Optimization of shake flask-fermentation conditions for Iturin A production by endophytic Bacillus amyloliquefaciens CC09

Abstract:

[Objective] In order to improve the production of Iturin A from Bacillus amyloliquefaciens CC09. [Methods] We first investigate the alterative constitutes and their concentrations (various carbon and nitrogen sources), NaCl concentration and pH based on LB medium, and the cultural conditions in the flask including temperature, shaking speed, medium volume using single factor experiments. Based on the results obtained from the single factor experiments, four key factors, including nitrogen concentration, pH, temperature, and medium volume were further optimized using orthogonal experiment. [Results] Through the optimization of medium and cultural condition, the growth speed and Iturin A production of strain CC09 could be improved. Soluble starch and a suitable ratio of tryptone to yeast powder were respectively good carbon and nitrogen sources for strain CC09 to synthesize Iturin A. Moreover, cultural conditions including temperature, medium volume and pH had significant influences on the Iturin A production of strain CC09. The optimal fermentation condition is as follow, medium composition is 5 g/L starch, 15 g/L tryptone and yeast powder mix (3:1, V/V), 1 g/L NaCl; cultural condition is pH 6.0, shaking speed 120 r/min, medium volume 20%, temperature 28 °C. [Conclusion] Under the optimal fermentation condition, the production of Iturin A of strain CC09 was up to 690 mg/L, 4 times higher than when it was cultured in LB medium (138 mg/L).