title: Acetate-mediated pH-stat fed-batch cultivation of transconjugant Enterobacter sp. BL-2S over-expressing glmS gene for excretive production of microbial polyglucosamine PGB-1.
abstract: A unique cationic polyglucosamine biopolymer PGB-1 comprising more than 95% D-glucosamine was excretively produced from a new bacterial strain Enterobacter sp. BL-2 under acetate-mediated culture conditions. Since the biopolymer PGB-1 could be synthesized from the UDP-N-acetylglucosamine monomer derived from the hexosamine pathway, three glmS, glmM, and glmU genes in the hexosamine pathway were cloned from Enterobacter sp. BL-2, and their molecular structures were elucidated. The cloned glmS, glmM, and glmU genes were reintroduced into the parent strain Enterobacter sp. BL-2 through a conjugative transformation for the overproduction of the biopolymer PGB-1. The biopolymer production increased 1.5-fold in the transconjugant Enterobacter sp. BL-2S over-expressing the first-step glmS gene encoding glucosamine-6-phosphate synthase. The transconjugant Enterobacter sp. BL-2S was cultivated pH-stat fed-batch widely, while intermittently feeding an acetate solution to maintain a constant pH level of 8.0 for 72 h, resulting in 1.15 g/L of the extracellular polyglucosamine biopolymer PGB-1.
authors.affiliation: Department of Genetic Engineering, College of Natural Sciences, Kyungpook National University, Daegu 702-701, South Korea.
authors.forename: Mi-Kyung
authors.initials: MK
authors.lastname: Son
authors.forename: Soo-Jung
authors.initials: SJ
authors.lastname: Hong
authors.forename: Yong-Hyun
authors.initials: YH
authors.lastname: Lee
mesh_terms: D000085:Acetates; D001704:Biopolymers / Q000096:biosynthesis*; D003227:Conjugation, Genetic; D003470:Culture Media; D004754:Enterobacter / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D015870:Gene Expression; D005798:Genes, Bacterial / Q000235:genetics; D005944:Glucosamine / Q000096:biosynthesis*; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing) / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology / Q000379:methods*; D009097:Multienzyme Complexes / Q000235:genetics; D010733:Phosphoglucomutase / Q000235:genetics*
chemical_list: D000085:Acetates; D001704:Biopolymers; D003470:Culture Media; D009097:Multienzyme Complexes; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing); D010733:Phosphoglucomutase; D005944:Glucosamine