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https://www.readbyqxmd.com/read/28426144/a-multiplex-culture-system-for-the-long-term-growth-of-fission-yeast-cells
#1
Celine Callens, Nelson C Coelho, Aaron W Miller, Maria Rosa Domino Sananes, Maitreya J Dunham, Matthieu Denoual, Damien Coudreuse
Maintenance of long-term cultures of yeast cells is central to a broad range of investigations, from metabolic studies to laboratory evolution assays. However, repeated dilutions of batch cultures lead to variations in medium composition, with implications for cell physiology. In S. cerevisiae, powerful miniaturized chemostat setups, or ministat arrays, have been shown to allow for constant dilution of multiple independent cultures. Here we set out to adapt these arrays for continuous culture of a morphologically and physiologically distinct yeast, the fission yeast Schizosaccharomyces pombe, with the goal of maintaining constant population density over time...
April 20, 2017: Yeast
https://www.readbyqxmd.com/read/28389726/tracing-aquatic-priming-effect-during-microbial-decomposition-of-terrestrial-dissolved-organic-carbon-in-chemostat-experiments
#2
Karoline Morling, Julia Raeke, Norbert Kamjunke, Thorsten Reemtsma, Jörg Tittel
Microbial decomposition of terrestrial carbon may be enhanced by the addition of easily decomposable compounds, a phenomenon referred to as priming effect. We investigated the microbial decomposition of terrestrial dissolved organic carbon (DOC) in one-stage and two-stage flow-through cultures (chemostats) in the absence and presence of growing phytoplankton as phytoplankton-derived organic matter might facilitate the mineralization of more refractory terrestrial compounds. Peat water and soil leachate were used as terrestrial substrates, and only slight DOC decomposition was observed in the absence of phytoplankton for both substrates...
April 7, 2017: Microbial Ecology
https://www.readbyqxmd.com/read/28374997/ecological-and-transcriptional-responses-of-anode-respiring-communities-to-nitrate-in-a-microbial-fuel-cell
#3
Varun N Srinivasan, Caitlyn S Butler
A poorly understood phenomenon with a potentially significant impact on electron recovery is competition in microbial fuel cells (MFC) between anode-respiring bacteria and microorganisms that use other electron acceptors. Nitrate is a constituent of different wastewaters and can act as a competing electron acceptor in the anode. Studies investigating the impact of competition on population dynamics in mixed communities in the anode are lacking. Here, we investigated the impact of nitrate at different C/N ratios of 1...
April 18, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28364739/numerical-proof-for-chemostat-chaos-of-shilnikov-s-type
#4
Bo Deng, Maoan Han, Sze-Bi Hsu
A classical chemostat model is considered that models the cycling of one essential abiotic element or nutrient through a food chain of three trophic levels. The long-time behavior of the model was known to exhibit complex dynamics more than 20 years ago. It is still an open problem to prove the existence of chaos analytically. In this paper, we aim to solve the problem numerically. In our approach, we introduce an artificial singular parameter to the model and construct singular homoclinic orbits of the saddle-focus type which is known for chaos generation...
March 2017: Chaos
https://www.readbyqxmd.com/read/28361917/the-low-affinity-glucose-transporter-hxtb-is-also-involved-in-glucose-signalling-and-metabolism-in-aspergillus-nidulans
#5
Thaila Fernanda Dos Reis, Benjamin M Nitsche, Pollyne Borborema Almeida de Lima, Leandro José de Assis, Laura Mellado, Steven D Harris, Vera Meyer, Renato A Corrêa Dos Santos, Diego M Riaño-Pachón, Laure Nicolas Annick Ries, Gustavo H Goldman
One of the drawbacks during second-generation biofuel production from plant lignocellulosic biomass is the accumulation of glucose, the preferred carbon source of microorganisms, which causes the repression of hydrolytic enzyme secretion by industrially relevant filamentous fungi. Glucose sensing, subsequent transport and cellular signalling pathways have been barely elucidated in these organisms. This study therefore characterized the transcriptional response of the filamentous fungus Aspergillus nidulans to the presence of high and low glucose concentrations under continuous chemostat cultivation with the aim to identify novel factors involved in glucose sensing and signalling...
