commercial scale due to the high cost of cultivation medium. This is the first report on the application of effluent from chicken manure bio-gas plant, a high protein content agricultural waste, as an alternative growth medium for carbonate precipitation by B. pasteurii KCTC3558. Urease activity of B. pasteurii KCTC3558 cultured in chicken manure effluent medium and other three standard media were examined using phenate method. The highest urease production was achieved in chicken manure effluent medium (16.756Umg(-1) protein). Cost per liter of chicken manure effluent medium is up to 88.2% lower than other standard media. The most effective cultivation media was selected for carbonate precipitation study in cement cubes. Water absorption, voids, apparent density and compressive strength of cement cubes were measured according to the ASTM standard. The correlation between the increasing density and compressive strength of bacterial added cement cube was evident. The density of bacterial cement cube is 5.1% higher than control while the compressive strength of cement mixed with bacterial cells in chicken manure effluent medium increases up to 30.2% compared with control. SEM and XRD analysis also found the crystalline phase of calcium carbonate within bacterial cement which confirmed that the increasing density and compressive strength were resulted from bacterial carbonate precipitation. This study indicated that the effluent from chicken manure bio-gas plant could be used as an alternative cost effective culture medium for cultivation and biocalcification of B. pasteurii KCTC3558 in cement. Copyright © 2016. Published by Elsevier GmbH.

Microcoupon Assay Of Adhesion And Growth Of Bacterial Films

NASA Technical Reports Server (NTRS)

Pierson, Duane L.; Koenig, David W.

1994-01-01

Microbiological assay technique facilitates determination of some characteristics of sessile bacteria like those that attach to and coat interior walls of water-purification systems. Biofilms cause sickness and interfere with purification process. Technique enables direct measurement of rate of attachment of bacterial cells, their metabolism, and effects of chemicals on them. Used to quantify effects of both bactericides and growth-stimulating agents and in place of older standard plate-count and tube-dilution techniques.

High density growth of T7 expression strains with auto-induction option

DOEpatents

Studier, F William [Stony Brook, NY

2009-07-14

Disclosed is a method for promoting auto-induction of transcription of cloned DNA in cultures of bacterial cells grown batchwise, the transcription being under the control of a promoter whose activity can be induced by an exogenous inducer whose ability to induce said promoter is dependent on the metabolic state of said bacterial cells. Initially, a culture media is provided which includes: i) an inducer that causes induction of transcription from said promoter in said bacterial cells; and ii) a metabolite that prevents induction by said inducer, the concentration of said metabolite being adjusted so as to substantially preclude induction by said inducer in the early stages of growth of the bacterial culture, but such that said metabolite is depleted to a level that allows induction by said inducer at a later stage of growth. The culture medium is inoculated with a bacterial inoculum, the inoculum comprising bacterial cells containing cloned DNA, the transcription of which is induced by said inducer. The culture is then incubated under conditions appropriate for growth of the bacterial cells.

Effect of bicarbonate concentration on aerobic growth of campylobacter in a fumarate-pyruvate medium

USDA-ARS?s Scientific Manuscript database

The purpose of the present study was to examine the effect of sodium bicarbonate (NaHCO3) concentration on aerobic growth of Campylobacter in a fumarate-pyruvate medium. Fumarate-pyruvate broth medium was supplemented with 0.00 to 0.10% NaHCO3 and inoculated with Campylobacter coli 33559, Campyloba...

Simulation of the Growth of Austenite from As-Quenched Martensite in Medium Mn Steels

NASA Astrophysics Data System (ADS)

Huyan, Fei; Yan, Jia-Yi; Höglund, Lars; Ågren, John; Borgenstam, Annika

2018-04-01

As part of an ongoing development of third-generation advanced high-strength steels with acceptable cost, austenite reversion treatment of medium Mn steels becomes attractive because it can give rise to a microstructure of fine mixture of ferrite and austenite, leading to both high strength and large elongation. The growth of austenite during intercritical annealing is crucial for the final properties, primarily because it determines the fraction, composition, and phase stability of austenite. In the present work, the growth of austenite from as-quenched lath martensite in medium Mn steels has been simulated using the DICTRA software package. Cementite is added into the simulations based on experimental observations. Two types of systems (cells) are used, representing, respectively, (1) austenite and cementite forming apart from each other, and (2) austenite forming on the cementite/martensite interface. An interfacial dissipation energy has also been added to take into account a finite interface mobility. The simulations using the first type of setup with an addition of interfacial dissipation energy are able to reproduce the observed austenite growth in medium Mn steels reasonably well.

Modelling microbial metabolic rewiring during growth in a complex medium.

PubMed

Fondi, Marco; Bosi, Emanuele; Presta, Luana; Natoli, Diletta; Fani, Renato

2016-11-24

In their natural environment, bacteria face a wide range of environmental conditions that change over time and that impose continuous rearrangements at all the cellular levels (e.g. gene expression, metabolism). When facing a nutritionally rich environment, for example, microbes first use the preferred compound(s) and only later start metabolizing the other one(s). A systemic re-organization of the overall microbial metabolic network in response to a variation in the composition/concentration of the surrounding nutrients has been suggested, although the range and the entity of such modifications in organisms other than a few model microbes has been scarcely described up to now. We used multi-step constraint-based metabolic modelling to simulate the growth in a complex medium over several time steps of the Antarctic model organism Pseudoalteromonas haloplanktis TAC125. As each of these phases is characterized by a specific set of amino acids to be used as carbon and energy source our modelling framework describes the major consequences of nutrients switching at the system level. The model predicts that a deep metabolic reprogramming might be required to achieve optimal biomass production in different stages of growth (different medium composition), with at least half of the cellular metabolic network involved (more than 50% of the metabolic genes). Additionally, we show that our modelling framework is able to capture metabolic functional association and/or common regulatory features of the genes embedded in our reconstruction (e.g. the presence of common regulatory motifs). Finally, to explore the possibility of a sub-optimal biomass objective function (i.e. that cells use resources in alternative metabolic processes at the expense of optimal growth) we have implemented a MOMA-based approach (called nutritional-MOMA) and compared the outcomes with those obtained with Flux Balance Analysis (FBA). Growth simulations under this scenario revealed the deep impact of

Development of a semidefined growth medium for Pedobacter cryoconitis BG5 using statistical experimental design.

PubMed

Ong, Magdalena; Ongkudon, Clarence M; Wong, Clemente Michael Vui Ling

2016-10-02

Pedobacter cryoconitis BG5 are psychrophiles isolated from the cold environment and capable of proliferating and growing well at low temperature regime. Their cellular products have found a broad spectrum of applications, including in food, medicine, and bioremediation. Therefore, it is imperative to develop a high-cell density cultivation strategy coupled with optimized growth medium for P. cryoconitis BG5. To date, there has been no published report on the design and optimization of growth medium for P. cryoconitis, hence the objective of this research project. A preliminary screening of four commercially available media, namely tryptic soy broth, R2A, Luria Bertani broth, and nutrient broth, was conducted to formulate the basal medium. Based on the preliminary screening, tryptone, glucose, NaCl, and K2HPO4 along with three additional nutrients (yeast extract, MgSO4, and NH4Cl) were identified to form the basal medium which was further analyzed by Plackett-Burman experimental design. Central composite experimental design using response surface methodology was adopted to optimize tryptone, yeast extract, and NH4Cl concentrations in the formulated growth medium. Statistical data analysis showed a high regression factor of 0.84 with a predicted optimum optical (600 nm) cell density of 7.5 using 23.7 g/L of tryptone, 8.8 g/L of yeast extract, and 0.7 g/L of NH4Cl. The optimized medium for P. cryoconitis BG5 was tested, and the observed optical density was 7.8. The cost-effectiveness of the optimized medium was determined as 6.25 unit prices per gram of cell produced in a 250-ml Erlenmeyer flask.

A novel liquid medium for the efficient growth of the salmonid pathogen Piscirickettsia salmonis and optimization of culture conditions.

PubMed

Henríquez, Mirtha; González, Ernesto; Marshall, Sergio H; Henríquez, Vitalia; Gómez, Fernando A; Martínez, Irene; Altamirano, Claudia

2013-01-01

Piscirickettsia salmonis is the bacterium that causes Piscirickettsiosis, a systemic disease of salmonid fish responsible for significant economic losses within the aquaculture industry worldwide. The growth of the bacterium for vaccine formulation has been traditionally accomplished by infecting eukaryotic cell lines, a process that involves high production costs and is time-consuming. Recent research has demonstrated that it is possible to culture pure P. salmonis in a blood containing (cell-free) medium. In the present work we demonstrate the growth of P. salmonis in a liquid medium free from blood and serum components, thus establishing a novel and simplified bacteriological medium. Additionally, the new media reported provides improved growth conditions for P. salmonis, where biomass concentrations of approximately 800 mg cell dry weight L(-1) were obtained, about eight times higher than those reported for the blood containing medium. A 2- level full factorial design was employed to evaluate the significance of the main medium components on cell growth and an optimal temperature range of 23-27°C was determined for the microorganism to grow in the novel liquid media. Therefore, these results represent a breakthrough regarding P. salmonis research in order to optimize pure P. salmonis growth in liquid blood and serum free medium.

Indoleacetic acid production and plant growth promoting potential of bacterial endophytes isolated from rice (Oryza sativa L.) seeds.

PubMed

Shahzad, Raheem; Waqas, Muhammad; Khan, Abdul Latif; Al-Hosni, Khadija; Kang, Sang-Mo; Seo, Chang-Woo; Lee, In-Jung

2017-06-01

Bacterial endophytes from the phyllosphere and rhizosphere have been used to produce bioactive metabolites and to promote plant growth. However, little is known about the endophytes residing in seeds. This study aimed to isolate and identify seed-borne bacterial endophytes from rice and elucidate their potential for phytohormone production and growth enhancement. The isolated endophytes included Micrococcus yunnanensis RWL-2, Micrococcus luteus RWL-3, Enterobacter soli RWL-4, Leclercia adecarboxylata RWL-5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7, which were identified using 16S rRNA sequencing and phylogenetic analysis. These strains were analyzed for indoleacetic acid (IAA) production by using GC-MS and IAA was found in the range of 11.50 ± 0.77 μg ml -1 to 38.80 ± 1.35 μg ml -1 . We also assessed the strains for plant growth promoting potential because these isolates were able to produce IAA in pure culture. Most of the growth attributes of rice plants (shoot and root length, fresh and dry biomass, and chlorophyll content) were significantly increased by bacterial endophytes compared to the controls. These results show that IAA producing bacterial endophytes can improve hostplant growth traits and can be used as bio-fertilizers.

Bacterial population in intestines of the black tiger shrimp (Penaeus monodon) under different growth stages.

PubMed

Rungrassamee, Wanilada; Klanchui, Amornpan; Chaiyapechara, Sage; Maibunkaew, Sawarot; Tangphatsornruang, Sithichoke; Jiravanichpaisal, Pikul; Karoonuthaisiri, Nitsara

2013-01-01

Intestinal bacterial communities in aquaculture have been drawn to attention due to potential benefit to their hosts. To identify core intestinal bacteria in the black tiger shrimp (Penaeus monodon), bacterial populations of disease-free shrimp were characterized from intestines of four developmental stages (15-day-old post larvae (PL15), 1- (J1), 2- (J2), and 3-month-old (J3) juveniles) using pyrosequencing, real-time PCR and denaturing gradient gel electrophoresis (DGGE) approaches. A total of 25,121 pyrosequencing reads (reading length = 442±24 bases) were obtained, which were categorized by barcode for PL15 (7,045 sequences), J1 (3,055 sequences), J2 (13,130 sequences) and J3 (1,890 sequences). Bacteria in the phyla Bacteroides, Firmicutes and Proteobacteria were found in intestines at all four growth stages. There were 88, 14, 27, and 20 bacterial genera associated with the intestinal tract of PL15, J1, J2 and J3, respectively. Pyrosequencing analysis revealed that Proteobacteria (class Gammaproteobacteria) was a dominant bacteria group with a relative abundance of 89% for PL15 and 99% for J1, J2 and J3. Real-time PCR assay also confirmed that Gammaproteobacteria had the highest relative abundance in intestines from all growth stages. Intestinal bacterial communities from the three juvenile stages were more similar to each other than that of the PL shrimp based on PCA analyses of pyrosequencing results and their DGGE profiles. This study provides descriptive bacterial communities associated to the black tiger shrimp intestines during these growth development stages in rearing facilities.

The effects of a low-intensity red laser on bacterial growth, filamentation and plasmid DNA

NASA Astrophysics Data System (ADS)

Roos, C.; Santos, J. N.; Guimarães, O. R.; Geller, M.; Paoli, F.; Fonseca, A. S.

2013-07-01

Exposure of nonphotosynthesizing microorganisms to light could increase cell division in cultures, a phenomenon denominated as biostimulation. However, data concerning the importance of the genetic characteristics of cells on this effect are as yet scarce. The aim of this work was to evaluate the effects of a low-intensity red laser on the growth, filamentation and plasmids in Escherichia coli cells proficient and deficient in DNA repair. E. coli cultures were exposed to a laser (658 nm, 10 mW, 1 and 8 J cm-2) to study bacterial growth and filamentation. Also, bacterial cultures hosting pBSK plasmids were exposed to the laser to study DNA topological forms from the electrophoretic profile in agarose gels. Data indicate the low-intensity red laser: (i) had no effect on the growth of E. coli wild type and exonuclease III deficient cells; (ii) induced bacterial filamentation, (iii) led to no alteration in the electrophoretic profile of plasmids from exonuclease III deficient cells, but plasmids from wild type cells were altered. A low-intensity red laser at the low fluences used in phototherapy has no effect on growth, but induces filamentation and alters the topological forms of plasmid DNA in E. coli cultures depending on the DNA repair mechanisms.

Thin stillage supplementation greatly enhances bacterial cellulose production by Gluconacetobacter xylinus.

PubMed

Wu, Jyh-Ming; Liu, Ren-Han

2012-09-01

Thin stillage (TS), a wastewater from rice wine distillery can well sustain the growth of Gluconacetobacter xylinus for production of bacterial cellulose (BC). When used as a supplement to the traditional BC production medium (Hestrin and Schramm medium), the enhancement of BC production increased with the amount of TS supplemented in a static culture of G. xylinus. When TS was employed to replace distilled water for preparing HS medium (100%TS-HS medium), the BC production in this 100%TS-HS medium was enhanced 2.5-fold to a concentration of 10.38 g/l with sugar to BC conversion yield of 57% after 7 days cultivation. The cost-free TS as a supplement in BC production medium not only can greatly enhance the BC production, but also can effectively dispose the nuisance wastewater of rice wine distillery. Copyright © 2012 Elsevier Ltd. All rights reserved.

Monitoring of oil pollution at Gemsa Bay and bioremediation capacity of bacterial isolates with biosurfactants and nanoparticles.

PubMed

El-Sheshtawy, H S; Khalil, N M; Ahmed, W; Abdallah, R I

2014-10-15

Fifteen crude oil-degrading bacterial isolates were isolated from an oil-polluted area in Gemsa Bay, Red Sea, Egypt. Two bacterial species showed the highest growth rate on crude oil hydrocarbons. From an analysis of 16S rRNA sequences, these isolates were identified as Pseudomonas xanthomarina KMM 1447 and Pseudomonas stutzeri ATCC 17588. Gas Chromatographic (GC) analysis of the crude oil remaining in the culture medium after one week at 30°C showed that the optimum biodegradation of crude petroleum oil was demonstrated at 50% in medium containing biosurfactant with two types of nanoparticles separately and two bacterial species. The complete degradation of some different members of polyaromatics and the percentage biodegradation of other polyaromatics increased in microcosm containing two different types of nanoparticles with biosurfactant after 7 days. In conclusion, these bacterial strains may be useful for the bioremediation process in the Gemsa Bay, Red Sea decreasing oil pollution in this marine ecosystem. Copyright © 2014 Elsevier Ltd. All rights reserved.

Platelet-rich plasma affects bacterial growth in vitro.

PubMed

Mariani, Erminia; Filardo, Giuseppe; Canella, Valentina; Berlingeri, Andrea; Bielli, Alessandra; Cattini, Luca; Landini, Maria Paola; Kon, Elizaveta; Marcacci, Maurilio; Facchini, Andrea

2014-09-01

Platelet-rich plasma (PRP), a blood derivative rich in platelets, is a relatively new technique used in tissue regeneration and engineering. The increased quantity of platelets makes this formulation of considerable value for their role in tissue healing and microbicidal activity. This activity was investigated against five of the most important strains involved in nosocomial infections (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae and Streptococcus faecalis) to understand the prophylactic role of pure (P)-PRP. Microbicidal proteins released from activated P-PRP platelets were also determined. The microbicidal activity of P-PRP and platelet-poor plasma (PPP) was evaluated on different concentrations of the five bacterial strains incubated for 1, 2, 4 and 18 h and plated on agar for 18-24 h. P-PRP and PPP-released microbicidal proteins were evaluated by means of multiplex bead-based immunoassays. P-PRP and PPP inhibited bacterial growth for up to 2 h of incubation. The effect of P-PRP was significantly higher than that of PPP, mainly at the low seeding concentrations and/or shorter incubation times, depending on the bacterial strain. Chemokine (C-C motif) ligand-3, chemokine (C-C motif) ligand-5 and chemokine (C-X-C motif) ligand-1 were the molecules mostly related to Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus faecalis inhibition. Escherichia coli and Klebsiella pneumoniae were less influenced. The present results show that P-PRP might supply an early protection against bacterial contaminations during surgical interventions because the inhibitory activity is already evident from the first hour of treatment, which suggests that physiological molecules supplied in loco might be important in the time frame needed for the activation of the innate immune response. Copyright © 2014 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

The Adc/Lmb System Mediates Zinc Acquisition in Streptococcus agalactiae and Contributes to Bacterial Growth and Survival.

PubMed

Moulin, Pauline; Patron, Kévin; Cano, Camille; Zorgani, Mohamed Amine; Camiade, Emilie; Borezée-Durant, Elise; Rosenau, Agnès; Mereghetti, Laurent; Hiron, Aurélia

2016-12-15

The Lmb protein of Streptococcus agalactiae is described as an adhesin that binds laminin, a component of the human extracellular matrix. In this study, we revealed a new role for this protein in zinc uptake. We also identified two Lmb homologs, AdcA and AdcAII, redundant binding proteins that combine with the AdcCB translocon to form a zinc-ABC transporter. Expression of this transporter is controlled by the zinc concentration in the medium through the zinc-dependent regulator AdcR. Triple deletion of lmb, adcA, and adcAII, or that of the adcCB genes, impaired growth and cell separation in a zinc-restricted environment. Moreover, we found that this Adc zinc-ABC transporter promotes S. agalactiae growth and survival in some human biological fluids, suggesting that it contributes to the infection process. These results indicated that zinc has biologically vital functions in S. agalactiae and that, under the conditions tested, the Adc/Lmb transporter constitutes the main zinc acquisition system of the bacterium. A zinc transporter, composed of three redundant binding proteins (Lmb, AdcA, and AdcAII), was characterized in Streptococcus agalactiae This system was shown to be essential for bacterial growth and morphology in zinc-restricted environments, including human biological fluids. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Bacterial Cell Production from Hexadecane at High Temperatures

PubMed Central

Sukatsch, Dieter A.; Johnson, Marvin J.

1972-01-01

On mineral medium with hexadecane as the sole carbon source, stable mixed bacterial enrichment cultures were obtained from soil inoculum at 25, 35, 45, 55, and 65 C. Cell yields (grams of dry cells per gram of hexadecane) were determined for each of the enrichment cultures grown at the temperature at which they were enriched, and also for the 55 and 65 C cultures grown at various temperatures. In all cases, cell yields decreased with increasing growth temperature. The highest yield obtained at 65 C was 0.26, and the lowest yield obtained at 25 or 35 C was 1.02. Slower growth was observed at higher temperatures. PMID:5021971

An evaluation of microbial growth and corrosion of 316L SS in glycol/seawater mixtures

NASA Technical Reports Server (NTRS)

Lee, Jason S.; Ray, Richard I.; Lowe, Kristine L.; Jones-Meehan, Joanne; Little, Brenda J.

2003-01-01

Glycol/seawater mixtures containing > 50% glycol inhibit corrosion of 316L stainless steel and do not support bacterial growth. The results indicate bacteria are able to use low concentrations of glycol (10%) as a growth medium, but bacterial growth decreased with increasing glycol concentration. Pitting potential, determined by anodic polarization, was used to evaluate susceptibility of 316L SS to corrosion in seawater-contaminated glycol. Mixture containing a minimum concentration of 50% propylene glycol-based coolant inhibited pitting corrosion. A slightly higher minimum concentration (55%) was needed for corrosion protection in ethylene glycol mixtures.

Effect of lag time distribution on the lag phase of bacterial growth - a Monte Carlo analysis

USDA-ARS?s Scientific Manuscript database

The objective of this study is to use Monte Carlo simulation to evaluate the effect of lag time distribution of individual bacterial cells incubated under isothermal conditions on the development of lag phase. The growth of bacterial cells of the same initial concentration and mean lag phase durati...

Effect of environmental and cultural conditions on medium pH and explant growth performance of Douglas-fir ( Pseudotsuga menziesii) shoot cultures

PubMed Central

Chen, Chien-Chih; Bates, Rick; Carlson, John

2015-01-01

The medium pH level of plant tissue cultures has been shown to be essential to many aspects of explant development and growth. Sensitivity or tolerance of medium pH change in vitro varies according to specific requirements of individual species. The objectives of this study are to 1) determine medium pH change over time in storage conditions and with presence of explants, 2) evaluate the effects of medium pH change on explant growth performance and 3) assess the effects of adding a pH stabilizer, 2-(N-morpholino)ethanesulfonic acid (MES) that is commonly used in Douglas-fir micropropagation medium. Vegetative buds were collected in the spring before breaking dormancy from juvenile and mature donor trees for conducting these evaluations. Medium, with or without MES, was pre-adjusted to five pH levels before adding MES, agar and autoclaving. Medium pH changes and explant growth parameters were measured at eight different incubation times. Overall, MES provided a more stable medium pH, relative to starting pH values, under both light and dark storage conditions as well as with presence of explants. A general trend of decreasing medium pH over time was found comparing explants from juvenile and mature donor genotypes. Explant height and weight growth increased over time, but differ among explants from juvenile and mature donor genotypes. Our findings suggest that a 21-day subculture practice may best sustain medium freshness, medium pH level and desirable explant growth. PMID:26535110

Bacterial Population in Intestines of the Black Tiger Shrimp (Penaeus monodon) under Different Growth Stages

PubMed Central

Rungrassamee, Wanilada; Klanchui, Amornpan; Chaiyapechara, Sage; Maibunkaew, Sawarot; Tangphatsornruang, Sithichoke; Jiravanichpaisal, Pikul; Karoonuthaisiri, Nitsara

2013-01-01

Intestinal bacterial communities in aquaculture have been drawn to attention due to potential benefit to their hosts. To identify core intestinal bacteria in the black tiger shrimp (Penaeus monodon), bacterial populations of disease-free shrimp were characterized from intestines of four developmental stages (15-day-old post larvae (PL15), 1- (J1), 2- (J2), and 3-month-old (J3) juveniles) using pyrosequencing, real-time PCR and denaturing gradient gel electrophoresis (DGGE) approaches. A total of 25,121 pyrosequencing reads (reading length = 442±24 bases) were obtained, which were categorized by barcode for PL15 (7,045 sequences), J1 (3,055 sequences), J2 (13,130 sequences) and J3 (1,890 sequences). Bacteria in the phyla Bacteroides, Firmicutes and Proteobacteria were found in intestines at all four growth stages. There were 88, 14, 27, and 20 bacterial genera associated with the intestinal tract of PL15, J1, J2 and J3, respectively. Pyrosequencing analysis revealed that Proteobacteria (class Gammaproteobacteria) was a dominant bacteria group with a relative abundance of 89% for PL15 and 99% for J1, J2 and J3. Real-time PCR assay also confirmed that Gammaproteobacteria had the highest relative abundance in intestines from all growth stages. Intestinal bacterial communities from the three juvenile stages were more similar to each other than that of the PL shrimp based on PCA analyses of pyrosequencing results and their DGGE profiles. This study provides descriptive bacterial communities associated to the black tiger shrimp intestines during these growth development stages in rearing facilities. PMID:23577162

Bacterial growth, flow, and mixing shape human gut microbiota density and composition.

PubMed

Arnoldini, Markus; Cremer, Jonas; Hwa, Terence

2018-03-13

The human gut microbiota is highly dynamic, and host physiology and diet exert major influences on its composition. In our recent study, we integrated new quantitative measurements on bacterial growth physiology with a reanalysis of published data on human physiology to build a comprehensive modeling framework. This can generate predictions of how changes in different host factors influence microbiota composition. For instance, hydrodynamic forces in the colon, along with colonic water absorption that manifests as transit time, exert a major impact on microbiota density and composition. This can be mechanistically explained by their effect on colonic pH which directly affects microbiota competition for food. In this addendum, we describe the underlying analysis in more detail. In particular, we discuss the mixing dynamics of luminal content by wall contractions and its implications for bacterial growth and density, as well as the broader implications of our insights for the field of gut microbiota research.

Substrate and metabolite diffusion within model medium for soft cheese in relation to growth of Penicillium camembertii.

PubMed

Aldarf, Mazen; Fourcade, Florence; Amrane, Abdeltif; Prigent, Yves

2006-08-01

Penicillium camembertii was cultivated on a jellified peptone-lactate based medium to simulate the composition of Camembert cheese. Diffusional limitations due to substrate consumption were not involved in the linear growth recorded during culture, while nitrogen (peptone) limitation accounted for growth cessation. Examination of gradients confirmed that medium neutralization was the consequence of lactate consumption and ammonium production. The diffusion of the lactate assimilated from the core to the rind and that of the ammonium produced from the rind to the core was described by means of a diffusion/reaction model involving a partial linking of consumption or production to growth. The model matched experimental data throughout growth.

Oral iron acutely elevates bacterial growth in human serum.

PubMed

Cross, James H; Bradbury, Richard S; Fulford, Anthony J; Jallow, Amadou T; Wegmüller, Rita; Prentice, Andrew M; Cerami, Carla

2015-11-23

Iron deficiency is the most common nutrient deficiency worldwide and routine supplementation is standard policy for pregnant mothers and children in most low-income countries. However, iron lies at the center of host-pathogen competition for nutritional resources and recent trials of iron administration in African and Asian children have resulted in significant excesses of serious adverse events including hospitalizations and deaths. Increased rates of malaria, respiratory infections, severe diarrhea and febrile illnesses of unknown origin have all been reported, but the mechanisms are unclear. We here investigated the ex vivo growth characteristics of exemplar sentinel bacteria in adult sera collected before and 4 h after oral supplementation with 2 mg/kg iron as ferrous sulfate. Escherichia coli, Yersinia enterocolitica and Salmonella enterica serovar Typhimurium (all gram-negative bacteria) and Staphylococcus epidermidis (gram-positive) showed markedly elevated growth in serum collected after iron supplementation. Growth rates were very strongly correlated with transferrin saturation (p < 0.0001 in all cases). Growth of Staphylococcus aureus, which preferentially scavenges heme iron, was unaffected. These data suggest that even modest oral supplements with highly soluble (non-physiological) iron, as typically used in low-income settings, could promote bacteremia by accelerating early phase bacterial growth prior to the induction of immune defenses.

Impact of electro-stimulation on denitrifying bacterial growth and analysis of bacterial growth kinetics using a modified Gompertz model in a bio-electrochemical denitrification reactor.

PubMed

Liu, Hengyuan; Chen, Nan; Feng, Chuanping; Tong, Shuang; Li, Rui

2017-05-01

This study aimed to investigate the effect of electro-stimulation on denitrifying bacterial growth in a bio-electrochemical reactor, and the growth were modeled using modified Gompertz model under different current densities at three C/Ns. It was found that the similar optimum current density of 250mA/m 2 was obtained at C/N=0.75, 1.00 and 1.25, correspondingly the maximum nitrate removal efficiencies were 98.0%, 99.2% and 99.9%. Moreover, ATP content and cell membrane permeability of denitrifying bacteria were significantly increased at optimum current density. Furthermore, modified Gompertz model fitted well with the microbial growth curves, and the highest maximum growth rates (µ max ) and shorter lag time were obtained at the optimum current density for all C/Ns. This study demonstrated that the modified Gompertz model could be used for describing microbial growth under different current densities and C/Ns in a bio-electrochemical denitrification reactor, and it provided an alternative for improving the performance of denitrification process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of substrate mineralogy on bacterial mineralization of calcium carbonate: implications for stone conservation.

PubMed

Rodriguez-Navarro, Carlos; Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

2012-06-01

The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed.

Influence of Substrate Mineralogy on Bacterial Mineralization of Calcium Carbonate: Implications for Stone Conservation

PubMed Central

Jroundi, Fadwa; Schiro, Mara; Ruiz-Agudo, Encarnación; González-Muñoz, María Teresa

2012-01-01

The influence of mineral substrate composition and structure on bacterial calcium carbonate productivity and polymorph selection was studied. Bacterial calcium carbonate precipitation occurred on calcitic (Iceland spar single crystals, marble, and porous limestone) and silicate (glass coverslips, porous sintered glass, and quartz sandstone) substrates following culturing in liquid medium (M-3P) inoculated with different types of bacteria (Myxococcus xanthus, Brevundimonas diminuta, and a carbonatogenic bacterial community isolated from porous calcarenite stone in a historical building) and direct application of sterile M-3P medium to limestone and sandstone with their own bacterial communities. Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), powder X-ray diffraction (XRD), and 2-dimensional XRD (2D-XRD) analyses revealed that abundant highly oriented calcite crystals formed homoepitaxially on the calcitic substrates, irrespective of the bacterial type. Conversely, scattered spheroidal vaterite entombing bacterial cells formed on the silicate substrates. These results show that carbonate phase selection is not strain specific and that under equal culture conditions, the substrate type is the overruling factor for calcium carbonate polymorph selection. Furthermore, carbonate productivity is strongly dependent on the mineralogy of the substrate. Calcitic substrates offer a higher affinity for bacterial attachment than silicate substrates, thereby fostering bacterial growth and metabolic activity, resulting in higher production of calcium carbonate cement. Bacterial calcite grows coherently over the calcitic substrate and is therefore more chemically and mechanically stable than metastable vaterite, which formed incoherently on the silicate substrates. The implications of these results for technological applications of bacterial carbonatogenesis, including building stone conservation, are discussed. PMID:22447589

Lactic acid bacterial extract as a biogenic mineral growth modifier

NASA Astrophysics Data System (ADS)

Borah, Ballav M.; Singh, Atul K.; Ramesh, Aiyagari; Das, Gopal

2009-04-01

The formation of minerals and mechanisms by which bacteria could control their formation in natural habitats is now of current interest for material scientists to have an insight of the mechanism of in vivo mineralization, as well as to seek industrial and technological applications. Crystalline uniform structures of calcium and barium minerals formed micron-sized building blocks when synthesized in the presence of an organic matrix consisting of secreted protein extracts from three different lactic acid bacteria (LAB) viz.: Lactobacillus plantarum MTCC 1325, Lactobacillus acidophilus NRRL B4495 and Pediococcus acidilactici CFR K7. LABs are not known to form organic matrix in biological materialization processes. The influence of these bacterial extracts on the crystallization behavior was investigated in details to test the basic coordination behavior of the acidic protein. In this report, varied architecture of the mineral crystals obtained in presence of high molecular weight protein extracts of three different LAB strains has been discussed. The role of native form of high molecular weight bacterial protein extracts in the generation of nucleation centers for crystal growth was clearly established. A model for the formation of organic matrix-cation complex and the subsequent events leading to crystal growth is proposed.

Viability of 3h grown bacterial micro-colonies after direct Raman identification.

PubMed

Mathey, R; Dupoy, M; Espagnon, I; Leroux, D; Mallard, F; Novelli-Rousseau, A

2015-02-01

Clinical diagnostics in routine microbiology still mostly relies on bacterial growth, a time-consuming process that prevents test results to be used directly as key decision-making elements for therapeutic decisions. There is some evidence that Raman micro-spectroscopy provides clinically relevant information from a limited amount of bacterial cells, thus holding the promise of reduced growth times and accelerated result delivery. Indeed, bacterial identification at the species level directly from micro-colonies at an early time of growth (6h) directly on their growth medium has been demonstrated. However, such analysis is suspected to be partly destructive and could prevent the further growth of the colony needed for other tests, e.g. antibiotic susceptibility testing (AST). In the present study, we evaluated the effect of the powerful laser excitation used for Raman identification on micro-colonies probed after very short growth times. We show here, using envelope integrity markers (Syto 9 and Propidium Iodide) directly on ultra-small micro-colonies of a few tens of Escherichia coli and Staphylococcus epidermidis cells (3h growth time), that only the cells that are directly impacted by the laser lose their membrane integrity. Growth kinetics experiments show that the non-probed surrounding cells are sometimes also affected but that the micro-colonies keep their ability to grow, resulting in normal aspect and size of colonies after 15h of growth. Thus, Raman spectroscopy could be used for very early (<3h) identification of grown micro-organisms without impairing further antibiotics susceptibility characterization steps. Copyright © 2014 Elsevier B.V. All rights reserved.

Effects of inoculation with organic-phosphorus-mineralizing bacteria on soybean (Glycine max) growth and indigenous bacterial community diversity.

PubMed

Sun, Wei; Qian, Xun; Gu, Jie; Wang, Xiao-Juan; Li, Yang; Duan, Man-Li

2017-05-01

Three different organic-phosphorus-mineralizing bacteria (OPMB) strains were inoculated to soil planted with soybean (Glycine max), and their effects on soybean growth and indigenous bacterial community diversity were investigated. Inoculation with Pseudomonas fluorescens Z4-1 and Brevibacillus agri L7-1 increased organic phosphorus degradation by 22% and 30%, respectively, compared with the control at the mature stage. Strains P. fluorescens Z4-1 and B. agri L7-1 significantly improved the soil alkaline phosphatase activity, average well color development, and the soybean root activity. Terminal restriction fragment length polymorphism analysis demonstrated that P. fluorescens Z4-1 and B. agri L7-1 could persist in the soil at relative abundances of 2.0%-6.4% throughout soybean growth. Thus, P. fluorescens Z4-1 and B. agri L7-1 could potentially be used in organic-phosphorus-mineralizing biofertilizers. OPMB inoculation altered the genetic structure of the soil bacterial communities but had no apparent influence on the carbon source utilization profiles of the soil bacterial communities. Principal components analysis showed that the changes in the carbon source utilization profiles of bacterial community depended mainly on the plant growth stages rather than inoculation with OPMB. The results help to understand the evolution of the soil bacterial community after OPMB inoculation.

Implications in studies of environmental risk assessments: Does culture medium influence the results of toxicity tests of marine bacteria?

PubMed

Díaz-García, Alejandra; Borrero-Santiago, Ana R; Riba, Inmaculada

2018-04-14

Two marine bacterial populations (Roseobacter sp. and Pseudomonas litoralis) were exposed to different concentrations of zinc (300, 625, 1250, 2000, 2500 and 5000 mg L -1 ) and cadmium (75, 250, 340, 500 and 1000 mg L -1 ) using two culture media (full nutrient Marine Broth 2216 "MB" and 1:10 (vol/vol) dilution with seawater of Marine Broth 2216 "MB SW "), in order to assess population responses depending on the culture medium and also potential adverse effects associated with these two metals. Different responses were found depending on the culture medium (Bacterial abundance (cells·mL -1 ), growth rates (μ, hours -1 ), and production of Extracellular Polysaccharides Substances (EPS) (μg glucose·cells -1 ). Results showed negative effects in both strains after the exposure to Zn treatments. Both strains showed highest metal sensitivity at low concentrations using both culture media. However, different results were found when exposing the bacterial populations to Cd treatments depending on the culture medium. Highest toxicity was observed using MB at low levels of Cd concentrations, whereas MB SW showed toxicity to bacteria at higher concentrations of Cd. Results not only showed adverse effects on Roseobacter sp. and Pseudomonas litoralis associated with the concentration of Zn and Cd, but also confirm that depending on the culture medium results can differ. This work suggests MB SW as an adequate culture medium to study metal toxicity bioassays in order to predict realistic effects on marine bacterial populations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Wheat seeds harbour bacterial endophytes with potential as plant growth promoters and biocontrol agents of Fusarium graminearum.

