Project description:Inhibition of the anaerobic digestion process through accumulation of volatile fatty acids (VFA) is a recurring problem which is the result of unbalanced growth between acidogenic bacteria and methanogens. A speedy recovery is essential for an establishment of a feasible economical biogas productions. Yet, little is known regarding the organisms participating in the recovery. In this study the organisms involved in the recovery were studied using protein-stable isotope probing (Protein-SIP) and mapping this data onto a binned metagenome. Under acetate-accumulated simulating conditions a formation of 13C-labeled CO2 and CH4 was detected immediately after the addition of [U-13C]acetate, indicative of a high turnover rate of acetate. Several labeled peptides were detected in protein-SIP analysis. These 13C-labeled peptides were mapped onto a binned metagenome for improved taxanomical classification of the organisms involved. The results revealed that Methanosarcina and Methanoculleus were actively involved in acetate turnover, as were five subspecies of Clostridia and one Bacteroidetes. The organisms affiliating with Clostridia and Bacteroidetes all contained the FTFHS gene for formyltetrahydrofolate synthetase, a key enzyme for reductive acetogenesis; indicating that these organisms are possible syntrophic acetate-oxidizing bacteria (SAOB) that can facilitate acetate consumption via syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis (SAO-HM). This study represents the first study applying protein-SIP for analysis of complex biogas samples, a promising method for identifying key microorganisms involved in specific pathways.
2016-05-11 | PXD002996 | Pride
Project description:Identification of novel syntrophic Butyrate-oxidizing bacteria
Project description:Acetate, propionate and butyrate are the main short-chain fatty acids (SCFAs) that arise from the fermentation of fibers by the colonic microbiota. While many studies focus on the regulatory role of SCFAs, their quantitative role as a catabolic or anabolic substrate for the host has received relatively little attention. To investigate this aspect, we infused conscious mice with physiological quantities of stable isotopes [1-13C]acetate, [2-13C]propionate or [2,4-13C2]butyrate directly into the cecum, which is the natural production site in mice, and analyzed their interconversion by the microbiota as well as their metabolism by the host. Cecal interconversion - pointing to microbial cross-feeding - was high between acetate and butyrate, low between butyrate and propionate and almost absent between acetate and propionate. As much as 62% of infused propionate was used in whole-body glucose production, in line with its role as gluconeogenic substrate. Conversely, glucose synthesis from propionate accounted for 69% of total glucose production. The synthesis of palmitate and cholesterol in the liver was high from cecal acetate (2.8% and 0.7%, respectively) and butyrate (2.7% and 0.9%, respectively) as substrates, but low or absent from propionate (0.6% and 0.0%, respectively). Label incorporation due to chain elongation of stearate was approximately 8-fold higher than de novo synthesis of stearate. Microarray data suggested that SCFAs exert only a mild regulatory effect on the expression of genes involved in hepatic metabolic pathways during the 6h infusion period. Altogether, gut-derived acetate, propionate and butyrate play important roles as substrates for glucose, cholesterol and lipid metabolism.
Project description:Acetate, propionate and butyrate are the main short-chain fatty acids (SCFAs) that arise from the fermentation of fibers by the colonic microbiota. While many studies focus on the regulatory role of SCFAs, their quantitative role as a catabolic or anabolic substrate for the host has received relatively little attention. To investigate this aspect, we infused conscious mice with physiological quantities of stable isotopes [1-13C]acetate, [2-13C]propionate or [2,4-13C2]butyrate directly into the cecum, which is the natural production site in mice, and analyzed their interconversion by the microbiota as well as their metabolism by the host. Cecal interconversion - pointing to microbial cross-feeding - was high between acetate and butyrate, low between butyrate and propionate and almost absent between acetate and propionate. As much as 62% of infused propionate was used in whole-body glucose production, in line with its role as gluconeogenic substrate. Conversely, glucose synthesis from propionate accounted for 69% of total glucose production. The synthesis of palmitate and cholesterol in the liver was high from cecal acetate (2.8% and 0.7%, respectively) and butyrate (2.7% and 0.9%, respectively) as substrates, but low or absent from propionate (0.6% and 0.0%, respectively). Label incorporation due to chain elongation of stearate was approximately 8-fold higher than de novo synthesis of stearate. Microarray data suggested that SCFAs exert only a mild regulatory effect on the expression of genes involved in hepatic metabolic pathways during the 6h infusion period. Altogether, gut-derived acetate, propionate and butyrate play important roles as substrates for glucose, cholesterol and lipid metabolism. Mice were infused in cecum with stably-labelled isotopes of the three main short chain fatty acids or control solution. After 6 hrs, livers were removed and pooled RNA samples were subjected to gene expression profiling.
Project description:Volatile fatty acids found in effluents of the dark fermentation of biowastes can be used for mixotrophic growth of microalgae, improving productivity and reducing the cost of the feedstock. Microalgae can use the acetate in the effluents very well, but butyrate is poorly assimilated and can inhibit growth above 1 gC.L-1. The non-photosynthetic chlorophyte alga Polytomella sp. SAG 198.80 was found to be able to assimilate butyrate fast. To decipher the metabolic pathways implicated in butyrate assimilation, a large-scale differential proteomics study was developed comparing Polytomella sp. cells grown on acetate and butyrate at 1 gC.L-1.
Project description:Background and Aims: Many inflammatory diseases are associated with microbial dysbiosis, which may considerably alter the production of short-chain fatty acids (SCFAs). SCFAs are produced in the large bowel through bacterial fermentation of dietary fiber and play an important role in maintaining gut homeostasis. SCFAs, particularly acetate and butyrate, show beneficial immunomodulatory effects contributing to the prevention of inflammatory and allergic reactions. Thus, reduced production of SCFAs may impact on the mucosal immune responses critical to fighting pathogens. This study aims to determine the influence of SCFAs on a murine model of colonic bacterial infection. Methods: In the present study, we used acetate- (HAMSA) or butyrate- (HAMSB) yielding diets to deliver high concentrations of individual SCFAs to the large bowel of mice infected with C. rodentium. We assessed the effects of these SCFAs on clinical burden and gut pathogenicity in correlation with changes in bacteria growth, fecal microbiota composition, function and changes in the immunological profile. Results: Here we show in vitro that acetate and butyrate directly inhibited growth of the attaching and effacing (A/E) pathogen C. rodentium in a bacteriostatic manner. This correlated with reduced expression of Tir, a gene responsible for bacterial adherence and pathogenicity. Interestingly, HAMSA-fed mice presented reduced clinical scores during C. rodentium infection associated with high concentrations of fecal acetate. This was linked with compositional and functional changes in the microbiota when examining 16s sequencing and proteomics analysis. The HAMSA mediated is protection involved increased expression IL-22 and Muc-2 in the colon and increased numbers of CD8αα+ TCRγδ T cells in the colonic epithelium. These effects were dependent on GPR43, a metabolite-sensing GPCR that binds acetate. Conclusions: We established a promising new approach to moderate bacterial gut infections by manipulating the gut microbiota and mucosal immune tolerance through diets that yield the SCFA acetate.
2022-02-15 | PXD008149 | Pride
Project description:DNA-SIP metagenomics of anaerobic butyrate degrading microbial communities
Project description:Comparison of acetate- to butyrate-grown F. placidus cells to identify genes that are potentially involved in fatty acid degradation by this unique hypertherophilic archaeon.