CPOS Seminar: "Understanding and characterization of unusual metabolic pathways in anaerobic microbes"
Speaker: Bo Zhang, ExFAB Fellow, Postdoctoral Researcher, O’Malley Lab, Department of Chemical Engineering, UCSB
Microbes carry out anaerobic fermentation producing fermentation products including acetate, ethanol, propionate, lactate, H2, etc. These microbial fermentation products have broad importance for foods, agriculture, and industry. For instance, in industry, acetate is transformed into various polymeric materials and derivatives such as vinyl acetate monomer and acetic esters. H2 is an energy carrier and widely used in industrial processes. Despite their importance, the metabolic pathways for forming some fermentation products by anaerobic microbes remain unclear, limiting efforts in metabolic engineering to control their productions.
In this presentation, I will talk about (1) a new pathway for forming acetate in bacteria, and (2) our latest work on mechanism of H2 production by hydrogenosome of anaerobic gut fungi. Briefly, by combing genomic and proteomic analysis, metabolic profiling, and enzyme assays, we found a biochemical pathway for forming acetate and synthesizing energy (ATP) that was unknown in prokaryotes. The pathway is composed of two enzymes (succinyl coenzyme A:acetate CoA-transferase and succinyl-CoA synthetase) and they are encoded in a diverse range of bacteria (DOI: 10.1128/AEM.02959-20). Using similar methods, we found that anaerobic fungal hydrogenosomes produce H2 via a non-bifurcating NADH-dependent hydrogenase that has not been reported in eukaryotes. Understanding the unknown pathways for forming these fermentation products is critical for controlling their yields during fermentation, with relevance for foods, agriculture, and industry.