PubMed

Díaz Herrera, Silvana; Grossi, Cecilia; Zawoznik, Myriam; Groppa, María Daniela

2016-01-01

The role of endophytic communities of seeds is still poorly characterised. The purpose of this work was to survey the presence of bacterial endophytes in the seeds of a commercial wheat cultivar widely sown in Argentina and to look for plant growth promotion features and biocontrol abilities against Fusarium graminearum among them. Six isolates were obtained from wheat seeds following a culture-dependent protocol. Four isolates were assignated to Paenibacillus genus according to their 16S rRNA sequencing. The only gammaproteobacteria isolated, presumably an Enterobactereaceae of Pantoea genus, was particularly active as IAA and siderophore producer, and also solubilised phosphate and was the only one that grew on N-free medium. Several of these isolates demonstrated ability to restrain F. graminearum growth on dual culture and in a bioassay using barley and wheat kernels. An outstanding ability to form biofilm on an inert surface was corroborated for those Paenibacillus which displayed greater biocontrol of F. graminearum, and the inoculation with one of these isolates in combination with the Pantoea isolate resulted in greater chlorophyll content in barley seedlings. Our results show a significant ecological potential of some components of the wheat seed endophytic community. Copyright © 2016 Elsevier GmbH. All rights reserved.

Influence of medium components on the expression of recombinant lipoproteins in Escherichia coli.

PubMed

Tseng, Chi-Ling; Leng, Chih-Hsiang

2012-02-01

Bacterial lipoproteins are crucial antigens for protective immunity against bacterial pathogens. Expression of exogenous lipoproteins in Escherichia coli at high levels is thought to be an extremely difficult endeavor because it frequently results in incomplete or absent lipid modification. Previously, we identified a fusion sequence (D1) from a Neisseria meningitidis lipoprotein that induced a non-lipidated protein, E3 (the domain III of the dengue virus envelope protein), to become lipidated. However, without optimizing the growth conditions, some of the D1-fusion proteins were not lipidated. Here, we report the influence of medium components on the expression of recombinant lipoproteins in E. coli. For high-level expression of mature lipoproteins in the C43 (DE3) strain, M9 medium was better than M63 and the rich medium. Furthermore, we analyzed the influence of other media factors (including nitrogen and carbon sources, phosphate, ferrous ions, calcium, magnesium, and pH) on the levels of lipoprotein expression. The results showed that excess nitrogen sources and phosphate in M9 medium could increase the amount of immature lipoproteins, and glucose was a better carbon source than glycerol for expressing mature lipoproteins. We also found that lipoproteins tended to be completely processed in the alkaline environment, even in the nutrient-rich medium. Additional constructs expressing different immunogens or lipid signal peptides as targets were also utilized, demonstrating that these targets could be expressed as completely mature lipoproteins in the M9 medium but not in the rich medium. Our results provide the useful information for expressing mature exogenous lipoproteins in E. coli.

Impact of short-term acidification on nitrification and nitrifying bacterial community dynamics in soilless cultivation media.

PubMed

Cytryn, Eddie; Levkovitch, Irit; Negreanu, Yael; Dowd, Scot; Frenk, Sammy; Silber, Avner

2012-09-01

Soilless medium-based horticulture systems are highly prevalent due to their capacity to optimize growth of high-cash crops. However, these systems are highly dynamic and more sensitive to physiochemical and pH perturbations than traditional soil-based systems, especially during nitrification associated with ammonia-based fertilization. The objective of this study was to assess the impact of nitrification-generated acidification on ammonia oxidation rates and nitrifying bacterial community dynamics in soilless growth media. To achieve this goal, perlite soilless growth medium from a commercial bell pepper greenhouse was incubated with ammonium in bench-scale microcosm experiments. Initial quantitative real-time PCR analysis indicated that betaproteobacterial ammonia oxidizers were significantly more abundant than ammonia-oxidizing archaea, and therefore, research focused on this group. Ammonia oxidation rates were highest between 0 and 9 days, when pH values dropped from 7.4 to 4.9. Pyrosequencing of betaproteobacterial ammonia-oxidizing amoA gene fragments indicated that r-strategist-like Nitrosomonas was the dominant ammonia-oxidizing bacterial genus during this period, seemingly due to the high ammonium concentration and optimal growth conditions in the soilless media. Reduction of pH to levels below 4.8 resulted in a significant decrease in both ammonia oxidation rates and the diversity of ammonia-oxidizing bacteria, with increased relative abundance of the r-strategist-like Nitrosospira. Nitrite oxidizers (Nitrospira and Nitrobacter) were on the whole more abundant and less sensitive to acidification than ammonia oxidizers. This study demonstrates that nitrification and nitrifying bacterial community dynamics in high-N-load intensive soilless growth media may be significantly different from those in in-terra agricultural systems.

Impact of Short-Term Acidification on Nitrification and Nitrifying Bacterial Community Dynamics in Soilless Cultivation Media

PubMed Central

Levkovitch, Irit; Negreanu, Yael; Dowd, Scot; Frenk, Sammy; Silber, Avner

2012-01-01

Soilless medium-based horticulture systems are highly prevalent due to their capacity to optimize growth of high-cash crops. However, these systems are highly dynamic and more sensitive to physiochemical and pH perturbations than traditional soil-based systems, especially during nitrification associated with ammonia-based fertilization. The objective of this study was to assess the impact of nitrification-generated acidification on ammonia oxidation rates and nitrifying bacterial community dynamics in soilless growth media. To achieve this goal, perlite soilless growth medium from a commercial bell pepper greenhouse was incubated with ammonium in bench-scale microcosm experiments. Initial quantitative real-time PCR analysis indicated that betaproteobacterial ammonia oxidizers were significantly more abundant than ammonia-oxidizing archaea, and therefore, research focused on this group. Ammonia oxidation rates were highest between 0 and 9 days, when pH values dropped from 7.4 to 4.9. Pyrosequencing of betaproteobacterial ammonia-oxidizing amoA gene fragments indicated that r-strategist-like Nitrosomonas was the dominant ammonia-oxidizing bacterial genus during this period, seemingly due to the high ammonium concentration and optimal growth conditions in the soilless media. Reduction of pH to levels below 4.8 resulted in a significant decrease in both ammonia oxidation rates and the diversity of ammonia-oxidizing bacteria, with increased relative abundance of the r-strategist-like Nitrosospira. Nitrite oxidizers (Nitrospira and Nitrobacter) were on the whole more abundant and less sensitive to acidification than ammonia oxidizers. This study demonstrates that nitrification and nitrifying bacterial community dynamics in high-N-load intensive soilless growth media may be significantly different from those in in-terra agricultural systems. PMID:22773643

Bacterial Standing Stock, Activity, and Carbon Production during Formation and Growth of Sea Ice in the Weddell Sea, Antarctica.

PubMed

Grossmann, S; Dieckmann, G S

1994-08-01

Bacterial response to formation and growth of sea ice was investigated during autumn in the northeastern Weddell Sea. Changes in standing stock, activity, and carbon production of bacteria were determined in successive stages of ice development. During initial ice formation, concentrations of bacterial cells, in the order of 1 x 10 to 3 x 10 liter, were not enhanced within the ice matrix. This suggests that physical enrichment of bacteria by ice crystals is not effective. Due to low concentrations of phytoplankton in the water column during freezing, incorporation of bacteria into newly formed ice via attachment to algal cells or aggregates was not recorded in this study. As soon as the ice had formed, the general metabolic activity of bacterial populations was strongly suppressed. Furthermore, the ratio of [H]leucine incorporation into proteins to [H]thymidine incorporation into DNA changed during ice growth. In thick pack ice, bacterial activity recovered and growth rates up to 0.6 day indicated actively dividing populations. However, biomass-specific utilization of organic compounds remained lower than in open water. Bacterial concentrations of up to 2.8 x 10 cells liter along with considerably enlarged cell volumes accumulated within thick pack ice, suggesting reduced mortality rates of bacteria within the small brine pores. In the course of ice development, bacterial carbon production increased from about 0.01 to 0.4 mug of C liter h. In thick ice, bacterial secondary production exceeded primary production of microalgae.

The bio-physics of condensation of divalent cations into the bacterial wall has implications for growth of Gram-positive bacteria.

PubMed

Rauch, Cyril; Cherkaoui, Mohammed; Egan, Sharon; Leigh, James

2017-02-01

The anionic-polyelectrolyte nature of the wall of Gram-positive bacteria has long been suspected to be involved in homeostasis of essential cations and bacterial growth. A better understanding of the coupling between the biophysics and the biology of the wall is essential to understand some key features at play in ion-homeostasis in this living system. We consider the wall as a polyelectrolyte gel and balance the long-range electrostatic repulsion within this structure against the penalty entropy required to condense cations around wall polyelectrolytes. The resulting equations define how cations interact physically with the wall and the characteristic time required for a cation to leave the wall and enter into the bacterium to enable its usage for bacterial metabolism and growth. The model was challenged against experimental data regarding growth of Gram-positive bacteria in the presence of varying concentration of divalent ions. The model explains qualitatively and quantitatively how divalent cations interact with the wall as well as how the biophysical properties of the wall impact on bacterial growth (in particular the initiation of bacterial growth). The interplay between polymer biophysics and the biology of Gram positive bacteria is defined for the first time as a new set of variables that contribute to the kinetics of bacterial growth. Providing an understanding of how bacteria capture essential metal cations in way that does not follow usual binding laws has implications when considering the control of such organisms and their ability to survive and grow in extreme environments. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

Motility of Escherichia coli in a quasi-two-dimensional porous medium.

PubMed

Sosa-Hernández, Juan Eduardo; Santillán, Moisés; Santana-Solano, Jesús

2017-03-01

Bacterial migration through confined spaces is critical for several phenomena, such as biofilm formation, bacterial transport in soils, and bacterial therapy against cancer. In the present work, E. coli (strain K12-MG1655 WT) motility was characterized by recording and analyzing individual bacterium trajectories in a simulated quasi-two-dimensional porous medium. The porous medium was simulated by enclosing, between slide and cover slip, a bacterial-culture sample mixed with uniform 2.98-μm-diameter spherical latex particles. The porosity of the medium was controlled by changing the latex particle concentration. By statistically analyzing several trajectory parameters (instantaneous velocity, turn angle, mean squared displacement, etc.), and contrasting with the results of a random-walk model developed ad hoc, we were able to quantify the effects that different obstacle concentrations have upon bacterial motility.

Phenotypic indications of FtsZ inhibition in hok/sok-induced bacterial growth changes and stress response.

PubMed

Chukwudi, Chinwe Uzoma; Good, Liam

2018-01-01

The hok/sok locus has been shown to enhance the growth of bacteria in adverse growth conditions such as high temperature, low starting-culture densities and antibiotic treatment. This is in addition to their well-established plasmid-stabilization effect via post-segregational killing of plasmid-free daughter cells. It delays the onset of growth by prolonging the lag phase of bacterial culture, and increases the rate of exponential growth when growth eventually begins. This enables the cells adapt to the prevailing growth conditions and enhance their survival in stressful conditions. These effects functionally complement defective SOS response mechanism, and appear analogous to the growth effects of FtsZ in the SOS pathway. In this study, the role of FtsZ in the hok/sok-induced changes in bacterial growth and cell division was investigated. Morphologic studies of early growth-phase cultures and cells growing under temperature stress showed elongated cells typical of FtsZ inhibition/deficiency. Both ftsZ silencing and over-expression produced comparable growth effects in control cells, and altered the growth changes observed otherwise in the hok/sok + cells. These changes were diminished in SOS-deficient strain containing mutant FtsZ. The involvement of FtsZ in the hok/sok-induced growth changes may be exploited as drug target in host bacteria, which often propagate antibiotic resistance elements. Copyright © 2017 Elsevier Ltd. All rights reserved.

Responses of growth cones to changes in osmolality of the surrounding medium.

PubMed

Bray, D; Money, N P; Harold, F M; Bamburg, J R

1991-04-01

The possible involvement of osmotically generated hydrostatic pressure in driving actin-rich extensions of the cell surface was examined using cultures of chick neurons. Estimation of the excess internal osmotic pressure of chick neural tissue by vapor pressure deficit osmometry, and of the excess internal hydrostatic pressure in cultured chick neurons using a calibrated pressure pipette, gave upper limits of 10 mosM and 0.1 atmosphere (1 atmosphere = 101325 Pa), respectively. Increases in the osmolality of the medium surrounding cultured neurons by addition of sucrose, mannitol or polyethylene glycol by amounts that should eliminate any internal pressure not only failed to arrest the growth of filopodia but caused them to increase in length up to twofold in 3-5 min. Lamellipodia remained unchanged following hyperosmotic shifts of 20 mosM, but higher levels caused a small decrease in area. Reduction of osmolality by the addition of water to the culture fluid down to 50% of its normal value failed to show any detectable change in either filopodial length or lamellipodia area. These observations argue against an osmotic mechanism for growth cone extension and show that the growth of filopodia, in particular, is unlikely to be driven by osmotically generated hydrostatic pressure. In contrast to the short-term effects on growth cone morphology, the slower elongation of the neuritic cylinder showed a consistent osmotic response. Growth rates were reduced following addition of osmolytes and increased in rate (as much as sixfold) following addition of water to the culture medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic Laser-Light Scattering Study on Bacterial Growth

NASA Astrophysics Data System (ADS)

Miike, Hidetoshi; Hideshima, Masao; Hashimoto, Hajime; Ebina, Yoshio

1984-08-01

The motility changes in growing bacteria in a culture medium were observed with a dynamic light-scattering technique used to analyse the frequency spectrum of the scattered light intensity. Two typical enterobacteriaceae, E. coil and P. morganii, were examined, and the change in the velocity distribution of the bacteria with time was analysed using the observed spectrum. The distribution pattern was found to change from a Gaussian-type to a Saclay-type with time, and the mean speed of the bacteria had a maximum value at around the turning point of the growth curve.

Induction of a global stress response during the first step of Escherichia coli plate growth.

PubMed

Cuny, Caroline; Lesbats, Maïalène; Dukan, Sam

2007-02-01

We have investigated the first events that occur when exponentially grown cells are transferred from a liquid medium (Luria-Bertani [LB]) to a solid medium (LB agar [LBA]). We observed an initial lag phase of 180 min for the wild type MG1655 without any apparent growth. This lack of growth was independent of the bacterial physiological state (either the stationary or the exponential phase), the solid medium composition, or the number of cells on the plate, but it was dependent on the bacterial genotype. Using lacZ-reporter fusions and two-dimensional electrophoresis analysis, we observed that when cells from exponential-phase cultures were plated on LBA, several global regulons, like heat shock regulons (RpoH, RpoE, CpxAR) and oxidative-stress regulons (SoxRS, OxyR, Fur), were immediately induced. Our results indicate that in order to grow on plates, bacteria must not only adapt to new conditions but also perceive a real stress.

Thermal design and turbidity sensor for autonomous bacterial growth measurements in spaceflight.

PubMed

van Benthem, Roel; Krooneman, Janneke; de Grave, Wubbo; Hammenga-Dorenbos, Hilma

2009-04-01

For application of biological air filters in manned spacecraft, research on bacterial growth is carried out under microgravity conditions. For the BIOFILTER experiment, flown in 2005 on FOTON M2, eight turbidity sensors to measure the growth rate of the bacterium Xanthobacter autotrophicus GJ10 were used. Also thermal management provisions were implemented to control the internal temperature. The design and performance of the BIOFILTER equipment as well as results of the biological ground reference experiments performed in 2006 are discussed. High-performance thermal (vacuum) insulation (lambda= 0.7 mW/mK) and phase change material were implemented, keeping the BIOFILTER internal temperature below 16 degrees C during the 4-day integration period between transport and launch. After launch, in microgravity, the growth of X. autotrophicus GJ10 was successfully triggered by a temperature increase by using an internal heater to 26 degrees C. Although the operation of the sensor electronics was not fully satisfying, the bacterial growth was measured with the sensors, revealing growth rates between 0.046 and 0.077 h(-1) in microgravity, that is, approximately 1.5-2.5 times slower than routinely measured on Earth under optimal laboratory conditions. For the ground-reference experiments the equipment box, containing the eight sensors, was placed on a random positioning machine performing random rotations at 0.5 degrees /min (settling compensation) and 90 degrees /min (microgravity simulation) while the environment was controlled, accurately repeating the BIOFILTER internal temperature profile. Despite the rotation speed differences, growth rates of 0.115 h(-1) were confirmed by both the ground reference experiments. Biological interpretation of the measurements is, however, compromised owing to poor mixing and other unknown physical and biological phenomena that need to be addressed for further space experiments using these kinds of systems.

A new predictive dynamic model describing the effect of the ambient temperature and the convective heat transfer coefficient on bacterial growth.

PubMed

Ben Yaghlene, H; Leguerinel, I; Hamdi, M; Mafart, P

2009-07-31

In this study, predictive microbiology and food engineering were combined in order to develop a new analytical model predicting the bacterial growth under dynamic temperature conditions. The proposed model associates a simplified primary bacterial growth model without lag, the secondary Ratkowsky "square root" model and a simplified two-parameter heat transfer model regarding an infinite slab. The model takes into consideration the product thickness, its thermal properties, the ambient air temperature, the convective heat transfer coefficient and the growth parameters of the micro organism of concern. For the validation of the overall model, five different combinations of ambient air temperature (ranging from 8 degrees C to 12 degrees C), product thickness (ranging from 1 cm to 6 cm) and convective heat transfer coefficient (ranging from 8 W/(m(2) K) to 60 W/(m(2) K)) were tested during a cooling procedure. Moreover, three different ambient air temperature scenarios assuming alternated cooling and heating stages, drawn from real refrigerated food processes, were tested. General agreement between predicted and observed bacterial growth was obtained and less than 5% of the experimental data fell outside the 95% confidence bands estimated by the bootstrap percentile method, at all the tested conditions. Accordingly, the overall model was successfully validated for isothermal and dynamic refrigeration cycles allowing for temperature dynamic changes at the centre and at the surface of the product. The major impact of the convective heat transfer coefficient and the product thickness on bacterial growth during the product cooling was demonstrated. For instance, the time needed for the same level of bacterial growth to be reached at the product's half thickness was estimated to be 5 and 16.5 h at low and high convection level, respectively. Moreover, simulation results demonstrated that the predicted bacterial growth at the air ambient temperature cannot be assumed to be

Gold biorecovery from e-waste: An improved strategy through spent medium leaching with pH modification.

PubMed

Natarajan, Gayathri; Ting, Yen-Peng

2015-10-01

Rapid technological advancement and relatively short life time of electronic goods have resulted in an alarming growth rate of electronic waste which often contains significant quantities of toxic and precious metals. Compared to conventional recovery methods, bioleaching is an environmentally friendly process for metal extraction. Gold was bioleached from electronic scrap materials (ESM) via gold-cyanide complexation using cyanide produced from pure and mixed cultures of cyanogenic bacteria Chromobacterium violaceum, Pseudomonas aeruginosa and Pseudomonas fluorescens. As ESM was toxic to the bacteria, a two-step bioleaching approach was adopted where the solid waste was added to the bacterial culture after it has reached maximum growth and cyanide production during early stationary phase. Pure culture of C. violaceum showed the highest cyanide production, yielding maximum gold recovery of 11.3% at 0.5% w/v pulp density of ESM in two-step bioleaching. At the same pulp density of ESM, spent medium bioleaching using bacterial cell-free metabolites achieved gold recovery of 18%. Recovery increased to 30% when the pH of the spent medium was increased to shift the equilibrium in favor of cyanide ions production. It is demonstrated for the first time that pH modification of spent medium further improved metal solubilization and yielded higher metal recovery (compared to two-step bioleaching). Copyright © 2015 Elsevier Ltd. All rights reserved.

In-Situ Quantification of the Interfacial Rheological Response of Bacterial Biofilms to Environmental Stimuli

PubMed Central

Rühs, Patrick A.; Böni, Lukas; Fuller, Gerald G.; Inglis, R. Fredrik; Fischer, Peter

2013-01-01

Understanding the numerous factors that can affect biofilm formation and stability remain poorly understood. One of the major limitations is the accurate measurement of biofilm stability and cohesiveness in real-time when exposed to changing environmental conditions. Here we present a novel method to measure biofilm strength: interfacial rheology. By culturing a range of bacterial biofilms on an air-liquid interface we were able to measure their viscoelastic growth profile during and after biofilm formation and subsequently alter growth conditions by adding surfactants or changing the nutrient composition of the growth medium. We found that different bacterial species had unique viscoelastic growth profiles, which was also highly dependent on the growth media used. We also found that we could reduce biofilm formation by the addition of surfactants or changing the pH, thereby altering the viscoelastic properties of the biofilm. Using this technique we were able to monitor changes in viscosity, elasticity and surface tension online, under constant and varying environmental conditions, thereby providing a complementary method to better understand the dynamics of both biofilm formation and dispersal. PMID:24244319

The Leucine Incorporation Method Estimates Bacterial Growth Equally Well in Both Oxic and Anoxic Lake Waters

PubMed Central

Bastviken, David; Tranvik, Lars

2001-01-01

Bacterial biomass production is often estimated from incorporation of radioactively labeled leucine into protein, in both oxic and anoxic waters and sediments. However, the validity of the method in anoxic environments has so far not been tested. We compared the leucine incorporation of bacterial assemblages growing in oxic and anoxic waters from three lakes differing in nutrient and humic contents. The method was modified to avoid O2 contamination by performing the incubation in syringes. Isotope saturation levels in oxic and anoxic waters were determined, and leucine incorporation rates were compared to microscopically observed bacterial growth. Finally, we evaluated the effects of O2 contamination during incubation with leucine, as well as the potential effects of a headspace in the incubation vessel. Isotope saturation occurred at a leucine concentration of above about 50 nM in both oxic and anoxic waters from all three lakes. Leucine incorporation rates were linearly correlated to observed growth, and there was no significant difference between oxic and anoxic conditions. O2 contamination of anoxic water during 1-h incubations with leucine had no detectable impact on the incorporation rate, while a headspace in the incubation vessel caused leucine incorporation to increase in both anoxic and O2-contaminated samples. The results indicate that the leucine incorporation method relates equally to bacterial growth rates under oxic and anoxic conditions and that incubation should be performed without a headspace. PMID:11425702

Impact of Medium and Substrate on Growth of Pseudomonas Fluorescens Biofilms on Polyurethane Paint

DTIC Science & Technology

2011-02-01

biofilm formation on polyurethane (PU) coatings, and to define how those parameters contribute to polyurethane biodegradation. We used a batch flow system...determine which factors best support the growth and persistence of Pseudomonas fluorescens biofilms . Factors that enhance biofilm formation and...AFRL-RX-WP-TP-2011-4131 IMPACT OF MEDIUM AND SUBSTRATE ON GROWTH OF PSEUDOMONAS FLUORESCENS BIOFILMS ON POLYURETHANE PAINT Wendy L. Goodson

Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences

PubMed Central

Purohit, Vishnudutt; Bode, J. Christian; Bode, Christiane; Brenner, David A.; Choudhry, Mashkoor A.; Hamilton, Frank; Kang, Y. James; Keshavarzian, Ali; Rao, Radhakrishna; Sartor, R. Balfour; Swanson, Christine; Turner, Jerrold R.

2008-01-01

This report is a summary of the symposium on Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences, organized by National Institute on Alcohol Abuse and Alcoholism, Office of Dietary Supplements, and National Institute of Diabetes and Digestive and Kidney Diseases of National Institutes of Health in Rockville, Maryland, October 11, 2006. Alcohol exposure can promote the growth of Gram negative bacteria in the intestine which may result in accumulation of endotoxin. In addition, alcohol metabolism by Gram negative bacteria and intestinal epithelial cells can result in accumulation of acetaldehyde, which in turn can increase intestinal permeability to endotoxin by increasing tyrosine phosphorylation of tight junction and adherens junction proteins. Alcohol-induced generation of nitric oxide may also contribute to increased permeability to endotoxin by reacting with tubulin, which may cause damage to microtubule cytoskeleton and subsequent disruption of intestinal barrier function. Increased intestinal permeability can lead to increased transfer of endotoxin from the intestine to the liver and general circulation where endotoxin may trigger inflammatory changes in the liver and other organs. Alcohol may also increase intestinal permeability to peptidoglycan which can initiate inflammatory response in liver and other organs. In addition, acute alcohol exposure may potentiate the effect of burn injury on intestinal bacterial growth and permeability. Decreasing the number of Gram negative bacteria in the intestine can result in decreased production of endotoxin as well as acetaldehyde which is expected to decrease intestinal permeability to endotoxin. In addition, intestinal permeability may be preserved by administering epidermal growth factor, L-glutamine, oats supplementation, or zinc thereby preventing the transfer of endotoxin to the general circulation. Thus reducing the number of intestinal Gram negative bacteria and

Bacterial Signaling Nucleotides Inhibit Yeast Cell Growth by Impacting Mitochondrial and Other Specifically Eukaryotic Functions

PubMed Central

Vergnano, Marta; Wan, Chris

2017-01-01

ABSTRACT We have engineered Saccharomyces cerevisiae to inducibly synthesize the prokaryotic signaling nucleotides cyclic di-GMP (cdiGMP), cdiAMP, and ppGpp in order to characterize the range of effects these nucleotides exert on eukaryotic cell function during bacterial pathogenesis. Synthetic genetic array (SGA) and transcriptome analyses indicated that, while these compounds elicit some common reactions in yeast, there are also complex and distinctive responses to each of the three nucleotides. All three are capable of inhibiting eukaryotic cell growth, with the guanine nucleotides exhibiting stronger effects than cdiAMP. Mutations compromising mitochondrial function and chromatin remodeling show negative epistatic interactions with all three nucleotides. In contrast, certain mutations that cause defects in chromatin modification and ribosomal protein function show positive epistasis, alleviating growth inhibition by at least two of the three nucleotides. Uniquely, cdiGMP is lethal both to cells growing by respiration on acetate and to obligately fermentative petite mutants. cdiGMP is also synthetically lethal with the ribonucleotide reductase (RNR) inhibitor hydroxyurea. Heterologous expression of the human ppGpp hydrolase Mesh1p prevented the accumulation of ppGpp in the engineered yeast and restored cell growth. Extensive in vivo interactions between bacterial signaling molecules and eukaryotic gene function occur, resulting in outcomes ranging from growth inhibition to death. cdiGMP functions through a mechanism that must be compensated by unhindered RNR activity or by functionally competent mitochondria. Mesh1p may be required for abrogating the damaging effects of ppGpp in human cells subjected to bacterial infection. PMID:28743817

Characterizing endophytic competence and plant growth promotion of bacterial endophytes inhabiting the seed endosphere of Rice.

PubMed

Walitang, Denver I; Kim, Kiyoon; Madhaiyan, Munusamy; Kim, Young Kee; Kang, Yeongyeong; Sa, Tongmin

2017-10-26

Rice (Oryza sativa L. ssp. indica) seeds as plant microbiome present both an opportunity and a challenge to colonizing bacterial community living in close association with plants. Nevertheless, the roles and activities of bacterial endophytes remain largely unexplored and insights into plant-microbe interaction are compounded by its complexity. In this study, putative functions or physiological properties associated with bacterial endophytic nature were assessed. Also, endophytic roles in plant growth and germination that may allow them to be selectively chosen by plants were also studied. The cultivable seed endophytes were dominated by Proteobacteria particularly class Gammaproteobacteria. Highly identical type strains were isolated from the seed endosphere regardless of the rice host's physiological tolerance to salinity. Among the type strains, Flavobacterium sp., Microbacterium sp. and Xanthomonas sp. were isolated from the salt-sensitive and salt-tolerant cultivars. PCA-Biplot ordination also showed that specific type strains isolated from different rice cultivars have distinguishing similar characteristics. Flavobacterium sp. strains are phosphate solubilizers and indole-3-acetic acid producers with high tolerance to salinity and osmotic stress. Pseudomonas strains are characterized as high siderophore producers while Microbacterium sp. and Xanthomonas sp. strains have very high pectinase and cellulase activity. Among the physiological traits of the seed endophytes, bacterial pectinase and cellulase activity are positively correlated as well as salt and osmotic tolerance. Overall characterization shows that majority of the isolates could survive in 4-8% salt concentration as well as in 0.6 M and 1.2 M sucrose solution. The activities of catalase, pectinase and cellulase were also observed in almost all of the isolates indicating the importance of these characteristics for survival and colonization into the seed endosphere. Seed bacterial endophytes also

Complex conductivity response to microbial growth and biofilm formation on phenanthrene spiked medium

NASA Astrophysics Data System (ADS)

Albrecht, Remy; Gourry, Jean Christophe; Simonnot, Marie-Odile; Leyval, Corinne

2011-11-01

Several laboratory studies have recently demonstrated the utility of geophysical methods for the investigation of microbial-induced changes over contaminated sites. However, it remains difficult to distinguish the effects due to the new physical properties imparted by microbial processes, to bacterial growth, or to the development of bacterial biofilm. We chose to study the influence of biofilm formation on geophysical response using complex conductivity measurements (0.1-1000 Hz) in phenanthrene-contaminated media. Biotic assays were conducted with two phenanthrene (PHE) degrading bacterial strains: Burkholderia sp (NAH1), which produced biofilm and Stenophomonas maltophilia (MATE10), which did not, and an abiotic control. Results showed that bacterial densities for NAH1 and MATE10 strains continuously increased at the same rate during the experiment. However, the complex conductivity signature showed noticeable differences between the two bacteria, with a phase shift of 50 mrad at 4 Hz for NAH1, which produced biofilm. Biofilm volume was quantified by Scanning Confocal Laser Microscopy (SCLM). Significant correlations were established between phase shift decrease and biofilm volume for NAH1 assays. Results suggest that complex conductivity measurements, specifically phase shift, can be a useful indicator of biofilm formation inside the overall signal of microbial activity on contaminated sites.

Growth of 48 built environment bacterial isolates on board the International Space Station (ISS)

PubMed Central

Neches, Russell Y.; Lang, Jenna M.; Brown, Wendy E.; Severance, Mark; Cavalier, Darlene

2016-01-01

Background. While significant attention has been paid to the potential risk of pathogenic microbes aboard crewed spacecraft, the non-pathogenic microbes in these habitats have received less consideration. Preliminary work has demonstrated that the interior of the International Space Station (ISS) has a microbial community resembling those of built environments on Earth. Here we report the results of sending 48 bacterial strains, collected from built environments on Earth, for a growth experiment on the ISS. This project was a component of Project MERCCURI (Microbial Ecology Research Combining Citizen and University Researchers on ISS). Results. Of the 48 strains sent to the ISS, 45 of them showed similar growth in space and on Earth using a relative growth measurement adapted for microgravity. The vast majority of species tested in this experiment have also been found in culture-independent surveys of the ISS. Only one bacterial strain showed significantly different growth in space. Bacillus safensis JPL-MERTA-8-2 grew 60% better in space than on Earth. Conclusions. The majority of bacteria tested were not affected by conditions aboard the ISS in this experiment (e.g., microgravity, cosmic radiation). Further work on Bacillus safensis could lead to interesting insights on why this strain grew so much better in space. PMID:27019789

Growth of 48 built environment bacterial isolates on board the International Space Station (ISS).

PubMed

Coil, David A; Neches, Russell Y; Lang, Jenna M; Brown, Wendy E; Severance, Mark; Cavalier, Darlene; Eisen, Jonathan A

2016-01-01

Background. While significant attention has been paid to the potential risk of pathogenic microbes aboard crewed spacecraft, the non-pathogenic microbes in these habitats have received less consideration. Preliminary work has demonstrated that the interior of the International Space Station (ISS) has a microbial community resembling those of built environments on Earth. Here we report the results of sending 48 bacterial strains, collected from built environments on Earth, for a growth experiment on the ISS. This project was a component of Project MERCCURI (Microbial Ecology Research Combining Citizen and University Researchers on ISS). Results. Of the 48 strains sent to the ISS, 45 of them showed similar growth in space and on Earth using a relative growth measurement adapted for microgravity. The vast majority of species tested in this experiment have also been found in culture-independent surveys of the ISS. Only one bacterial strain showed significantly different growth in space. Bacillus safensis JPL-MERTA-8-2 grew 60% better in space than on Earth. Conclusions. The majority of bacteria tested were not affected by conditions aboard the ISS in this experiment (e.g., microgravity, cosmic radiation). Further work on Bacillus safensis could lead to interesting insights on why this strain grew so much better in space.

Systematic development and optimization of chemically defined medium supporting high cell density growth of Bacillus coagulans.

PubMed

Chen, Yu; Dong, Fengqing; Wang, Yonghong

2016-09-01

With determined components and experimental reducibility, the chemically defined medium (CDM) and the minimal chemically defined medium (MCDM) are used in many metabolism and regulation studies. This research aimed to develop the chemically defined medium supporting high cell density growth of Bacillus coagulans, which is a promising producer of lactic acid and other bio-chemicals. In this study, a systematic methodology combining the experimental technique with flux balance analysis (FBA) was proposed to design and simplify a CDM. The single omission technique and single addition technique were employed to determine the essential and stimulatory compounds, before the optimization of their concentrations by the statistical method. In addition, to improve the growth rationally, in silico omission and addition were performed by FBA based on the construction of a medium-size metabolic model of B. coagulans 36D1. Thus, CDMs were developed to obtain considerable biomass production of at least five B. coagulans strains, in which two model strains B. coagulans 36D1 and ATCC 7050 were involved.

Antibacterial effect of silver nanoparticles and the modeling of bacterial growth kinetics using a modified Gompertz model.

PubMed

Chatterjee, Tanaya; Chatterjee, Barun K; Majumdar, Dipanwita; Chakrabarti, Pinak

2015-02-01

An alternative to conventional antibiotics is needed to fight against emerging multiple drug resistant pathogenic bacteria. In this endeavor, the effect of silver nanoparticle (Ag-NP) has been studied quantitatively on two common pathogenic bacteria Escherichia coli and Staphylococcus aureus, and the growth curves were modeled. The effect of Ag-NP on bacterial growth kinetics was studied by measuring the optical density, and was fitted by non-linear regression using the Logistic and modified Gompertz models. Scanning Electron Microscopy and fluorescence microscopy were used to study the morphological changes of the bacterial cells. Generation of reactive oxygen species for Ag-NP treated cells were measured by fluorescence emission spectra. The modified Gompertz model, incorporating cell death, fits the observed data better than the Logistic model. With increasing concentration of Ag-NP, the growth kinetics of both bacteria shows a decline in growth rate with simultaneous enhancement of death rate constants. The duration of the lag phase was found to increase with Ag-NP concentration. SEM showed morphological changes, while fluorescence microscopy using DAPI showed compaction of DNA for Ag-NP-treated bacterial cells. E. coli was found to be more susceptible to Ag-NP as compared to S. aureus. The modified Gompertz model, using a death term, was found to be useful in explaining the non-monotonic nature of the growth curve. The modified Gompertz model derived here is of general nature and can be used to study any microbial growth kinetics under the influence of antimicrobial agents. Copyright © 2014 Elsevier B.V. All rights reserved.

A new model for the spectral induced polarization signature of bacterial growth in porous media

NASA Astrophysics Data System (ADS)

Zhang, C.; Revil, A.; Atekwana, E. A.; Jardani, A.; Smith, S.

2012-12-01

Recent biogeophysics studies demonstrated the sensitivity of complex conductivity to bacterial growth and microbial mediated mineral transformations in porous media. Frequency-domain induced polarization is a minimally invasive manner to measure the complex conductivity of a material over a broad range of frequencies. The real component of complex conductivity is associated with electromigration of the charge carriers, and the imaginary component represents reversible energy storage of charge carriers at polarization length scales. Quantitative relationship between frequency-domain induced polarization responses and bacterial growth and decay in porous media is analyzed in this study using a new developed model. We focus on the direct contribution of bacteria themselves to the complex conductivity in porous media in the absence of biomineralization. At low frequencies, the induced polarization of bacteria (α-polarization) is related to the properties of the electrical double layer surrounding the membrane surface of bacteria. Surface conductivity and α-polarization are due to the Stern layer of the counterions occurring in a brush of polymers coating the surface of the bacteria, and can be related to the cation exchange capacity of the bacteria. From the modeling results, at low frequencies (< 10 Hz), the mobility of the counterions (K+) in the Stern layer of bacteria is found to be extremely small (4.7×10-10 m2s-1 V-1 at 25°C), and is close to the mobility of the same counterions along the surface of clay minerals (Na+, 1.5×10-10 m2s-1 V-1 at 25°C). This result is in agreement with experimental observations and it indicates a very low relaxation frequency for the α-polarization of the bacteria cells (typically around 0.1 to 5 Hertz). By coupling this new model with reactive transport modeling in which the evolution of bacterial populations are usually described by Monod kinetics, we show that the changes in imaginary conductivity with time can be used to

Use of Gifu Anaerobic Medium for culturing 32 dominant species of human gut microbes and its evaluation based on short-chain fatty acids fermentation profiles.

