Breeding of Bacillus licheniformis Mutant by ARTP and Optimization of Bacitracin-producing Process

The bacitracin-producing Bacillus licheniformis ZZ061 was isolated from an aquaculture facility.From the isolated bacteria,mutants with enhanced capability of generating bacitrcin were bred by means of ARTP mutagenesis.In the process,Micrococcus luteus was used as the indicator bacterium,and the bacteriostatic circle method employed for the screening.One of the mutants,SF1406,showed the greatest increase,i.e.,130% higher than the wild strain,in its bacitrcin productivity.Subsequently,an orthogonal experiment was conducted to optimize the culture medium formulation.It was found that the medium consisting of 3% corn starch,1.5%ammonium sulfate,1%soybean powder and 3%sucrose rendered the most desirable results with an additional 44%productivity increase on the yield of 810U·mL-1.