keyword
MENU ▼
Read by QxMD icon Read
search

chemostat

keyword
https://www.readbyqxmd.com/read/28550811/influence-of-solids-residence-time-and-carbon-storage-on-nitrogen-and-phosphorus-recovery-by-microalgae-across-diel-cycles
#1
D A Gardner-Dale, I M Bradley, J S Guest
Microalgal treatment systems could advance nutrient recovery from wastewater by achieving effluent nitrogen (N) and phosphorus (P) levels below the current limit of technology, but their successful implementation requires an understanding of how design decisions influence nutrient uptake over daily (i.e., diel) cycles. This work demonstrates the ability to influence microalgal N:P recovery ratio via solids residence time (SRT) while maintaining complete nutrient removal across day/night cycles through carbon storage and mobilization...
May 18, 2017: Water Research
https://www.readbyqxmd.com/read/28545207/quality-and-reactivity-of-dissolved-organic-matter-in-a-mediterranean-river-across-hydrological-and-spatial-gradients
#2
Elisabet Ejarque, Anna Freixa, Eusebi Vazquez, Alba Guarch, Stefano Amalfitano, Stefano Fazi, Anna M Romaní, Andrea Butturini
Understanding DOM transport and reactivity in rivers is essential to having a complete picture of the global carbon cycle. In this study, we explore the effects of hydrological variability and downstream transport on dissolved organic matter (DOM) dynamics in a Mediterranean river. We sampled the main stem of the river Tordera from the source to the sea, over a range of fifteen hydrological conditions including extreme events (flood and drought). By exploring spatial and temporal gradients of DOM fluorescence properties, river hydrology was found to be a significant predictor of DOM spatial heterogeneity...
May 20, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28527885/maintenance-of-atp-homeostasis-triggers-metabolic-shifts-in-gas-fermenting-acetogens
#3
Kaspar Valgepea, Renato de Souza Pinto Lemgruber, Kieran Meaghan, Robin William Palfreyman, Tanus Abdalla, Björn Daniel Heijstra, James Bruce Behrendorff, Ryan Tappel, Michael Köpke, Séan Dennis Simpson, Lars Keld Nielsen, Esteban Marcellin
Acetogens are promising cell factories for producing fuels and chemicals from waste feedstocks via gas fermentation, but quantitative characterization of carbon, energy, and redox metabolism is required to guide their rational metabolic engineering. Here, we explore acetogen gas fermentation using physiological, metabolomics, and transcriptomics data for Clostridium autoethanogenum steady-state chemostat cultures grown on syngas at various gas-liquid mass transfer rates. We observe that C. autoethanogenum shifts from acetate to ethanol production to maintain ATP homeostasis at higher biomass concentrations but reaches a limit at a molar acetate/ethanol ratio of ∼1...
May 24, 2017: Cell Systems
https://www.readbyqxmd.com/read/28526017/the-effect-of-hypoxia-on-the-lipidome-of-recombinant-pichia-pastoris
#4
Núria Adelantado, Pablo Tarazona, Karlheinz Grillitsch, Xavier García-Ortega, Sergi Monforte, Francisco Valero, Ivo Feussner, Günther Daum, Pau Ferrer
BACKGROUND: Cultivation of recombinant Pichia pastoris (Komagataella sp.) under hypoxic conditions has a strong positive effect on specific productivity when the glycolytic GAP promoter is used for recombinant protein expression, mainly due to upregulation of glycolytic conditions. In addition, transcriptomic analyses of hypoxic P. pastoris pointed out important regulation of lipid metabolism and unfolded protein response (UPR). Notably, UPR that plays a role in the regulation of lipid metabolism, amino acid metabolism and protein secretion, was found to be upregulated under hypoxia...
May 19, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28499906/a-numerical-approach-to-determine-mutant-invasion-fitness-and-evolutionary-singular-strategies
#5
Coralie Fritsch, Fabien Campillo, Otso Ovaskainen
We propose a numerical approach to study the invasion fitness of a mutant and to determine evolutionary singular strategies in evolutionary structured models in which the competitive exclusion principle holds. Our approach is based on a dual representation, which consists of the modeling of the small size mutant population by a stochastic model and the computation of its corresponding deterministic model. The use of the deterministic model greatly facilitates the numerical determination of the feasibility of invasion as well as the convergence-stability of the evolutionary singular strategy...