PubMed

Gotoh, Aina; Nara, Misaki; Sugiyama, Yuta; Sakanaka, Mikiyasu; Yachi, Hiroyuki; Kitakata, Aya; Nakagawa, Akira; Minami, Hiromichi; Okuda, Shujiro; Katoh, Toshihiko; Katayama, Takane; Kurihara, Shin

2017-10-01

Recently, a "human gut microbial gene catalogue," which ranks the dominance of microbe genus/species in human fecal samples, was published. Most of the bacteria ranked in the catalog are currently publicly available; however, the growth media recommended by the distributors vary among species, hampering physiological comparisons among the bacteria. To address this problem, we evaluated Gifu anaerobic medium (GAM) as a standard medium. Forty-four publicly available species of the top 56 species listed in the "human gut microbial gene catalogue" were cultured in GAM, and out of these, 32 (72%) were successfully cultured. Short-chain fatty acids from the bacterial culture supernatants were then quantified, and bacterial metabolic pathways were predicted based on in silico genomic sequence analysis. Our system provides a useful platform for assessing growth properties and analyzing metabolites of dominant human gut bacteria grown in GAM and supplemented with compounds of interest.

Bacterial Signaling Nucleotides Inhibit Yeast Cell Growth by Impacting Mitochondrial and Other Specifically Eukaryotic Functions.

PubMed

Hesketh, Andy; Vergnano, Marta; Wan, Chris; Oliver, Stephen G

2017-07-25

We have engineered Saccharomyces cerevisiae to inducibly synthesize the prokaryotic signaling nucleotides cyclic di-GMP (cdiGMP), cdiAMP, and ppGpp in order to characterize the range of effects these nucleotides exert on eukaryotic cell function during bacterial pathogenesis. Synthetic genetic array (SGA) and transcriptome analyses indicated that, while these compounds elicit some common reactions in yeast, there are also complex and distinctive responses to each of the three nucleotides. All three are capable of inhibiting eukaryotic cell growth, with the guanine nucleotides exhibiting stronger effects than cdiAMP. Mutations compromising mitochondrial function and chromatin remodeling show negative epistatic interactions with all three nucleotides. In contrast, certain mutations that cause defects in chromatin modification and ribosomal protein function show positive epistasis, alleviating growth inhibition by at least two of the three nucleotides. Uniquely, cdiGMP is lethal both to cells growing by respiration on acetate and to obligately fermentative petite mutants. cdiGMP is also synthetically lethal with the ribonucleotide reductase (RNR) inhibitor hydroxyurea. Heterologous expression of the human ppGpp hydrolase Mesh1p prevented the accumulation of ppGpp in the engineered yeast and restored cell growth. Extensive in vivo interactions between bacterial signaling molecules and eukaryotic gene function occur, resulting in outcomes ranging from growth inhibition to death. cdiGMP functions through a mechanism that must be compensated by unhindered RNR activity or by functionally competent mitochondria. Mesh1p may be required for abrogating the damaging effects of ppGpp in human cells subjected to bacterial infection. IMPORTANCE During infections, pathogenic bacteria can release nucleotides into the cells of their eukaryotic hosts. These nucleotides are recognized as signals that contribute to the initiation of defensive immune responses that help the infected

Isolation and Identification of Aspergillus fumigatus Mycotoxins on Growth Medium and Some Building Materials

PubMed Central

Nieminen, Susanna M.; Kärki, Riikka; Auriola, Seppo; Toivola, Mika; Laatsch, Hartmut; Laatikainen, Reino; Hyvärinen, Anne; von Wright, Atte

2002-01-01

Genotoxic and cytotoxic compounds were isolated and purified from the culture medium of an indoor air mold, Aspergillus fumigatus. One of these compounds was identified as gliotoxin, a known fungal secondary metabolite. Growth of A. fumigatus and gliotoxin production on some building materials were also studied. Strong growth of the mold and the presence of gliotoxin were detected on spruce wood, gypsum board, and chipboard under saturation conditions. PMID:12324333

Bacterial growth rates are influenced by cellular characteristics of individual species when immersed in electromagnetic fields.

PubMed

Tessaro, Lucas W E; Murugan, Nirosha J; Persinger, Michael A

2015-03-01

Previous studies have shown that exposure to extremely low-frequency electromagnetic fields (ELF-EMFs) have negative effects on the rate of growth of bacteria. In the present study, two Gram-positive and two Gram-negative species were exposed to six magnetic field conditions in broth cultures. Three variations of the 'Thomas' pulsed frequency-modulated pattern; a strong-static "puck" magnet upwards of 5000G in intensity; a pair of these magnets rotating opposite one another at ∼30rpm; and finally a strong dynamic magnetic field generator termed the 'Resonator' with an average intensity of 250μT were used. Growth rate was discerned by optical density (OD) measurements every hour at 600nm. ELF-EMF conditions significantly affected the rates of growth of the bacterial cultures, while the two static magnetic field conditions were not statistically significant. Most interestingly, the 'Resonator' dynamic magnetic field increased the rates of growth of three species (Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli), while slowing the growth of one (Serratia marcescens). We suggest that these effects are due to individual biophysical characteristics of the bacterial species. Copyright © 2015 Elsevier GmbH. All rights reserved.

Bacterial growth tolerance to concentrations of chlorate and perchlorate salts relevant to Mars

NASA Astrophysics Data System (ADS)

Al Soudi, Amer F.; Farhat, Omar; Chen, Fei; Clark, Benton C.; Schneegurt, Mark A.

2017-07-01

The Phoenix lander at Mars polar cap found appreciable levels of (per)chlorate salts, a mixture of perchlorate and chlorate salts of Ca, Fe, Mg and Na at levels of ~0.6% in regolith. These salts are highly hygroscopic and can form saturated brines through deliquescence, likely producing aqueous solutions with very low freezing points on Mars. To support planetary protection efforts, we have measured bacterial growth tolerance to (per)chlorate salts. Existing bacterial isolates from the Great Salt Plains of Oklahoma (NaCl-rich) and Hot Lake in Washington (MgSO4-rich) were tested in high concentrations of Mg, K and Na salts of chlorate and perchlorate. Strong growth was observed with nearly all of these salinotolerant isolates at 1% (~0.1 M) (per)chlorate salts, similar to concentrations observed in bulk soils on Mars. Growth in perchlorate salts was observed at concentrations of at least 10% (~1.0 M). Greater tolerance was observed for chlorate salts, where growth was observed to 2.75 M (>25%). Tolerance to K salts was greatest, followed by Mg salts and then Na salts. Tolerances varied among isolates, even among those within the same phylogenetic clade. Tolerant bacteria included genera that also are found in spacecraft assembly facilities. Substantial microbial tolerance to (per)chlorate salts is a concern for planetary protection since tolerant microbes contaminating spacecraft would have a greater chance for survival and proliferation, despite the harsh chemical conditions found near the surface of Mars.

Identification and elimination of bacterial contamination during in vitro propagation of Guadua angustifolia Kunth.

PubMed

Nadha, Harleen Kaur; Salwan, Richa; Kasana, Ramesh Chand; Anand, Manju; Sood, Anil

2012-04-01

Guadua angustifolia Kunth is a very important bamboo species with significant utility in pharmaceutical, paper, charcoal, and construction industries. Microbial contamination is a major problem encountered during establishment of in vitro cultures of Guadua. This study has been designed to analyze the identity of contaminating bacteria and to develop the strategy to eliminate them during micropropagation of Guadua. We isolated and consequently analyzed partial sequence analysis of the 16S rRNA gene to identify two contaminating bacteria as (1) Pantoea agglomerans and (2) Pantoea ananatis. In addition, we also- performed antibiotic sensitivity testing on these bacterial isolates. We identified kanamycin and streptomycin sulfate as potentially useful antibiotics in eliminating the contaminating bacteria. We grew shoots on multiplication medium containing BAP (2 mg/l) and adenine sulfate (10 mg/l) supplemented with kanamycin (10 μg/ml) for 10 days and transferred them to fresh medium without antibiotics and found that bacterial growth was inhibited. Moreover, we observed intensive formation of high-quality shoots. Streptomycin sulfate also inhibited bacterial growth but at higher concentration. We also demonstrated that shoots grown in streptomycin sulfate tended to be shorter and had yellow leaves. Thus, we have developed a novel strategy to identify and inhibit intriguing microbial contaminations of (1) Pantoea agglomerans and (2) Pantoea ananatis during establishment of in vitro cultures of Guadua. This would improve in vitro establishment of an important bamboo, Guadua angustifolia Kunth for large scale propagation.

Bacterial growth kinetics in ACD-A apheresis platelets: comparison of plasma and PAS III storage.

PubMed

Dumont, Larry J; Wood, Tammara A; Housman, Molly; Herschel, Louise; Brantigan, Barbara; Heber, Cheryl; Houghton, Jaime

2011-05-01

Our objective was to determine the growth kinetics of bacteria in leukoreduced apheresis platelets (LR-AP) in a platelet (PLT) additive solution (PAS; InterSol, Fenwal, Inc.) compared to LR-AP stored in plasma. Hyperconcentrated, double-dose LR-AP were collected from healthy donors with a separator (AMICUS, Fenwal, Inc.). LR-AP were evenly divided, InterSol was added to half (65% InterSol:35% plasma [PAS]), and PLTs in autologous plasma were used for a paired control (PL). Bacteria were inoculated into each LR-AP PAS/PL pair (0.5-1.6 colony-forming units [CFUs]/mL), and bacterial growth was followed for up to 7 days. Time to the end of the lag phase, doubling times, maximum concentration (conc-max), and time to maximum concentration (time-max) were estimated. Streptococcus viridans did not grow to detectable levels in either PAS or PL units. The other bacteria had no significant overall difference in the conc-max (p = 0.47) or time-max (p = 0.7) between PL and PAS LR-AP; PL had a 0.14 hours faster doubling rate (p = 0.023); and PAS had a 4.7 hours shorter lag time (p = 0.016). We observed that five index organisms will grow in LR-AP stored in a 35%:65% ratio of plasma to InterSol where initial bacterial concentrations are 0.5 to 1.6 CFUs/mL. The more rapid initiation of log-phase growth for bacteria within a PAS storage environment resulted in a bacterial concentration up to 4 logs higher in the PAS units compared to the plasma units at 24 hours, but with no difference in the conc-max. This may present an early bacterial detection advantage for PAS-stored PLTs. © 2010 American Association of Blood Banks.

Bacterial growth and substrate degradation by BTX-oxidizing culture in response to salt stress.

PubMed

Lee, Chi-Yuan; Lin, Ching-Hsing

2006-01-01

Interactions between microbial growth and substrate degradation are important in determining the performance of trickle-bed bioreactors (TBB), especially when salt is added to reduce biomass formation in order to alleviate media clogging. This study was aimed at quantifying salinity effects on bacterial growth and substrate degradation, and at acquiring kinetic information in order to improve the design and operation of TBB. Experiment works began by cultivating a mixed culture in a chemostat reactor receiving artificial influent containing a mixture of benzene, toluene, and xylene (BTX), followed by using the enrichment culture to degrade the individual BTX substrates under a particular salinity, which ranged 0-50 g l(-1) in batch mode. Then, the measured concentrations of biomass and residual substrate versus time were analyzed with the microbial kinetics; moreover, the obtained microbial kinetic constants under various salinities were modeled using noncompetitive inhibition kinetics. For the three substrates the observed bacterial yields appeared to be decreased from 0.51-0.74 to 0.20-0.22 mg mg(-1) and the maximum specific rate of substrate utilization, q, declined from 0.25-0.42 to 0.07-0.11 h(-1), as the salinity increased from 0 to 50 NaCl g l(-1). The NaCl acted as noncompetitive inhibitor, where the modeling inhibitions of the coefficients, K ( T(S)), were 22.7-29.7 g l(-1) for substrate degradation and K ( T(mu)), 13.0-19.0 g l(-1), for biomass formation. The calculated ratios for the bacterial maintenance rate, m (S), to q, further indicated that the percentage energy spent on maintenance increased from 19-24 to 86-91% as salinity level increased from 0 to 50 g l(-1). These results revealed that the bacterial growth was more inhibited than substrate degradation by the BTX oxidizers under the tested salinity levels. The findings from this study demonstrate the potential of applying NaCl salt to control excessive biomass formation in biotrickling filters.

Transition metal ions mediated tyrosine based short peptide amphiphile nanostructures inhibit bacterial growth.

PubMed

Joshi, Khashti Ballabh; Singh, Ramesh; Mishra, Narendra Kumar; Kumar, Vikas; Vinayak, Vandana

2018-05-17

We report the design and synthesis of biocompatible small peptide based molecule for the controlled and targeted delivery of the encapsulated bioactive metal ions via transforming their internal nanostructures. Tyrosine based short peptide amphiphile (sPA) was synthesized which self-assembled into β-sheet like secondary structures. The self assembly of the designed sPA was modulated by using different bioactive transition metal ions which is confirmed by spectroscopic and microscopic techniques. These bioactive metal ions conjugated sPA hybrid structures are further used to develop antibacterial materials. It is due to the excellent antibacterial activity of zinc ions that the growth of clinically relevant bacteria such as E. Coli was inhibited in the presence of zinc-sPA conjugate. The bacterial test demonstrated that owing to high biocompatibility with bacterial cell, the designed sPA worked as metal ions delivery agent and therefore it can show great potential in locally addressing bacterial infections. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Illumination of growth, division and secretion by metabolic labeling of the bacterial cell surface

PubMed Central

Siegrist, M. Sloan; Swarts, Benjamin M.; Fox, Douglas M.; Lim, Shion An; Bertozzi, Carolyn R.

2015-01-01

The cell surface is the essential interface between a bacterium and its surroundings. Composed primarily of molecules that are not directly genetically encoded, this highly dynamic structure accommodates the basic cellular processes of growth and division as well as the transport of molecules between the cytoplasm and the extracellular milieu. In this review, we describe aspects of bacterial growth, division and secretion that have recently been uncovered by metabolic labeling of the cell envelope. Metabolite derivatives can be used to label a variety of macromolecules, from proteins to non-genetically-encoded glycans and lipids. The embedded metabolite enables precise tracking in time and space, and the versatility of newer chemoselective detection methods offers the ability to execute multiple experiments concurrently. In addition to reviewing the discoveries enabled by metabolic labeling of the bacterial cell envelope, we also discuss the potential of these techniques for translational applications. Finally, we offer some guidelines for implementing this emerging technology. PMID:25725012

Metallic copper corrosion rates, moisture content, and growth medium influence survival of copper-ion resistant bacteria

PubMed Central

Elguindi, Jutta; Moffitt, Stuart; Hasman, Henrik; Andrade, Cassandra; Raghavan, Srini; Rensing, Christopher

2013-01-01

The rapid killing of various bacteria in contact with metallic copper is thought to be influenced by influx of copper ions into the cells but the exact mechanism is not fully understood. This study showed that the kinetics of contact-killing of copper surfaces depended greatly on the amount of moisture present, copper content of alloys, type of medium used, and type of bacteria. We examined antibiotic- and copper-ion resistant strains of Escherichia coli and Enterococcus faecium isolated from pig farms following the use of copper sulfate as feed supplement. The results showed rapid killing of both copper-ion resistant E. coli and E. faecium strains when samples in rich medium were spread in a thin, moist layer on copper alloys with 85% or greater copper content. E. coli strains were rapidly killed under dry conditions while E. faecium strains were less affected. Electroplated copper surface corrosion rates were determined from electro-chemical polarization tests using the Stern-Geary method and revealed decreased corrosion rates with benzotriazole and thermal oxide coating. Copper-ion resistant E. coli and E. faecium cells suspended in 0.8% NaCl showed prolonged survival rates on electroplated copper surfaces with benzotriazole coating and thermal oxide coating compared to surfaces without anti-corrosion treatment. Control of surface corrosion affected the level of copper ion influx into bacterial cells which contributed directly to bacterial killing. PMID:21085951

[Effects of sludge compost used as lawn medium on lawn growth and soil and water environment].

PubMed

Jin, Shu-Quan; Zhou, Jin-Bo; Chen, Ruo-Xia; Lin, Bin; Wang, De-Yao

2013-10-01

To address effect of the sludge compost-containing medium on the growth of Manila lawn and environment quality, a pot experiment was conducted using six treatments based on contrasting sludge compost addition volume ratios in the soil system (i. e., 0% , 10% , 25% , 50% , 75% and 100%). The results indicated that the growth potential of Manila lawn was increased with increasing sludge compost addition volume ratio. The content of Hg in Manila plant was significantly positively correlated with that in the lawn medium. Although the contents of Cr, Cd and Hg in the lawn medium were synchronously increased with increasing sludge compost addition volume ratio in the soil system, their contents were all lower than the critical levels of third-class standard in the National Soil Environmental Quality Standard. The heavy metal and nitrate concentrations detected in percolating water were significantly positively correlated with those in the lawn medium, respectively. When the sludge compost addition volume ratio was more than 50% in this study, both heavy metal and nitrate concentrations in percolating water would exceed the maximum allowable levels of the National Groundwater Environment Quality Standard.

Selective medium for aerobic incubation of Campylobacter

USDA-ARS?s Scientific Manuscript database

Studies were conducted on the formulation of a selective medium that could be used to isolate Campylobacter from mixed bacterial cultures using aerobic incubation. A non-selective, basal broth medium was prepared and supplemented with Bolton, Cefex, or Skirrow antibiotic mixtures. The ability of pur...

Vizantin inhibits bacterial adhesion without affecting bacterial growth and causes Streptococcus mutans biofilm to detach by altering its internal architecture.

PubMed

Takenaka, Shoji; Oda, Masataka; Domon, Hisanori; Ohsumi, Tatsuya; Suzuki, Yuki; Ohshima, Hayato; Yamamoto, Hirofumi; Terao, Yutaka; Noiri, Yuichiro

2016-11-11

An ideal antibiofilm strategy is to control both in the quality and quantity of biofilm while maintaining the benefits derived from resident microflora. Vizantin, a recently developed immunostimulating compound, has also been found to have antibiofilm property. This study evaluated the influence on biofilm formation of Streptococcus mutans in the presence of sulfated vizantin and biofilm development following bacterial adhesion on a hydroxyapatite disc coated with sulfated vizantin. Supplementation with sulfated vizantin up to 50 μM did not affect either bacterial growth or biofilm formation, whereas 50 μM sulfated vizantin caused the biofilm to readily detach from the surface. Sulfated vizantin at the concentration of 50 μM upregulated the expression of the gtfB and gtfC genes, but downregulated the expression of the gtfD gene, suggesting altered architecture in the biofilm. Biofilm development on the surface coated with sulfated vizantin was inhibited depending on the concentration, suggesting prevention from bacterial adhesion. Among eight genes related to bacterial adherence in S. mutans, expression of gtfB and gtfC was significantly upregulated, whereas the expression of gtfD, GbpA and GbpC was downregulated according to the concentration of vizantin, especially with 50 μM vizantin by 0.8-, 0.4-, and 0.4-fold, respectively. These findings suggest that sulfated vizantin may cause structural degradation as a result of changing gene regulation related to bacterial adhesion and glucan production of S. mutans. Copyright © 2016 Elsevier Inc. All rights reserved.

Investigation of mixotrophic, heterotrophic, and autotrophic growth of Chlorella vulgaris under agricultural waste medium.

PubMed

Mohammad Mirzaie, M A; Kalbasi, M; Mousavi, S M; Ghobadian, B

2016-01-01

Growth of Chlorella vulgaris and its lipid production were investigated under autotrophic, heterotrophic, and mixotrophic conditions. Cheap agricultural waste molasses and corn steep liquor from industries were used as carbon and nitrogen sources, respectively. Chlorella vulgaris grew remarkably under this agricultural waste medium, which resulted in a reduction in the final cost of the biodiesel production. Maximum dry weight of 2.62 g L(-1) was obtained in mixotrophic growth with the highest lipid concentration of 0.86 g L(-1). These biomass and lipid concentrations were, respectively, 140% and 170% higher than autotrophic growth and 300% and 1200% higher than heterotrophic growth. In mixotrophic growth, independent or simultaneous occurrence of autotrophic and heterotrophic metabolisms was investigated. The growth of the microalgae was observed to take place first heterotrophically to a minimum substrate concentration with a little fraction in growth under autotrophic metabolism, and then the cells grew more autotrophically. It was found that mixotrophic growth was not a simple combination of heterotrophic and autotrophic growth.

Multi-Affinity for Growing Rough Interfaces of Bacterial Colonies

NASA Astrophysics Data System (ADS)

Kobayashi, N.; Ozawa, T.; Saito, K.; Yamazaki, Y.; Matsuyama, T.; Matsushita, M.

We have examined whether rough interfaces of bacterial colonies are multi-affine. We have used the bacterial species called textit{Bacillus subtilis}, which has been found to exhibit a variety of colony patterns when varying both the concentration of nutrient and solidity of agar medium. Consequently, we have found that the colony interface on a nutrient-rich, solid agar medium is multi-affine. On the other hand, the colony interface on a nutrient-rich, semi-solid agar medium is self-affine.

Changes in urine composition after trauma facilitate bacterial growth

PubMed Central

2012-01-01

Background Critically ill patients including trauma patients are at high risk of urinary tract infection (UTI). The composition of urine in trauma patients may be modified due to inflammation, systemic stress, rhabdomyolysis, life support treatment and/or urinary catheter insertion. Methods Prospective, single-centre, observational study conducted in patients with severe trauma and without a history of UTIs or recent antibiotic treatment. The 24-hour urine samples were collected on the first and the fifth days and the growth of Escherichia coli in urine from patients and healthy volunteers was compared. Biochemical and hormonal modifications in urine that could potentially influence bacterial growth were explored. Results Growth of E. coli in urine from trauma patients was significantly higher on days 1 and 5 than in urine of healthy volunteers. Several significant modifications of urine composition could explain these findings. On days 1 and 5, trauma patients had an increase in glycosuria, in urine iron concentration, and in the concentrations of several amino acids compared to healthy volunteers. On day 1, the urinary osmotic pressure was significantly lower than for healthy volunteers. Conclusion We showed that urine of trauma patients facilitated growth of E. coli when compared to urine from healthy volunteers. This effect was present in the first 24 hours and until at least the fifth day after trauma. This phenomenon may be involved in the pathophysiology of UTIs in trauma patients. Further studies are required to define the exact causes of such modifications. PMID:23194649

[Effects of bamboo charcoal on the growth of Trifolium repens and soil bacterial community structure].

PubMed

Li, Song-Hao; He, Dong-Hua; Shen, Qiu-Lan; Xu, Qiu-Fang

2014-08-01

The effects of addition rates (0, 3% and 9%) and particle sizes (0.05, 0.05-1.0 and 1.0-2.0 mm) of bamboo charcoal on the growth of Trifolium repens and soil microbial community structure were investigated. The results showed that bamboo charcoal addition greatly promoted the early growth of T. repens, with the 9% charcoal addition rate being slightly better than the 3% charcoal addition rate. The effects of different particle sizes of bamboo charcoal on the growth of T. repens were not different significantly. Growth promotion declined with time during 120 days after sowing, and disappeared completely after 5 months. DGGE analysis of the bacterial 16S rDNA V3 fragment indicated that bamboo charcoal altered the soil bacterial community structure. The amount and Shannon diversity index of bacteria in the bamboo charcoal addition treatments increased compared with CK. The quantitative analysis showed that the amount of bacteria in the treatment with bamboo charcoal of fine particle (D < 0.05 mm) at the 9% addition rate was significantly higher than in the other treatments. The fine bamboo charcoal had a great effect on soil bacteria amount compared with the charcoal of other sizes at the same addition rate.

A Model to Explain Plant Growth Promotion Traits: A Multivariate Analysis of 2,211 Bacterial Isolates

PubMed Central

da Costa, Pedro Beschoren; Granada, Camille E.; Ambrosini, Adriana; Moreira, Fernanda; de Souza, Rocheli; dos Passos, João Frederico M.; Arruda, Letícia; Passaglia, Luciane M. P.

2014-01-01

Plant growth-promoting bacteria can greatly assist sustainable farming by improving plant health and biomass while reducing fertilizer use. The plant-microorganism-environment interaction is an open and complex system, and despite the active research in the area, patterns in root ecology are elusive. Here, we simultaneously analyzed the plant growth-promoting bacteria datasets from seven independent studies that shared a methodology for bioprospection and phenotype screening. The soil richness of the isolate's origin was classified by a Principal Component Analysis. A Categorical Principal Component Analysis was used to classify the soil richness according to isolate's indolic compound production, siderophores production and phosphate solubilization abilities, and bacterial genera composition. Multiple patterns and relationships were found and verified with nonparametric hypothesis testing. Including niche colonization in the analysis, we proposed a model to explain the expression of bacterial plant growth-promoting traits according to the soil nutritional status. Our model shows that plants favor interaction with growth hormone producers under rich nutrient conditions but favor nutrient solubilizers under poor conditions. We also performed several comparisons among the different genera, highlighting interesting ecological interactions and limitations. Our model could be used to direct plant growth-promoting bacteria bioprospection and metagenomic sampling. PMID:25542031

Preventing bacterial growth on implanted device with an interfacial metallic film and penetrating X-rays.

PubMed

An, Jincui; Sun, An; Qiao, Yong; Zhang, Peipei; Su, Ming

2015-02-01

Device-related infections have been a big problem for a long time. This paper describes a new method to inhibit bacterial growth on implanted device with tissue-penetrating X-ray radiation, where a thin metallic film deposited on the device is used as a radio-sensitizing film for bacterial inhibition. At a given dose of X-ray, the bacterial viability decreases as the thickness of metal film (bismuth) increases. The bacterial viability decreases with X-ray dose increases. At X-ray dose of 2.5 Gy, 98% of bacteria on 10 nm thick bismuth film are killed; while it is only 25% of bacteria are killed on the bare petri dish. The same dose of X-ray kills 8% fibroblast cells that are within a short distance from bismuth film (4 mm). These results suggest that penetrating X-rays can kill bacteria on bismuth thin film deposited on surface of implant device efficiently.

Custom fabrication of biomass containment devices using 3-D printing enables bacterial growth analyses with complex insoluble substrates

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

Nelson, Cassandra E.; Beri, Nina R.; Gardner, Jeffrey G.

Physiological studies of recalcitrant polysaccharide degradation are challenging for several reasons, one of which is the difficulty in obtaining a reproducibly accurate real-time measurement of bacterial growth using insoluble substrates. Current methods suffer from several problems including (i) high background noise due to the insoluble material interspersed with cells, (ii) high consumable and reagent cost and (iii) significant time delay between sampling and data acquisition. A customizable substrate and cell separation device would provide an option to study bacterial growth using optical density measurements. To test this hypothesis we used 3-D printing to create biomass containment devices that allow interactionmore » between insoluble substrates and microbial cells but do not interfere with spectrophotometer measurements. Evaluation of materials available for 3-D printing indicated that UV-cured acrylic plastic was the best material, being superior to nylon or stainless steel when examined for heat tolerance, reactivity, and ability to be sterilized. Cost analysis of the 3-D printed devices indicated they are a competitive way to quantitate bacterial growth compared to viable cell counting or protein measurements, and experimental conditions were scalable over a 100-fold range. The presence of the devices did not alter growth phenotypes when using either soluble substrates or insoluble substrates. Furthermore, we applied biomass containment to characterize growth of Cellvibrio japonicus on authentic lignocellulose (non-pretreated corn stover), and found physiological evidence that xylan is a significant nutritional source despite an abundance of cellulose present.« less

Custom fabrication of biomass containment devices using 3-D printing enables bacterial growth analyses with complex insoluble substrates

DOE PAGES

Nelson, Cassandra E.; Beri, Nina R.; Gardner, Jeffrey G.

2016-09-21

Physiological studies of recalcitrant polysaccharide degradation are challenging for several reasons, one of which is the difficulty in obtaining a reproducibly accurate real-time measurement of bacterial growth using insoluble substrates. Current methods suffer from several problems including (i) high background noise due to the insoluble material interspersed with cells, (ii) high consumable and reagent cost and (iii) significant time delay between sampling and data acquisition. A customizable substrate and cell separation device would provide an option to study bacterial growth using optical density measurements. To test this hypothesis we used 3-D printing to create biomass containment devices that allow interactionmore » between insoluble substrates and microbial cells but do not interfere with spectrophotometer measurements. Evaluation of materials available for 3-D printing indicated that UV-cured acrylic plastic was the best material, being superior to nylon or stainless steel when examined for heat tolerance, reactivity, and ability to be sterilized. Cost analysis of the 3-D printed devices indicated they are a competitive way to quantitate bacterial growth compared to viable cell counting or protein measurements, and experimental conditions were scalable over a 100-fold range. The presence of the devices did not alter growth phenotypes when using either soluble substrates or insoluble substrates. Furthermore, we applied biomass containment to characterize growth of Cellvibrio japonicus on authentic lignocellulose (non-pretreated corn stover), and found physiological evidence that xylan is a significant nutritional source despite an abundance of cellulose present.« less

Influence of Thawing Methods and Storage Temperatures on Bacterial Diversity, Growth Kinetics, and Biogenic Amine Development in Atlantic Mackerel.

PubMed

Onyango, S; Palmadottir, H; Tómason, T; Marteinsson, V T; Njage, P M K; Reynisson, E

2016-11-01

Limited knowledge is currently available on the influence of fish thawing and subsequent storage conditions on bacterial growth kinetics, succession, and diversity alongside the production of biogenic amines. This study aimed to address these factors during the thawing and subsequent storage of mackerel. Thawing was either done fast in 18°C water for 2 h or slowly at 30°C overnight. Subsequent storage was at 30°C (ambient) for 36 h and 2 to 5°C (refrigerated) for 12 days. The cultivation methods used were total viable counts, hydrogen sulfide-producing bacteria, and Pseudomonas . Maximum growth rate, population density, and lag time were fitted on the counts using the Baranyi model. The bacterial diversity and succession were based on sequencing of 16S rRNA amplicons, and biogenic amines were quantified on high-pressure liquid chromatography-UV. The results show that lag time of hydrogen sulfide-producing bacteria was significantly affected by both thawing methods, and further, the interaction between thawing and storage significantly affected the maximum growth rate of these bacteria. However, the maximum growth rate of Pseudomonas was higher during refrigerated storage compared with storage at ambient temperature. Total viable counts showed longer lag time and reduced growth rate under refrigerated storage. Higher bacterial diversity was correlated to slow thawing and storage at ambient temperature compared with slow thawing and refrigerated storage. Overall, Acinetobacter and Psychrobacter genera were the dominant bacterial populations. The amine levels were low and could not be differentiated along the thawing and storage approaches, despite a clear increase in bacterial load, succession, and diversity. This corresponded well with the low abundance of biogenic amine-producing bacteria, with the exception of the genus Proteus , which was 8.6% in fast-thawed mackerel during storage at ambient temperature. This suggests that the decarboxylation potential is

Influence of nutrient medium composition on uranium toxicity and choice of the most sensitive growth related endpoint in Lemna minor.

PubMed

Horemans, Nele; Van Hees, May; Saenen, Eline; Van Hoeck, Arne; Smolders, Valérie; Blust, Ronny; Vandenhove, Hildegarde

2016-01-01

Uranium (U) toxicity is known to be highly dependent on U speciation and bioavailability. To assess the impact of uranium on plants, a growth inhibition test was set up in the freshwater macrophyte Lemna minor. First growth media with different compositions were tested in order to find a medium fit for testing U toxicity in L. minor. Following arguments were used for medium selection: the ability to sustain L. minor growth, a high solubility of U in the medium and a high percentage of the more toxic U-species namely UO2(2+). Based on these selection criteria a with a low phosphate concentration of 0.5 mg L(-1) and supplemented with 5 mM MES (2-(N-morpholino)ethanesulfonic acid) to ensure pH stability was chosen. This medium also showed highest U toxicity compared to the other tested media. Subsequently a full dose response curve for U was established by exposing L. minor plants to U concentrations ranging from 0.05 μM up to 150 μM for 7 days. Uranium was shown to adversely affect growth of L. minor in a dose dependent manner with EC10, EC30 and EC50 values ranging between 1.6 and 4.8 μM, 7.7-16.4 μM and 19.4-37.2 μM U, respectively, depending on the growth endpoint. Four different growth related endpoints were tested: frond area, frond number, fresh weight and dry weight. Although differences in relative growth rates and associated ECx-values calculated on different endpoints are small (maximal twofold difference), frond area is recommended to be used to measure U-induced growth effects as it is a sensitive growth endpoint and easy to measure in vivo allowing for measurements over time. Copyright © 2015 Elsevier Ltd. All rights reserved.

A brief history of bacterial growth physiology.

PubMed

Schaechter, Moselio

2015-01-01

Arguably, microbial physiology started when Leeuwenhoek became fascinated by observing a Vorticella beating its cilia, my point being that almost any observation of microbes has a physiological component. With the advent of modern microbiology in the mid-19th century, the field became recognizably distinctive with such discoveries as anaerobiosis, fermentation as a biological phenomenon, and the nutritional requirements of microbes. Soon came the discoveries of Winogradsky and his followers of the chemical changes in the environment that result from microbial activities. Later, during the first half of the 20th century, microbial physiology became the basis for much of the elucidation of central metabolism. Bacterial physiology then became a handmaiden of molecular biology and was greatly influenced by the discovery of cellular regulatory mechanisms. Microbial growth, which had come of age with the early work of Hershey, Monod, and others, was later pursued by studies on a whole cell level by what became known as the "Copenhagen School." During this time, the exploration of physiological activities became coupled to modern inquiries into the structure of the bacterial cell. Recent years have seen the development of a further phase in microbial physiology, one seeking a deeper quantitative understanding of phenomena on a whole cell level. This pursuit is exemplified by the emergence of systems biology, which is made possible by the development of technologies that permit the gathering of information in huge amounts. As has been true through history, the research into microbial physiology continues to be guided by the development of new methods of analysis. Some of these developments may well afford the possibility of making stunning breakthroughs.

New microbial growth factor

NASA Technical Reports Server (NTRS)

Bok, S. H.; Casida, L. E., Jr.

1977-01-01

A screening procedure was used to isolate from soil a Penicillium sp., two bacterial isolates, and a Streptomyces sp. that produced a previously unknown microbial growth factor. This factor was an absolute growth requirement for three soil bacteria. The Penicillium sp. and one of the bacteria requiring the factor, an Arthrobacter sp., were selected for more extensive study concerning the production and characteristics of the growth factor. It did not seem to be related to the siderochromes. It was not present in soil extract, rumen fluid, or any other medium component tested. It appears to be a glycoprotein of high molecular weight and has high specific activity. When added to the diets for a meadow-vole mammalian test system, it caused an increased consumption of diet without a concurrent increase in rate of weight gain.

Effects of an EPSPS-transgenic soybean line ZUTS31 on root-associated bacterial communities during field growth

PubMed Central

Cheng, Jing; Wang, Gu-Hao; Zhu, Yin-Ling; Zhang, Li-Ya; Shou, Hui-Xia; Qi, Jin-Liang

2018-01-01

The increased worldwide commercial cultivation of transgenic crops during the past 20 years is accompanied with potential effects on the soil microbial communities, because many rhizosphere and endosphere bacteria play important roles in promoting plant health and growth. Previous studies reported that transgenic plants exert differential effects on soil microbial communities, especially rhizobacteria. Thus, this study compared the soybean root-associated bacterial communities between a 5-enolpyruvylshikimate-3-phosphate synthase -transgenic soybean line (ZUTS31 or simply Z31) and its recipient cultivar (Huachun3 or simply HC3) at the vegetative, flowering, and seed-filling stages. High-throughput sequencing of 16S rRNA gene (16S rDNA) V4 hypervariable region amplicons via Illumina MiSeq and real-time quantitative PCR (qPCR) were performed. Our results revealed no significant differences in the overall alpha diversity of root-associated bacterial communities at the three developmental stages and in the beta diversity of root-associated bacterial communities at the flowering stage between Z31 and HC3 under field growth. However, significant differences in the beta diversity of rhizosphere bacterial communities were found at the vegetative and seed-filling stages between the two groups. Furthermore, the results of next generation sequencing and qPCR showed that the relative abundances of root-associated main nitrogen-fixing bacterial genera, especially Bradyrhizobium in the roots, evidently changed from the flowering stage to the seed-filling stage. In conclusion, Z31 exerts transitory effects on the taxonomic diversity of rhizosphere bacterial communities at the vegetative and seed-filling stages compared to the control under field conditions. In addition, soybean developmental change evidently influences the main symbiotic nitrogen-fixing bacterial genera in the roots from the flowering stage to the seed-filling stage. PMID:29408918

Antimicrobial effects of virgin coconut oil and its medium-chain fatty acids on Clostridium difficile.