March 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28358919/beware-batch-culture-seasonality-and-niche-construction-predicted-to-favor-bacterial-adaptive-diversification
#6
Charles Rocabert, Carole Knibbe, Jessika Consuegra, Dominique Schneider, Guillaume Beslon
Metabolic cross-feeding interactions between microbial strains are common in nature, and emerge during evolution experiments in the laboratory, even in homogeneous environments providing a single carbon source. In sympatry, when the environment is well-mixed, the reasons why emerging cross-feeding interactions may sometimes become stable and lead to monophyletic genotypic clusters occupying specific niches, named ecotypes, remain unclear. As an alternative to evolution experiments in the laboratory, we developed Evo2Sim, a multi-scale model of in silico experimental evolution, equipped with the whole tool case of experimental setups, competition assays, phylogenetic analysis, and, most importantly, allowing for evolvable ecological interactions...
March 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28323066/development-of-an-economical-autonomous-phstat-system-for-culturing-phytoplankton-under-steady-state-or-dynamic-conditions
#7
Rachel L Golda, Mark D Golda, Jacqueline A Hayes, Tawnya D Peterson, Joseph A Needoba
Laboratory investigations of physiological processes in phytoplankton require precise control of experimental conditions. Chemostats customized to control and maintain stable pH levels (pHstats) are ideally suited for investigations of the effects of pH on phytoplankton physiology, for example in context of ocean acidification. Here we designed and constructed a simple, flexible pHstat system and demonstrated its operational capabilities under laboratory culture conditions. In particular, the system is useful for simulating natural cyclic pH variability within aquatic ecosystems, such as diel fluctuations that result from metabolic activity or tidal mixing in estuaries...
March 18, 2017: Journal of Microbiological Methods
https://www.readbyqxmd.com/read/28287505/design-and-implementation-of-an-automated-illuminating-culturing-and-sampling-system-for-microbial-optogenetic-applications
#8
Cameron J Stewart, Megan N McClean
Optogenetic systems utilize genetically-encoded proteins that change conformation in response to specific wavelengths of light to alter cellular processes. There is a need for culturing and measuring systems that incorporate programmed illumination and stimulation of optogenetic systems. We present a protocol for building and using a continuous culturing apparatus to illuminate microbial cells with programmed doses of light, and automatically acquire and analyze images of cells in the effluent. The operation of this apparatus as a chemostat allows the growth rate and the cellular environment to be tightly controlled...
February 19, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28279939/decadal-and-seasonal-trends-of-nutrient-concentration-and-export-from-highly-managed-coastal-catchments
#9
Yongshan Wan, Lei Wan, Yuncong Li, Peter Doering
Understanding anthropogenic and hydro-climatic influences on nutrient concentrations and export from highly managed catchments often necessitates trend detection using long-term monitoring data. This study analyzed the temporal trend (1979-2014) of total nitrogen (TN) and total phosphorus (TP) concentrations and export from four adjacent coastal basins in south Florida where land and water resources are highly managed through an intricate canal network. The method of integrated seasonal-trend decomposition using LOESS (LOcally weighted regrESSion) was employed for trend detection...
March 2, 2017: Water Research
https://www.readbyqxmd.com/read/28251388/high-performance-recombinant-protein-production-with-escherichia-coli-in-continuously-operated-cascades-of-stirred-tank-reactors
#10
Andreas Schmideder, Dirk Weuster-Botz
The microbial expression of intracellular, recombinant proteins in continuous bioprocesses suffers from low product concentrations. Hence, a process for the intracellular production of photoactivatable mCherry with Escherichia coli in a continuously operated cascade of two stirred-tank reactors was established to separate biomass formation (first reactor) and protein expression (second reactor) spatially. Cascades of miniaturized stirred-tank reactors were implemented, which enable the 24-fold parallel characterization of cascade processes and the direct scale-up of results to the liter scale...
