Efficient production of poly-γ-glutamic acid by Bacillus velezensis via solid-state fermentation and its application

A novel glutamate-dependent poly-γ-glutamic acid (γ-PGA)-producing strain Bacillus velezensis CAU263 isolated from Chinese traditional Douchi was evaluated. An efficient method of γ-PGA production was performed by this strain via solid-state fermentation (SSF) using guar meal. The maximal yield of γ-PGA reached 158.5 g/kg dry weight (DW) in 250 mL flasks and 155.1 g/kg DW in shallow tray, respectively. The molecular weight of γ-PGA was 3.8 × 106 Da, the ratio of L/D-glutamic acid was 26.1% and 73.9%. Additionally, γ-PGA significantly improved the operating characteristics of wheat dough, the specific volume of bread was increased by 15.8% and the bread hardness was reduced by 44.2% owing to the addition of 0.3 g/kg γ-PGA. Thus, γ-PGA could be produced by Bacillus velezensis CAU263 at high level using guar meal and might have potential application prospect in food industry.