PubMed

Shilling, Michael; Matt, Laurie; Rubin, Evelyn; Visitacion, Mark Paul; Haller, Nairmeen A; Grey, Scott F; Woolverton, Christopher J

2013-12-01

Clostridium difficile is the leading cause of hospital-acquired antibiotic-associated diarrhea worldwide; in addition, the proliferation of antibiotic-resistant C. difficile is becoming a significant problem. Virgin coconut oil (VCO) has been shown previously to have the antimicrobial activity. This study evaluates the lipid components of VCO for the control of C. difficile. VCO and its most active individual fatty acids were tested to evaluate their antimicrobial effect on C. difficile in vitro. The data indicate that exposure to lauric acid (C12) was the most inhibitory to growth (P<.001), as determined by a reduction in colony-forming units per milliliter. Capric acid (C10) and caprylic acid (C8) were inhibitory to growth, but to a lesser degree. VCO did not inhibit the growth of C. difficile; however, growth was inhibited when bacterial cells were exposed to 0.15-1.2% lipolyzed coconut oil. Transmission electron microscopy (TEM) showed the disruption of both the cell membrane and the cytoplasm of cells exposed to 2 mg/mL of lauric acid. Changes in bacterial cell membrane integrity were additionally confirmed for VCO and select fatty acids using Live/Dead staining. This study demonstrates the growth inhibition of C. difficile mediated by medium-chain fatty acids derived from VCO.

Genome-wide analysis of bacterial determinants of plant growth promotion and induced systemic resistance by Pseudomonas fluorescens.

PubMed

Cheng, Xu; Etalo, Desalegn W; van de Mortel, Judith E; Dekkers, Ester; Nguyen, Linh; Medema, Marnix H; Raaijmakers, Jos M

2017-11-01

Pseudomonas fluorescens strain SS101 (Pf.SS101) promotes growth of Arabidopsis thaliana, enhances greening and lateral root formation, and induces systemic resistance (ISR) against the bacterial pathogen Pseudomonas syringae pv. tomato (Pst). Here, targeted and untargeted approaches were adopted to identify bacterial determinants and underlying mechanisms involved in plant growth promotion and ISR by Pf.SS101. Based on targeted analyses, no evidence was found for volatiles, lipopeptides and siderophores in plant growth promotion by Pf.SS101. Untargeted, genome-wide analyses of 7488 random transposon mutants of Pf.SS101 led to the identification of 21 mutants defective in both plant growth promotion and ISR. Many of these mutants, however, were auxotrophic and impaired in root colonization. Genetic analysis of three mutants followed by site-directed mutagenesis, genetic complementation and plant bioassays revealed the involvement of the phosphogluconate dehydratase gene edd, the response regulator gene colR and the adenylsulfate reductase gene cysH in both plant growth promotion and ISR. Subsequent comparative plant transcriptomics analyses strongly suggest that modulation of sulfur assimilation, auxin biosynthesis and transport, steroid biosynthesis and carbohydrate metabolism in Arabidopsis are key mechanisms linked to growth promotion and ISR by Pf.SS101. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Enhanced growth medium and method for culturing human mammary epithelial cells

DOEpatents

Stampfer, Martha R.; Smith, Helene S.; Hackett, Adeline J.

1983-01-01

Methods are disclosed for isolating and culturing human mammary epithelial cells of both normal and malignant origin. Tissue samples are digested with a mixture including the enzymes collagenase and hyaluronidase to produce clumps of cells substantially free from stroma and other undesired cellular material. Growing the clumps of cells in mass culture in an enriched medium containing particular growth factors allows for active cell proliferation and subculture. Clonal culture having plating efficiencies of up to 40% or greater may be obtained using individual cells derived from the mass culture by plating the cells on appropriate substrates in the enriched media. The clonal growth of cells so obtained is suitable for a quantitative assessment of the cytotoxicity of particular treatment. An exemplary assay for assessing the cytotoxicity of the drug adriamycin is presented.

[Risk factors associated with bacterial growth in derivative systems from cerebrospinal liquid in pediatric patients].

PubMed

de Jesús Vargas-Lares, José; Andrade-Aguilera, Angélica Rocío; Díaz-Peña, Rafael; Barrera de León, Juan Carlos

2015-01-01

To determine risk factors associated with bacterial growth in systems derived from cerebrospinal fluid in pediatric patients. Case and controls study from January to December 2012, in patients aged <16 years who were carriers of hydrocephalus and who required placement or replacement of derivative system. Cases were considered as children with cultures with bacterial growth and controls with negative bacterial growth. Inferential statistics with Chi-squared and Mann-Whitney U tests. Association of risk with odds ratio. We reviewed 746 registries, cases n=99 (13%) and controls n=647 (87%). Masculine gender 58 (57%) vs. feminine gender 297 (46%) (p=0.530). Age of cases: median, five months and controls, one year (p=0.02). Median weight, 7 vs. 10 kg (p=0.634). Surgical interventions: median n=2 (range, 1-8) vs. n=1 (range, 1-7). Infection rate, 13.2%. Main etiology ductal stenosis, n=29 (29%) vs. n=50 (23%) (p=0.530). Non-communicating, n=50 (51%) vs. 396 (61%) (p=0.456). Predominant microorganisms: enterobacteria, pseudomonas, and enterococcus. Non-use of iodized dressing OR=2.6 (range, 1.8-4.3), use of connector OR=6.8 (range, 1.9-24.0), System replacement OR=2.0 (range, 1.3-3.1), assistant without surgical facemask OR=9.7 (range, 2.3-42.0). Being a breastfeeding infant, of low weight, non-application of iodized dressing, use of connector, previous derivation, and lack of adherence to aseptic technique were all factors associated with ependymitis.

Glucose and D-Allulose contained medium to support the growth of lactic acid bacteria

NASA Astrophysics Data System (ADS)

Al-Baarri, A. N.; Legowo, A. M.; Pramono, Y. B.; Sari, D. I.; Pangestika, W.

2018-01-01

Monosaccharide has been known as support agent for the growth of lactic acid bacteria. However the combination among monosaccharides for supporting the living of bacteria has not been understood well. This research was done for analyzing the combination glucose and D-allulose for the growth of Lactobacillus acidophilus and Streptococcus thermophillus. The NaCl medium containing glucose and D-allulose was used to analyse the growth of bacteria. The study showed that glucose and D-allulose have been detected as supportive agent to L. acidophilus and S. thermophillus specifically. As conclusion, glucose and D-allulose supported the growth of lactic acid bacteria equally. This finding might provide the beneficial information for industry to utilize D-allulose as well as glucose.

Allochthonous carbon is a major regulator to bacterial growth and community composition in subarctic freshwaters

PubMed Central

Roiha, Toni; Peura, Sari; Cusson, Mathieu; Rautio, Milla

2016-01-01

In the subarctic region, climate warming and permafrost thaw are leading to emergence of ponds and to an increase in mobility of catchment carbon. As carbon of terrestrial origin is increasing in subarctic freshwaters the resource pool supporting their microbial communities and metabolism is changing, with consequences to overall aquatic productivity. By sampling different subarctic water bodies for a one complete year we show how terrestrial and algal carbon compounds vary in a range of freshwaters and how differential organic carbon quality is linked to bacterial metabolism and community composition. We show that terrestrial drainage and associated nutrients supported higher bacterial growth in ponds and river mouths that were influenced by fresh terrestrial carbon than in large lakes with carbon from algal production. Bacterial diversity, however, was lower at sites influenced by terrestrial carbon inputs. Bacterial community composition was highly variable among different water bodies and especially influenced by concentrations of dissolved organic carbon (DOC), fulvic acids, proteins and nutrients. Furthermore, a distinct preference was found for terrestrial vs. algal carbon among certain bacterial tribes. The results highlight the contribution of the numerous ponds to cycling of terrestrial carbon in the changing subarctic and arctic regions. PMID:27686416

Allochthonous carbon is a major regulator to bacterial growth and community composition in subarctic freshwaters.

PubMed

Roiha, Toni; Peura, Sari; Cusson, Mathieu; Rautio, Milla

2016-09-30

In the subarctic region, climate warming and permafrost thaw are leading to emergence of ponds and to an increase in mobility of catchment carbon. As carbon of terrestrial origin is increasing in subarctic freshwaters the resource pool supporting their microbial communities and metabolism is changing, with consequences to overall aquatic productivity. By sampling different subarctic water bodies for a one complete year we show how terrestrial and algal carbon compounds vary in a range of freshwaters and how differential organic carbon quality is linked to bacterial metabolism and community composition. We show that terrestrial drainage and associated nutrients supported higher bacterial growth in ponds and river mouths that were influenced by fresh terrestrial carbon than in large lakes with carbon from algal production. Bacterial diversity, however, was lower at sites influenced by terrestrial carbon inputs. Bacterial community composition was highly variable among different water bodies and especially influenced by concentrations of dissolved organic carbon (DOC), fulvic acids, proteins and nutrients. Furthermore, a distinct preference was found for terrestrial vs. algal carbon among certain bacterial tribes. The results highlight the contribution of the numerous ponds to cycling of terrestrial carbon in the changing subarctic and arctic regions.

Effect of humic substance photodegradation on bacterial growth and respiration in lake water

USGS Publications Warehouse

Anesio, A.M.; Graneli, W.; Aiken, G.R.; Kieber, D.J.; Mopper, K.

2005-01-01

This study addresses how humic substance (HS) chemical composition and photoreactivity affect bacterial growth, respiration, and growth efficiency (BGE) in lake water. Aqueous solutions of HSs from diverse aquatic environments representing different dissolved organic matter sources (autochthonous and allochthonous) were exposed to artificial solar UV radiation. These solutions were added to lake water passed through a 0.7-??m-pore-size filter (containing grazer-free lake bacteria) followed by dark incubation for 5, 43, and 65 h. For the 5-h incubation, several irradiated HSs inhibited bacterial carbon production (BCP) and this inhibition was highly correlated with H 2O2 photoproduction. The H2O2 decayed in the dark, and after 43 h, nearly all irradiated HSs enhanced BCP (average 39% increase relative to nonirradiated controls, standard error = 7.5%, n = 16). UV exposure of HSs also increased bacterial respiration (by ???18%, standard error = 5%, n = 4), but less than BCP, resulting in an average increase in BGE of 32% (standard error = 10%, n = 4). Photoenhancement of BCP did not correlate to HS bulk properties (i.e., elemental and chemical composition). However, when the photoenhancement of BCP was normalized to absorbance, several trends with HS origin and extraction method emerged. Absorbance-normalized hydrophilic acid and humic acid samples showed greater enhancement of BCP than hydrophobic acid and fulvic acid samples. Furthermore, absorbance-normalized autochthonous samples showed ???10-fold greater enhancement of BCP than allochthonous-dominated samples, indicating that the former are more efficient photoproducers of biological substrates. Copyright ?? 2005, American Society for Microbiology. All Rights Reserved.

Effects of High Hydrostatic Pressure on Bacterial Growth on Human Ossicles Explanted from Cholesteatoma Patients

PubMed Central

Ostwald, Jürgen; Lindner, Tobias; Zautner, Andreas Erich; Arndt, Kathleen; Pau, Hans Wilhelm; Podbielski, Andreas

2012-01-01

Background High hydrostatic pressure (HHP) treatment can eliminate cholesteatoma cells from explanted human ossicles prior to re-insertion. We analyzed the effects of HHP treatment on the microbial flora on ossicles and on the planktonic and biofilm states of selected isolates. Methodology Twenty-six ossicles were explanted from cholesteatoma patients. Five ossicles were directly analyzed for microbial growth without further treatment. Fifteen ossicles were cut into two pieces. One piece was exposed to HHP of 350 MPa for 10 minutes. Both the treated and untreated (control) pieces were then assessed semi-quantitatively. Three ossicles were cut into two pieces and exposed to identical pressure conditions with or without the addition of one of two different combinations of antibiotics to the medium. Differential effects of 10-minute in vitro exposure of planktonic and biofilm bacteria to pressures of 100 MPa, 250 MPa, 400 MPa and 540 MPa in isotonic and hypotonic media were analyzed using two patient isolates of Staphylococcus epidermidis and Neisseria subflava. Bacterial cell inactivation and biofilm destruction were assessed by colony counting and electron microscopy. Principal Findings A variety of microorganisms were isolated from the ossicles. Irrespective of the medium, HHP treatment at 350 MPa for 10 minutes led to satisfying but incomplete inactivation especially of Gram-negative bacteria. The addition of antibiotics increased the efficacy of elimination. A comparison of HHP treatment of planktonic and biofilm cells showed that the effects of HPP were reduced by about one decadic logarithmic unit when HPP was applied to biofilms. High hydrostatic pressure conditions that are suitable to inactivate cholesteatoma cells fail to completely sterilize ossicles even if antibiotics are added. As a result of the reduced microbial load and the viability loss of surviving bacteria, however, there is a lower risk of re-infection after re-insertion. PMID:22291908

Behçet Disease serum is immunoreactive to neurofilament medium which share common epitopes to bacterial HSP-65, a putative trigger.

PubMed

Lule, S; Colpak, A I; Balci-Peynircioglu, B; Gursoy-Ozdemir, Y; Peker, S; Kalyoncu, U; Can, A; Tekin, N; Demiralp, D; Dalkara, T

2017-11-01

Autoimmune and dysimmune inflammatory mechanisms on a genetically susceptible background are implicated in the etiology of Behçet's Disease (BD). Heat-shock protein-65 (HSP-65) derived from Streptococcus sanguinis was proposed as a triggering factor based on its homology with human HSP-60. However, none of the autoantigens identified so far in sera from BD share common epitopes with bacterial HSP-65 or has a high prevalence. Here, we report that sera from BD patients are immunoreactive against filamentous neuronal processes in the mouse brain, retina and scrotal skin in great majority of patients. By using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and peptide mass fingerprinting, Western blotting and peptide blocking experiments, we have identified neurofilament medium (NF-M) as the probable antigen for the serologic response observed. Clustal Omega analyses detected significant structural homology between the human NF-M and bacterial HSP-65 corresponding to amino acids 111-126, 213-232 and 304-363 of mycobacterial HSP-65, which were previously identified to induce proliferation of lymphocytes obtained from BD patients. We also found that sera immunoreactive against NF-M cross-reacted with bacterial HSP-65. These findings suggest that NF-M may be involved in autoimmunity in BD due to its molecular mimicry with bacterial HSP-65. Copyright © 2017 Elsevier Ltd. All rights reserved.

Combination of therapeutic ultrasound with antibiotics interfere with the growth of bacterial culture that colonizes skin ulcers: An in-vitro study.

PubMed

Guirro, Elaine Caldeira de Oliveira; Angelis, Dejanira de Franceschi de; Sousa, Natanael Teixeira Alves de; Guirro, Rinaldo Roberto de Jesus

2016-09-01

Staphylococcus aureus and Escherichia coli are among the major bacterial species that colonize skin ulcers. Therapeutic ultrasound (TUS) produces biophysical effects that are relevant to wound healing; however, its application over a contaminated injury is not evidence-based. The objective of this research was to analyze the effect of TUS on in vitro-isolated S. aureus and E. coli, including the combination of ultrasound and antibiotics, in order to assess their antibiotic action on bacterial susceptibility. For the experiments, the bacterial strains were suspended in saline, then diluted (10(4)CFU/mL) for irradiation (at 1 and 3MHz, 0.5 and 0.8W/cm(2) for 0 and 15min) and the combination treatment of ultrasonication and antibiotics was administered by adding nalidixic acid (S. aureus) and tetracycline (E. coli) at concentrations equivalent to 50% of the minimum inhibitory concentration (MIC). The experiments were carried out in duplicate with six repetitions. The suspensions were inoculated on to Petri plates and incubated at 37°C and the colony forming units (CFUs) were counted after 24h. The results were subjected to the Shapiro-Wilk normality test, followed by parametric ANOVA and Tukey's post hoc test at a significance level of 1%. The results demonstrated that the action of TUS at 1MHz inhibited bacterial growth while at 3MHz, bacterial growth was observed in both species. However, the synergistic combination of ultrasound and antibiotics was able to inhibit the growth of both bacteria completely after 15min of ultrasonication. The results suggest that the action of ultrasound on S. aureus and E. coli are dependent on the oscillation frequency as well as the intensity and time of application. The combination of ultrasound with antibiotics was able to inhibit bacterial growth fully at all frequencies and doses in both species. Copyright © 2016 Elsevier B.V. All rights reserved.

Importance of inoculum properties on the structure and growth of bacterial communities during Recolonisation of humus soil with different pH.

PubMed

Pettersson, Marie; Bååth, Erland

2013-08-01

The relationship between community structure and growth and pH tolerance of a soil bacterial community was studied after liming in a reciprocal inoculum study. An unlimed (UL) humus soil with a pH of 4.0 was fumigated with chloroform for 4 h, after which < 1 % of the initial bacterial activity remained. Half of the fumigated soil was experimentally limed (EL) to a pH of 7.6. Both the UL and the EL soil were then reciprocally inoculated with UL soil or field limed (FL) soil with a pH of 6.2. The FL soil was from a 15-year-old experiment. The structural changes were measured on both bacteria in soil and on bacteria able to grow on agar plates using phospholipids fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) analysis. The developing community pH tolerance and bacterial growth were also monitored over time using thymidine incorporation. The inoculum source had a significant impact on both growth and pH tolerance of the bacterial community in the EL soil. These differences between the EL soil inoculated with UL soil and FL soil were correlated to structural changes, as evidenced by both PLFA and DGGE analyses on the soil. Similar correlations were seen to the fraction of the community growing on agar plates. There were, however, no differences between the soil bacterial communities in the unlimed soils with different inocula. This study showed the connection between the development of function (growth), community properties (pH tolerance) and the structure of the bacterial community. It also highlighted the importance of both the initial properties of the community and the selection pressure after environmental changes in shaping the resulting microbial community.

Putative bacterial volatile-mediated growth in soybean (Glycine max L. Merrill) and expression of induced proteins under salt stress.

PubMed

Vaishnav, A; Kumari, S; Jain, S; Varma, A; Choudhary, D K

2015-08-01

Plant root-associated rhizobacteria elicit plant immunity referred to as induced systemic tolerance (IST) against multiple abiotic stresses. Among multibacterial determinants involved in IST, the induction of IST and promotion of growth by putative bacterial volatile compounds (VOCs) is reported in the present study. To characterize plant proteins induced by putative bacterial VOCs, proteomic analysis was performed by MALDI-MS/MS after exposure of soybean seedlings to a new strain of plant growth promoting rhizobacteria (PGPR) Pseudomonas simiae strain AU. Furthermore, expression analysis by Western blotting confirmed that the vegetative storage protein (VSP), gamma-glutamyl hydrolase (GGH) and RuBisCo large chain proteins were significantly up-regulated by the exposure to AU strain and played a major role in IST. VSP has preponderant roles in N accumulation and mobilization, acid phosphatase activity and Na(+) homeostasis to sustain plant growth under stress condition. More interestingly, plant exposure to the bacterial strain significantly reduced Na(+) and enhanced K(+) and P content in root of soybean seedlings under salt stress. In addition, high accumulation of proline and chlorophyll content also provided evidence of protection against osmotic stress during the elicitation of IST by bacterial exposure. The present study reported for the first time that Ps. simiae produces a putative volatile blend that can enhance soybean seedling growth and elicit IST against 100 mmol l(-1) NaCl stress condition. The identification of such differentially expressed proteins provide new targets for future studies that will allow assessment of their physiological roles and significance in the response of glycophytes to stresses. Further work should uncover more about the chemical side of VOC compounds and a detailed study about their molecular mechanism responsible for plant growth. © 2015 The Society for Applied Microbiology.

Growth factors for nanobacteria

NASA Astrophysics Data System (ADS)

Ciftcioglu, Neva; Kajander, E. Olavi

1999-12-01

Nanobacteria are novel microorganisms recently isolated from fetal bovine serum and blood of cows and humans. These coccoid, gram negative bacteria in alpha-2 subgroup of Proteobacteria grow slowly under mammalian cell culture conditions but not in common media for microbes. Now we have found two different kinds of culture supplement preparations that improve their growth and make them culturable in the classical sense. These are supernatant fractions of conditioned media obtained from 1 - 3 months old nanobacteria cultures and from about a 2 weeks old Bacillus species culture. Both improved multiplication and particle yields and the latter increased their resistance to gentamicin. Nanobacteria cultured with any of the methods shared similar immunological property, structure and protein pattern. The growth supporting factors were heat-stabile and nondialyzable, and dialysis improved the growth promoting action. Nanobacteria formed stony colonies in a bacteriological medium supplemented with the growth factors. This is an implication that nanobacterial growth is influenced by pre-existing bacterial flora.

Bacterial cellulose membrane as separation medium

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

Shibazaki, Hideki; Kuga, Shigenori; Onabe, Fumihiko

1993-11-10

A thin membrane of bacterial cellulose (BC) obtained from Acetobacter culture was tested for its performance as a dialysis membrane in aqueous systems. The BC membrane showed superior mechanical strength to that of a dialysis-grade regenerated cellulose membrane, allowing the use of a thinner membrane than the latter. As a result, the BC membrane gave higher permeation rates for poly(ethylene glycols) as probe solutes. The cutoff molecular weight of the original BC membrane, significantly greater than that of regenerated cellulose, could be modified by concentrated alkali treatments of the membrane. The nature of the change at the ultrastructural level causedmore » by the alkali treatments was studied by X-ray diffraction and scanning electron microscopy.« less

Kinetics of substrate utilization and bacterial growth of crude oil degraded by Pseudomonas aeruginosa.

PubMed

Talaiekhozani, Amirreza; Jafarzadeh, Nematollah; Fulazzaky, Mohamad Ali; Talaie, Mohammad Reza; Beheshti, Masoud

2015-01-01

Pollution associated with crude oil (CO) extraction degrades the quality of waters, threatens drinking water sources and may ham air quality. The systems biology approach aims at learning the kinetics of substrate utilization and bacterial growth for a biological process for which very limited knowledge is available. This study uses the Pseudomonas aeruginosa to degrade CO and determines the kinetic parameters of substrate utilization and bacterial growth modeled from a completely mixed batch reactor. The ability of Pseudomonas aeruginosa can remove 91 % of the total petroleum hydrocarbons and 83 % of the aromatic compounds from oily environment. The value k of 9.31 g of substrate g(-1) of microorganism d(-1) could be far higher than the value k obtained for petrochemical wastewater treatment and that for municipal wastewater treatment. The production of new cells of using CO as the sole carbon and energy source can exceed 2(3) of the existing cells per day. The kinetic parameters are verified to contribute to improving the biological removal of CO from oily environment.

Custom fabrication of biomass containment devices using 3-D printing enables bacterial growth analyses with complex insoluble substrates.

PubMed

Nelson, Cassandra E; Beri, Nina R; Gardner, Jeffrey G

2016-11-01

Physiological studies of recalcitrant polysaccharide degradation are challenging for several reasons, one of which is the difficulty in obtaining a reproducibly accurate real-time measurement of bacterial growth using insoluble substrates. Current methods suffer from several problems including (i) high background noise due to the insoluble material interspersed with cells, (ii) high consumable and reagent cost and (iii) significant time delay between sampling and data acquisition. A customizable substrate and cell separation device would provide an option to study bacterial growth using optical density measurements. To test this hypothesis we used 3-D printing to create biomass containment devices that allow interaction between insoluble substrates and microbial cells but do not interfere with spectrophotometer measurements. Evaluation of materials available for 3-D printing indicated that UV-cured acrylic plastic was the best material, being superior to nylon or stainless steel when examined for heat tolerance, reactivity, and ability to be sterilized. Cost analysis of the 3-D printed devices indicated they are a competitive way to quantitate bacterial growth compared to viable cell counting or protein measurements, and experimental conditions were scalable over a 100-fold range. The presence of the devices did not alter growth phenotypes when using either soluble substrates or insoluble substrates. We applied biomass containment to characterize growth of Cellvibrio japonicus on authentic lignocellulose (non-pretreated corn stover), and found physiological evidence that xylan is a significant nutritional source despite an abundance of cellulose present. Copyright © 2016 Elsevier B.V. All rights reserved.

Medium Chain-Length Polyhydroxyalkanoate Copolymer Modified by Bacterial Cellulose for Medical Devices.

PubMed

Panaitescu, Denis Mihaela; Lupescu, Irina; Frone, Adriana Nicoleta; Chiulan, Ioana; Nicolae, Cristian Andi; Tofan, Vlad; Stefaniu, Amalia; Somoghi, Raluca; Trusca, Roxana

2017-10-09

Medium chain-length polyhydroxyalkanoates (mPHAs) are flexible elastomeric biopolymers with valuable properties for biomedical applications like artificial arteries and other medical implants. However, an environmentally friendly and high productivity process together with the tuning of the mechanical and biological properties of mPHAs are mandatory for this purpose. Here, for the first time, a melt processing technique was applied for the preparation of bionanocomposites starting from poly(3-hydroxyoctanoate) (PHO) and bacterial cellulose nanofibers (BC). The incorporation of only 3 wt % BC in PHO improved its thermal stability with 25 °C and reinforced it, increasing the Young's modulus with 76% and the tensile strength with 44%. The percolation threshold calculated with the aspect ratio of the fibers after melt processing was very low and close to 3 wt %. We showed that this bionanocomposite is able to preserve the ductile behavior during storage, no important aging being noted between 3 h and one month after compression-molding. Moreover, this study is the first to investigate the melt processability of PHO nanocomposite for tube extrusion. In addition, biocompatibility study showed no proinflammatory immune response and better cell adhesion for PHO/BC nanocomposite with 3 wt % BC and demonstrated the high feasibility of this bionanocomposite for in vivo application of tissue-engineered blood vessels.

In Vitro Selective Growth-Inhibitory Effect of 8-Hydroxyquinoline on Clostridium perfringens versus Bifidobacteria in a Medium Containing Chicken Ileal Digesta.

PubMed

Skrivanova, Eva; Van Immerseel, Filip; Hovorkova, Petra; Kokoska, Ladislav

2016-01-01

Clostridium perfringens-induced necrotic enteritis is generally controlled by antibiotics. However, because of increasing antibiotic resistance, other antibacterial agents are required, preferably ones that do not affect the beneficial intestinal microbiota of the host. This study evaluated the in vitro selective growth-inhibitory effect of 8-hydroxyquinoline (8HQ) on C. perfringens vs. bifidobacteria in a medium containing chicken ileal digesta. Prior to the experiments, the minimum inhibitory concentrations of 8HQ and penicillin G were determined by broth microdilution assay. The minimum inhibitory concentration values of 8HQ for C. perfringens were 16-32 times lower than the values for bifidobacteria. Treatment of autoclaved and non-autoclaved chicken ileal digesta with 8HQ showed a selective anticlostridial effect. After incubation of C. perfringens with autoclaved ileal digesta for 3 h, all 8HQ concentrations tested (32-2048 μg/mL) significantly reduced C. perfringens bacterial count. In contrast, the same treatment had no or only a slight effect on bifidobacteria counts. Unlike 8HQ, penicillin G did not exhibit any selectivity. Similar results were obtained after incubation for 24 h. In non-autoclaved ileal digesta, all 8HQ concentrations tested significantly reduced C. perfringens bacterial counts after incubation for 30 min and 3 h, while no effect was observed on bifidobacteria. These results suggest that 8HQ may serve as a prospective veterinary compound for use against necrotic enteritis in poultry.

Ozone Application for Tofu Waste Water Treatment and Its Utilisation for Growth Medium of Microalgae Spirulina sp

NASA Astrophysics Data System (ADS)

Hadiyanto, Hadiyanto

2018-02-01

Tofu industries produce waste water containing high organic contents and suspendid solid which is harmful if directly discharged to the environment. This waste can lead to disruption of water quality and lowering the environmental carrying capacity of waters around the tofu industries. Besides, the tofu waste water still contains high nitrogen contents which can be used for microalgae growth. This study was aimed to reduce the pollution load (chemical oxygen demand-COD) of tofue wastewater by using ozone treatments and to utilize nutrients in treated tofu waste water as medium growth of microalgae. The result showed that the reduction of COD by implementation of ozone treatment followed first order kinetic. Under variation of waste concentrations between 10-40%, the degradation rate constant was in the range of 0.00237-0.0149 min-1. The microalgae was able to grow in the tofue waste medium by the growth rate constants of 0.15-0.29 day-1. This study concluded that tofu waste was highly potent for microalgae growth.

Bacterial Compatibility in Combined Inoculations Enhances the Growth of Potato Seedlings.

PubMed

Santiago, Christine D; Yagi, Shogo; Ijima, Motoaki; Nashimoto, Tomoya; Sawada, Maki; Ikeda, Seishi; Asano, Kenji; Orikasa, Yoshitake; Ohwada, Takuji

2017-03-31

The compatibility of strains is crucial for formulating bioinoculants that promote plant growth. We herein assessed the compatibility of four potential bioinoculants isolated from potato roots and tubers (Sphingomonas sp. T168, Streptomyces sp. R170, Streptomyces sp. R181, and Methylibium sp. R182) that were co-inoculated in order to improve plant growth. We screened these strains using biochemical tests, and the results obtained showed that R170 had the highest potential as a bioinoculant, as indicated by its significant ability to produce plant growth-promoting substances, its higher tolerance against NaCl (2%) and AlCl 3 (0.01%), and growth in a wider range of pH values (5.0-10.0) than the other three strains. Therefore, the compatibility of R170 with other strains was tested in combined inoculations, and the results showed that the co-inoculation of R170 with T168 or R182 synergistically increased plant weight over un-inoculated controls, indicating the compatibility of strains based on the increased production of plant growth promoters such as indole-3-acetic acid (IAA) and siderophores as well as co-localization on roots. However, a parallel test using strain R181, which is the same Streptomyces genus as R170, showed incompatibility with T168 and R182, as revealed by weaker plant growth promotion and a lack of co-localization. Collectively, our results suggest that compatibility among bacterial inoculants is important for efficient plant growth promotion, and that R170 has potential as a useful bioinoculant, particularly in combined inoculations that contain compatible bacteria.

Bacterial endophytes enhance competition by invasive plants.

PubMed

Rout, Marnie E; Chrzanowski, Thomas H; Westlie, Tara K; DeLuca, Thomas H; Callaway, Ragan M; Holben, William E

2013-09-01

Invasive plants can alter soil microbial communities and profoundly alter ecosystem processes. In the invasive grass Sorghum halepense, these disruptions are consequences of rhizome-associated bacterial endophytes. We describe the effects of N2-fixing bacterial strains from S. halepense (Rout and Chrzanowski, 2009) on plant growth and show that bacteria interact with the plant to alter soil nutrient cycles, enabling persistence of the invasive. • We assessed fluxes in soil nutrients for ∼4 yr across a site invaded by S. halepense. We assayed the N2-fixing bacteria in vitro for phosphate solubilization, iron chelation, and production of the plant-growth hormone indole-3-acetic acid (IAA). We assessed the plant's ability to recruit bacterial partners from substrates and vertically transmit endophytes to seeds and used an antibiotic approach to inhibit bacterial activity in planta and assess microbial contributions to plant growth. • We found persistent alterations to eight biogeochemical cycles (including nitrogen, phosphorus, and iron) in soils invaded by S. halepense. In this context, three bacterial isolates solubilized phosphate, and all produced iron siderophores and IAA in vitro. In growth chamber experiments, bacteria were transmitted vertically, and molecular analysis of bacterial community fingerprints from rhizomes indicated that endophytes are also horizontally recruited. Inhibiting bacterial activity with antibiotics resulted in significant declines in plant growth rate and biomass, with pronounced rhizome reductions. • This work suggests a major role of endophytes on growth and resource allocation of an invasive plant. Indeed, bacterial isolate physiology is correlated with invader effects on biogeochemical cycles of nitrogen, phosphate, and iron.

Continuous monitoring of bacterial biofilm growth using uncoated Thickness-Shear Mode resonators

NASA Astrophysics Data System (ADS)

Castro, P.; Resa, P.; Durán, C.; Maestre, J. R.; Mateo, M.; Elvira, L.

2012-12-01

Quartz Crystal Microbalances (QCM) were used to nondestructively monitor in real time the microbial growth of the bacteria Staphylococcus epidermidis (S. epidermidis) in a liquid broth. QCM, sometimes referred to as Thickness-Shear Mode (TSM) resonators, are highly sensitive sensors not only able to measure very small mass, but also non-gravimetric contributions of viscoelastic media. These devices can be used as biosensors for bacterial detection and are employed in many applications including their use in the food industry, water and environment monitoring, pharmaceutical sciences and clinical diagnosis. In this work, three strains of S. epidermidis (which differ in the ability to produce biofilm) have been continuously monitored using an array of piezoelectric TSM resonators, at 37 °C in a selective culturing media. Microbial growth was followed by measuring the changes in the crystal resonant frequency and bandwidth at several harmonics. It was shown that microbial growth can be monitored in real time using multichannel and multiparametric QCM sensors.

Determination of specific growth stages of plant cell suspension cultures by monitoring conductivity changes in the medium.

PubMed

Hahlbrock, K; Ebel, J; Oaks, A; Auden, J; Liersch, M

1974-03-01

Conductivity changes in the medium of cultured soybean (Glycine max L.) cells were shown to be strictly correlated with nitrate uptake and growth of the cultures. A continuous record of the conductivity was used as a simple and reliable method of determining specific growth stages and concomitant peaks in the activities of nitrate reductase and phenylalanine ammonia-lyase.

Staphylococcus aureus Growth using Human Hemoglobin as an Iron Source

PubMed Central

Pishchany, Gleb; Haley, Kathryn P.; Skaar, Eric P.

2013-01-01

S. aureus is a pathogenic bacterium that requires iron to carry out vital metabolic functions and cause disease. The most abundant reservoir of iron inside the human host is heme, which is the cofactor of hemoglobin. To acquire iron from hemoglobin, S. aureus utilizes an elaborate system known as the iron-regulated surface determinant (Isd) system1. Components of the Isd system first bind host hemoglobin, then extract and import heme, and finally liberate iron from heme in the bacterial cytoplasm2,3. This pathway has been dissected through numerous in vitro studies4-9. Further, the contribution of the Isd system to infection has been repeatedly demonstrated in mouse models8,10-14. Establishing the contribution of the Isd system to hemoglobin-derived iron acquisition and growth has proven to be more challenging. Growth assays using hemoglobin as a sole iron source are complicated by the instability of commercially available hemoglobin, contaminating free iron in the growth medium, and toxicity associated with iron chelators. Here we present a method that overcomes these limitations. High quality hemoglobin is prepared from fresh blood and is stored in liquid nitrogen. Purified hemoglobin is supplemented into iron-deplete medium mimicking the iron-poor environment encountered by pathogens inside the vertebrate host. By starving S. aureus of free iron and supplementing with a minimally manipulated form of hemoglobin we induce growth in a manner that is entirely dependent on the ability to bind hemoglobin, extract heme, pass heme through the bacterial cell envelope and degrade heme in the cytoplasm. This assay will be useful for researchers seeking to elucidate the mechanisms of hemoglobin-/heme-derived iron acquisition in S. aureus and possibly other bacterial pathogens. PMID:23426144

Nanoparticle growth and surface chemistry changes in cell-conditioned culture medium.

PubMed

Kendall, Michaela; Hodges, Nikolas J; Whitwell, Harry; Tyrrell, Jess; Cangul, Hakan

2015-02-05

When biomolecules attach to engineered nanoparticle (ENP) surfaces, they confer the particles with a new biological identity. Physical format may also radically alter, changing ENP stability and agglomeration state within seconds. In order to measure which biomolecules are associated with early ENP growth, we studied ENPs in conditioned medium from A549 cell culture, using dynamic light scattering (DLS) and linear trap quadrupole electron transfer dissociation mass spectrometry. Two types of 100 nm polystyrene particles (one uncoated and one with an amine functionalized surface) were used to measure the influence of surface type. In identically prepared conditioned medium, agglomeration was visible in all samples after 1 h, but was variable, indicating inter-sample variability in secretion rates and extracellular medium conditions. In samples conditioned for 1 h or more, ENP agglomeration rates varied significantly. Agglomerate size measured by DLS was well correlated with surface sequestered peptide number for uncoated but not for amine coated polystyrene ENPs. Amine-coated ENPs grew much faster and into larger agglomerates associated with fewer sequestered peptides, but including significant sequestered lactose dehydrogenase. We conclude that interference with extracellular peptide balance and oxidoreductase activity via sequestration is worthy of further study, as increased oxidative stress via this new mechanism may be important for cell toxicity. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Evaluation of effect of high frequency electromagnetic field on growth and antibiotic sensitivity of bacteria.

