Identification and Simulation Mutation of a High-productive Strain of Poly (γ-glutamic acid) Independent of Glutamic Acid

Abstract:

A high productive poly γ-glutamic acid (γ-PGA) strain PGA-N in a culture medium containing no L-glutamine was isolated from fermentation products. With the following identifications of colony morphology, physiological and biochemistry experiments, and genetics, the strain PGA-N was classified as a Bacillus licheniformis. According to the product environment, the base culture medium having no L-glutamine was simulated. In order to enhance the production of the strain PGA-N, the fermentation conditions, such as carbon source, nitrogen source, were optimized and the γ-glutamic acid production reached 5.16 g/L after getting the optimum formulation of this culture medium. PGA-N was mutagenized with combination of NTG and UV. A mutant PGA-N-C10 was screened which PGA production was increased from 5.16 g/L to 8.82 g/L. The study also investigated the effects of agitation speed on the cell biomass, γ-PGA production and the γ-PGA molecular weight. The γ-PGA yield of PGA-N-C10 was as high as 11.00 g/L when the agitation speed was 400 r/min.