title: Deletion of genes involved in glutamate metabolism to improve poly-gamma-glutamic acid production in B. amyloliquefaciens LL3.
abstract: Here, we attempted to elevate poly-gamma-glutamic acid (γ-PGA) production by modifying genes involved in glutamate metabolism in Bacillus amyloliquefaciens LL3. Products of rocR, rocG and gudB facilitate the conversion from glutamate to 2-oxoglutarate in Bacillus subtillis. The gene odhA is responsible for the synthesis of a component of the 2-oxoglutarate dehydrogenase complex that catalyzes the oxidative decarboxylation of 2-oxoglutarate to succinyl coenzyme A. In-frame deletions of these four genes were performed. In shake flask experiments the gudB/rocG double mutant presented enhanced production of γ-PGA, a 38 % increase compared with wild type. When fermented in a 5-L fermenter with pH control, the γ-PGA yield of the rocR mutant was increased to 5.83 g/L from 4.55 g/L for shake flask experiments. The gudB/rocG double mutant produced 5.68 g/L γ-PGA compared with that of 4.03 g/L for the wild type, a 40 % increase. Those results indicated the possibility of improving γ-PGA production by modifying glutamate metabolism, and identified potential genetic targets to improve γ-PGA production.
authors.affiliation: Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, College of Life Sciences, Nankai University, Tianjin, People's Republic of China, nk13123@163.com.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Yulian
authors.initials: Y
authors.lastname: He
authors.forename: Weixia
authors.initials: W
authors.lastname: Gao
authors.forename: Jun
authors.initials: J
authors.lastname: Feng
authors.forename: Mingfeng
authors.initials: M
authors.lastname: Cao
authors.forename: Chao
authors.initials: C
authors.lastname: Yang
authors.forename: Cunjiang
authors.initials: C
authors.lastname: Song
authors.forename: Shufang
authors.initials: S
authors.lastname: Wang
mesh_terms: D001407:Bacillus / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D017353:Gene Deletion; D005798:Genes, Bacterial; D018698:Glutamic Acid / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007656:Ketoglutaric Acids / Q000378:metabolism; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D007656:Ketoglutaric Acids; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid; D018698:Glutamic Acid