PubMed

Salmen, Saleh H; Alharbi, Sulaiman A; Faden, Asmaa A; Wainwright, M

2018-01-01

This study was aimed to evaluate the impact of high frequency electromagnetic fields (HF-EMF at 900 and 1800 MHz) on DNA, growth rate and antibiotic susceptibility of S. aureus , S. epidermidis , and P. aeruginosa . In this study, bacteria were exposed to 900 and 1800 MHz for 2 h and then inoculated to new medium when their growth rate and antibiotic susceptibility were evaluated. Results for the study of bacterial DNA unsuccessful to appearance any difference exposed and non-exposed S. aureus and S. epidermidis . Exposure of S. epidermidis and S. aureus to electromagnetic fields mostly produced no statistically significant decrease in bacterial growth, except for S. aureus when exposure to 900 MHz at 12 h. Exposure of P. aeruginosa to electromagnetic fields at 900 MHz however, lead to a significant reduction in growth rate, while 1800 MHz had insignificant effect. With the exception of S. aureus , treated with amoxicillin (30 µg) and exposed to electromagnetic fields, radiation treatment had no significant effect on bacterial sensitivity to antibiotics.

Kinetics of Bacterial Growth on Chlorinated Aliphatic Compounds

PubMed Central

van den Wijngaard, Arjan J.; Wind, Richèle D.; Janssen, Dick B.

1993-01-01

With the pure bacterial cultures Ancylobacter aquaticus AD20 and AD25, Xanthobacter autotrophicus GJ10, and Pseudomonas sp. strain AD1, Monod kinetics was observed during growth in chemostat cultures on 1,2-dichloroethane (AD20, AD25, and GJ10), 2-chloroethanol (AD20 and GJ10), and 1,3-dichloro-2-propanol (AD1). Both the Michaelis-Menten constants (Km) of the first catabolic (dehalogenating) enzyme and the Monod half-saturation constants (Ks) followed the order 2-chloroethanol, 1,3-dichloro-2-propanol, epichlorohydrin, and 1,2-dichloroethane. The Ks values of strains GJ10, AD20, and AD25 for 1,2-dichloroethane were 260, 222, and 24 μM, respectively. The low Ks value of strain AD25 was correlated with a higher haloalkane dehalogenase content of this bacterium. The growth rates of strains AD20 and GJ10 in continuous cultures on 1,2-dichloroethane were higher than the rates predicted from the kinetics of the haloalkane dehalogenase and the concentration of the enzyme in the cells. The results indicate that the efficiency of chlorinated compound removal is indeed influenced by the kinetic properties and cellular content of the first catabolic enzyme. The cell envelope did not seem to act as a barrier for permeation of 1,2-dichloroethane. PMID:16348981

Growth medium alterations improve in vitro cold storage of pear germplasm.

PubMed

Kovalchuk, I; Zhumagulova, Z; Turdiev, T; Reed, B M

2014-01-01

Development of new fruit cultivars is dependent on genetic resource collections such as those at the Pomological Garden of the Institute of Horticulture and Viticulture near Almaty, Kazakhstan. The pear germplasm collection of the Pomological Garden contains 615 cultivars and three species. In vitro cold storage of the collection would provide additional security to the field collection. This study was designed to improve medium-term in vitro storage of pear germplasm. Shoots of seven pear cultivars (Pyrus communis L.) were stored in plastic five-section bags at 4 degree C and a 10-h photoperiod (7 μmol/m2/s). Treatments included medium with four carbohydrate sources (3% sucrose, 2% or 3% mannitol, or 2% sucrose + 2% mannitol) with 0.5 mg/l BAP and 0.1 mg/l IBA or without plant growth regulators (PGRs) and at three Murashige and Skoog (MS) nitrogen concentrations (100%, 50% or 25%). Pear shoots remained viable for 9 to 15 months without repropagation on the control MS medium with 3% sucrose without PGRs. There were significant impacts of cultivar and treatment on the duration of cold storage. Shoots of 'Mramornaya' remained viable (rating of ≥ 2) for 27 months with PGRs and 2% sucrose + 2% mannitol compared to 12 months for the PGR + 3% sucrose treatment. Talgarskaya Krasaviza stored for 18 months on 2% sucrose + 2% mannitol while all other treatments lasted only 6 to 9 months. Treatments with 0.5 or 1 mg/l abscisic acid (ABA) with 3% sucrose increased storage duration as did reducing the concentration of nitrogen in the medium to 25% without PGRs and with 3% sucrose.

Inhibition of heparin precipitation, bacterial growth, and fungal growth with a combined isopropanol-ethanol locking solution for vascular access devices.

PubMed

Restrepo, Daniel; Laconi, Nicholas S; Alcantar, Norma A; West, Leigh A; Buttice, Audrey L; Patel, Saumil; Kayton, Mark L

2015-03-01

Clinical reports of ethanol-lock use for the prevention of catheter-related bloodstream infections have been marked by the occurrence of serious catheter occlusions, particularly among children with mediports. We hypothesized that precipitate forms when ethanol mixes with heparin at the concentrations relevant for vascular access devices, but that the use of a combination of two alcohols, ethanol and isopropanol, would diminish heparin-related precipitation, while retaining anti-bacterial and anti-fungal effects. Heparin (0-100units/mL) was incubated in ethanol-water solutions (30%-70% vol/vol) or in an aqueous solution containing equal parts (35% and 35% vol/vol) of isopropanol and ethanol. Precipitation at temperatures from 4 to 40°C was measured in nephelometric turbidity units using a benchtop turbidimeter. Growth of Escherichia coli, Staphylococcus aureus, and Candida albicans colonies were measured following exposure to solutions of ethanol or isopropanol-ethanol. Groupwise comparisons were performed using analysis of variance with Bonferroni-corrected, post-hoc T-testing. Seventy percent ethanol and heparin exhibit dose-dependent precipitation that is pronounced and significant at the concentrations typically used in mediports (p<0.05). Precipitate is significantly reduced by use of a combined 35% isopropanol-35% ethanol solution rather than 70% ethanol (p<0.05), while maintaining the solution's anti-bacterial and anti-fungal properties. On the other hand, although ethanol solutions under 70% form less precipitate with heparin, such concentrations are also less effective at bacterial colony inhibition than solutions of either 70% ethanol or 35% isopropanol-35% ethanol (p<0.05). A combined 35% isopropanol-35% ethanol locking solution inhibits bacterial and fungal growth similarly to 70% ethanol, but results in less precipitate than 70% ethanol when exposed to heparin. Further study of a combined isopropanol-ethanol locking solution for the prevention of

Differential effects of catecholamines on in vitro growth of pathogenic bacteria

NASA Technical Reports Server (NTRS)

Belay, Tesfaye; Sonnenfeld, Gerald

2002-01-01

Supplementation of minimal medium inoculated with bacterial cultures with norepinephrine, epinephrine, dopamine, or isoproterenol resulted in marked increases in growth compared to controls. Norepinephrine and dopamine had the greatest enhancing effects on growth of cultures of Pseudomonas aeruginosa and Klebsiella pneumoniae, while epinephrine and isoproterenol also enhanced growth to a lesser extent. The growth of Escherichia coli in the presence of norepinephrine was greater than growth in the presence of the three other neurochemicals used in the study. Growth of Staphylococcus aureus was also enhanced in the presence of norepinephrine, but not to the same degree as was the growth of gram negative bacteria. Addition of culture supernatants from E. coli cultures that had been grown in the presence of norepinephrine was able to enhance the growth of K. pneumoniae. Addition of the culture supernatant fluid culture from E. coli cultures that had been grown in the presence of norepinephrine did not enhance growth of P. aeruginosa or S. aureus. Culture supernatant fluids from bacteria other than E. coli grown in the presence of norepinephrine were not able to enhance the growth of any bacteria tested. The results suggest that catecholamines can enhance growth of pathogenic bacteria, which may contribute to development of pathogenesis; however, there is no uniform effect of catecholamines on bacterial growth.

Growth medium sterilization using decomposition of peracetic acid for more cost-efficient production of omega-3 fatty acids by Aurantiochytrium.

PubMed

Cho, Chang-Ho; Shin, Won-Sub; Woo, Do-Wook; Kwon, Jong-Hee

2018-06-01

Aurantiochytrium can produce significant amounts of omega-3 fatty acids, specifically docosahexaenoic acid and docosapentaenoic acid. Use of a glucose-based medium for heterotrophic growth is needed to achieve a high growth rate and production of abundant lipids. However, heat sterilization for reliable cultivation is not appropriate to heat-sensitive materials and causes a conversion of glucose via browning (Maillard) reactions. Thus, the present study investigated the use of a direct degradation of Peracetic acid (PAA) for omega-3 production by Aurantiochytrium. Polymer-based bioreactor and glucose-containing media were chemically co-sterilized by 0.04% PAA and neutralized through a reaction with ferric ion (III) in HEPES buffer. Mono-cultivation was achieved without the need for washing steps and filtration, thereby avoiding the heat-induced degradation and dehydration of glucose. Use of chemically sterilized and neutralized medium, rather than heat-sterilized medium, led to a twofold faster growth rate and greater productivity of omega-3 fatty acids.

Method for Bacterial Growth and Ammonia Production and Effect of Inhibitory Substances in Disposable Absorbent Hygiene Products.

PubMed

Forsgren-Brusk, Ulla; Yhlen, Birgitta; Blomqvist, Marie; Larsson, Peter

The purpose of this study was to evaluate a pragmatic laboratory method to provide a technique for developing incontinence products better able to reduce malodor when used in the clinical setting. Bacterial growth and bacterially formed ammonia in disposable absorbent incontinence products was measured by adding synthetic urine inoculated with bacteria to test samples cut from the crotch area of the product. The inhibitory effect's of low pH (4.5 and 4.9) and 3 antimicrobial substances-chlorhexidine, polyhexamethylene biguanide (PHMB), and thymol-at 2 concentrations each, were studied. From the initial inocula of 3.3 log colony-forming units per milliliter (cfu/mL) at baseline, the bacterial growth of the references increased to 5.0 to 6.0 log cfu/mL at 6 hours for Escherichia coli, Proteus mirabilis, and Enterococcus faecalis. At 12 hours there was a further increase to 7.0 to 8.9 log cfu/mL. Adjusting the pH of the superabsorbent in the incontinence product from 6.0 to pH 4.5 and pH 4.9 significantly (P < .05) inhibited the bacterial growth rates, in most cases, both at 6 and 12 hours. The effect was most pronounced at pH 4.5. Chlorhexidine had significant (P < .05) inhibitory effect on E. coli and E. faecalis, and at 12 hours also on P. mirabilis. For PHMB and thymol the results varied. At 6 hours, the ammonia concentration in the references (pH 6.0) was 200 to 300 ppm and it was 1500 to 1600 ppm at 8 hours. At pH 4.5, no or little ammonia production was measured at 6 and 8 hours. At pH 4.9, there was a significant reduction (P < .01). Chlorhexidine and PHMB exerted a significant (P < .01 or P < .001) inhibitory effect on ammonia production at both concentrations and at 6 and 8 hours. Thymol 0.003% and 0.03% showed inhibitory effect at both 6 hours (P < .01 or P < .001) and at 8 hours (P < .05 or P < .001). The method described in this study can be used to compare the ability of various disposable absorbent products to inhibit bacterial growth and ammonia

Phytoplankton and bacterial community structures and their interaction during red-tide phenomena

NASA Astrophysics Data System (ADS)

Ismail, Mona Mohamed; Ibrahim, Hassan Abd Allah

2017-09-01

Phytoplankton and bacteria diversity were studied before, during and after red tide phenomena during spring season 2015 in the Eastern Harbour (E.H.) of Alexandria, Egypt. Fifty five species of phytoplankton were identified and represented different distinct classes "Bacillariophyceae; Dinophyceae, Chlorophyceae, Cyanophyceae and Eugelenophyceae". Also, Diatom formed the most dominant group. The average number of the phytoplankton density varied from 4.8 × 104 to 1.1 × 106 cell l-1 during the study period and Skeletonema costatum was the agent causing the red tide. The existence percentages of bacteria ranged from 2.6 to 17.9% on all media tested. The bacterial isolates on the nutrient agar medium represented the highest existence with a total percentage of 43.6%, followed by MSA medium (25.7%), while the lowest percentage was for the AA medium at 7.8%. However, twelve isolates were selected as representative for bacterial community during study interval. Based on the morphological, biochemical, physiological and enzymatic characteristics, the bacterial strains were described. Depending on the 16S rDNA gene sequence, three common antagonists were aligned as: Vibrio toranzoniae strain Vb 10.8, Ruegeria pelagia strain NBRC 102038 and Psychrobacter adeliensis strain DSM 15333. The interaction between these bacteria and S. costatum was studied. The growth of S. costatum was significantly lower whenever each bacterium was present as compared to axenic culture. More specifically, 30% (v/v) of the all tested bacteria showed the strongest algicidal activities, as all S. costatum cells were killed after two days. 10% of R. pelagia and P. adeliensis also showed significant algicidal activities within six days.

The Influence of Container Type and Potting Medium on Growth of Black Walnut Seedlings

Treesearch

David T. Funk; Paul L Roth; C. K. Celmer

1980-01-01

Container size and shape, potting medium, and genotype interacted to influence the growth of black walnut (Juglans nigra L.) seedlings. Larger containers tended to produce larger trees. In tall, narrow, vent-pipe containers, different, proportions of peat and sand in potting media had no effect on total weight; a higher proportion of peat than of very fine sand in...

Bacterial Respiration and Growth Rates Affect the Feeding Preferences, Brood Size and Lifespan of Caenorhabditis elegans

PubMed Central

Yu, Li; Yan, Xiaomei; Ye, Chenglong; Zhao, Haiyan; Chen, Xiaoyun; Hu, Feng; Li, Huixin

2015-01-01

Bacteria serve as live food and nutrients for bacterial-feeding nematodes (BFNs) in soils, and influence nematodes behavior and physiology through their metabolism. Five bacterial taxa (Bacillus amyloliquefaciens JX1, Variovorax sp. JX14, Bacillus megaterium JX15, Pseudomonas fluorescens Y1 and Escherichia coli OP50) and the typical BFN Caenorhabditis elegans were selected to study the effects of bacterial respiration and growth rates on the feeding preferences, brood size and lifespan of nematodes. P. fluorescens Y1 and E. coli OP50 were found to be more active, with high respiration and rapid growth, whereas B. amyloliquefaciens JX1 and B. megaterium JX15 were inactive. The nematode C. elegans preferred active P. fluorescens Y1 and E. coli OP50 obviously. Furthermore, worms that fed on these two active bacteria produced more offspring but had shorter lifespan, while inactive and less preferred bacteria had increased nematodes lifespan and decreased the brood size. Based on these results, we propose that the bacterial activity may influence the behavior and life traits of C. elegans in the following ways: (1) active bacteria reproduce rapidly and emit high levels of CO2 attracting C. elegans; (2) these active bacteria use more resources in the nematodes’ gut to sustain their survival and reproduction, thereby reducing the worm's lifespan; (3) inactive bacteria may provide less food for worms than active bacteria, thus increasing nematodes lifespan but decreasing their fertility. Nematodes generally require a balance between their preferred foods and beneficial foods, only preferred food may not be beneficial for nematodes. PMID:26222828

GROWTH OF A LOCALIZED SEED MAGNETIC FIELD IN A TURBULENT MEDIUM

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

Cho, Jungyeon; Yoo, Hyunju, E-mail: jcho@cnu.ac.kr

2012-11-10

Turbulence dynamo deals with the amplification of a seed magnetic field in a turbulent medium and has been studied mostly for uniform or spatially homogeneous seed magnetic fields. However, some astrophysical processes (e.g., jets from active galaxies, galactic winds, or ram-pressure stripping in galaxy clusters) can provide localized seed magnetic fields. In this paper, we numerically study amplification of localized seed magnetic fields in a turbulent medium. Throughout the paper, we assume that the driving scale of turbulence is comparable to the size of the system. Our findings are as follows. First, turbulence can amplify a localized seed magnetic fieldmore » very efficiently. The growth rate of magnetic energy density is as high as that for a uniform seed magnetic field. This result implies that magnetic field ejected from an astrophysical object can be a viable source of a magnetic field in a cluster. Second, the localized seed magnetic field disperses and fills the whole system very fast. If turbulence in a system (e.g., a galaxy cluster or a filament) is driven at large scales, we expect that it takes a few large-eddy turnover times for the magnetic field to fill the whole system. Third, growth and turbulence diffusion of a localized seed magnetic field are also fast in high magnetic Prandtl number turbulence. Fourth, even in decaying turbulence, a localized seed magnetic field can ultimately fill the whole system. Although the dispersal rate of the magnetic field is not fast in purely decaying turbulence, it can be enhanced by an additional forcing.« less

Stochastic Individual-Based Modeling of Bacterial Growth and Division Using Flow Cytometry.

PubMed

García, Míriam R; Vázquez, José A; Teixeira, Isabel G; Alonso, Antonio A

2017-01-01

A realistic description of the variability in bacterial growth and division is critical to produce reliable predictions of safety risks along the food chain. Individual-based modeling of bacteria provides the theoretical framework to deal with this variability, but it requires information about the individual behavior of bacteria inside populations. In this work, we overcome this problem by estimating the individual behavior of bacteria from population statistics obtained with flow cytometry. For this objective, a stochastic individual-based modeling framework is defined based on standard assumptions during division and exponential growth. The unknown single-cell parameters required for running the individual-based modeling simulations, such as cell size growth rate, are estimated from the flow cytometry data. Instead of using directly the individual-based model, we make use of a modified Fokker-Plank equation. This only equation simulates the population statistics in function of the unknown single-cell parameters. We test the validity of the approach by modeling the growth and division of Pediococcus acidilactici within the exponential phase. Estimations reveal the statistics of cell growth and division using only data from flow cytometry at a given time. From the relationship between the mother and daughter volumes, we also predict that P. acidilactici divide into two successive parallel planes.

Intestinal Epithelial Cells Modulate Antigen-Presenting Cell Responses to Bacterial DNA

PubMed Central

Campeau, J. L.; Salim, S. Y.; Albert, E. J.; Hotte, N.

2012-01-01

Intestinal epithelial cells and antigen-presenting cells orchestrate mucosal innate immunity. This study investigated the role of bacterial DNA in modulating epithelial and bone marrow-derived antigen-presenting cells (BM-APCs) and subsequent T-lymphocyte responses. Murine MODE-K epithelial cells and BM-APCs were treated with DNA from either Bifidobacterium breve or Salmonella enterica serovar Dublin directly and under coculture conditions with CD4+ T cells. Apical stimulation of MODE-K cells with S. Dublin DNA enhanced secretion of cytokines from underlying BM-APCs and induced interleukin-17 (IL-17) and gamma interferon (IFN-γ) secretion from CD4+ T cells. Bacterial DNA isolated from either strain induced maturation and increased cytokine secretion from BM-APCs. Conditioned medium from S. Dublin-treated MODE-K cells elicited an increase in cytokine secretion similar to that seen for S. Dublin DNA. Treatment of conditioned medium from MODE-K cells with RNase and protease prevented the S. Dublin-induced increased cytokine secretion. Oral feeding of mice with B. breve DNA resulted in enhanced levels of colonic IL-10 and transforming growth factor β (TGFβ) compared with what was seen for mice treated with S. Dublin DNA. In contrast, feeding mice with S. Dublin DNA increased levels of colonic IL-17 and IL-12p70. T cells from S. Dublin DNA-treated mice secreted high levels of IL-12 and IFN-γ compared to controls and B. breve DNA-treated mice. These results demonstrate that intestinal epithelial cells are able to modulate subsequent antigen-presenting and T-cell responses to bacterial DNA with pathogenic but not commensal bacterial DNA inducing effector CD4+ T lymphocytes. PMID:22615241

Mycelium-Like Networks Increase Bacterial Dispersal, Growth, and Biodegradation in a Model Ecosystem at Various Water Potentials.

PubMed

Worrich, Anja; König, Sara; Miltner, Anja; Banitz, Thomas; Centler, Florian; Frank, Karin; Thullner, Martin; Harms, Hauke; Kästner, Matthias; Wick, Lukas Y

2016-05-15

Fungal mycelia serve as effective dispersal networks for bacteria in water-unsaturated environments, thereby allowing bacteria to maintain important functions, such as biodegradation. However, poor knowledge exists on the effects of dispersal networks at various osmotic (Ψo) and matric (Ψm) potentials, which contribute to the water potential mainly in terrestrial soil environments. Here we studied the effects of artificial mycelium-like dispersal networks on bacterial dispersal dynamics and subsequent effects on growth and benzoate biodegradation at ΔΨo and ΔΨm values between 0 and -1.5 MPa. In a multiple-microcosm approach, we used a green fluorescent protein (GFP)-tagged derivative of the soil bacterium Pseudomonas putida KT2440 as a model organism and sodium benzoate as a representative of polar aromatic contaminants. We found that decreasing ΔΨo and ΔΨm values slowed bacterial dispersal in the system, leading to decelerated growth and benzoate degradation. In contrast, dispersal networks facilitated bacterial movement at ΔΨo and ΔΨm values between 0 and -0.5 MPa and thus improved the absolute biodegradation performance by up to 52 and 119% for ΔΨo and ΔΨm, respectively. This strong functional interrelationship was further emphasized by a high positive correlation between population dispersal, population growth, and degradation. We propose that dispersal networks may sustain the functionality of microbial ecosystems at low osmotic and matric potentials. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Two-colour fluorescence fluorimetric analysis for direct quantification of bacteria and its application in monitoring bacterial growth in cellulose degradation systems.

PubMed

Duedu, Kwabena O; French, Christopher E

2017-04-01

Monitoring bacterial growth is an important technique required for many applications such as testing bacteria against compounds (e.g. drugs), evaluating bacterial composition in the environment (e.g. sewage and wastewater or food suspensions) and testing engineered bacteria for various functions (e.g. cellulose degradation). T?=1,^FigItem(1) ^ReloadFigure=Yesraditionally, rapid estimation of bacterial growth is performed using spectrophotometric measurement at 600nm (OD600) but this estimation does not differentiate live and dead cells or other debris. Colony counting enumerates live cells but the process is laborious and not suitable for large numbers of samples. Enumeration of live bacteria by flow cytometry is a more suitable rapid method with the use of dual staining with SYBR I Green nucleic acid gel stain and Propidium Iodide (SYBR-I/PI). Flow cytometry equipment and maintenance costs however are relatively high and this technique is unavailable in many laboratories that may require a rapid method for evaluating bacteria growth. We therefore sought to adapt and evaluate the SYBR-I/PI technique of enumerating live bacterial cells for a cheaper platform, a fluorimeter. The fluorimetry adapted SYBR-I/PI enumeration of bacteria in turbid growth media had direct correlations with OD600 (p>0.001). To enable comparison of fluorescence results across labs and instruments, a fluorescence intensity standard unit, the equivalent fluorescent DNA (EFD) was proposed, evaluated and found useful. The technique was further evaluated for its usefulness in enumerating bacteria in turbid media containing insoluble particles. Reproducible results were obtained which OD600 could not give. An alternative method based on the assessment of total protein using the Pierce Coomassie Plus (Bradford) Assay was also evaluated and compared. In all, the SYBR-I/PI method was found to be the quickest and most reliable. The protocol is potentially useful for high-throughput applications such as

The enhanced effects of antibiotics irradiated of extremely high frequency electromagnetic field on Escherichia coli growth properties.

PubMed

Torgomyan, Heghine; Trchounian, Armen

2015-01-01

The effects of extremely high frequency electromagnetic irradiation and antibiotics on Escherichia coli can create new opportunities for applications in different areas—medicine, agriculture, and food industry. Previously was shown that irradiated bacterial sensitivity against antibiotics was changed. In this work, it was presented the results that irradiation of antibiotics and then adding into growth medium was more effective compared with non-irradiated antibiotics bactericidal action. The selected antibiotics (tetracycline, kanamycin, chloramphenicol, and ceftriaxone) were from different groups. Antibiotics irradiation was performed with low intensity 53 GHz frequency during 1 h. The E. coli growth properties—lag-phase duration and specific growth rate—were markedly changed. Enhanced bacterial sensitivity to irradiated antibiotics is similar to the effects of antibiotics of higher concentrations.

Transcriptome landscape of a bacterial pathogen under plant immunity.

PubMed

Nobori, Tatsuya; Velásquez, André C; Wu, Jingni; Kvitko, Brian H; Kremer, James M; Wang, Yiming; He, Sheng Yang; Tsuda, Kenichi

2018-03-27

Plant pathogens can cause serious diseases that impact global agriculture. The plant innate immunity, when fully activated, can halt pathogen growth in plants. Despite extensive studies into the molecular and genetic bases of plant immunity against pathogens, the influence of plant immunity in global pathogen metabolism to restrict pathogen growth is poorly understood. Here, we developed RNA sequencing pipelines for analyzing bacterial transcriptomes in planta and determined high-resolution transcriptome patterns of the foliar bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana with a total of 27 combinations of plant immunity mutants and bacterial strains. Bacterial transcriptomes were analyzed at 6 h post infection to capture early effects of plant immunity on bacterial processes and to avoid secondary effects caused by different bacterial population densities in planta We identified specific "immune-responsive" bacterial genes and processes, including those that are activated in susceptible plants and suppressed by plant immune activation. Expression patterns of immune-responsive bacterial genes at the early time point were tightly linked to later bacterial growth levels in different host genotypes. Moreover, we found that a bacterial iron acquisition pathway is commonly suppressed by multiple plant immune-signaling pathways. Overexpression of a P. syringae sigma factor gene involved in iron regulation and other processes partially countered bacterial growth restriction during the plant immune response triggered by AvrRpt2. Collectively, this study defines the effects of plant immunity on the transcriptome of a bacterial pathogen and sheds light on the enigmatic mechanisms of bacterial growth inhibition during the plant immune response.

Growth, antioxidant capacity and total carotene of Dunaliella salina DCCBC15 in a low cost enriched natural seawater medium.

PubMed

Tran, Duc; Doan, Nguyen; Louime, Clifford; Giordano, Mario; Portilla, Sixto

2014-01-01

Dunaliella is currently drawing worldwide attention as an alternative source of nutraceuticals. Commercially, β-carotene making up over 10% of Dunaliella biomass is generating the most interest. These compounds, because of their non-toxic properties, have found applications in the food, drug and cosmetic industry. The β-carotene content of Dunaliella cells, however, depends heavily on the growth conditions and especially on the availability of nutrients, salinity, irradiance and temperature in the growth medium. A chemically well defined medium is usually required, which significantly contributes to the cost of pigment production; hence a desire for low cost marine media. The present study aimed at evaluating the suitability of six different media, especially exploiting local potential resources, for the mass production of Dunaliella salina DCCBC15 as functional food and medicine. The efficacy of a new selected low-cost enriched natural seawater medium (MD4), supplemented with industrial N-P-K fertilizer, was investigated with respect to biomass production, chlorophyll, antioxidant capacity, and total carotene by Dunaliella though culture conditions were not optimized yet. This new medium (MD4) appears extremely promising, since it affords a higher production of Dunaliella biomass and pigments compared with the control, a common artificial medium (MD1), while allowing a substantial reduction in the production costs. The medium is also recommended for culturing other marine algae.

R software package based statistical optimization of process components to simultaneously enhance the bacterial growth, laccase production and textile dye decolorization with cytotoxicity study

PubMed Central

Dudhagara, Pravin; Tank, Shantilal

2018-01-01

The thermophilic bacterium, Bacillus licheniformis U1 is used for the optimization of bacterial growth (R1), laccase production (R2) and synthetic disperse blue DBR textile dye decolorization (R3) in the present study. Preliminary optimization has been performed by one variable at time (OVAT) approach using four media components viz., dye concentration, copper sulphate concentration, pH, and inoculum size. Based on OVAT result further statistical optimization of R1, R2 and R3 performed by Box–Behnken design (BBD) using response surface methodology (RSM) in R software with R Commander package. The total 29 experimental runs conducted in the experimental design study towards the construction of a quadratic model. The model indicated that dye concentration 110 ppm, copper sulphate 0.2 mM, pH 7.5 and inoculum size 6% v/v were found to be optimum to maximize the laccase production and bacterial growth. Whereas, maximum dye decolorization achieved in media containing dye concentration 110 ppm, copper sulphate 0.6 mM, pH 6 and inoculum size 6% v/v. R package predicted R2 of R1, R2 and R3 were 0.9917, 0.9831 and 0.9703 respectively; likened to Design-Expert (Stat-Ease) (DOE) predicted R2 of R1, R2, and R3 were 0.9893, 0.9822 and 0.8442 respectively. The values obtained by R software were more precise, reliable and reproducible, compared to the DOE model. The laccase production was 1.80 fold increased, and 2.24 fold enhancement in dye decolorization was achieved using optimized medium than initial experiments. Moreover, the laccase-treated sample demonstrated the less cytotoxic effect on L132 and MCF-7 cell lines compared to untreated sample using MTT assay. Higher cell viability and lower cytotoxicity observed in a laccase-treated sample suggest the impending application of bacterial laccase in the reduction of toxicity of dye to design rapid biodegradation process. PMID:29718934

Mars soil - A sterile regolith or a medium for plant growth?

NASA Technical Reports Server (NTRS)

Banin, Amos

1989-01-01

The mineralogical composition and the physical, chemical and mechanical properties of the Mars soil have been the subject of a number of studies. Though definitive mineralogical measurements are lacking, elemental-chemical analyses and simulation experiments have indicated that clays are major components of the soil and that iron is present as adsorbed ion and as amorphous mineral coating the clay particles (Banin, 1986). Whether this soil can support plant growth or food production, utilizing conventional or advanced cultivational technologies, is a question that has not been thoroughly analyzed, but may be of importance and usefulness for the future exploration of Mars. Assuming that the proposed model of Mars soil components is valid, and drawing additional information from the analyses of the SNC meteorites believed to be ejected Mars rocks - the present contribution analyzes and evaluates the suitability of the soil as a medium for plant growth, attempting to identify the most critical limiting factors for such an undertaking and the possible remedies.

Temperature adaptation of bacterial communities in experimentally warmed forest soils.

PubMed

Rousk, Johannes; Frey, Serita D; Bååth, Erland

2012-10-01

A detailed understanding of the influence of temperature on soil microbial activity is critical to predict future atmospheric CO 2 concentrations and feedbacks to anthropogenic warming. We investigated soils exposed to 3-4 years of continuous 5 °C-warming in a field experiment in a temperate forest. We found that an index for the temperature adaptation of the microbial community, T min for bacterial growth, increased by 0.19 °C per 1 °C rise in temperature, showing a community shift towards one adapted to higher temperature with a higher temperature sensitivity (Q 10(5-15 °C) increased by 0.08 units per 1 °C). Using continuously measured temperature data from the field experiment we modelled in situ bacterial growth. Assuming that warming did not affect resource availability, bacterial growth was modelled to become 60% higher in warmed compared to the control plots, with the effect of temperature adaptation of the community only having a small effect on overall bacterial growth (<5%). However, 3 years of warming decreased bacterial growth, most likely due to substrate depletion because of the initially higher growth in warmed plots. When this was factored in, the result was similar rates of modelled in situ bacterial growth in warmed and control plots after 3 years, despite the temperature difference. We conclude that although temperature adaptation for bacterial growth to higher temperatures was detectable, its influence on annual bacterial growth was minor, and overshadowed by the direct temperature effect on growth rates. © 2012 Blackwell Publishing Ltd.

Targeting of a chlamydial protease impedes intracellular bacterial growth.

PubMed

Christian, Jan G; Heymann, Julia; Paschen, Stefan A; Vier, Juliane; Schauenburg, Linda; Rupp, Jan; Meyer, Thomas F; Häcker, Georg; Heuer, Dagmar

2011-09-01

Chlamydiae are obligate intracellular bacteria that propagate in a cytosolic vacuole. Recent work has shown that growth of Chlamydia induces the fragmentation of the Golgi apparatus (GA) into ministacks, which facilitates the acquisition of host lipids into the growing inclusion. GA fragmentation results from infection-associated cleavage of the integral GA protein, golgin-84. Golgin-84-cleavage, GA fragmentation and growth of Chlamydia trachomatis can be blocked by the peptide inhibitor WEHD-fmk. Here we identify the bacterial protease chlamydial protease-like activity factor (CPAF) as the factor mediating cleavage of golgin-84 and as the target of WEHD-fmk-inhibition. WEHD-fmk blocked cleavage of golgin-84 as well as cleavage of known CPAF targets during infection with C. trachomatis and C. pneumoniae. The same effect was seen when active CPAF was expressed in non-infected cells and in a cell-free system. Ectopic expression of active CPAF in non-infected cells was sufficient for GA fragmentation. GA fragmentation required the small GTPases Rab6 and Rab11 downstream of CPAF-activity. These results define CPAF as the first protein that is essential for replication of Chlamydia. We suggest that this role makes CPAF a potential anti-infective therapeutic target.

Production of plant growth modulating volatiles is widespread among rhizosphere bacteria and strongly depends on culture conditions.

PubMed

Blom, D; Fabbri, C; Connor, E C; Schiestl, F P; Klauser, D R; Boller, T; Eberl, L; Weisskopf, L

2011-11-01

Recent studies have suggested that bacterial volatiles play an important role in bacterial-plant interactions. However, few reports of bacterial species that produce plant growth modulating volatiles have been published, raising the question whether this is just an anecdotal phenomenon. To address this question, we performed a large screen of strains originating from the soil for volatile-mediated effects on Arabidopsis thaliana. All of the 42 strains tested showed significant volatile-mediated plant growth modulation, with effects ranging from plant death to a sixfold increase in plant biomass. The effects of bacterial volatiles were highly dependent on the cultivation medium and the inoculum quantity. GC-MS analysis of the tested strains revealed over 130 bacterial volatile compounds. Indole, 1-hexanol and pentadecane were selected for further studies because they appeared to promote plant growth. None of these compounds triggered a typical defence response, using production of ethylene and of reactive oxygen species (ROS) as read-outs. However, when plants were challenged with the flg-22 epitope of bacterial flagellin, a prototypical elicitor of defence responses, additional exposure to the volatiles reduced the flg-22-induced production of ethylene and ROS in a dose-dependent manner, suggesting that bacterial volatiles may act as effectors to inhibit the plant's defence response. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

Human neuroblastoma growth inhibitory factor (h-NGIF), derived from human astrocytoma conditioned medium, has neurotrophic properties.

PubMed

Eksioglu, Y Z; Iida, J; Asai, K; Ueki, T; Nakanishi, K; Isobe, I; Yamagata, K; Kato, T

1994-05-02

Investigations on the general characteristics of human astrocytoma cell line NAC-1 revealed neuroblastoma growth inhibitory activity in conditioned medium. Neuroblastoma growth inhibitory factor (NGIF) was partially purified by Econo Q, Econo CM, and Superose 12 column chromatography. The protein is weakly basic with an estimated M(r) of 120,000, possibly having an M(r) 60,000 dimeric structure. NGIF inhibits the growth of human neuroblastoma cell lines but has no effect on morphology nor does it produce any change in the growth of human glioblastoma cell lines. Interestingly, NGIF appears to promote survival and neurite outgrowth of embryonal rat cortical neurons. These neurotrophic properties suggest a role for NGIF in the development of the nervous system.

Macroalgal-bacterial interactions: Role of dimethylsulfoniopropionate in microbial gardening by Ulva (Chlorophyta).

PubMed

Kessler, Ralf W; Weiss, Anne; Kuegler, Stefan; Hermes, Cornelia; Wichard, Thomas

2018-04-01

The marine macroalga Ulva mutabilis (Chlorophyta) develops into callus-like colonies consisting of undifferentiated cells and abnormal cell walls under axenic conditions. Ulva mutabilis is routinely cultured with two bacteria, the Roseovarius sp. MS2 strain and the Maribacter sp. MS6 strain, which release morphogenetic compounds and ensure proper algal morphogenesis. Using this tripartite community as an emerging model system, we tested the hypothesis that the bacterial-algal interactions evolved as a result of mutually taking advantage of signals in the environment. Our study aimed to determine whether cross-kingdom crosstalk is mediated by the attraction of bacteria through algal chemotactic signals. Roseovarius sp. MS2 senses the known osmolyte dimethylsulfoniopropionate (DMSP) released by Ulva into the growth medium. Roseovarius sp. is attracted by DMSP and takes it up rapidly such that DMSP can only be determined in axenic growth media. As DMSP did not promote bacterial growth under the tested conditions, Roseovarius benefited solely from glycerol as the carbon source provided by Ulva. Roseovarius quickly catabolized DMSP into methanethiol (MeSH) and dimethylsulphide (DMS). We conclude that many bacteria can use DMSP as a reliable signal indicating a food source and promote the subsequent development and morphogenesis in Ulva. © 2017 John Wiley & Sons Ltd.