May 10, 2017: Theoretical Population Biology
https://www.readbyqxmd.com/read/28497287/role-of-nitrite-in-the-competition-between-denitrification-and-dnra-in-a-chemostat-enrichment-culture
#6
Eveline M van den Berg, Julius L Rombouts, J Gijs Kuenen, Robbert Kleerebezem, Mark C M van Loosdrecht
Denitrification and dissimilatory nitrate reduction to ammonium (DNRA) are two microbial processes that compete for oxidized nitrogen compounds in the environment. The objective of this work was to determine the role of nitrite versus nitrate as terminal electron acceptor on the competition between DNRA and denitrification. Initially, a mixed culture chemostat was operated under nitrate limitation and performed DNRA. Stepwise, the influent nitrate was replaced with nitrite until nitrite was the sole electron acceptor and N-source present...
December 2017: AMB Express
https://www.readbyqxmd.com/read/28497245/single-species-growth-consuming-inorganic-carbon-with-internal-storage-in-a-poorly-mixed-habitat
#7
Sze-Bi Hsu, King-Yeung Lam, Feng-Bin Wang
This paper presents a PDE system modeling the growth of a single species population consuming inorganic carbon that is stored internally in a poorly mixed habitat. Inorganic carbon takes the forms of "CO2" (dissolved CO2 and carbonic acid) and "CARB" (bicarbonate and carbonate ions), which are substitutable in their effects on algal growth. We first establish a threshold type result on the extinction/persistence of the species in terms of the sign of a principal eigenvalue associated with a nonlinear eigenvalue problem...
May 11, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28495957/resolving-the-complex-genetic-basis-of-phenotypic-variation-and-variability-of-cellular-growth
#8
Naomi Ziv, Bentley M Shuster, Mark L Siegal, David Gresham
In all organisms, many traits vary continuously between individuals. Explaining the genetic basis of quantitative trait variation requires comprehensively accounting for genetic and non-genetic factors as well as their interactions. The growth of microbial cells can be characterized by a lag duration, an exponential growth phase and a stationary phase. Parameters that characterize these growth phases can vary among genotypes (phenotypic variation), environmental conditions (phenotypic plasticity) and among isogenic cells in a given environment (phenotypic variability)...
May 11, 2017: Genetics
https://www.readbyqxmd.com/read/28494362/transformation-of-carbon-tetrachloride-and-chloroform-by-trichloroethene-respiring-anaerobic-mixed-cultures-and-supernatant
#9
Kyle E Vickstrom, Mohammad F Azizian, Lewis Semprini
Carbon tetrachloride (CT) and chloroform (CF) were transformed in batch reactor experiments conducted with anaerobic dechlorinating cultures and supernatant (ADC + S) harvested from continuous flow reactors. The Evanite (EV) and Victoria/Stanford (VS) cultures, capable of respiring trichloroethene (TCE), 1,2-cis-dichloroethene (cDCE), and vinyl chloride (VC) to ethene (ETH), were grown in continuous flow reactors receiving an influent feed of saturated TCE (10 mM; 60 mEq) and formate (45 mM; 90 mEq) but no CT or CF...
April 29, 2017: Chemosphere
https://www.readbyqxmd.com/read/28490602/processes-on-the-emergent-landscapes-of-biochemical-reaction-networks-and-heterogeneous-cell-population-dynamics-differentiation-in-living-matters
#10
REVIEW
Sui Huang, Fangting Li, Joseph X Zhou, Hong Qian
The notion of an attractor has been widely employed in thinking about the nonlinear dynamics of organisms and biological phenomena as systems and as processes. The notion of a landscape with valleys and mountains encoding multiple attractors, however, has a rigorous foundation only for closed, thermodynamically non-driven, chemical systems, such as a protein. Recent advances in the theory of nonlinear stochastic dynamical systems and its applications to mesoscopic reaction networks, one reaction at a time, have provided a new basis for a landscape of open, driven biochemical reaction systems under sustained chemostat...
