title: Study of the role of anaerobic metabolism in succinate production by Enterobacter aerogenes.
abstract: 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 ΔadhE/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.
authors: Institute for Innovation, Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki, 210-8681, Japan, yoshinori_tajima@ajinomoto.com.
authors: Yoshinori
authors: Y
authors: Tajima
authors: Kenichi
authors: K
authors: Kaida
authors: Atsushi
authors: A
authors: Hayakawa
authors: Keita
authors: K
authors: Fukui
authors: Yousuke
authors: Y
authors: Nishio
authors: Kenichi
authors: K
authors: Hashiguchi
authors: Ryosuke
authors: R
authors: Fudou
authors: Kazuhiko
authors: K
authors: Matsui
authors: Yoshihiro
authors: Y
authors: Usuda
authors: Koji
authors: K
authors: Sode
mesh_terms: D000693:Anaerobiosis; D021902:Enterobacter aerogenes / Q000378:metabolism*; D005285:Fermentation / Q000502:physiology; D013386:Succinates / Q000378:metabolism; D019802:Succinic Acid / Q000378:metabolism*
chemical_list: D013386:Succinates; D019802:Succinic Acid