Effect of tungsten concentration on growth of acetobacter xylinum as a promising agent for eco-friendly recycling system

NASA Astrophysics Data System (ADS)

Nandiyanto, A. B. D.; Halimatul, H. S.; Rosyid, N. H.; Effendi, D. B.

2016-04-01

Effect of tungsten (W) concentration on Acetobacter xylinum growth was studied. In the experimental procedure, concentration of W in the bacterial growth medium containing pineapple peels waste was varied from 0.5 to 50 ppm. To confirm the influence of W, the bacterial incubation process was carried out for 72 hours. Spectrophotometer analysis showed that the growth rate of Acetobacter xylinum decreased with increasing concentration of W. The result from fourier transform infra red analysis showed a slightly change on the absorption peak intensities and informing the interaction of W ion and bacteria cell. The result confirmed that Acetobacter xylinum was able to uptake W concentration up to 15 ppm, indicating that Acetobacter xylinum might act as a promising agent for eco-friendly recycling system.

Growth and heavy metal removal by Klebsiella aerogenes at different pH and temperature

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

Al-Shahwani, M.F.; Jazrawi, S.F.; Al-Rawi, E.H.

1984-01-01

A strain of Klebsiella aerogenes isolated from Rustamiyah Station for treatment of wastewater was examined for its ability to grow in a media supplemented with maximum tolerance concentrations of Pb/sup + +/, Zn/sup + +/, Ni/sup + +/, and Cd/sup + +/, separately, at different temperatures and initial pH. The results indicated that at 28/sup 0/C during the first 24 hr, Pb/sup + +/ and Ni/sup + +/ had no effect on the growth of the bacteria, while the presence of Zn/sup + +/ and Cd/sup + +/ decreased the cell count. The growth reached a maximum level after themore » second day and started to decrease gradually. The bacterial count at 37/sup 0/C was less than that at 28/sup 0/C. No bacterial multiplication occurred at 44/sup 0/C. There was little difference between heavy metal removal at 28 and 37/sup 0/C. At 44/sup 0/C, little removal took place. In general, slightly acidic or neutral medium was better for both bacterial growth and metal removal.« less

Heterologous Expression of Secreted Bacterial BPP and HAP Phytases in Plants Stimulates Arabidopsis thaliana Growth on Phytate.

PubMed

Valeeva, Lia R; Nyamsuren, Chuluuntsetseg; Sharipova, Margarita R; Shakirov, Eugene V

2018-01-01

Phytases are specialized phosphatases capable of releasing inorganic phosphate from myo -inositol hexakisphosphate (phytate), which is highly abundant in many soils. As inorganic phosphorus reserves decrease over time in many agricultural soils, genetic manipulation of plants to enable secretion of potent phytases into the rhizosphere has been proposed as a promising approach to improve plant phosphorus nutrition. Several families of biotechnologically important phytases have been discovered and characterized, but little data are available on which phytase families can offer the most benefits toward improving plant phosphorus intake. We have developed transgenic Arabidopsis thaliana plants expressing bacterial phytases PaPhyC (HAP family of phytases) and 168phyA (BPP family) under the control of root-specific inducible promoter Pht1;2 . The effects of each phytase expression on growth, morphology and inorganic phosphorus accumulation in plants grown on phytate hydroponically or in perlite as the only source of phosphorus were investigated. The most enzymatic activity for both phytases was detected in cell wall-bound fractions of roots, indicating that these enzymes were efficiently secreted. Expression of both bacterial phytases in roots improved plant growth on phytate and resulted in larger rosette leaf area and diameter, higher phosphorus content and increased shoot dry weight, implying that these plants were indeed capable of utilizing phytate as the source of phosphorus for growth and development. When grown on phytate the HAP-type phytase outperformed its BPP-type counterpart for plant biomass production, though this effect was only observed in hydroponic conditions and not in perlite. Furthermore, we found no evidence of adverse side effects of microbial phytase expression in A. thaliana on plant physiology and seed germination. Our data highlight important functional differences between these members of bacterial phytase families and indicate that future

Heterologous Expression of Secreted Bacterial BPP and HAP Phytases in Plants Stimulates Arabidopsis thaliana Growth on Phytate

PubMed Central

Valeeva, Lia R.; Nyamsuren, Chuluuntsetseg; Sharipova, Margarita R.; Shakirov, Eugene V.

2018-01-01

Phytases are specialized phosphatases capable of releasing inorganic phosphate from myo-inositol hexakisphosphate (phytate), which is highly abundant in many soils. As inorganic phosphorus reserves decrease over time in many agricultural soils, genetic manipulation of plants to enable secretion of potent phytases into the rhizosphere has been proposed as a promising approach to improve plant phosphorus nutrition. Several families of biotechnologically important phytases have been discovered and characterized, but little data are available on which phytase families can offer the most benefits toward improving plant phosphorus intake. We have developed transgenic Arabidopsis thaliana plants expressing bacterial phytases PaPhyC (HAP family of phytases) and 168phyA (BPP family) under the control of root-specific inducible promoter Pht1;2. The effects of each phytase expression on growth, morphology and inorganic phosphorus accumulation in plants grown on phytate hydroponically or in perlite as the only source of phosphorus were investigated. The most enzymatic activity for both phytases was detected in cell wall-bound fractions of roots, indicating that these enzymes were efficiently secreted. Expression of both bacterial phytases in roots improved plant growth on phytate and resulted in larger rosette leaf area and diameter, higher phosphorus content and increased shoot dry weight, implying that these plants were indeed capable of utilizing phytate as the source of phosphorus for growth and development. When grown on phytate the HAP-type phytase outperformed its BPP-type counterpart for plant biomass production, though this effect was only observed in hydroponic conditions and not in perlite. Furthermore, we found no evidence of adverse side effects of microbial phytase expression in A. thaliana on plant physiology and seed germination. Our data highlight important functional differences between these members of bacterial phytase families and indicate that future crop

Phytodegradation of organophosphorus compounds by transgenic plants expressing a bacterial organophosphorus hydrolase.

PubMed

Wang, Xiaoxue; Wu, Ningfeng; Guo, Jun; Chu, Xiaoyu; Tian, Jian; Yao, Bin; Fan, Yunliu

2008-01-18

Organophosphorus (OP) compounds are widely used as pesticides in agriculture but cause broad-area environmental pollution. In this work, we have expressed a bacterial organophosphorus hydrolase (OPH) gene in tobacco plants. An assay of enzyme activity showed that transgenic plants could secrete OPH into the growth medium. The transgenic plants were resistant to methyl parathion (Mep), an OP pesticide, as evidenced by a toxicity test showing that the transgenic plants produced greater shoot and root biomass than did the wild-type plants. Furthermore, at 0.02% (v/v) Mep, the transgenic plants degraded more than 99% of Mep after 14 days of growth. Our work indicates that transgenic plants expressing an OPH gene may provide a new strategy for decontaminating OP pollutants.

Laboratory Comparison of the Anti-Bacterial Effects of Spearmint Extract and Hypochlorite Sodium on Enterococcus Faecalis Bacteria.

PubMed

S, Hajimaghsoodi; H, Zandi; M, Bahrami; R, Hakimian

2016-12-01

It is necessary to use irrigation solutions during cleaning and shaping of root canals to efficiently reduce the number of micro organisms. Sodium hypochlorite is used as an effective antibacterial endodontic irrigants. However, the extract of pennyroyal plant has also shown anti-bacterial characteristics comparable with antibacterial drugs. To compare the anti-bacterial effect of spearmint extract on Enterococcus faecalis bacteria with that of sodium hypochlorite 5.25%. In this experimental study, Muller Hinton medium, including 5% sheep blood was prepared. The two solutions used including sodium hypochlorite 5.25% and spearmint extracts were put adjacent to Enterococcus faecalis bacteria after preparing. Two groups, each containing 10 samples, with the total of 20 samples were used. The disks, including each solution were placed 2 cm apart on a plate containing Muller Hinton medium and the bacteria. The plate was subsequently incubated at 37°C for 48 hours. After incubation, the mean diameter of the halo around each disk, which represents the lack of bacterial growth, was measured and compared using a ruler. Penicillin disk was used for positive control and a sterile blank disk containing physiologic serum was utilized as the negative control. This process was repeated 10 times for each solution. Data were analyzed in SPSS 17 statistical software using t -test. The results showed that the mean diameter of halo in the spearmint extract group was zero and in the sodium hypochlorite group it was 23.7 ± 1.49 mm. There was a significant difference between the mean diameter of the lack of growth halo of the spearmint extract and that of hypochlorite sodium 5.25% on Enterococcus faecalis bacteria ( p ≤ 0.001). Considering the limitations of an experimental study, it seems that spearmint extract does not have any anti-bacterial effect against Enterococcus faecalis bacteria, in contrast to hypochlorite sodium 5.25%.

Preparation, Imaging, and Quantification of Bacterial Surface Motility Assays

PubMed Central

Morales-Soto, Nydia; Anyan, Morgen E.; Mattingly, Anne E.; Madukoma, Chinedu S.; Harvey, Cameron W.; Alber, Mark; Déziel, Eric; Kearns, Daniel B.; Shrout, Joshua D.

2015-01-01

Bacterial surface motility, such as swarming, is commonly examined in the laboratory using plate assays that necessitate specific concentrations of agar and sometimes inclusion of specific nutrients in the growth medium. The preparation of such explicit media and surface growth conditions serves to provide the favorable conditions that allow not just bacterial growth but coordinated motility of bacteria over these surfaces within thin liquid films. Reproducibility of swarm plate and other surface motility plate assays can be a major challenge. Especially for more “temperate swarmers” that exhibit motility only within agar ranges of 0.4%-0.8% (wt/vol), minor changes in protocol or laboratory environment can greatly influence swarm assay results. “Wettability”, or water content at the liquid-solid-air interface of these plate assays, is often a key variable to be controlled. An additional challenge in assessing swarming is how to quantify observed differences between any two (or more) experiments. Here we detail a versatile two-phase protocol to prepare and image swarm assays. We include guidelines to circumvent the challenges commonly associated with swarm assay media preparation and quantification of data from these assays. We specifically demonstrate our method using bacteria that express fluorescent or bioluminescent genetic reporters like green fluorescent protein (GFP), luciferase (lux operon), or cellular stains to enable time-lapse optical imaging. We further demonstrate the ability of our method to track competing swarming species in the same experiment. PMID:25938934

Isolation of a lead tolerant novel bacterial species, Achromobacter sp. TL-3: assessment of bioflocculant activity.

PubMed

Batta, Neha; Subudhi, Sanjukta; Lal, Banwari; Devi, Arundhuti

2013-11-01

Lead is one of the four heavy metals that has a profound damaging effects on human health. In the recent past there has been an increasing global concern for development of sustainable bioremediation technologies for detoxification of lead contaminant. Present investigation highlights for lead biosorption by a newly isolated novel bacterial species; Achromobacter sp. TL-3 strain, isolated from activated sludge samples contaminated with heavy metals (collected from oil refinery, Assam, North-East India). For isolation of lead tolerant bacteria, sludge samples were enriched into Luria Broth medium supplemented separately with a range of lead nitrate; 250, 500, 750, 1000, 1250 and 1500 ppm respectively. The bacterial consortium that could tolerate 1500 ppm of lead nitrate was selected further for purification of lead tolerant bacterial isolates. Purified lead tolerant bacterial isolates were then eventually inoculated into production medium supplemented with ethanol and glycerol as carbon and energy source to investigate for bioflocculant production. Bioflocculant production was estimated by monitoring the potential of lead tolerant bacterial isolate to flocculate Kaolin clay in presence of 1% CaCl2. Compared to other isolates, TL-3 isolate demonstrated for maximum bioflocculant activity of 95% and thus was identified based on 16S rRNA gene sequence analysis. TL3 isolate revealed maximum homology (98%) with Achromobacter sp. and thus designated as Achromobacter sp. TL-3. Bioflocculant activity of TL-3 isolate was correlated with the change in pH and growth. Achromobacter sp. TL-3 has significant potential for lead biosorption and can be effectively employed for detoxification of lead contaminated waste effluents/waste waters.

Bacterially mediated mineralization of vaterite

NASA Astrophysics Data System (ADS)

Rodriguez-Navarro, Carlos; Jimenez-Lopez, Concepcion; Rodriguez-Navarro, Alejandro; Gonzalez-Muñoz, Maria Teresa; Rodriguez-Gallego, Manuel

2007-03-01

Myxococcus xanthus, a common soil bacterium, plays an active role in the formation of spheroidal vaterite. Bacterial production of CO 2 and NH 3 and the transformation of the NH 3 to NH4+ and OH -, thus increasing solution pH and carbonate alkalinity, set the physicochemical conditions (high supersaturation) leading to vaterite precipitation in the microenvironment around cells, and directly onto the surface of bacterial cells. In the latter case, fossilization of bacteria occurs. Vaterite crystals formed by aggregation of oriented nanocrystals with c-axis normal to the bacterial cell-wall, or to the core of the spherulite when bacteria were not encapsulated. While preferred orientation of vaterite c-axis appears to be determined by electrostatic affinity (ionotropic effect) between vaterite crystal (0001) planes and the negatively charged functional groups of organic molecules on the bacterium cell-wall or on extracellular polymeric substances (EPS), analysis of the changes in the culture medium chemistry as well as high resolution transmission electron microscopy (HRTEM) observations point to polymorph selection by physicochemical (kinetic) factors (high supersaturation) and stabilization by organics, both connected with bacterial activity. The latter is in agreement with inorganic precipitation of vaterite induced by NH 3 and CO 2 addition in the protein-rich sterile culture medium. Our results as well as recent studies on vaterite precipitation in the presence of different types of bacteria suggest that bacterially mediated vaterite precipitation is not strain-specific, and could be more common than previously thought.

Reflected scatterometry for noninvasive interrogation of bacterial colonies

NASA Astrophysics Data System (ADS)

Kim, Huisung; Doh, Iyll-Joon; Sturgis, Jennifer; Bhunia, Arun K.; Robinson, J. Paul; Bae, Euiwon

2016-10-01

A phenotyping of bacterial colonies on agar plates using forward-scattering diffraction-pattern analysis provided promising classification of several different bacteria such as Salmonella, Vibrio, Listeria, and E. coli. Since the technique is based on forward-scattering phenomena, light transmittance of both the colony and the medium is critical to ensure quality data. However, numerous microorganisms and their growth media allow only limited light penetration and render the forward-scattering measurement a challenging task. For example, yeast, Lactobacillus, mold, and several soil bacteria form colorful and dense colonies that obstruct most of the incoming light passing through them. Moreover, blood agar, which is widely utilized in the clinical field, completely blocks the incident coherent light source used in forward scatterometry. We present a newly designed reflection scatterometer and validation of the resolving power of the instrument. The reflectance-type instrument can acquire backward elastic scatter patterns for both highly opaque media and colonies and has been tested with three different bacterial genera grown on blood agar plates. Cross-validation results show a classification rate above 90% for four genera.

Role of water-soluble polysaccharides in bacterial cellulose production.

PubMed

Ishida, Takehiko; Mitarai, Makoto; Sugano, Yasushi; Shoda, Makoto

2003-08-20

Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC) and a water-soluble polysaccharide called acetan in corn steep liquor-fructose medium. Acetobacter xylinum EP1, which is incapable of acetan production was derived by disrupting the aceA gene of BPR2001. The BC production by EP1 (2.88 g/L) was lower than that by BPR2001 (4.6 g/L) in baffled-flask culture. When purified acetan or agar was added to the medium from the start of cultivation, the BC production by EP1 was enhanced and the final BC yield of EP1 was almost the same as that of BPR2001. A similar improvement of BC production by EP1 by the addition of agar was also confirmed by cultivation in a 50-L airlift reactor. From these results, the role of acetan in BC production is associated with the increase in the viscosity of the culture medium which may hinder coagulation of BC and cells in the culture, thereby accelerating the growth of BPR2001 and BC production by BPR2001. Copyright 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 474-478, 2003.

Features of the Functioning Bacterial Ecosystems in the Antarctic

NASA Astrophysics Data System (ADS)

Yakushev, A. V.; Churilin, N.; Soina, V. S.; Vorobyova, E. A.; Mergelov, N. S.

2014-10-01

Studies of bacterial communities in the samples of Antarctic soils by different methods showed that, both in liquid soil suspensions and in situ, microbial complexes are functioning presumably by forming biofilms -- the phenomenon that is more expressed in such habitat than in soils of temperate zones. Functional (trophic) diversity and physiological state of hydrolytic bacteria was studied in the samples at the upper layer (0-2 cm) of gravel pavement with algae, in the underlying peat horizon (2-4 cm) with inclusions of dead biomass and its underlying mineral horizon (4-10 cm) with signs of fungal mycelium. The investigated samples of Antarctic soils revealed different trophic diversity and the maximum specific growth rate on mineral medium with different biopolymers as the sole carbon source (starch, chitin, pectin, xylan, dextran-500, tween-20, casein); this can testify to differences in the physiological state of hydrolytic bacteria in various soil horizons and their readiness for growth. The most remarkable characteristics of the studied Antarctic soil as compared to the soils of temperate zone, was the unusual ability of hydrolytic community to consume chitin in the mineral horizon; this can be explained by the presence of fungal mycelium. Also, an almost complete lack in consumption of tween-20 (a water-soluble analogue of fat) by bacterial community of Arctic soil horizons are not explained and needs further verification. The higher functional diversity was detected in the upper horizon of the gravel pavement, which "protects" microorganisms from exposure to extreme temperatures, UV radiation, and desiccation, but the maximum specific growth rate was higher in the lower mineral horizon; this can be explained by the specificity of bacterial colonizing processes and unique formation of Antarctic soil microprofiles in the Larsemann oasis. The obtained data indicate a specific environmental strategy in the samples of Antarctic soils: development in lower

Bacterial Growth Kinetics under a Novel Flexible Methacrylate Dressing Serving as a Drug Delivery Vehicle for Antiseptics

PubMed Central

Forstner, Christina; Leitgeb, Johannes; Schuster, Rupert; Dosch, Verena; Kramer, Axel; Cutting, Keith F.; Leaper, David J.; Assadian, Ojan

2013-01-01

A flexible methacrylate powder dressing (Altrazeal®) transforms into a wound contour conforming matrix once in contact with wound exudate. We hypothesised that it may also serve as a drug delivery vehicle for antiseptics. The antimicrobial efficacy and influence on bacterial growth kinetics in combination with three antiseptics was investigated in an in vitro porcine wound model. Standardized in vitro wounds were contaminated with Staphylococcus aureus (MRSA; ATCC 33591) and divided into six groups: no dressing (negative control), methacrylate dressing alone, and combinations with application of 0.02% Polyhexamethylene Biguanide (PHMB), 0.4% PHMB, 0.1% PHMB + 0.1% betaine, 7.7 mg/mL Povidone-iodine (PVP-iodine), and 0.1% Octenidine-dihydrochloride (OCT) + 2% phenoxyethanol. Bacterial load per gram tissue was measured over five days. The highest reduction was observed with PVP-iodine at 24 h to log10 1.43 cfu/g, followed by OCT at 48 h to log10 2.41 cfu/g. Whilst 0.02% PHMB resulted in a stable bacterial load over 120 h to log10 4.00 cfu/g over 120 h, 0.1% PHMB + 0.1% betaine inhibited growth during the first 48 h, with slightly increasing bacterial numbers up to log10 5.38 cfu/g at 120 h. These results indicate that this flexible methacrylate dressing can be loaded with various antiseptics serving as drug delivery system. Depending on the selected combination, an individually shaped and controlled antibacterial effect may be achieved using the same type of wound dressing. PMID:23698780

Fully Dedifferentiated Chondrocytes Expanded in Specific Mesenchymal Stem Cell Growth Medium with FGF2 Obtains Mesenchymal Stem Cell Phenotype In Vitro but Retains Chondrocyte Phenotype In Vivo

PubMed Central

Lee, Jungsun; Lee, Jin-Yeon; Chae, Byung-Chul; Jang, Jeongho

2017-01-01

Given recent progress in regenerative medicine, we need a means to expand chondrocytes in quantity without losing their regenerative capability. Although many reports have shown that growth factor supplementation can have beneficial effects, the use of growth factor–supplemented basal media has widespread effect on the characteristics of chondrocytes. Chondrocytes were in vitro cultured in the 2 most widely used chondrocyte growth media, conventional chondrocyte culture medium and mesenchymal stem cell (MSC) culture medium, both with and without fibroblast growth factor-2 (FGF2) supplementation. Their expansion rates, expressions of extracellular matrix–related factors, senescence, and differentiation potentials were examined in vitro and in vivo. Our results revealed that chondrocytes quickly dedifferentiated during expansion in all tested media, as assessed by the loss of type II collagen expression. The 2 basal media (chondrocyte culture medium vs. MSC culture medium) were associated with distinct differences in cell senescence. Consistent with the literature, FGF2 was associated with accelerated dedifferentiation during expansion culture and superior redifferentiation upon induction. However, chondrocytes expanded in FGF2-containing conventional chondrocyte culture medium showed MSC-like features, as indicated by their ability to direct ectopic bone formation and cartilage formation. In contrast, chondrocytes cultured in FGF2-supplemented MSC culture medium showed potent chondrogenesis and almost no bone formation. The present findings show that the chosen basal medium can exert profound effects on the characteristics and activity of in vitro–expanded chondrocytes and indicate that right growth factor/medium combination can help chondrocytes retain a high-level chondrogenic potential without undergoing hypertrophic transition. PMID:29251111

Application of a microcomputer-based system to control and monitor bacterial growth.

PubMed

Titus, J A; Luli, G W; Dekleva, M L; Strohl, W R

1984-02-01

A modular microcomputer-based system was developed to control and monitor various modes of bacterial growth. The control system was composed of an Apple II Plus microcomputer with 64-kilobyte random-access memory; a Cyborg ISAAC model 91A multichannel analog-to-digital and digital-to-analog converter; paired MRR-1 pH, pO(2), and foam control units; and in-house-designed relay, servo control, and turbidimetry systems. To demonstrate the flexibility of the system, we grew bacteria under various computer-controlled and monitored modes of growth, including batch, turbidostat, and chemostat systems. The Apple-ISAAC system was programmed in Labsoft BASIC (extended Applesoft) with an average control program using ca. 6 to 8 kilobytes of memory and up to 30 kilobytes for datum arrays. This modular microcomputer-based control system was easily coupled to laboratory scale fermentors for a variety of fermentations.

Application of a Microcomputer-Based System to Control and Monitor Bacterial Growth

PubMed Central

Titus, Jeffrey A.; Luli, Gregory W.; Dekleva, Michael L.; Strohl, William R.

1984-01-01

A modular microcomputer-based system was developed to control and monitor various modes of bacterial growth. The control system was composed of an Apple II Plus microcomputer with 64-kilobyte random-access memory; a Cyborg ISAAC model 91A multichannel analog-to-digital and digital-to-analog converter; paired MRR-1 pH, pO2, and foam control units; and in-house-designed relay, servo control, and turbidimetry systems. To demonstrate the flexibility of the system, we grew bacteria under various computer-controlled and monitored modes of growth, including batch, turbidostat, and chemostat systems. The Apple-ISAAC system was programmed in Labsoft BASIC (extended Applesoft) with an average control program using ca. 6 to 8 kilobytes of memory and up to 30 kilobytes for datum arrays. This modular microcomputer-based control system was easily coupled to laboratory scale fermentors for a variety of fermentations. PMID:16346462

[Characteristics of growth and changes in the ultrafine structure of bacteria in the course of continuous cultivation on media containing ethanol].

PubMed

Kvasnikov, E I; Gavrilenko, M N; Sumnevich, V G; Stepaniuk, V V; Eluseeva, G S; Stognii, I P

1977-01-01

A large number of bacterial strains assimilating chemical ethanol has been isolated using an original technique. Active growth of strains belonging to the genera Pseudomonas and, particularly, Acinetobacter was registered on mineral media containing ethanol. A mathematical model was constructed select a strain of Acinetobacter calcoaceticus K-9 during its continuous cultivation on media containing ethanol. The model makes it possible to determine conditions for producing a present amount of the biomass, the percentage of its yield, and the produc;iveness as a function of the dilution rate, temperature, and the concentration of ethanol and phosphoric acid in the medium. The main characteristics of the growth process in the studied factor space were established. The optimum conditions were calculated for growth of the strain with respect to each of the criteria. Under various conditions of bacterial growth, changes in the morphology and ultra-fine structure of the cells correlated with their physiological activity. The volume of the cells increased with the rate of dilution of the medium: the process can be described by a saturation curve. The presence of mesosomal structures is typical of the cells growing at low flow rates.

Sweet scents from good bacteria: Case studies on bacterial volatile compounds for plant growth and immunity.

PubMed

Chung, Joon-hui; Song, Geun Cheol; Ryu, Choong-Min

2016-04-01

Beneficial bacteria produce diverse chemical compounds that affect the behavior of other organisms including plants. Bacterial volatile compounds (BVCs) contribute to triggering plant immunity and promoting plant growth. Previous studies investigated changes in plant physiology caused by in vitro application of the identified volatile compounds or the BVC-emitting bacteria. This review collates new information on BVC-mediated plant-bacteria airborne interactions, addresses unresolved questions about the biological relevance of BVCs, and summarizes data on recently identified BVCs that improve plant growth or protection. Recent explorations of bacterial metabolic engineering to alter BVC production using heterologous or endogenous genes are introduced. Molecular genetic approaches can expand the BVC repertoire of beneficial bacteria to target additional beneficial effects, or simply boost the production level of naturally occurring BVCs. The effects of direct BVC application in soil are reviewed and evaluated for potential large-scale field and agricultural applications. Our review of recent BVC data indicates that BVCs have great potential to serve as effective biostimulants and bioprotectants even under open-field conditions.

Growth performance and carcase quality in broiler chickens fed on bacterial protein grown on natural gas.

PubMed

Øverland, M; Schøyen, H F; Skrede, A

2010-10-01

1. The effects of increasing concentrations (0, 40, 80 or 120 g/kg) of bacterial protein meal (BPM) and bacterial protein autolysate (BPA) grown on natural gas on growth performance and carcase quality in broiler chickens were examined. 2. Adding BPM to diets reduced feed intake and improved gain: feed from 0 to 21 d and overall to 35 d, but did not significantly affect weight gain compared to the soybean meal based control diet. 3. Increasing concentrations of BPA significantly reduced growth rate, feed intake, gain: feed, carcase weight and dressing percentage, but significantly increased carcase dry matter, fat and energy content. 4. Adding BPM to diets had no effect on viscosity of diets and jejunal digesta, and minor effects on litter quality, whereas BPA increased the viscosity of diets and jejunal digesta, improved litter quality at 21 d, but decreased litter quality at 32 d. 5. To conclude, broiler chickens performed better on a BPM product with intact proteins than on an autolysate with ruptured cell walls and a high content of free amino acids and low molecular-weight peptides.

Growth medium and incubation temperature alter the Pseudogymnoascus destructans transcriptome: implications in identifying virulence factors.

PubMed

Donaldson, Michael E; Davy, Christina M; Vanderwolf, Karen J; Willis, Craig K R; Saville, Barry J; Kyle, Christopher J

2018-02-23

Pseudogymnoascus destructans is the causal agent of bat white-nose syndrome (WNS), which is devastating some North American bat populations. Previous transcriptome studies provided insight regarding the molecular mechanisms involved in WNS; however, it is unclear how different environmental parameters could influence pathogenicity. This information could be useful in developing management strategies to mitigate the negative impacts of P. destructans on bats. We cultured three P. destructans isolates from Atlantic Canada on two growth media (potato dextrose agar and Sabouraud dextrose agar) that differ in their nitrogen source, and at two separate incubation temperatures (4 C and 15 C) that approximate the temperature range of bat hibernacula during the winter and a temperature within its optimal mycelial growth range. We conducted RNA sequencing to determine transcript levels in each sample and performed differential gene expression (DGE) analyses to test the influence of growth medium and incubation temperature on gene expression. We also compared our in vitro results with previous RNA-sequencing data sets generated from P. destructans growing on the wings of a susceptible host, Myotis lucifugus. Our findings point to a critical role for substrate and incubation temperature in influencing the P. destructans transcriptome. DGE analyses suggested that growth medium plays a larger role than temperature in determining P. destructans gene expression and that although the psychrophilic fungus responds to different nitrogen sources, it may have evolved for continued growth at a broad range of low temperatures. Further, our data suggest that down-regulation of the RNA-interference pathway and increased fatty acid metabolism are involved in the P. destructans-bat interaction. Finally, we speculate that to reduce the activation of host defense responses, P. destructans minimizes changes in the expression of genes encoding secreted proteins during bat colonization.

Effect of volatile metabolites of dill, radish and garlic on growth of bacteria

NASA Astrophysics Data System (ADS)

Tirranen, L. S.; Borodina, E. V.; Ushakova, S. A.; Rygalov, V. Ye; Gitelson, J. I.

2001-07-01

In a model experiment plants were grown in sealed chambers on expanded clay aggregate under the luminance of 150 W/m 2 PAR and the temperature of 24°C. Seven bacterial strains under investigation, replicated on nutrient medium surface in Petri dishes, were grown in the atmosphere of cultivated plants. Microbial response was evaluated by the difference between colony size in experiment and in control. In control, bacteria grew in the atmosphere of clean air. To study the effect of volatile metabolites of various plant on microbial growth, the experimental data were compared with the background values defined for each individual experiment. Expanded clay aggregate, luminance, temperature and sealed chamber (without plants) for the background were the same. Volatile metabolites from 28-days old radish plants have been reliably established to have no effect on the growth of microbes under investigation. Metabolites of 30-days old dill and 50-days old garlic have been established to have reliable bacteriostatic effect on the growth of three bacterial strains. Dill and garlic have been found to have different range of effects of volatile substances on bacterial growth. Volatile metabolites of dill and garlic differed in their effect on the sensitivity spectrum of bacteria. An attempt has been made to describe the obtained data mathematically.

Effects of Interactions of Auxin-Producing Bacteria and Bacterial-Feeding Nematodes on Regulation of Peanut Growths

PubMed Central

Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

2015-01-01

The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil. PMID:25867954

Effects of interactions of auxin-producing bacteria and bacterial-feeding nematodes on regulation of peanut growths.

PubMed

Xu, Li; Xu, Wensi; Jiang, Ying; Hu, Feng; Li, Huixin

2015-01-01

The influences of an IAA (indole-3-acetic acid)-producing bacterium (Bacillus megaterium) and two bacterial-feeding nematodes (Cephalobus sp. or Mesorhabditis sp.) on the growth of peanut (Arachis hypogaea L. cv. Haihua 1) after various durations of time were investigated in natural soils. The addition of bacteria and nematodes and incubation time all significantly affected plant growth, plant root growth, plant nutrient concentrations, soil nutrient concentrations, soil microorganisms and soil auxin concentration. The addition of nematodes caused greater increases in these indices than those of bacteria, while the addition of the combination of bacteria and nematodes caused further increases. After 42-day growth, the increases in soil respiration differed between the additions of two kinds of nematodes because of differences in their life strategies. The effects of the bacteria and nematodes on the nutrient and hormone concentrations were responsible for the increases in plant growth. These results indicate the potential for promoting plant growth via the addition of nematodes and bacteria to soil.

Long-term nitrogen fertilization decreases bacterial diversity and favors the growth of Actinobacteria and Proteobacteria in agro-ecosystems across the globe

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

Dai, Zhongmin; Su, Weiqin; Chen, Huaihai

Long-term Elevated nitrogen (N) input from anthropogenic sources may cause soil acidification and decrease crop yield, yet the response of the belowground microbial community to long-term N input and the input of N combined with phosphorus (P) and potassium (K) is still poorly understood. Here, we explored the effect of long-term N and NPK fertilization on soil bacterial diversity and community composition using meta-analysis of a global dataset. Nitrogen fertilization decreased soil pH, and increased soil organic carbon (C) and available N contents. Bacterial taxonomic diversity was decreased by N fertilization alone, but was increased by NPK fertilization. The effectmore » of N fertilization on bacterial diversity depends on soil texture and water management, but independent of crop type or N application rate. Both soil pH and organic C content were positively related to changes in bacterial diversity under N fertilization, while soil organic C was the dominant factor determining changes in bacterial diversity under NPK fertilization. Microbial biomass C decreased with decreasing bacterial diversity under long-term N fertilization. Nitrogen fertilization increased the relative abundance of copiotrophic bacteria (i.e. Proteobacteria and Actinobacteria), but reduced the abundance of oligotrophic taxa (i.e. Acidobacteria), consistent with the general life history strategy theory for bacteria. The relative abundance of Proteobacteria was also increased by NPK fertilization. The positive correlation between N application rate and the relative abundance of Actinobacteria indicates that increased N availability favored the growth of Actinobacteria. This first global analysis of long-term N and NPK fertilization effect on bacterial diversity and community composition suggests that N input decreases bacterial diversity but favors the growth of copiotrophic bacteria, providing a reference for nutrient management strategies for maintaining belowground microbial diversity

Long-term nitrogen fertilization decreases bacterial diversity and favors the growth of Actinobacteria and Proteobacteria in agro-ecosystems across the globe

DOE PAGES

Dai, Zhongmin; Su, Weiqin; Chen, Huaihai; ...

2018-04-25

Long-term Elevated nitrogen (N) input from anthropogenic sources may cause soil acidification and decrease crop yield, yet the response of the belowground microbial community to long-term N input and the input of N combined with phosphorus (P) and potassium (K) is still poorly understood. Here, we explored the effect of long-term N and NPK fertilization on soil bacterial diversity and community composition using meta-analysis of a global dataset. Nitrogen fertilization decreased soil pH, and increased soil organic carbon (C) and available N contents. Bacterial taxonomic diversity was decreased by N fertilization alone, but was increased by NPK fertilization. The effectmore » of N fertilization on bacterial diversity depends on soil texture and water management, but independent of crop type or N application rate. Both soil pH and organic C content were positively related to changes in bacterial diversity under N fertilization, while soil organic C was the dominant factor determining changes in bacterial diversity under NPK fertilization. Microbial biomass C decreased with decreasing bacterial diversity under long-term N fertilization. Nitrogen fertilization increased the relative abundance of copiotrophic bacteria (i.e. Proteobacteria and Actinobacteria), but reduced the abundance of oligotrophic taxa (i.e. Acidobacteria), consistent with the general life history strategy theory for bacteria. The relative abundance of Proteobacteria was also increased by NPK fertilization. The positive correlation between N application rate and the relative abundance of Actinobacteria indicates that increased N availability favored the growth of Actinobacteria. This first global analysis of long-term N and NPK fertilization effect on bacterial diversity and community composition suggests that N input decreases bacterial diversity but favors the growth of copiotrophic bacteria, providing a reference for nutrient management strategies for maintaining belowground microbial diversity

The effect of different growth regimes on the endophytic bacterial communities of the fern, Dicksonia sellowiana hook (Dicksoniaceae).

PubMed

de Araújo Barros, Irene; Luiz Araújo, Welington; Lúcio Azevedo, João

2010-10-01

Endophytic bacteria associated with the fern Dicksonia sellowiana were investigated. The bacterial communities from the surface-sterilized pinnae and rachis segments of the plants from the Brazilian Atlantic Rainforest that grew in native field conditions were compared with the bacterial communities from plants grown in greenhouses and plants that were initially grown in greenhouses and then transferred to the forest. From 540 pinnae and 540 rachis segments, 163 (30.2%) and 346 (64.2%) were colonized by bacteria, respectively. The main bacterial genera and species that were isolated included Bacillus spp. ( B. cereus, B. megaterium, B. pumilus and B. subtilis ) , Paenibacillus sp. , Amphibacillus sp. , Gracilibacillus sp. , Micrococcus sp. and Stenotrophomonas spp. ( S. maltophilia and S. nitroreducens ). B. pumilus was the most frequently isolated bacterial species . Amphibacillus and Gracilibacillus were reported as endophytes for the first time. Other commonly found bacterial genera were not observed in D. sellowiana , which may reflect preferences of specific bacterial communities inside this fern or detection limitations due to the isolation procedures. Plants that were grown in greenhouses and plants that were reintroduced into the forest displayed more bacterial genera and species diversity than native field plants, suggesting that reintroduction shifts the bacterial diversity. Endophytic bacteria that displayed antagonistic properties against different microorganisms were detected, but no obvious correlation was found between their frequencies with plant tissues or with plants from different growth regimes. This paper reports the first isolation of endophytic bacteria from a fern.