May 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28474106/asymptotic-behavior-of-a-chemostat-model-with-constant-recycle-sludge-concentration
#11
Mohamed Amine Hamra, Karim Yadi
In this work, we study a several species aerobic chemostat model with constant recycle sludge concentration in continuous culture. We reduce the number of parameters by considering a dimensionless model. First, the existence of a global positive uniform attractor for the model with different removal rates is proved using the theory of dissipative dynamical systems. Hence, we investigate the asymptotic behavior of the model under small perturbations using methods of singular perturbation theory and we prove that, in the case of two species in competition, the unique equilibrium which is positive is globally asymptotically stable...
May 4, 2017: Acta Biotheoretica
https://www.readbyqxmd.com/read/28456462/analysis-of-stability-to-cheaters-in-models-of-antibiotic-degrading-microbial-communities
#12
András Szilágyi, Gergely Boza, István Scheuring
Antibiotic resistance carried out by antibiotic degradation has been suggested recently as a new mechanism to maintain coexistence of microbial species competing on a single limiting resource, even in well-mixed homogeneous environments. Species diversity and community stability, however, critically depend on resistance against social cheaters, mutants that do not invest in production, but still enjoy the benefits provided by others. Here we investigate how different mutant cheaters affect the stability of antibiotic producing and degrading microbial communities...
April 27, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28450459/experimental-evolution-reveals-favored-adaptive-routes-to-cell-aggregation-in-yeast
#13
Elyse A Hope, Clara J Amorosi, Aaron W Miller, Kolena Dang, Caiti Smukowski Heil, Maitreya J Dunham
Yeast flocculation is a community-building cell aggregation trait that is an important mechanism of stress resistance and a useful phenotype for brewers; however, it is also a nuisance in many industrial processes, in clinical settings, and in the laboratory. Chemostat-based evolution experiments are impaired by inadvertent selection for aggregation, which we observe in 35% of populations. These populations provide a testing ground for understanding the breadth of genetic mechanisms Saccharomyces cerevisiae uses to flocculate, and which of those mechanisms provide the biggest adaptive advantages...
April 26, 2017: Genetics
https://www.readbyqxmd.com/read/28448019/a-tandem-liquid-chromatography-mass-spectrometry-based-approach-for-metabolite-analysis-of-staphylococcus-aureus
#14
David J Samuels, Zhe Wang, Kyu Y Rhee, Shaun R Brinsmade
In an effort to thwart bacterial pathogens, hosts often limit the availability of nutrients at the site of infection. This limitation can alter the abundances of key metabolites to which regulatory factors respond, adjusting cellular metabolism. In recent years, a number of proteins and RNA have emerged as important regulators of virulence gene expression. For example, the CodY protein responds to levels of branched-chain amino acids and GTP and is widely conserved in low G+C Gram-positive bacteria. As a global regulator in Staphylococcus aureus, CodY controls the expression of dozens of virulence and metabolic genes...
March 28, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28434212/effects-of-environmental-factors-on-cyanobacterial-production-of-odorous-compounds-geosmin-and-2-methylisoborneol
#15
Hyung-Seok Oh, Chang Soo Lee, Ankita Srivastava, Hee-Mock Oh, Chi-Yong Ahn
Geosmin and 2-methylisoborneol (2-MIB), responsible for earthy or musty smell, are a major concern for safe drinking water supplies. This study investigated the effects of environmental factors on odorous compounds production and cell growth in cyanobacterial strains. Anabaena sp. FACHB-1384, a 2-MIB producer, was sensitive to low temperature (<20°C). However, geosmin producers, Anabaena sp. Chusori and Anabaena sp. NIER, were sensitive to high light intensity (>100 μmol/m²/sec), but not to low temperature...
April 21, 2017: Journal of Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28426144/a-multiplex-culture-system-for-the-long-term-growth-of-fission-yeast-cells
#16
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
#17
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
#18
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
#19
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
#20
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
keyword
keyword
103881
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"