Study of the role of anaerobic metabolism in succinate production by Enterobacter aerogenes.

Applied microbiology and biotechnology

PubMedID: 24962116

Tajima Y, Kaida K, Hayakawa A, Fukui K, Nishio Y, Hashiguchi K, Fudou R, Matsui K, Usuda Y, Sode K. Study of the role of anaerobic metabolism in succinate production by Enterobacter aerogenes. Appl Microbiol Biotechnol. 2014;.
Succinate is a core biochemical building block; optimizing succinate production from biomass by microbial fermentation is a focus of basic and applied biotechnology research. Lowering pH in anaerobic succinate fermentation culture is a cost-effective and environmentally friendly approach to reducing the use of sub-raw materials such as alkali, which are needed for neutralization. To evaluate the potential of bacteria-based succinate fermentation under weak acidic (pH <6.2) and anaerobic conditions, we characterized the anaerobic metabolism of Enterobacter aerogenes AJ110637, which rapidly assimilates glucose at pH 5.0. Based on the profile of anaerobic products, we constructed single-gene knockout mutants to eliminate the main anaerobic metabolic pathways involved in NADH re-oxidation. These single-gene knockout studies showed that the ethanol synthesis pathway serves as the dominant NADH re-oxidation pathway in this organism. To generate a metabolically engineered strain for succinate production, we eliminated ethanol formation and introduced a heterogeneous carboxylation enzyme, yielding E. aerogenes strain ?adhE/PCK. The strain produced succinate from glucose with a 60.5 % yield (grams of succinate produced per gram of glucose consumed) at pH <6.2 and anaerobic conditions. Thus, we showed the potential of bacteria-based succinate fermentation under weak acidic conditions.