The effect of different growth regimes on the endophytic bacterial communities of the fern, Dicksonia sellowiana hook (Dicksoniaceae)

PubMed Central

de Araújo Barros, Irene; Luiz Araújo, Welington; Lúcio Azevedo, João

2010-01-01

Endophytic bacteria associated with the fern Dicksonia sellowiana were investigated. The bacterial communities from the surface-sterilized pinnae and rachis segments of the plants from the Brazilian Atlantic Rainforest that grew in native field conditions were compared with the bacterial communities from plants grown in greenhouses and plants that were initially grown in greenhouses and then transferred to the forest. From 540 pinnae and 540 rachis segments, 163 (30.2%) and 346 (64.2%) were colonized by bacteria, respectively. The main bacterial genera and species that were isolated included Bacillus spp. ( B. cereus, B. megaterium, B. pumilus and B. subtilis ) , Paenibacillus sp. , Amphibacillus sp. , Gracilibacillus sp. , Micrococcus sp. and Stenotrophomonas spp. ( S. maltophilia and S. nitroreducens ). B. pumilus was the most frequently isolated bacterial species . Amphibacillus and Gracilibacillus were reported as endophytes for the first time. Other commonly found bacterial genera were not observed in D. sellowiana , which may reflect preferences of specific bacterial communities inside this fern or detection limitations due to the isolation procedures. Plants that were grown in greenhouses and plants that were reintroduced into the forest displayed more bacterial genera and species diversity than native field plants, suggesting that reintroduction shifts the bacterial diversity. Endophytic bacteria that displayed antagonistic properties against different microorganisms were detected, but no obvious correlation was found between their frequencies with plant tissues or with plants from different growth regimes. This paper reports the first isolation of endophytic bacteria from a fern. PMID:24031575

Modeling of the Competitive Growth of Listeria monocytogenes and Lactococcus lactis in Vegetable Broth

PubMed Central

Breidt, Frederick; Fleming, Henry P.

1998-01-01

Current mathematical models used by food microbiologists do not address the issue of competitive growth in mixed cultures of bacteria. We developed a mathematical model which consists of a system of nonlinear differential equations describing the growth of competing bacterial cell cultures. In this model, bacterial cell growth is limited by the accumulation of protonated lactic acid and decreasing pH. In our experimental system, pure and mixed cultures of Lactococcus lactis and Listeria monocytogenes were grown in a vegetable broth medium. Predictions of the model indicate that pH is the primary factor that limits the growth of L. monocytogenes in competition with a strain of L. lactis which does not produce the bacteriocin nisin. The model also predicts the values of parameters that affect the growth and death of the competing populations. Further development of this model will incorporate the effects of additional inhibitors, such as bacteriocins, and may aid in the selection of lactic acid bacterium cultures for use in competitive inhibition of pathogens in minimally processed foods. PMID:9726854

Identification of Limiting Factors for the Optimum Growth of Fusarium Oxysporum in Liquid Medium

PubMed Central

Srivastava, Shilpi; Pathak, Neelam; Srivastava, Prachi

2011-01-01

Fusarium oxysporum is a highly ubiquitous species that infects a wide range of hosts causing various diseases such as vascular wilts, yellows, rots, and damping-off. Despite the immense economic significance of this phytopathogen, few workers have reported growth studies in this genus in submerged culture. In the present study, several parameters such as change in media pH, biomass, pattern of substrate utilization, viability of the fungal cells, and protein content were observed over a period of time. The fungal biomass increased at a slow rate for the initial 48 h and thereafter increased at an exponential rate. However, after about 8 days the rapid growth stabilized and the trend became more toward stationary phase. The concentration of glucose in the liquid media decreased rapidly up to the initial 4 days, followed by a slow decrease. The pH of the medium gradually decreased as the fungal growth progressed, the reduction being more pronounced in the initial 48 h. This study would be of immense importance for utilization of F. oxysporum for diverse applications because we can predict the growth pattern in the fungus and modulate its growth for human benefit. PMID:21976815

Effects of Eyjafjallajökull volcanic ash on innate immune system responses and bacterial growth in vitro.

PubMed

Monick, Martha M; Baltrusaitis, Jonas; Powers, Linda S; Borcherding, Jennifer A; Caraballo, Juan C; Mudunkotuwa, Imali; Peate, David W; Walters, Katherine; Thompson, Jay M; Grassian, Vicki H; Gudmundsson, Gunnar; Comellas, Alejandro P

2013-06-01

On 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions. We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20-100 µg/cm(2)), primary rat and human alveolar macrophages (5-20 µg/cm(2)), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria). Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides. These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals.

Effects of Eyjafjallajökull Volcanic Ash on Innate Immune System Responses and Bacterial Growth in Vitro

PubMed Central

Baltrusaitis, Jonas; Powers, Linda S.; Borcherding, Jennifer A.; Caraballo, Juan C.; Mudunkotuwa, Imali; Peate, David W.; Walters, Katherine; Thompson, Jay M.; Grassian, Vicki H.; Gudmundsson, Gunnar; Comellas, Alejandro P.

2013-01-01

Background: On 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions. Methods: We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20–100 µg/cm2), primary rat and human alveolar macrophages (5–20 µg/cm2), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria). Results: Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides. Conclusions: These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals. PMID:23478268

Production of pectate lyases and cellulases by Chryseomonas luteola strain MFCL0 depends on the growth temperature and the nature of the culture medium: evidence for two critical temperatures.

PubMed

Laurent, P; Buchon, L; Guespin-Michel, J F; Orange, N

2000-04-01

Several extracellular enzymes that are responsible for plant tissue maceration were detected in culture supernatant of the psychrotrophic bacterium Chryseomonas luteola MFCL0. Isoelectrofocusing experiments showed that pectate lyase (PL) activity resulted from the cumulative action of three major isoenzymes, designated PLI, PLII, and PLIII. Cellulolytic activity was also detected in culture supernatants. These enzymes exhibited different behaviors with respect to growth temperature. PLII was not regulated by temperature, whereas PLI and PLIII were regulated similarly by growth temperature. Maximal levels of PLI and PLIII were produced at 14 degrees C when cells were grown in polygalacturonate-containing synthetic medium and at around 20 to 24 degrees C in nutrient broth. In contrast, thermoregulation of cellulolytic activity production differed from thermoregulation of PL. The level of cellulolytic activity was low in all media at temperatures up to 20 degrees C, and then it increased dramatically until the temperature was 28 degrees C, which is the optimal temperature for growth of C. luteola. Previously, we defined the critical temperature by using the modified Arrhenius equation to characterize bacterial behavior. This approach consists of monitoring changes in the maximal specific growth rate as a function of temperature. Our most striking result was the finding that the temperature at which maximum levels of PLI and PLIII were produced in two different media was the same as the critical temperature for growth observed in these two media.

Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

PubMed Central

Bancroft, K; Maloney, S W; McElhaney, J; Suffet, I H; Pipes, W O

1983-01-01

The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study. PMID:6639023

Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

PubMed

Bancroft, K; Maloney, S W; McElhaney, J; Suffet, I H; Pipes, W O

1983-09-01

The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study.

Effect of cholesterol deposition on bacterial adhesion to contact lenses.

PubMed

Babaei Omali, Negar; Zhu, Hua; Zhao, Zhenjun; Ozkan, Jerome; Xu, Banglao; Borazjani, Roya; Willcox, Mark D P

2011-08-01

To examine the effect of cholesterol on the adhesion of bacteria to silicone hydrogel contact lenses. Contact lenses, collected from subjects wearing Acuvue Oasys or PureVision lenses, were extracted in chloroform:methanol (1:1, v/v) and amount of cholesterol was estimated by thin-layer chromatography. Unworn lenses were soaked in cholesterol, and the numbers of Pseudomonas aeruginosa strains or Staphylococcus aureus strains that adhered to the lenses were measured. Cholesterol was tested for effects on bacterial growth by incubating bacteria in medium containing cholesterol. From ex vivo PureVision lenses, 3.4 ± 0.3 μg/lens cholesterol was recovered, and from Acuvue Oasys lenses, 2.4 ± 0.2 to 1.0 ± 0.1 μg/lens cholesterol was extracted. Cholesterol did not alter the total or viable adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). However, worn PureVision lenses reduced the numbers of viable cells of P. aeruginosa (5.8 ± 0.4 log units) compared with unworn lenses (6.4 ± 0.2 log units, p = 0.001). Similarly, there were fewer numbers of S. aureus 031 adherent to worn PureVision (3.05 ± 0.8 log units) compared with unworn PureVision (4.6 ± 0.3 log units, p = 0.0001). Worn Acuvue Oasys lenses did not affect bacterial adhesion. Cholesterol showed no effect on the growth of any test strain. Although cholesterol has been shown to adsorb to contact lenses during wear, this lipid does not appear to modulate bacterial adhesion to a lens surface.

Growth and differentiation of a murine interleukin-3-producing myelomonocytic leukemia cell line in a protein-free chemically defined medium.

PubMed

Kajigaya, Y; Ikuta, K; Sasaki, H; Matsuyama, S

1990-10-01

We established the continuous growth of WEHI-3B D+ cells in protein-free chemically defined F-12 medium by stepwise decreases in the concentration of fetal calf serum. This cell line, designated as WEHI-3B-Y1, has now been propagated in protein-free F-12 medium for 3 years. The population-doubling time of the cells in culture is about 24 hr. WEHI-3B-Y1 cells are immature undifferentiated cells which show positive staining for naphthol ASD chloroacetate esterase and alpha-naphthyl butyrate esterase and spontaneously exhibit a low level of differentiation to mature granulocytes and macrophages. Medium conditioned by WEHI-3B-Y1 cells stimulated the proliferation of an interleukin-3 (IL-3)-dependent FDCP-2 cell line. This conditioned medium was shown to have erythroid burst-promoting activity when assayed using normal murine bone marrow. The colony formation of WEHI-3B-Y1 cells in semi-solid agar culture was not stimulated by purified recombinant human granulocyte colony-stimulating factor (rhG-CSF). However, in the presence of human transferrin, rhG-CSF enhanced the number of colonies of WEHI-3B-Y1 cells but did not induce their differentiation. These results suggest that WEHI-3B-Y1 cells cultured in protein-free medium produced murine IL-3. In addition, human G-CSF enhanced the clonal growth but did not induce the differentiation of WEHI-3B-Y1 cells cultured in serum-free medium.

Antibiotic Conditioned Growth Medium of Pseudomonas Aeruginosa

ERIC Educational Resources Information Center

Benathen, Isaiah A.; Cazeau, Barbara; Joseph, Njeri

2004-01-01

A simple method to study the consequences of bacterial antibiosis after interspecific competition between microorganisms is presented. Common microorganisms are used as the test organisms and Pseudomonas aeruginosa are used as the source of the inhibitor agents.

Study Of Functioning of Bacterial Complexes in East Antarctic Soils

NASA Astrophysics Data System (ADS)

Yakushev, A. V.; Churilin, N. A.

2014-11-01

Studies of bacterial communities in the samples of Antarctic soils by different methods showed that, both in liquid soil suspensions and in situ, microbial complexes are functioning presumably by forming biofilms - the phenomenon that is more expressed in such habitat than in soils of temperate zones. Functional (trophic) diversity and physiological state of hydrolytic bacteria was studied in the samples at the upper layer (0-2 cm) of gravel pavement with algae, in the underlying peat horizon (2-4 cm) with inclusions of dead biomass and its underlying mineral horizon (4-10 cm) with signs of fungal mycelium. The investigated samples of Antarctic soils revealed different trophic diversity and the maximum specific growth rate on mineral medium with different biopolymers as the sole carbon source (starch, chitin, pectin, xylan, dextran-500, tween-20, casein); this can testify to differences in the physiological state of hydrolytic bacteria in various soil horizons and their readiness for growth. The most remarkable characteristics of the studied Antarctic soil as compared to the soils of temperate zone, was the unusual ability of hydrolytic community to consume chitin in the mineral horizon; this can be explained by the presence of fungal mycelium. Also, an almost complete lack in consumption of tween-20 (a water-soluble analogue of fat) by bacterial community of Arctic soil horizons are not explained and needs further verification. The higher functional diversity was detected in the upper horizon of the gravel pavement, which "protects" microorganisms from exposure to extreme temperatures, UV radiation, and desiccation, but the maximum specific growth rate was higher in the lower mineral horizon; this can be explained by the specificity of bacterial colonizing processes and unique formation of Antarctic soil microprofiles in the Larsemann oasis. The obtained data indicate a specific environmental strategy in the samples of Antarctic soils: development in lower mineral

Enhanced production of ATP-binding cassette protein exporter-dependent lipase by modifying the growth medium components of Pseudomonas fluorescens.

PubMed

Eom, Gyeong Tae; Song, Jae Kwang

2014-08-01

The industrially-important thermostable lipase, TliA, was extracellularly produced in the recombinant Pseudomonas fluorescens by the homologous expression of TliA and its cognate ABC protein exporter, TliDEF. To increase the secretory production of TliA, we optimized the growth temperature and the culture medium of P. fluorescens. The total amount and the specific productivity of lipase was highest at 25 °C of cell growth temperature, although maximal cell growth was observed at 30 °C. Using the culture medium composed of 20 g dextrin l(-1), 40 g Tween 80 l(-1) and 30 g peptone l(-1), TliA was produced at a level of 2,200 U ml(-1) in a flask culture. The TliA production increased about 3.8-fold (8,450 U ml(-1)) in batch fermentation using a 2.5 l fermentor, which was about 7.7-fold higher than that of previously reported TliA production.

BIODEGRADATION DURING CONTAMINANT TRANSPORT IN POROUS MEDIA. 4. IMPACT OF MICROBIAL LAG AND BACTERIAL CELL GROWTH. (R825415)

EPA Science Inventory

Abstract

Miscible-displacement experiments were conducted to examine the impact of microbial lag and bacterial cell growth on the transport of salicylate, a model hydrocarbon compound. The impacts of these processes were examined separately, as well as jointly, to dete...

Glycogen storage disease type 1: impact of medium-chain triglycerides on metabolic control and growth.

PubMed

Das, Anibh M; Lücke, Thomas; Meyer, Uta; Hartmann, Hans; Illsinger, Sabine

2010-01-01

Hypoketotic hypoglycaemia and hypertriglyceridaemia are biochemical hallmarks of glycogen storage disease (GSD) 1. Increased malonyl coenzyme A production which compromises oxidation of long-chain fatty acids via carnitine palmitoyltransferase (CPT) 1 inhibition plays a crucial role in the pathogenesis of these complications. Therapy consists primarily of nutritional support including frequent carbohydrate-rich meals. We studied the effect of a diet enriched in medium-chain triglycerides (MCT) on metabolic control/growth in GSD 1 as medium-chain fatty acids can be oxidised independently of CPT 1. An adult female, a 1.6-year-old boy with GSD 1a and a 6.5-year-old girl with GSD 1b treated with a classical GSD diet were enrolled; their 'classical GSD diet' was supplemented with MCT fats. Concentrations of glucose, lactate, ketone bodies triglycerides, uric acid, acylcarnitines in blood and organic acids in urine were determined. No clinical or biochemical side-effects were observed. The MCT diet led to a decrease in uric acid concentrations in all patients. Triglyceride levels were reduced only in the youngest patient, while lactate concentrations did not significantly decrease. The MCT diet allowed for a reduction in carbohydrate and caloric intake required to maintain euglycaemia and led to improvement in growth in the two prepubertal patients. MCT supplementation had a positive effect on metabolic control and growth in our patients suffering from GSD 1. (c) 2010 S. Karger AG, Basel.

Human serum provided additional values in growth factors supplemented medium for human chondrocytes monolayer expansion and engineered cartilage construction.

PubMed

Chua, K H; Aminuddin, B S; Fuzina, N H; Ruszymah, B H I

2004-05-01

We have previously formulated an optimized human chondrocytes growth medium based on 2% fetal bovine serum supplementation. For clinical usage, the animal serum must be replaced by patient own serum. We investigated the effects of human serum concentration for human nasal septum chondrocytes monolayer culture and cartilage reconstruction. Human serum demonstrated a dose dependent manner in promoting chondrocytes growth and cartilage engineering.

The influence of ultrasonic treatment on the growth of the strains of Salmonella enterica subs. typhimurium.

PubMed

Sienkiewicz, Jolanta Joanna; Wesołowski, Andrzej; Stankiewicz, Wanda; Kotowski, Romuald

2017-07-01

This study proposes the destruction of pathogenic bacteria with the use of ultrasound waves because the more commonly used thermal processing methods often result in lowering the nutritional value of food. The study presents the impact of ultrasound of 20, 40 and 100 kHz frequencies and the power of 10.5 W/cm 2 on the growth of the strain of Salmonella enterica subs. typhimurium . The tests were carried out both in chilled and non-chilled treatment mediums, with an average bacterial population >10 5 and >10 8  CFU/cm 3 . The total inactivation of Salmonella spp. was observed in the tests in the low-population non-chilled treatment medium after sonication at 20 and 40 kHz for 30 min, and in high bacterial population at 20 kHz for 30 min. A reduction in the average number of bacteria was reported in the low-population non-chilled medium after 15 min of sonication at 20, 40 and 100 kHz; after 15 min of sonication at 20 and 100 kHz of the material of high bacterial population; and in the low-population chilled treatment mediums after 15 and 30 min at 20 kHz. The samples with inactivated bacteria and those with reduced bacterial counts maintained the same levels when stored at 4 °C for 24 and 48 h. Bacteria inactivation obtained after sonication lasted for up to 48 h in storage at 21 °C. For the samples with reduced bacterial counts stored at 21 °C, a rise in the average number of bacteria was recorded.

Growth promotion and colonization of switchgrass (Panicum virgatum) cv. Alamo by bacterial endophyte Burkholderia phytofirmans strain PsJN

PubMed Central

2012-01-01

Background Switchgrass is one of the most promising bioenergy crop candidates for the US. It gives relatively high biomass yield and can grow on marginal lands. However, its yields vary from year to year and from location to location. Thus it is imperative to develop a low input and sustainable switchgrass feedstock production system. One of the most feasible ways to increase biomass yields is to harness benefits of microbial endophytes. Results We demonstrate that one of the most studied plant growth promoting bacterial endophytes, Burkholderia phytofirmans strain PsJN, is able to colonize and significantly promote growth of switchgrass cv. Alamo under in vitro, growth chamber, and greenhouse conditions. In several in vitro experiments, the average fresh weight of PsJN-inoculated plants was approximately 50% higher than non-inoculated plants. When one-month-old seedlings were grown in a growth chamber for 30 days, the PsJN-inoculated Alamo plants had significantly higher shoot and root biomass compared to controls. Biomass yield (dry weight) averaged from five experiments was 54.1% higher in the inoculated treatment compared to non-inoculated control. Similar results were obtained in greenhouse experiments with transplants grown in 4-gallon pots for two months. The inoculated plants exhibited more early tillers and persistent growth vigor with 48.6% higher biomass than controls. We also found that PsJN could significantly promote growth of switchgrass cv. Alamo under sub-optimal conditions. However, PsJN-mediated growth promotion in switchgrass is genotype specific. Conclusions Our results show B. phytofirmans strain PsJN significantly promotes growth of switchgrass cv. Alamo under different conditions, especially in the early growth stages leading to enhanced production of tillers. This phenomenon may benefit switchgrass establishment in the first year. Moreover, PsJN significantly stimulated growth of switchgrass cv. Alamo under sub-optimal conditions

Plasmodium falciparum: differing effects of non-esterified fatty acids and phospholipids on intraerythrocytic growth in serum-free medium.

PubMed

Asahi, Hiroko; Izumiyama, Shinji; Tolba, Mohammed Essa Marghany; Kwansa-Bentum, Bethel

2011-03-01

Different combinations of non-esterified fatty acids (NEFA) had variable effects on intraerythrocytic growth of Plasmodium falciparum. All stages of the parasite cultured in medium supplemented with cis-9-octadecenoic acid (C18:1-cis-9), hexadecanoic acid (C16:0), phospholipids (Pld) and bovine albumin free of NEFA were similar to those grown in complete growth medium. Three typical growth patterns indicating suppressed schizogony (SS), suppressed formation of merozoites (SMF), and inhibited invasion of merozoites (IMI) resulted from culture in other combinations of lipids. Unsaturated or saturated NEFA with longer or shorter carbon chains than C18:1-cis-9 or C16:0, higher degree of unsaturation, and trans-forms mainly resulted in SS and SMF effects. However, IMI or partial IMI was observed with tetradecanoic acid or octadecanoic acid enriched with C18:1-cis-9, and cis-9-hexadecenoic acid plus C16:0. Isoforms of C18:1-cis-9 also mainly resulted in partial IMI. SMF also occurred with C18:1-cis-9 plus C16:0 in the absence of Pld. Thus different NEFA exerted distinct roles in erythrocytic growth of the parasite by sustaining development at different stages. Copyright © 2010 Elsevier Inc. All rights reserved.

Preferential Promotion of Lycopersicon esculentum (Tomato) Growth by Plant Growth Promoting Bacteria Associated with Tomato.

PubMed

Vaikuntapu, Papa Rao; Dutta, Swarnalee; Samudrala, Ram Babu; Rao, Vukanti R V N; Kalam, Sadaf; Podile, Appa Rao

2014-12-01

A total of 74 morphologically distinct bacterial colonies were selected during isolation of bacteria from different parts of tomato plant (rhizoplane, phylloplane and rhizosphere) as well as nearby bulk soil. The isolates were screened for plant growth promoting (PGP) traits such as production of indole acetic acid, siderophore, chitinase and hydrogen cyanide as well as phosphate solubilization. Seven isolates viz., NR4, NR6, RP3, PP1, RS4, RP6 and NR1 that exhibited multiple PGP traits were identified, based on morphological, biochemical and 16S rRNA gene sequence analysis, as species that belonged to four genera Aeromonas, Pseudomonas, Bacillus and Enterobacter. All the seven isolates were positive for 1-aminocyclopropane-1-carboxylate deaminase. Isolate NR6 was antagonistic to Fusarium solani and Fusarium moniliforme, and both PP1 and RP6 isolates were antagonistic to F. moniliforme. Except RP6, all isolates adhered significantly to glass surface suggestive of biofilm formation. Seed bacterization of tomato, groundnut, sorghum and chickpea with the seven bacterial isolates resulted in varied growth response in laboratory assay on half strength Murashige and Skoog medium. Most of the tomato isolates positively influenced tomato growth. The growth response was either neutral or negative with groundnut, sorghum and chickpea. Overall, the results suggested that bacteria with PGP traits do not positively influence the growth of all plants, and certain PGP bacteria may exhibit host-specificity. Among the isolates that positively influenced growth of tomato (NR1, RP3, PP1, RS4 and RP6) only RS4 was isolated from tomato rhizosphere. Therefore, the best PGP bacteria can also be isolated from zones other than rhizosphere or rhizoplane of a plant.

Pore-Scale Hydrodynamics in a Progressively Bioclogged Three-Dimensional Porous Medium: 3-D Particle Tracking Experiments and Stochastic Transport Modeling

NASA Astrophysics Data System (ADS)

Carrel, M.; Morales, V. L.; Dentz, M.; Derlon, N.; Morgenroth, E.; Holzner, M.

2018-03-01

Biofilms are ubiquitous bacterial communities that grow in various porous media including soils, trickling, and sand filters. In these environments, they play a central role in services ranging from degradation of pollutants to water purification. Biofilms dynamically change the pore structure of the medium through selective clogging of pores, a process known as bioclogging. This affects how solutes are transported and spread through the porous matrix, but the temporal changes to transport behavior during bioclogging are not well understood. To address this uncertainty, we experimentally study the hydrodynamic changes of a transparent 3-D porous medium as it experiences progressive bioclogging. Statistical analyses of the system's hydrodynamics at four time points of bioclogging (0, 24, 36, and 48 h in the exponential growth phase) reveal exponential increases in both average and variance of the flow velocity, as well as its correlation length. Measurements for spreading, as mean-squared displacements, are found to be non-Fickian and more intensely superdiffusive with progressive bioclogging, indicating the formation of preferential flow pathways and stagnation zones. A gamma distribution describes well the Lagrangian velocity distributions and provides parameters that quantify changes to the flow, which evolves from a parallel pore arrangement under unclogged conditions, toward a more serial arrangement with increasing clogging. Exponentially evolving hydrodynamic metrics agree with an exponential bacterial growth phase and are used to parameterize a correlated continuous time random walk model with a stochastic velocity relaxation. The model accurately reproduces transport observations and can be used to resolve transport behavior at intermediate time points within the exponential growth phase considered.

Arsenite oxidation by the phyllosphere bacterial community associated with Wolffia australiana.

PubMed

Xie, Wan-Ying; Su, Jian-Qiang; Zhu, Yong-Guan

2014-08-19

Speciation is a key determinant in the toxicity, behavior, and fate of arsenic (As) in the environment. However, little is known about the transformation of As species mediated by floating macrophytes and the phyllosphere bacteria in aquatic and wetland environment. In this study, Wolffia australiana, a rootless floating duckweed, was cultured with (W+B) or without (W-B) phyllosphere bacteria to investigate its ability in arsenite (As(III)) oxidation. Results showed that sterile W. australiana did not oxidize As(III) in the growth medium or in plant tissue, whereas W. australiana with phyllpsphere bacteria displayed substantial As(III) oxidation in the medium. Quantitative PCR of As redox-related functional genes revealed the dominance of the arsenite oxidase (aioA) gene in the phyllosphere bacterial community. These results demonstrate that the phyllosphere bacteria were responsible for the As(III) oxidation in the W+B system. The rapid oxidation of As(III) by the phyllosphere bacterial community may suppress As accumulation in plant tissues under phosphate rich conditions. The aioA gene library showed that the majority of the phyllosphere arsenite-oxidizing bacteria related either closely to unidentified bacteria found in paddy environments or distantly to known arsenite-oxidizing bacteria. Our research suggests a previously overlooked diversity of arsenite-oxidizing bacteria in the phyllosphere of aquatic macrophytes which may have a substantial impact on As biogeochemistry in water environments, warranting further exploration.

Adaptations in bacterial catabolic enzyme activity and community structure in membrane-coupled bioreactors fed simple synthetic wastewater.

PubMed

LaPara, Timothy M; Klatt, Christian G; Chen, Ruoyu

2006-02-10

Membrane-coupled bioreactors (MBRs) offer substantial benefits compared to conventional reactor designs for biological wastewater treatment. MBR treatment efficiency, however, has not been optimized because the effects of the MBR on process microbiology are poorly understood. In this study, the structure and function of the microbial communities growing in MBRs fed simple synthetic wastewater were investigated. In four starch-fed MBRs, the bacterial community substantially increased its alpha-glucosidase affinity (>1000-fold), while the leucine aminopeptidase and heptanoate esterase affinities increased slightly (<40-fold) or remained relatively constant. Concomitant to these physiological adaptations, shifts in the bacterial community structure in two of the starch-fed MBRs were detected by PCR-DGGE. Four of the bacterial populations detected by PCR-DGGE were isolated and exhibited specific growth rates in batch culture ranging from 0.009 to 0.22 h(-1). Our results suggest that bacterial communities growing under increasingly stringent nutrient limitation adapt their enzyme activities primarily for the nutrients provided, but that there is also a more subtle response not linked to the substrates included in the feed medium. Our research also demonstrates that MBRs can support relatively complex bacterial communities even on simple feed media.

In vitro effect of Reiki treatment on bacterial cultures: Role of experimental context and practitioner well-being.

PubMed

Rubik, Beverly; Brooks, Audrey J; Schwartz, Gary E

2006-01-01

To measure effects of Reiki treatments on growth of heat-shocked bacteria, and to determine the influence of healing context and practitioner well-being. Overnight cultures of Escherichia coli K12 in fresh medium were used. Culture samples were paired with controls to minimize any ordering effects. Samples were heat-shocked prior to Reiki treatment, which was performed by Reiki practitioners for up to 15 minutes, with untreated controls. Plate-count assay using an automated colony counter determined the number of viable bacteria. Fourteen Reiki practitioners each completed 3 runs (n = 42 runs) without healing context, and another 2 runs (n = 28 runs) in which they first treated a pain patient for 30 minutes (healing context). Well-being questionnaires were administered to practitioners pre-post all sessions. No overall difference was found between the Reiki and control plates in the nonhealing context. In the healing context, the Reiki treated cultures overall exhibited significantly more bacteria than controls (p < 0.05). Practitioner social (p < 0.013) and emotional well-being (p < 0.021) correlated with Reiki treatment outcome on bacterial cultures in the nonhealing context. Practitioner social (p < 0.031), physical (p < 0.030), and emotional (p < 0.026) well-being correlated with Reiki treatment outcome on the bacterial cultures in the healing context. For practitioners starting with diminished well-being, control counts were likely to be higher than Reiki-treated bacterial counts. For practitioners starting with a higher level of well-being, Reiki counts were likely to be higher than control counts. Reiki improved growth of heat-shocked bacterial cultures in a healing context. The initial level of well-being of the Reiki practitioners correlates with the outcome of Reiki on bacterial culture growth and is key to the results obtained.

Lag Phase Is a Distinct Growth Phase That Prepares Bacteria for Exponential Growth and Involves Transient Metal Accumulation

PubMed Central

Rolfe, Matthew D.; Rice, Christopher J.; Lucchini, Sacha; Pin, Carmen; Thompson, Arthur; Cameron, Andrew D. S.; Alston, Mark; Stringer, Michael F.; Betts, Roy P.; Baranyi, József; Peck, Michael W.

2012-01-01

Lag phase represents the earliest and most poorly understood stage of the bacterial growth cycle. We developed a reproducible experimental system and conducted functional genomic and physiological analyses of a 2-h lag phase in Salmonella enterica serovar Typhimurium. Adaptation began within 4 min of inoculation into fresh LB medium with the transient expression of genes involved in phosphate uptake. The main lag-phase transcriptional program initiated at 20 min with the upregulation of 945 genes encoding processes such as transcription, translation, iron-sulfur protein assembly, nucleotide metabolism, LPS biosynthesis, and aerobic respiration. ChIP-chip revealed that RNA polymerase was not “poised” upstream of the bacterial genes that are rapidly induced at the beginning of lag phase, suggesting a mechanism that involves de novo partitioning of RNA polymerase to transcribe 522 bacterial genes within 4 min of leaving stationary phase. We used inductively coupled plasma mass spectrometry (ICP-MS) to discover that iron, calcium, and manganese are accumulated by S. Typhimurium during lag phase, while levels of cobalt, nickel, and sodium showed distinct growth-phase-specific patterns. The high concentration of iron during lag phase was associated with transient sensitivity to oxidative stress. The study of lag phase promises to identify the physiological and regulatory processes responsible for adaptation to new environments. PMID:22139505

Elevated guanosine 5'-diphosphate 3'-diphosphate level inhibits bacterial growth and interferes with FtsZ assembly.

PubMed

Yamaguchi, Takayoshi; Iida, Ken-Ichiro; Shiota, Susumu; Nakayama, Hiroaki; Yoshida, Shin-Ichi

2015-12-01

FtsZ, a protein essential for prokaryotic cell division, forms a ring structure known as the Z-ring at the division site. FtsZ has a GTP binding site and is assembled into linear structures in a GTP-dependent manner in vitro. We assessed whether guanosine 5'-diphosphate 3'-diphosphate (ppGpp), a global regulator of gene expression in starved bacteria, affects cell division in Salmonella Paratyphi A. Elevation of intracellular ppGpp levels by using the relA expression vector induced repression of bacterial growth and incorrect FtsZ assembly. We found that FtsZ forms helical structures in the presence of ppGpp by using the GTP binding site; however, ppGpp levels required to form helical structures were at least 20-fold higher than the required GTP levels in vitro. Furthermore, once formed, helical structures did not change to the straight form even after GTP addition. Our data indicate that elevation of the ppGpp level leads to inhibition of bacterial growth and interferes with FtsZ assembly. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Root ethylene signalling is involved in Miscanthus sinensis growth promotion by the bacterial endophyte Herbaspirillum frisingense GSF30T

PubMed Central

Ludewig, Uwe

2013-01-01

The bacterial endophyte Herbaspirillum frisingense GSF30T is a colonizer of several grasses grown in temperate climates, including the highly nitrogen-efficient perennial energy grass Miscanthus. Inoculation of Miscanthus sinensis seedlings with H. frisingense promoted root and shoot growth but had only a minor impact on nutrient concentrations. The bacterium affected the root architecture and increased fine-root structures. Although H. frisingense has the genetic requirements to fix nitrogen, only minor changes in nitrogen concentrations were observed. Herbaspirillum agglomerates were identified primarily in the root apoplast but also in the shoots. The short-term (3h) and long-term (3 weeks) transcriptomic responses of the plant to bacterial inoculation revealed that H. frisingense induced rapid changes in plant hormone signalling, most prominent in jasmonate signalling. Ethylene signalling pathways were also affected and persisted after 3 weeks in the root. Growth stimulation of the root by the ethylene precursor 1-aminocyclopropane 1-carboxylic acid was dose dependent and was affected by H. frisingense inoculation. Minor changes in the proteome were identified after 3 weeks. This study suggests that H. frisingense improves plant growth by modulating plant hormone signalling pathways and provides a framework to understand the beneficial effects of diazotrophic plant-growth-promoting bacteria, such as H. frisingense, on the biomass grass Miscanthus. PMID:24043849

Normal bacterial flora from vaginas of Criollo Limonero cows.

PubMed

Zambrano-Nava, Sunny; Boscán-Ocando, Julio; Nava, Jexenia

2011-02-01

In order to describe the normal bacterial flora in vaginas of Criollo Limonero cows, 51 healthy multiparous cows, at least 90-day postpartum, were selected. Duplicated swabs (N = 102) were taken from the vaginal fornix of cows to perform aerobic and anaerobic cultures as well as conventional biochemical tests. Out of 102 swabs, bacterial growth was obtained in 55 (53.9%) while the remaining 47 (46.1%) did not exhibited any bacterial growth. Of the 55 bacterial growths, 23 (41.8%) were aerobic whereas 32 (58.1%) were anaerobic. Likewise, 29 (52.72%) of bacterial growths were pure and 26 (47.27%) were mixed. Under both aerobic and anaerobic conditions, Gram positive bacteria were predominant (81.82% and 73.08%, respectively) over Gram negative bacteria (18.18% and 26.92%, respectively). Isolated bacteria were Arcanobacterium pyogenes (22.92%), Staphylococcus aureus (15.63%), Staphylococcus coagulase negative (17.71%), Erysipelothrix rhusiopathiae (6.25%), Bacteroides spp. (13.54%), and Peptostreptococcus spp. (7.29%). In conclusion, normal vaginal bacterial flora of Criollo Limonero cows was predominantly Gram positive and included A. pyogenes, S. aureus, coagulase negative Staphylococcus, E. rhusiopathiae, Bacteroides spp., and Peptostreptococcus spp. In Criollo Limonero cattle, adaptive aspects such as development of humoral and physical mechanisms for defense, and bacterial adaptation to host deserve research attention.

Bockron as a Medium of Learning in The Process of Inquiry based Learning to Improve Science Process Skills of Junior High School Students in Growth and Development Concept

NASA Astrophysics Data System (ADS)

Mayasari, D.

2017-02-01

Investigative research on Influence of bockron as a medium of learning in process of inquiry-based learning to the development of science process skills on the concept of growth and development. This research was done in an effort to follow up underdeveloped skills of observing, communicating andconclude on students. This research was conducted using classroom action research (PTK), which consisted of 3 cycles. Cycle 1 students observe differences in growth and development, cycle 2 students measure the growth rate, cycle 3 students observe factors that influence growth and development, In these three cycles is used as a planting medium bocron (bottles and dacron). It involves 8th grade junior high-school students of 14-15 years old as research subjects in six meetings. Indicators of process skill include observation, communication, interpretation and inference. Data is collected through students’ work sheets, written tests and observation. Processing of the data to see N-Gain used Microsoft Excel 2007, and the results showed that an increase in science process skills with a value of medium N-Gain (0,63). Bokron learning medium easily and cheaply obtainable around the students, particularly those in urban areas is quite difficult to get land to be used as aplanting medium. In addition to observation of growth and development, bokron media can also be used to observe the motion in plants. The use bokron as a learning medium can train and develop science process skills, attitude and scientific method also gives students concrete experience of the process of growth and development in plants.