March 1, 2017: Journal of Industrial Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28246966/different-responses-in-the-expression-of-alginases-alginate-polymerase-and-acetylation-genes-during-alginate-production-by-azotobacter-vinelandii-under-oxygen-controlled-conditions
#11
Alvaro Díaz-Barrera, Nataly Maturana, Ivette Pacheco-Leyva, Irene Martínez, Claudia Altamirano
Alginate production and gene expression of genes involved in alginate biosynthesis were evaluated in continuous cultures under dissolved oxygen tension (DOT) controlled conditions. Chemostat at 8% DOT showed an increase in the specific oxygen uptake rate [Formula: see text] from 10.9 to 45.3 mmol g(-1) h(-1) by changes in the dilution rate (D) from 0.06 to 0.10 h(-1), whereas under 1% DOT the [Formula: see text] was not affected. Alginate molecular weight was not affected by DOT. However, chemostat at 1% DOT showed a downregulation up to 20-fold in genes encoding both the alginate polymerase (alg8, alg44), alginate acetylases (algV, algI) and alginate lyase AlgL...
February 28, 2017: Journal of Industrial Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28237996/macromolecular-and-elemental-composition-analyses-of-leuconostoc-mesenteroides-atcc-8293-cultured-in-a-chemostat
#12
Jeongsu Bang, Ling Li, Hyunbin Seong, Ye Won Kwon, Dong-Yup Lee, Nam Soo Han
The cellular composition and metabolic compounds of Leuconostoc mesenteroides ATCC 8293 were analyzed after cultivation in an anaerobic chemostat. Macromolecular composition was 24.4% polysaccharide, 29.7% protein, 7.9% lipid, 2.9% DNA, and 7.4% RNA. Amino acid compositions included large amounts of lysine, glutamic acid, alanine, and leucine. Elements were in order of C > O > N > H > S. The metabolites in chemostat were lactic acid (73.34 mM), acetic acid (7.69 mM), and mannitol (9.93 mM). These data provide a first view of the cellular composition of L...
February 24, 2017: Journal of Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28231156/a-computational-study-of-amensalistic-control-of-listeria-monocytogenes-by-lactococcus-lactis-under-nutrient-rich-conditions-in-a-chemostat-setting
#13
Hassan Khassehkhan, Hermann J Eberl
We study a previously introduced mathematical model of amensalistic control of the foodborne pathogen Listeria monocytogenes by the generally regarded as safe lactic acid bacteria Lactococcus lactis in a chemostat setting under nutrient rich growth conditions. The control agent produces lactic acids and thus affects pH in the environment such that it becomes detrimental to the pathogen while it is much more tolerant to these self-inflicted environmental changes itself. The mathematical model consists of five nonlinear ordinary differential equations for both bacterial species, the concentration of lactic acids, the pH and malate...
September 9, 2016: Foods (Basel, Switzerland)
https://www.readbyqxmd.com/read/28220859/sensitivity-of-chemical-weathering-and-dissolved-carbon-dynamics-to-hydrological-conditions-in-a-typical-karst-river
#14
Jun Zhong, Si-Liang Li, Faxiang Tao, Fujun Yue, Cong-Qiang Liu
To better understand the mechanisms that hydrological conditions control chemical weathering and carbon dynamics in the large rivers, we investigated hydrochemistry and carbon isotopic compositions of dissolved inorganic carbon (DIC) based on high-frequency sampling in the Wujiang River draining the carbonate area in southwestern China. Concentrations of major dissolved solute do not strictly follow the dilution process with increasing discharge, and biogeochemical processes lead to variability in the concentration-discharge relationships...
February 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28220205/global-properties-of-nested-network-model-with-application-to-multi-epitope-hiv-ctl-dynamics
#15
Cameron Browne
Mathematical modeling and analysis can provide insight on the dynamics of ecosystems which maintain biodiversity in the face of competitive and prey-predator interactions. Of primary interests are the underlying structure and features which stabilize diverse ecological networks. Recently Korytowski and Smith (Theor Ecol 8(1):111-120, 2015) proved that a perfectly nested infection network, along with appropriate life history trade-offs, leads to coexistence and persistence of bacteria-phage communities in a chemostat model...
