Project description:Anaerobic digestion is a popular and effective microbial process for waste treatment. The performance of anaerobic digestion processes is contingent on the balance of the microbial food web in utilizing various substrates. Recently, co-digestion, i.e., supplementing the primary substrate with an organic-rich co-substrate has been exploited to improve waste treatment efficiency. Yet the potential effects of elevated organic loading on microbial functional gene community remains elusive. In this study, functional gene array (GeoChip 5.0) was used to assess the response of microbial community to the addition of poultry waste in anaerobic digesters treating dairy manure. Consistent with 16S rRNA gene sequences data, GeoChip data showed that microbial community compositions were significantly shifted in favor of copiotrophic populations by co-digestion, as taxa with higher rRNA gene copy number such as Bacilli were enriched. The acetoclastic methanogen Methanosarcina was also enriched, while Methanosaeta was unaltered but more abundant than Methanosarcina throughout the study period. The microbial functional diversity involved in anaerobic digestion were also increased under co-digestion.
Project description:Analysis of Pseudomonas aeruginosa transcriptomes during infection has identified a gene, PA1414 (PAO1 locus tag), that is highly expressed in various types of human infection. This gene was also found to be highly induced under low oxygen conditions, including anaerobic condition as well as static cultivation. Here we compared the proteomes of P. aeruginosa PA14 and the PA1414 mutant during anaerobic cultivation in Brain Heart Infusion (BHI) broth supplemented with 50 mM nitrate to identify the pathways regulated by PA1414.
Project description:Extremely low specific growth rates (below 0.01 h-1) represent a largely unexplored area of microbial physiology. Retentostats enable controlled, energy-limited cultivation at near-zero specific growth rates while avoiding starvation. In this study, anaerobic, glucose-limited retentostats were used to analyze physiological and genome-wide transcriptional responses of Saccharomyces cerevisiae to cultivation at near-zero specific growth rates. Cultures at near-zero specific growth rates exhibited several characteristics previously associated with quiescence, including accumulation of storage polymers and an increased expression of genes involved in storage metabolism, autophagy and exit from the replicative cell cycle into G0. Analysis of transcriptome data from glucose-limited retentostat and chemostat cultures showed, as specific growth rate was decreased, quiescence-related transcriptional responses already set in at specific growth rates above 0.025 h-1. Many genes involved in mitochondrial processes were specifically upregulated at near-zero specific growth rates, possibly reflecting an increased turn-over of organelles under these conditions. Prolonged (> 2 weeks) cultivation in retentostat cultures led to induction of several genes that were previously implicated in chronological ageing. These observations stress the need for systematic dissection of physiological responses to slow growth, quiescence, ageing and starvation and indicate that controlled cultivation systems such as retentostats can contribute to this goal.
Project description:Extremely low specific growth rates (below 0.01 h-1) represent a largely unexplored area of microbial physiology. Retentostats enable controlled, energy-limited cultivation at near-zero specific growth rates while avoiding starvation. In this study, anaerobic, glucose-limited retentostats were used to analyze physiological and genome-wide transcriptional responses of Saccharomyces cerevisiae to cultivation at near-zero specific growth rates. Cultures at near-zero specific growth rates exhibited several characteristics previously associated with quiescence, including accumulation of storage polymers and an increased expression of genes involved in storage metabolism, autophagy and exit from the replicative cell cycle into G0. Analysis of transcriptome data from glucose-limited retentostat and chemostat cultures showed, as specific growth rate was decreased, quiescence-related transcriptional responses already set in at specific growth rates above 0.025 h-1. Many genes involved in mitochondrial processes were specifically upregulated at near-zero specific growth rates, possibly reflecting an increased turn-over of organelles under these conditions. Prolonged (> 2 weeks) cultivation in retentostat cultures led to induction of several genes that were previously implicated in chronological ageing. These observations stress the need for systematic dissection of physiological responses to slow growth, quiescence, ageing and starvation and indicate that controlled cultivation systems such as retentostats can contribute to this goal. Independent duplicate retentostat cultures were subjected to microarray analysis at four time points after switching the effluent line to the filter unit (2, 9, 16 and 22 d). Microarray analysis of independent, triplicate anaerobic glucose-limited chemostat cultures grown at a specific growth rate of 0.025 h-1 (t = 0) were also performed as part of this study, resulting in a dataset of 11 arrays.
Project description:To get insights in the electrogenic anaerobic lifestyle of P. putida KT2440 cultivated in a bioelectrochemical system (BES), we employed whole genome microarray expression profile.
Project description:Lactobacillus plantarum WCFS1 was grown under anaerobic carbon-limited conditions in a chemostat with complete biomass retention (retentostat). In this cultivation system, the biomass concentration progressively increases while the dilution rate is kept constant, resulting in decreased specific susbtrate availibility, and hence, a progressive decrease in the specific growth rate. During the progressive transition from growth to virtually no growth, the global changes occurring at the level of metabolism and gene expression were studied using a genome-scale metabolic model and DNA microarrays.