Effects of Growth Medium on Matrix-Assisted Laser Desorption–Ionization Time of Flight Mass Spectra: a Case Study of Acetic Acid Bacteria

PubMed Central

Wieme, Anneleen D.; Spitaels, Freek; Aerts, Maarten; De Bruyne, Katrien; Van Landschoot, Anita

2014-01-01

The effect of the growth medium used on the matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectra generated and its consequences for species and strain level differentiation of acetic acid bacteria (AAB) were determined by using a set of 25 strains. The strains were grown on five different culture media that yielded a total of more than 600 mass spectra, including technical and biological replicates. The results demonstrate that the culture medium can have a profound effect on the mass spectra of AAB as observed in the presence and varying signal intensities of peak classes, in particular when culture media do not sustain optimal growth. The observed growth medium effects do not disturb species level differentiation but strongly affect the potential for strain level differentiation. The data prove that a well-constructed and robust MALDI-TOF mass spectrometry identification database should comprise mass spectra of multiple reference strains per species grown on different culture media to facilitate species and strain level differentiation. PMID:24362425

Evaluating the 4-hour and 30-minute rules: effects of room temperature exposure on red blood cell quality and bacterial growth.

PubMed

Ramirez-Arcos, Sandra; Mastronardi, Cherie; Perkins, Heather; Kou, Yuntong; Turner, Tracey; Mastronardi, Emily; Hansen, Adele; Yi, Qi-Long; McLaughlin, Natasha; Kahwash, Eiad; Lin, Yulia; Acker, Jason

2013-04-01

A 30-minute rule was established to limit red blood cell (RBC) exposure to uncontrolled temperatures during storage and transportation. Also, RBC units issued for transfusion should not remain at room temperature (RT) for more than 4 hours (4-hour rule). This study was aimed at determining if single or multiple RT exposures affect RBC quality and/or promote bacterial growth. Growth and RT exposure experiments were performed in RBCs inoculated with Serratia liquefaciens and Serratia marcescens. RBCs were exposed once to RT for 5 hours (S. liquefaciens) or five times to RT for 30 minutes (S. marcescens) with periodic sampling for bacterial counts. Noncontaminated units were exposed to RT once (5 hr) or five times (30 min each) and sampled to measure in vitro quality variables. RBC core temperature was monitored using mock units with temperature loggers. Growth and RT exposure experiments were repeated three and at least six times, respectively. Statistical analysis was done using mixed-model analysis. RBC core temperature ranged from 7.3 to 11.6°C during 30-minute RT exposures and the time to reach 10°C varied from 22 to 55 minutes during 5-hour RT exposures. RBC quality was preserved after single or multiple RT exposures. Increased growth of S. liquefaciens was only observed after 2 hours of continuous RT exposure. S. marcescens concentration increased significantly in multiple-exposed units compared to the controls but did not reach clinically important levels. Single or multiple RT exposures did not affect RBC quality but slightly promoted bacterial growth in contaminated units. The clinical significance of these results remains unclear and needs further investigation. © 2012 American Association of Blood Banks.

Bacterial body plans

PubMed Central

Rieger, Tomáš; Neubauer, Zdeněk; Blahůšková, Anna; Cvrčková, Fatima

2008-01-01

The bacterium Serratia marcescens produces a plethora of multicellular shapes of different colorations on solid substrates, allowing immediate visual detection of varieties. Such a plasticity allows studies on multicellular community scale spanning two extremes, from well-elaborated individual colonies to undifferentiated cell mass. For a single strain and medium, we obtained a range of different multicellular bodies, depending on the layout of initial plating. Four principal factors affecting the morphogenetic pathways of such bodies can be distinguished: (1) amount, density and distribution pattern of founder cells; (2) the configuration of surrounding free medium; (3) the presence and character of other bacterial bodies sharing the same niche; and (4) self-perception, resulting in delimitation towards other bodies. The last feature results in an ability of well-formed multicellular individuals to maintain their identity upon a close mutual contact, as well as in spontaneous separation of cell masses in experimental chimeras. We propose an “embryo-like” colony model where multicellular bacterial bodies develop along genuine ontogenetic pathways inherent to the given species (clone), while external shaping forces (like nutrient gradients, pH, etc.,) exert not formative, but only regulative roles in the process. PMID:19513204

Contact-dependent growth inhibition induces high levels of antibiotic-tolerant persister cells in clonal bacterial populations.

PubMed

Ghosh, Anirban; Baltekin, Özden; Wäneskog, Marcus; Elkhalifa, Dina; Hammarlöf, Disa L; Elf, Johan; Koskiniemi, Sanna

2018-05-02

Bacterial populations can use bet-hedging strategies to cope with rapidly changing environments. One example is non-growing cells in clonal bacterial populations that are able to persist antibiotic treatment. Previous studies suggest that persisters arise in bacterial populations either stochastically through variation in levels of global signalling molecules between individual cells, or in response to various stresses. Here, we show that toxins used in contact-dependent growth inhibition (CDI) create persisters upon direct contact with cells lacking sufficient levels of CdiI immunity protein, which would otherwise bind to and neutralize toxin activity. CDI-mediated persisters form through a feedforward cycle where the toxic activity of the CdiA toxin increases cellular (p)ppGpp levels, which results in Lon-mediated degradation of the immunity protein and more free toxin. Thus, CDI systems mediate a population density-dependent bet-hedging strategy, where the fraction of non-growing cells is increased only when there are many cells of the same genotype. This may be one of the mechanisms of how CDI systems increase the fitness of their hosts. © 2018 The Authors.

Chemically defined medium and Caenorhabditis elegans

NASA Technical Reports Server (NTRS)

Szewczyk, Nathaniel J.; Kozak, Elena; Conley, Catharine A.

2003-01-01

BACKGROUND: C. elegans has been established as a powerful genetic system. Use of a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of use in large-scale growth and screening of animals. RESULTS: We find that CeMM is versatile and culturing is simple. CeMM can be used in a solid or liquid state, it can be stored unused for at least a year, unattended actively growing cultures may be maintained longer than with standard techniques, and standard C. elegans protocols work well with animals grown in defined medium. We also find that there are caveats to using defined medium. Animals in defined medium grow more slowly than on standard medium, appear to display adaptation to the defined medium, and display altered growth rates as they change the composition of the defined medium. CONCLUSIONS: As was suggested with the introduction of C. elegans as a potential genetic system, use of defined medium with C. elegans should prove a powerful tool.

Functional properties of peanut fractions on the growth of probiotics and foodborne bacterial pathogens.

PubMed

Peng, Mengfei; Bitsko, Elizabeth; Biswas, Debabrata

2015-03-01

Various compounds found in peanut (Arachis hypogaea) have been shown to provide multiple benefits to human health and may influence the growth of a broad range of gut bacteria. In this study, we investigated the effects of peanut white kernel and peanut skin on 3 strains of Lactobacillus and 3 major foodborne enteric bacterial pathogens. Significant (P < 0.05) growth stimulation of Lactobacillus casei and Lactobacillus rhamnosus was observed in the presence of 0.5% peanut flour (PF) made from peanut white kernel, whereas 0.5% peanut skin extract (PSE) exerted the inhibitory effect on the growth of these beneficial microbes. We also found that within 72 h, PF inhibited growth of enterohemorrhagic Escherichia coli O157:H7 (EHEC), while PSE significantly (P < 0.05) inhibited Listeria monocytogenes but promoted the growth of both EHEC and Salmonella Typhimurium. The cell adhesion and invasion abilities of 3 pathogens to the host cells were also significantly (P < 0.05) reduced by 0.5% PF and 0.5% PSE. These results suggest that peanut white kernel might assist in improving human gut flora as well as reducing EHEC, whereas the beneficial effects of peanut skins require further research and investigation. © 2015 Institute of Food Technologists®

A selective medium for recovery and enumeration of endolithic bacteria.

PubMed

Bhattacharjee, Kaushik; Joshi, S R

2016-10-01

The study of lithic microbial communities, inhabiting rock substrates has been gathering momentum due to a growing attention of their wide importance as model systems in ecological studies and for their community structure. It is generally accepted that the success of cultivation-based technique is primarily based on suitable culture medium for isolation. The media available for enumeration and recovery of endolithic bacteria are mainly specific to particular type of rock which may not be suitable to isolate endolithic bacterial community from diverse lithobiontic niches. In this study, a new unoptimized medium was formulated, designated LM10 (unoptimized) for enumeration and recovery of endolithic bacteria by addition and/or omission of media components to the basal medium R2G, which was selected after experimental evaluation of five different existing media. The endolithic bacterial count in LM10 medium (unoptimized) was significantly higher than the R2G medium (t=-12.57, p<0.0001). The culture and nutritional parameters associated with unoptimized LM10 medium were optimized using statistical approach to maximize the recovery and enumeration of endolithic bacteria. The first phase of the study comprised of a Plackett-Burman (PB) design experiment conducted to screen thirteen medium components and two culture parameters as variables with effect on bacterial enumeration and recovery. Out of these, Yeast extract, Casein hydrolysate, Glucose, Starch and Sodium thiosulphate were found to be significantly affecting the bacterial count (p<0.05) based on PB design. On keeping rest of the media components and culture conditions at fixed value as per the PB design analyses (p>0.05 and coefficients), further optimization was carried out for significant factors using Box-Behnken design (BBD) of response surface methodology (RSM). Optimized media components obtained by BBD were Yeast extract, Casein hydrolysate, Glucose and Starch in 0.05g/l each and Sodium thiosulphate in 0

Use of plant growth promoting bacterial strains to improve Cytisus striatus and Lupinus luteus development for potential application in phytoremediation.

PubMed

Balseiro-Romero, María; Gkorezis, Panagiotis; Kidd, Petra S; Van Hamme, Jonathan; Weyens, Nele; Monterroso, Carmen; Vangronsveld, Jaco

2017-03-01

Plant growth promoting (PGP) bacterial strains possess different mechanisms to improve plant development under common environmental stresses, and are therefore often used as inoculants in soil phytoremediation processes. The aims of the present work were to study the effects of a collection of plant growth promoting bacterial strains on plant development, antioxidant enzyme activities and nutritional status of Cytisus striatus and/or Lupinus luteus plants a) growing in perlite under non-stress conditions and b) growing in diesel-contaminated soil. For this, two greenhouse experiments were designed. Firstly, C. striatus and L. luteus plants were grown from seeds in perlite, and periodically inoculated with 6 PGP strains, either individually or in pairs. Secondly, L. luteus seedlings were grown in soil samples of the A and B horizons of a Cambisol contaminated with 1.25% (w/w) of diesel and inoculated with best PGP inoculant selected from the first experiment. The results indicated that the PGP strains tested in perlite significantly improved plant growth. Combination treatments provoked better growth of L. luteus than the respective individual strains, while individual inoculation treatments were more effective for C. striatus. L. luteus growth in diesel-contaminated soil was significantly improved in the presence of PGP strains, presenting a 2-fold or higher increase in plant biomass. Inoculants did not provoke significant changes in plant nutritional status, with the exception of a subset of siderophore-producing and P-solubilising bacterial strains that resulted in significantly modification of Fe or P concentrations in leaf tissues. Inoculants did not cause significant changes in enzyme activities in perlite experiments, however they significantly reduced oxidative stress in contaminated soils suggesting an improvement in plant tolerance to diesel. Some strains were applied to non-host plants, indicating a non-specific performance of their plant growth promotion

Validation of a Medium-Throughput Method for Evaluation of Intracellular Growth of Mycobacterium tuberculosis▿

PubMed Central

Eklund, Daniel; Welin, Amanda; Schön, Thomas; Stendahl, Olle; Huygen, Kris; Lerm, Maria

2010-01-01

Intracellular pathogens such as Mycobacterium tuberculosis have adapted to a life inside host cells, in which they utilize host nutrients to replicate and spread. Ineffective methods for the evaluation of growth of intracellular pathogens in their true environment pose an obstacle for basic research and drug screening. Here we present the validation of a luminometry-based method for the analysis of intramacrophage growth of M. tuberculosis. The method, which is performed in a medium-throughput format, can easily be adapted for studies of other intracellular pathogens and cell types. The use of host cells in drug-screening assays dedicated to find antimicrobials effective against intracellular pathogens permits the discovery of not only novel antibiotics but also compounds with immunomodulatory and virulence-impairing activities, which may be future alternatives or complements to antibiotics. PMID:20107000

Enoyl-Acyl Carrier Protein Reductase I (FabI) Is Essential for the Intracellular Growth of Listeria monocytogenes

PubMed Central

Ericson, Megan E.; Frank, Matthew W.

2016-01-01

Enoyl-acyl carrier protein reductase catalyzes the last step in each elongation cycle of type II bacterial fatty acid synthesis and is a key regulatory protein in bacterial fatty acid synthesis. Genes of the facultative intracellular pathogen Listeria monocytogenes encode two functional enoyl-acyl carrier protein isoforms based on their ability to complement the temperature-sensitive growth phenotype of Escherichia coli strain JP1111 [fabI(Ts)]. The FabI isoform was inactivated by the FabI selective inhibitor AFN-1252, but the FabK isoform was not affected by the drug, as expected. Inhibition of FabI by AFN-1252 decreased endogenous fatty acid synthesis by 80% and lowered the growth rate of L. monocytogenes in laboratory medium. Robust exogenous fatty acid incorporation was not detected in L. monocytogenes unless the pathway was partially inactivated by AFN-1252 treatment. However, supplementation with exogenous fatty acids did not restore normal growth in the presence of AFN-1252. FabI inactivation prevented the intracellular growth of L. monocytogenes, showing that neither FabK nor the incorporation of host cellular fatty acids was sufficient to support the intracellular growth of L. monocytogenes. Our results show that FabI is the primary enoyl-acyl carrier protein reductase of type II bacterial fatty acid synthesis and is essential for the intracellular growth of L. monocytogenes. PMID:27736774

Enoyl-Acyl Carrier Protein Reductase I (FabI) Is Essential for the Intracellular Growth of Listeria monocytogenes.

PubMed

Yao, Jiangwei; Ericson, Megan E; Frank, Matthew W; Rock, Charles O

2016-12-01

Enoyl-acyl carrier protein reductase catalyzes the last step in each elongation cycle of type II bacterial fatty acid synthesis and is a key regulatory protein in bacterial fatty acid synthesis. Genes of the facultative intracellular pathogen Listeria monocytogenes encode two functional enoyl-acyl carrier protein isoforms based on their ability to complement the temperature-sensitive growth phenotype of Escherichia coli strain JP1111 [fabI(Ts)]. The FabI isoform was inactivated by the FabI selective inhibitor AFN-1252, but the FabK isoform was not affected by the drug, as expected. Inhibition of FabI by AFN-1252 decreased endogenous fatty acid synthesis by 80% and lowered the growth rate of L. monocytogenes in laboratory medium. Robust exogenous fatty acid incorporation was not detected in L. monocytogenes unless the pathway was partially inactivated by AFN-1252 treatment. However, supplementation with exogenous fatty acids did not restore normal growth in the presence of AFN-1252. FabI inactivation prevented the intracellular growth of L. monocytogenes, showing that neither FabK nor the incorporation of host cellular fatty acids was sufficient to support the intracellular growth of L. monocytogenes Our results show that FabI is the primary enoyl-acyl carrier protein reductase of type II bacterial fatty acid synthesis and is essential for the intracellular growth of L. monocytogenes. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Response of Escherichia coli growth rate to osmotic shock.

PubMed

Rojas, Enrique; Theriot, Julie A; Huang, Kerwyn Casey

2014-05-27

It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless "stored" growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan.

Response of Escherichia coli growth rate to osmotic shock

PubMed Central

Rojas, Enrique; Theriot, Julie A.; Huang, Kerwyn Casey

2014-01-01

It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless “stored” growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan. PMID:24821776

Fast coliform detection in portable microbe enrichment unit (PMEU) with Colilert(®) medium and bubbling.

PubMed

Hakalehto, Elias; Heitto, Anneli; Heitto, Lauri

2013-09-01

Laboratory strains of coliforms Escherichia coli and Klebsiella mobilis were used to artificially contaminate water samples in two different cultivation and detection systems, without and with bubble flow. Samples were collected with an automated system (ASCS). The positive coliform signal caused the color change into yellow (at 550-570nm). This signal could also be transmitted on-line to cell phones. E. coli containing samples emitted UV fluorescence at 480-560nm when activated by UV light. If cultivation was started with inocula varying from 10,000 to 1cfu/ml, the positive detection was obtained between 2 and 18h, respectively, in Colilert medium using Coline PMEU device without gas bubbling. Accordingly, a single K. mobilis cell produced detectable growth in 18h. Various clinical E. coli strains were compared to each other with equal inoculum sizes, and they showed slight variations in the initiation and speed of growth. The gas bubble flow in PMEU Spectrion promoted the mixing and interaction of bacteria and indicator media and speeded the onset of growth. Carbon dioxide also accelerated bacterial growth. In the presence of vancomycin, the onset of E. coli culture growth was speeded up by the volatile outlet flow from previous cultures. In the last cultivation syringe in a series of five, the lag phase disappeared and the growth of the inoculum continued without major interruption. the stimulation of the cultures by the gas flow turned out to be a useful means for improving the detection of indicator bacteria. It could also be used in combination with antibiotic selection in the broth medium. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Effect of Oxygen-Supply Rates on Growth of Escherichia coli

PubMed Central

McDaniel, L. E.; Bailey, E. G.; Zimmerli, A.

1965-01-01

The effect of oxygen-supply rates on bacterial growth was studied in commercially available unbaffled and baffled flasks with the use of Escherichia coli in a synthetic medium as a test system. The amount of growth obtained depended on the oxygen-supply rate. Based on oxygen-absorption rates (OAR) measured by the rate of sulfite oxidation, equal OAR values in different types of flasks did not give equal amounts of growth. However, growth was essentially equal at the equal sulfite-oxidation rates when these were determined in the presence of killed whole cultures. Specific growth rates were reduced only at oxygen-supply rates much lower than those at which the total amount of growth was reduced. For the physical set-up used in this work and with the biological system employed, Bellco 598 flasks and flasks fitted with Biotech stainless-steel baffles gave satisfactory results at workable broth volumes; unbaffled and Bellco 600 flasks did not. PMID:14264837

Chemically Defined Medium and Caenorhabditis elegans: A Powerful Approach

NASA Technical Reports Server (NTRS)

Szewczyk, N. J.; Kozak, E.; Conley, C. A.

2003-01-01

C. elegans has been established as a powerful genetic system. Growth in a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of me in large-scale growth and screening of animals. Here we present our initial results from developing culture systems with CeMM. We find that CeMM is versatile and culturing is simple. CeMM can be used in a solid or liquid state, it can be stored unused for at least a year, unattended actively growing cultures may be maintained longer than with standard techniques, and standard C. elegans protocols work well with animals grown in defined medium. We also find that there are caveats of using defined medium. Animals in defined medium grow more slowly than on standard medium, appear to display adaptation to the defined medium, and display altered growth rates as they change defined medium composition. As was suggested with the introduction of C. elegans as a potential genetic system, use of defined medium with C. elegans should prove a powerful tool.

Efficiency of plant growth-promoting P-solubilizing Bacillus circulans CB7 for enhancement of tomato growth under net house conditions.

PubMed

Mehta, Preeti; Walia, Abhishek; Kulshrestha, Saurabh; Chauhan, Anjali; Shirkot, Chand Karan

2015-01-01

P-solubilizing bacterial isolate CB7 isolated from apple rhizosphere soil of Himachal Pradesh, India was identified as Bacillus circulans on the basis of phenotypic characteristics, biochemical tests, fatty acid methyl esters analysis, and 16S rRNA gene sequence. The isolate exhibited plant growth-promoting traits of P-solubilization, auxin, 1-aminocyclopropane-1-carboxylate deaminase activity, siderophore, nitrogenase activity, and antagonistic activity against Dematophora necatrix. In vitro studies revealed that P-solubilization and other plant growth-promoting traits were dependent on the presence of glucose in PVK medium and removal of yeast extract had no significant effect on plant growth-promoting traits. Plant growth-promoting traits of isolate CB7 were repressed in the presence of KH2 PO4 . P-solubilization activity was associated with the release of organic acids and a drop in the pH of the Pikovskaya's medium. HPLC analysis detected gluconic and citric acid as major organic acids in the course of P-solubilization. Remarkable increase was observed in seed germination (22.32%), shoot length (15.91%), root length (25.10%), shoot dry weight (52.92%) and root dry weight (31.4%), nitrogen (18.75%), potassium (57.69%), and phosphorus (22.22%) content of shoot biomass over control. These results demonstrate that isolate CB7 has the promising PGPR attributes to be developed as a biofertilizer to enhance soil fertility and promote plant growth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

On the intrinsic constraint of bacterial growth rate: M. tuberculosis's view of the protein translation capacity.

PubMed

Zhu, Manlu; Dai, Xiongfeng

2018-01-15

In nature, the maximal growth rates vary widely among different bacteria species. Fast-growing bacteria species such as Escherichia coli can have a shortest generation time of 20 min. Slow-growing bacteria species are perhaps best known for Mycobacterium tuberculosis, a human pathogen with a generation time being no less than 16 h. Despite of the significant progress made on understanding the pathogenesis of M. tuberculosis, we know little on the origin of its intriguingly slow growth. From a global view, the intrinsic constraint of the maximal growth rate of bacteria remains to be a fundamental question in microbiology. In this review, we analyze and discuss this issue from the angle of protein translation capacity, which is the major demand for cell growth. Based on quantitative analysis, we propose four parameters: rRNA chain elongation rate, abundance of RNA polymerase engaged in rRNA synthesis, polypeptide chain elongation rate, and active ribosome fraction, which potentially limit the maximal growth rate of bacteria. We further discuss the relation of these parameters with the growth rate for M. tuberculosis as well as other bacterial species. We highlight future comprehensive investigation of these parameters for different bacteria species to understand how bacteria set their own specific growth rates.

Mechanisms of Bacterial (Serratia marcescens) Attachment to, Migration along, and Killing of Fungal Hyphae

PubMed Central

Hover, Tal; Maya, Tal; Ron, Sapir; Sandovsky, Hani; Shadkchan, Yana; Kijner, Nitzan; Mitiagin, Yulia; Fichtman, Boris; Harel, Amnon; Shanks, Robert M. Q.; Bruna, Roberto E.; García-Véscovi, Eleonora

2016-01-01

We have found a remarkable capacity for the ubiquitous Gram-negative rod bacterium Serratia marcescens to migrate along and kill the mycelia of zygomycete molds. This migration was restricted to zygomycete molds and several basidiomycete species. No migration was seen on any molds of the phylum Ascomycota. S. marcescens migration did not require fungal viability or surrounding growth medium, as bacteria migrated along aerial hyphae as well. S. marcescens did not exhibit growth tropism toward zygomycete mycelium. Bacterial migration along hyphae proceeded only when the hyphae grew into the bacterial colony. S. marcescens cells initially migrated along the hyphae, forming attached microcolonies that grew and coalesced to generate a biofilm that covered and killed the mycelium. Flagellum-defective strains of S. marcescens were able to migrate along zygomycete hyphae, although they were significantly slower than the wild-type strain and were delayed in fungal killing. Bacterial attachment to the mycelium does not necessitate type 1 fimbrial adhesion, since mutants defective in this adhesin migrated equally well as or faster than the wild-type strain. Killing does not depend on the secretion of S. marcescens chitinases, as mutants in which all three chitinase genes were deleted retained wild-type killing abilities. A better understanding of the mechanisms by which S. marcescens binds to, spreads on, and kills fungal hyphae might serve as an excellent model system for such interactions in general; fungal killing could be employed in agricultural fungal biocontrol. PMID:26896140

Indoor Heating Drives Water Bacterial Growth and Community Metabolic Profile Changes in Building Tap Pipes during the Winter Season

PubMed Central

Zhang, Hai-Han; Chen, Sheng-Nan; Huang, Ting-Lin; Shang, Pan-Lu; Yang, Xiao; Ma, Wei-Xing

2015-01-01

The growth of the bacterial community harbored in indoor drinking water taps is regulated by external environmental factors, such as indoor temperature. However, the effect of indoor heating on bacterial regrowth associated with indoor drinking water taps is poorly understood. In the present work, flow cytometry and community-level sole-carbon-source utilization techniques were combined to explore the effects of indoor heating on water bacterial cell concentrations and community carbon metabolic profiles in building tap pipes during the winter season. The results showed that the temperature of water stagnated overnight (“before”) in the indoor water pipes was 15–17 °C, and the water temperature decreased to 4–6 °C after flushing for 10 min (“flushed”). The highest bacterial cell number was observed in water stagnated overnight, and was 5–11 times higher than that of flushed water. Meanwhile, a significantly higher bacterial community metabolic activity (AWCD590nm) was also found in overnight stagnation water samples. The significant “flushed” and “taps” values indicated that the AWCD590nm, and bacterial cell number varied among the taps within the flushed group (p < 0.01). Heatmap fingerprints and principle component analyses (PCA) revealed a significant discrimination bacterial community functional metabolic profiles in the water stagnated overnight and flushed water. Serine, threonine, glucose-phosphate, ketobutyric acid, phenylethylamine, glycerol, putrescine were significantly used by “before” water samples. The results suggested that water stagnated at higher temperature should be treated before drinking because of bacterial regrowth. The data from this work provides useful information on reasonable utilization of drinking water after stagnation in indoor pipes during indoor heating periods. PMID:26516885

Cholesterol supplementation improves growth rates of Histomonas meleagridis in vitro.

PubMed

Gruber, Janine; Pletzer, Alena; Hess, Michael

2018-02-01

Research on the energy metabolism of various protozoan parasites showed the essentiality and benefits of cholesterol in the cultivation of these organisms. However, not much is known about the energy metabolism of Histomonas meleagridis, although such information is of high importance to improve cultivation of the parasite for advancements in diagnostics, research and vaccine development. By supplementing a serum enriched cultivation medium with cholesterol, numbers of parasites could be doubled in comparison to unsupplemented negative controls. This effect was demonstrated for two different strains of the parasite, at different levels of in vitro-passages and for histomonads under xenic or monoxenic settings. Supplementing medium free of serum with cholesterol, resulted in significant growth of the parasite over 72 h. However, there were differences in growth behaviour in serum free medium between the different histomonad cultures and continuous passaging of the cultures without serum was not possible. Monitoring the bacterial growth of two different co-cultivated E. coli strains in monoxenic histomonad cultures during these experiments showed that there was no significant impact of cholesterol on the bacteria. Therefore, a direct effect of cholesterol on the parasite itself could be demonstrated. The results of these experiments supply new insights into the metabolism of H. meleagridis and it can be concluded that cholesterol is an important component to enhance parasite growth in vitro. Copyright © 2018 Elsevier Inc. All rights reserved.

Effect of extremely low frequency electromagnetic fields on growth rate and morphology of bacteria.

PubMed

Inhan-Garip, Ayse; Aksu, Burak; Akan, Zafer; Akakin, Dilek; Ozaydin, A Nilufer; San, Tangul

2011-12-01

To determine the effect of extremely low frequency (<300 Hz) electromagnetic fields (ELF-EMF) on the growth rate of Gram-positive and Gram-negative bacteria and to determine any morphological changes that might have been caused by ELF-EMF. Six bacterial strains, three Gram-negative and three Gram-positive were subjected to 50 Hz, 0.5 mT ELF-EMF for 6 h. To determine growth rate after ELF-EMF application, bacteria exposed to ELF-EMF for 3 h were collected, transferred to fresh medium and cultured without field application for another 4 h. Growth-rate was determined by optical density (OD) measurements made every hour. Morphological changes were determined with Transmission electron microscopy (TEM) for two gram-negative and two gram-positive strains collected after 3 h of field application. A decrease in growth rate with respect to control samples was observed for all strains during ELF-EMF application. The decrease in growth-rate continued when exposed bacteria were cultured without field application. Significant ultrastructural changes were observed in all bacterial strains, which were seen to resemble the alterations caused by cationic peptides. This study shows that ELF-EMF induces a decrease in growth rate and morphological changes for both Gram-negative and Gram-positive bacteria.

Population Dynamics of a Salmonella Lytic Phage and Its Host: Implications of the Host Bacterial Growth Rate in Modelling

PubMed Central

Santos, Sílvio B.; Carvalho, Carla; Azeredo, Joana; Ferreira, Eugénio C.

2014-01-01

The prevalence and impact of bacteriophages in the ecology of bacterial communities coupled with their ability to control pathogens turn essential to understand and predict the dynamics between phage and bacteria populations. To achieve this knowledge it is essential to develop mathematical models able to explain and simulate the population dynamics of phage and bacteria. We have developed an unstructured mathematical model using delay-differential equations to predict the interactions between a broad-host-range Salmonella phage and its pathogenic host. The model takes into consideration the main biological parameters that rule phage-bacteria interactions likewise the adsorption rate, latent period, burst size, bacterial growth rate, and substrate uptake rate, among others. The experimental validation of the model was performed with data from phage-interaction studies in a 5 L bioreactor. The key and innovative aspect of the model was the introduction of variations in the latent period and adsorption rate values that are considered as constants in previous developed models. By modelling the latent period as a normal distribution of values and the adsorption rate as a function of the bacterial growth rate it was possible to accurately predict the behaviour of the phage-bacteria population. The model was shown to predict simulated data with a good agreement with the experimental observations and explains how a lytic phage and its host bacteria are able to coexist. PMID:25051248

Protein deposition and its effect on bacterial adhesion to contact lenses.

PubMed

Omali, Negar Babaei; Zhu, Hua; Zhao, Zhenjun; Willcox, Mark D P

2013-06-01

Bacterial adhesion to contact lenses is believed to be the initial step for the development of several adverse reactions that occur during lens wear such as microbial keratitis. This study examined the effect of combinations of proteins on the adhesion of bacteria to contact lenses. Unworn balafilcon A and senofilcon A lenses were soaked in commercially available pure protein mixtures to achieve the same amount of various proteins as found ex vivo. These lenses were then exposed to Pseudomonas aeruginosa and Staphylococcus aureus. Following incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. The possible effect of proteins on bacterial growth was investigated by incubating bacteria in medium containing protein. Although there was a significant (p < 0.003) increase in the total or viable counts of one strain of S. aureus (031) on balafilcon A lenses soaked in the lysozyme/lactoferrin combination, the protein adhered to lenses did not alter the adhesion of any other strains of P. aeruginosa or S. aureus (p > 0.05). Growth of S. aureus 031 (p < 0.0001) but not of P. aeruginosa 6294 was stimulated by addition of lysozyme/lactoferrin combination (2.8/0.5 mg/mL). Addition of lipocalin did not affect the growth of any strains tested (p > 0.05). Adsorption of amounts of lysozyme and lactoferrin or lipocalin equivalent to those extracted from worn contact lenses did not affect the adhesion of most strains of S. aureus or P. aeruginosa to lens surfaces.

Reduced bacterial growth and increased osteoblast proliferation on titanium with a nanophase TiO2 surface treatment.

PubMed

Bhardwaj, Garima; Webster, Thomas J

2017-01-01

The attachment and initial growth of bacteria on an implant surface dictates the progression of infection. Treatment often requires aggressive antibiotic use, which does not always work. To overcome the difficulties faced in systemic and local antibiotic delivery, scientists have forayed into using alternative techniques, which includes implant surface modifications that prevent initial bacterial adhesion, foreign body formation, and may offer a controlled inflammatory response. The current study focused on using electrophoretic deposition to treat titanium with a nanophase titanium dioxide surface texture to reduce bacterial adhesion and growth. Two distinct nanotopographies were analyzed, Ti-160, an antimicrobial surface designed to greatly reduce bacterial colonization, and Ti-120, an antimicrobial surface with a topography that upregulates osteoblast activity while reducing bacterial colonization; the number following Ti in the nomenclature represents the atomic force microscopy root-mean-square roughness value in nanometers. There was a 95.6% reduction in Staphylococcus aureus (gram-positive bacteria) for the Ti-160-treated surfaces compared to the untreated titanium alloy controls. There was a 90.2% reduction in Pseudomonas aeruginosa (gram-negative bacteria) on Ti-160-treated surfaces compared to controls. For ampicillin-resistant Escherichia coli , there was an 81.1% reduction on the Ti-160-treated surfaces compared to controls. Similarly for surfaces treated with Ti-120, there was an 86.8% reduction in S. aureus , an 82.1% reduction in P. aeruginosa , and a 48.6% reduction in ampicillin-resistant E. coli . The Ti-120 also displayed a 120.7% increase at day 3 and a 168.7% increase at day 5 of osteoblast proliferation over standard titanium alloy control surfaces. Compared to untreated surfaces, Ti-160-treated titanium surfaces demonstrated a statistically significant 1 log reduction in S. aureus and P. aeruginosa , whereas Ti-120 provided an additional

Growth of strain SES-3 with arsenate and other diverse electron acceptors

USGS Publications Warehouse

Laverman, A.M.; Blum, J.S.; Schaefer, J.K.; Phillips, E.J.P.; Lovley, D.R.; Oremland, R.S.

1995-01-01

The selenate-respiring bacterial strain SES-3 was able to use a variety of inorganic electron acceptors to sustain growth. SES-3 grew with the reduction of arsenate to arsenite, Fe(III) to Fe(II), or thiosulfate to sulfide. It also grew in medium in which elemental sulfur, Mn(IV), nitrite, trimethylamine N-oxide, or fumarate was provided as an electron acceptor. Growth on oxygen was microaerophilic. There was no growth with arsenite or chromate. Washed suspensions of cells grown on selenate or nitrate had a constitutive ability to reduce arsenate but were unable to reduce arsenite. These results suggest that strain SES-3 may occupy a niche as an environmental opportunist by being able to take advantage of a diversity of electron acceptors.

Investigation of Endophytic Bacterial Community in Supposedly Axenic Cultures of Pineapple and Orchids with Evidence on Abundant Intracellular Bacteria.

PubMed

Esposito-Polesi, Natalia Pimentel; de Abreu-Tarazi, Monita Fiori; de Almeida, Cristina Vieira; Tsai, Siu Mui; de Almeida, Marcílio

2017-01-01

Asepsis, defined as the absence of microbial contamination, is one of the most important requirements of plant micropropagation. In long-term micropropagated cultures, there may occasionally occur scattered microorganism growth in the culture medium. These microorganisms are common plant components and are known as latent endophytes. Thus, the aim of this research was to investigate the presence of endophytic bacteria in asymptomatic pineapple and orchid microplants, which were cultivated in three laboratories for 1 year. Isolation and characterization of bacterial isolates, PCR-DGGE from total genomic DNA of microplants and ultrastructural analysis of leaves were performed. In the culture-dependent technique, it was only possible to obtain bacterial isolates from pineapple microplants. In this case, the bacteria genera identified in the isolation technique were Bacillus, Acinetobacter, and Methylobacterium. The scanning electron microscopy and transmission electron microscopy (SEM and TEM) analyses revealed the presence of endophytic bacteria in intracellular spaces in the leaves of pineapple and orchid microplants, independent of the laboratory or cultivation protocol. Our results strongly indicate that there are endophytic bacterial communities inhabiting the microplants before initiation of the in vitro culture and that some of these endophytes persist in their latent form and can also grow in the culture medium even after long-term micropropagation, thus discarding the concept of "truly axenic plants."

Bacterial physiological diversity in the rhizosphere of range plants in response to retorted shale stress. [Agropyron smithii Rydb; Atriplex canescens (Pursh) Nutt

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

Metzger, W.C.; Klein, D.A.; Redente, E.F.

1986-10-01

Bacterial populations were isolated from the soil-root interface and root-free regions of Agropyron smithii Rydb. and Atriplex canescens (Pursh) Nutt. grown in soil, retorted shale, or soil over shale. Bacteria isolated from retorted shale exhibited a wider range of tolerance to alkalinity and salinity and decreased growth on amino acid substrates compared with bacteria from soil and soil-over-shale environments. Exoenzyme production was only slightly affected by growth medium treatment. Viable bacterial populations were higher in the rhizosphere and rhizoplane of plants grown in retorted shale than in plants grown in soil or soil over shale. In addition, a greater numbermore » of physiological groups of rhizosphere bacteria was observed in retorted shale, compared with soil alone. Two patterns of community similarity were observed in comparisons of bacteria from soil over shale with those from soil and retorted-shale environments. Root-associated populations from soil over shale had a higher proportion of physiological groups in common with those from the soil control than those from the retorted-shale treatment. However, in non-rhizosphere populations, bacterial groups from soil over shale more closely resembled the physiological groups from retorted shale.« less