February 20, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28212840/a-density-dependent-model-of-competition-for-one-resource-in-the-chemostat
#16
Radhouane Fekih-Salem, Claude Lobry, Tewfik Sari
This paper deals with a two-microbial species model in competition for a single-resource in the chemostat including general intra- and interspecific density-dependent growth rates with distinct removal rates for each species. In order to understand the effects of intra- and interspecific interference, this general model is first studied by determining the conditions of existence and local stability of steady states. With the same removal rate, the model can be reduced to a planar system and then the global stability results for each steady state are derived...
February 14, 2017: Mathematical Biosciences
https://www.readbyqxmd.com/read/28163782/coupling-and-uncoupling-of-triglyceride-and-beta-carotene-production-by-dunaliella-salina-under-nitrogen-limitation-and-starvation
#17
Hubert Bonnefond, Nina Moelants, Amélie Talec, Patrick Mayzaud, Olivier Bernard, Antoine Sciandra
BACKGROUND: Nitrogen starvation and limitation are known to induce important physiological changes especially in lipid metabolism of microalgae (triglycerides, membrane lipids, beta-carotene, etc.). Although little information is available for Dunaliella salina, it is a promising microalga for biofuel production and biotechnological applications due to its ability to accumulate lipid together with beta-carotene. RESULTS: Batch and chemostat experiments with various degrees of nitrogen limitation, ranging from starvation to nitrogen-replete conditions, were carried out to study carbon storage dynamics (total carbon, lipids, and beta-carotene) in steady state cultures of D...
2017: Biotechnology for Biofuels
https://www.readbyqxmd.com/read/28159643/metabolic-flexibility-of-a-butyrate-pathway-mutant-of-clostridium-acetobutylicum
#18
Minyeong Yoo, Christian Croux, Isabelle Meynial-Salles, Philippe Soucaille
Clostridium acetobutylicum possesses two homologous buk genes, buk (or buk1) and buk2, which encode butyrate kinases involved in the last step of butyrate formation. To investigate the contribution of buk in detail, an in-frame deletion mutant was constructed. However, in all the Δbuk mutants obtained, partial deletions of the upstream ptb gene were observed, and low phosphotransbutyrylase and butyrate kinase activities were measured. This demonstrates that i) buk (CA_C3075) is the key butyrate kinase-encoding gene and that buk2 (CA_C1660) that is poorly transcribed only plays a minor role; and ii) strongly suggests that a Δbuk mutant is not viable if the ptb gene is not also inactivated, probably due to the accumulation of butyryl-phosphate, which might be toxic for the cell...
January 31, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28130571/gaussian-approximations-for-chemostat-models-in-finite-and-infinite-dimensions
#19
Bertrand Cloez, Coralie Fritsch
In a chemostat, bacteria live in a growth container of constant volume in which liquid is injected continuously. Recently, Campillo and Fritsch introduced a mass-structured individual-based model to represent this dynamics and proved its convergence to a more classic partial differential equation. In this work, we are interested in the convergence of the fluctuation process. We consider this process in some Sobolev spaces and use central limit theorems on Hilbert space to prove its convergence in law to an infinite-dimensional Gaussian process...
January 27, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28117390/growth-rate-control-of-flagellar-assembly-in-escherichia-coli-strain-rp437
#20
Martin Sim, Santosh Koirala, David Picton, Henrik Strahl, Paul A Hoskisson, Christopher V Rao, Colin S Gillespie, Phillip D Aldridge
The flagellum is a rotary motor that enables bacteria to swim in liquids and swarm over surfaces. Numerous global regulators control flagellar assembly in response to cellular and environmental factors. Previous studies have also shown that flagellar assembly is affected by the growth-rate of the cell. However, a systematic study has not yet been described under controlled growth conditions. Here, we investigated the effect of growth rate on flagellar assembly in Escherichia coli using steady-state chemostat cultures where we could precisely control the cell growth-rate...
January 24, 2017: Scientific Reports
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