Isolation of a novel poly- γ -glutamic acid-producing Bacillus licheniformis A14 strain and optimization of fermentation conditions for high-level production.

In the present study, bacteria producing poly-gamma-glutamic acid were isolated from marine sands, and an efficient producer identified. gamma-PGA was rapidly screened by thin-layer chromatography and UV spectrophotometer assay. Media optimization was carried out, and for the cost-effective production of gamma-PGA, monosodium glutamate was used as the substrate for the synthesis of gamma-PGA instead of glutamic acid. Lastly, Plackett-Buman design (PB) and Response surface methodology (RSM) were used to determine significant media components and their interaction effect to achieve maximum gamma-PGA production. With this integrated method, a bacterial strain with a high yield of gamma-PGA was obtained rapidly, and the production was increased up to 37.8 g/L after optimization.