Optimization of Culture Conditions for Biosynthesis of Lipopeptide by <i>Bacillus Subtilis</i> with Starch

Study of the correlation between fengycin promoter expression and its production by Bacillus subtilis under different culture conditions and the impact on surfactin production

This work aimed to rely expression of the fengycin promoter to fengycin production under different culture conditions. To this end, Bacillus subtilis BBG208, derived from BBG21, which is a fengycin overproducing strain carrying the green fluorescent protein (GFP) under the control of fengycin promoter, was used to assess the effects of different carbon and nitrogen sources on surfactin and fengycin production and the fengycin promoter expression. The data showed that some carbon sources oriented synthesis of one family of lipopeptides, while most of the nitrogen sources allowed high co-production of fengycin and surfactin. High expressions of promoter P_fen and fengycin synthesis were obtained with urea or urea + ammonium mixture as nitrogen source and mannitol as carbon source. Moreover, temperature, pH and oxygenation influenced their biosynthesis based on the nutrition conditions. Optimization of the production medium increased the fengycin production to 768 mg L^-1, which is the highest level reported for this strain. This study defines the suitable nutrient conditions allowing as well the highest expression of the fengycin promoter and portrays the conditions relying on the fengycin and surfactin production.