Project description:Pyruvate fermentation pathway and energetics of Desulfovibrio alaskensis strain G20 under syntrophic coculture and fermentative monoculture conditions Expression data for Desulfovibrio alaskensis strain G20 grown in chemostats on pyruvate under respiratory conditions (sulfate-limited and pyruvate-limited monoculture, dilution rate 0.047 and 0.027 h-1), fermentative conditions (monoculture, dilution rate 0.036 h-1), and syntrophic conditions (coculture with Methanococcus maripaludis or Methanospirillum hungatei, dilution rate of 0.047 and 0.027 h-1)
Project description:The syntrophic growth of strain 195 with Desulfovibrio vulgaris Hildenborough (DVH) and/or Methanobacterium congolense (MC) enhanced TCE dechlorination process by faster dechlorination rate and more robust growth. Transcriptomes of strain 195 grown in isolation, co- and tri-cultures were obtained by microarray experiments to find out the differential expressed genes corresponding to the syntrophic growth. Thus we can better understand the role of DVH and MC within this syntrophy.
Project description:Syntrophus aciditrophicus is a model syntrophic bacterium that degrades fatty and aromatic acids into acetate, CO2, formate and H2 that are utilized by methanogens and other hydrogen-consuming microbes. The degradation of benzoate by S. aciditrophicus proceeds by a multi-step pathway that involves many reactive acyl-Coenzyme A species (RACS) as intermediates which can potentially result in Nε-acylation of lysine residues in proteins. Herein, we investigate post-translational modifications in the S. aciditrophicus proteome to identify and characterize a variety of acyl-lysine modifications that correspond to RACS present in the benzoate degradation pathway. Modification levels are sufficient to support post-translational modification analyses without antibody enrichment, enabling the study of a range of acylations located, presumably, on the most extensively acylated proteins. Seven types of acyl modifications were identified throughout the proteome, six of which correspond directly to RACS that are intermediates in the benzoate degradation pathway. Benzoate–degrading proteins are heavily represented among acylated proteins. The presence of functional deacylase enzymes in S. aciditrophicus indicates a potential regulatory system/mechanism by which these bacteria modulate acylation. Uniquely, Nε-acyl-lysine RACS are highly abundant in these syntrophic bacteria, raising the compelling possibility of enzyme modulation during benzoate degradation in this, and potentially, other syntrophic bacteria. Our results outline candidates to further study the impact of acylations within syntrophic systems.
Project description:Acetate is a simple carboxylic acid that is synthesized in various microorganisms. Although acetate toxicity and tolerance have been studied in many microorganisms, little is known about the effects of exogenous acetate on the cell growth of acetogenic bacteria. In this study, we report the phenotypic changes that occurred in the acetogenic bacterium Clostridium sp. AWRP as a result of an adaptive laboratory evolution under acetate challenge. When compared with the wild-type strain, the acetate-adapted strain displayed a tolerance to acetate up to 10 g L-1 and higher biomass yields in batch cultures, although the metabolite profiles greatly varied depending on culture conditions. Interestingly, genome sequencing revealed that the adapted strain harbored three point mutations in the genes encoding an electron-bifurcating hydrogenase, which is crucial to its autotrophic growth on CO2 + H2, in addition to one in the dnaK gene. Transcriptome analysis revealed the global change in the gene expression profile of the acetate-adapted strain. Strikingly, most genes involved in CO2-fixing Wood-Ljungdahl pathway and auxiliary pathways for energy conservation (e.g., Rnf complex, Nfn, etc.) were significantly down-regulated. In addition, we observed that a couple of metabolic pathways associated with dissimilation of nucleosides and carbohydrates were significantly up-regulated in the acetate-adapted strain as well as several amino acid biosynthetic pathways, indicating that the strain might increase its fitness by utilizing organic substrates in response to the down-regulation of carbon fixation. Further investigation into the carbon fixation degeneration of the acetate-adapted strain will provide practical implications in CO2 + H2 fermentation using acetogenic bacteria for long-term continuous fermentation. The transcriptome profiles of the wild-type Clostridium sp. AWRP and its acetate-tolerant derivative 46T-a were compared.
Project description:Expression data for Desulfovibrio alaskensis strain G20 grown on lactate in sulfate-limited monoculture and syntrophic coculture with Methanococcus maripaludis in chemostats at a high growth rate of 0.047h-1
Project description:In the syntrophic interaction between fermentative bacteria (Pelotomaculum thermopropionicum) and methanogenic archaea (methanogens: Methanothemobacter thermautotrophicus), reducing equivalents (e.g., H2) produced by fermentative bacteria should efficiently be consumed by methanogens in order for the fermentation of volatile fatty acids (VFA, e.g., butyrate, propionate, and acetate) to be thermodynamically feasible. It has been known that physical approximation (e.g., coaggregation) between VFA-fermenting syntrophic bacteria (syntrophs) and hydrogenotrophic methanogens is necessary for efficient H2 transfer between them. Our previous study has shown that, at an early exponential growth phase of syntrophic coculture, cells of Pelotomaculum thermopropionicum (syntroph) were connected to cells of Methanothermobacter thermautotrophicus (methanogen) via unidentified extracellular filamentous appendages, after which they started to coaggregate, suggesting that the filamentous appendages may have been important for their syntrophic interaction. The filamentous appendages seemed to specifically connect these syntrophic partners, since such pairwise connection has been observed neither in single-species cultures (monocultures) nor in mixtures with other microbes. <br> We found that P. thermopropionicum has putative gene clusters for flagellum and pilus, while no extracellular filament gene was identified in the M. thermautotrophicus genome. So we examined transcriptome responses of M. thermautotrophicus to the contact with flagellar filament protein (FliC) and flagellar cap protein (FliD) of P. thermopropionicum.
