Project description:Cell proliferation is achieved by numerous enzyme reactions. Temperature governs the activity of each enzyme, which overall determines the optimal growth temperature. Synthesizing useful chemicals and fuels utilizes only part of the metabolic pathways, especially the central metabolic pathways such as glycolysis and TCA cycle to metabolize glucose. However, the optimal temperature for the activity of the central metabolic pathways is inconclusive whether it is correlated with the optimal temperature for cell proliferation. Here, we found that Corynebacterium glutamicum wild type increased the metabolic activity to consume glucose under anaerobic (oxygen deprived) conditions at 42.5ºC, in which the cell hardly grows under aerobic conditions. Glucose consumption rate was increased by 24% at 42.5ºC compared to that at the optimal growth temperature of 30.0ºC. Transcriptional analysis showed that gapX gene encoding glycelaldehydre-3-phosphate dehydrogenase, glucokinase gene, and a gene involved in glucose uptake were upregulated at 42.5ºC. Production of fermentative lactate was increased by 69% than that at 30.0ºC, whereas succinate production was decreased by 13%. In addition to several glycolytic enzymes, the activity of pyruvate kinase was increased with increasing the temperature, whereas the activity of phosphoenolpyruvate carboxylase in anapleotic pathway leading to succinate synthesis was decreased. However, a metabolically engineered succinate over-producing strain, in which lactate production was shut off and pyruvate carboxylase encoding gene in another anapleotic pathway was overexpressed, produced 34% higher succinate at 42.5ºC than that at 30.0ºC with increased glucose consumption. This study provides the evidence that the optimal reaction temperature for production of fermentative products can be set beyond upper limit of growth temperature in C. glutamicum, and hence it could be applicable for producing various chemicals and fuels in C. glutamicum under anaerobic conditions and non-growing cell reactions in other microorganisms.
Project description:To unravel the adaptation strategies of D. shibae to anaerobic conditions in microaerobic to anaerobic parts of the ocean and to define the underlying regulatory network an anaerobic shift experiment in Salt-Water-Medium in a chemostate was established. Transcriptome analyses were used to investigate the physiological status of D. shibae under this conditions.
Project description:To unravel the adaptation strategies of D. shibae to anaerobic conditions in microaerobic to anaerobic parts of the ocean and to define the underlying regulatory network an anaerobic shift experiment in Salt-Water-Medium in a chemostate was established. Transcriptome analyses were used to investigate the physiological status of D. shibae under this conditions. Dinoroseobacter shibae wild type strain DSM 16493T was grown in a chemostate in saltwater mininmal medium (SWM) mimicking the conditions in the marine habitat under anaerobic conditions. For growth under oxygen depletion the media were supplemented with 50 mM KNO3 to sustain anaerobic respiration. Therefore, D. shibae was grown aerobically in the chemostate until the culture reached the exponential phase, than countinuously cultivaion was started. The dilution rate was 0.1 h-1, establishing the approximate half-maximum growth rate of D. shibae in the exponential phase. The anaerobic shift was initialised after 20 hours by stopping the aeration. The samples were harvested before (as reference) and 30 minutes after stopping the airation. Three biological replica were analyzed. Comparison: Identification of genes induced or repressed under aerobic conditions in the Dinoroseobacter shibae wild type strain DSM 16493T. Here we compared the transcriptome profile of D. shibae wild type strain DSM 16493T grown aerobically in the chemostate in exponential phase with the transcriptome profile of the D. shibae wild type strain DSM 16493T which was grown without aeration for 5, 10, 15, 20, 30, 60 and 120 min.
Project description:Investigation of whole genome gene expression level changes in Thermoplasma acidophilum cultured under aerobic and anaerobic conditions. The analysis are further described in Na Sun, Cuiping Pan, Stephan Nickell, Matthias Mann, Wolfgang Baumeister, and István Nagy, Quantitative proteome and transcriptome analysis of the archaeon Thermoplasma acidophilum cultured under aerobic and anaerobic conditions (submitted).
Project description:Transcript abundance profiles were examined over the first 24 hours of germination in rice grown under anaerobic conditions. Transcript abundance profiles were also examined for rice grown under aerobic conditions for 24 h and then switched to anaerobic conditions and vice versa.
Project description:Listeria monocytogenes is a food-borne pathogen and the causative agent of listeriosis, an infection which typically arises through the consumption of contaminated foodstuffs. L. monocytogenes is a psychotrophic and facultatively anaerobic; properties which permit growth under refrigeration conditions and within modified atmosphere packaging. Through transcriptional changes L. monocytogenes is able to mount adaptive responses against stressors. Such responses typically cross protect against subsequent stresses.
Project description:We found many binding sites for FNR under glucose fermentative anaerobic growth conditions. Also, many binding sites were identified for σ70 under both aerobic and anaerobic growthin conditions. Descirbed in the manuscript "Genome-scale Analysis of E. coli FNR Reveals the Complexity of Bacterial Regulon Structure"
Project description:Prp4-1 and wt strains were grown at 26°C to A600 of 1.0, then an equal volume of 48°C media was added to bring the temperature to 37°C. Both strains were allowed to grow at 37°C and samples were taken at 0 (before shift), 5, 15, 30, 60, and 120 mins after shift to restrictive temperature. Keywords = splicing Keywords: time-course
Project description:Cytochrome oxydases and quinol monooxygenase were removed from the E. coli genome resulting in oxygen-independent physiology We used microarray profiling to identify perturbed metabolic or regulatory functionality resulting in the inability to undergo aerobic-anaerobic shift. Affimetrics E. coli Arrays 2.0, Experiment (ECOM4) under both conditions (+O2/-O2) were analyzed in triplicates and compared to control (MG1655) under same conditions in triplicates
Project description:Actinobacillus pleuropneumoniae is an important porcine respiratory pathogen causing great economic losses in the pig industry worldwide. Oxygen deprivation is a stress that A. pleuropneumoniae will encounter during both early infection and the later, persistent stage. To understand modulation of A. pleuropneumoniae gene expression in response to the stress caused by anaerobic conditions, gene expression profiles under anaerobic and aerobic conditions were compared in this study. The microarray results showed that 631 genes (27.7% of the total ORFs) were differentially expressed in anaerobic conditions. Many genes encoding proteins involved in glycolysis, carbon source uptake systems, pyruvate metabolism, fermentation and the electron respiration transport chain were up-regulated. These changes led to an increased amount of pyruvate, lactate, ethanol and acetate in the bacterial cells as confirmed by metabolite detection. Genes encoding proteins involved in cell surface structures, especially biofilm formation, peptidoglycan biosynthesis and lipopolysaccharide biosynthesis were up-regulated as well. Biofilm formation was significantly enhanced under anaerobic conditions. These results indicate that induction of central metabolism is important for basic survival of A. pleuropneumoniae after a shift to an anaerobic environment. Enhanced biofilm formation may contribute to the persistence of this pathogen in the damaged anaerobic host tissue and also in the early colonization stage. These discoveries give new insights into adaptation mechanisms of A. pleuropneumoniae in response to environmental stress.