Improvement of lipopeptides production by Bacillus methylotrophicus DCS1 using Plackett-Burman design and response surface methodology

Abstract

Lipopeptides from Bacillus methylotrophicus DCS1 are endowed with interesting properties. The composition of production medium and culture conditions were optimized by studying the effect of 14 variables in a 23 run Plackett-Burman design (PBD) to screen for key factors with the aim of improving lipopeptides yield and surface activity with low production costs. In PBD, four significant factors (Urea, CaCl2, gruel and temperature) affecting the production, were choosed for further optimization and constructed via Box-Behnken design (BBD). Enhanced lipopeptides production was carried out using gruel as carbon source at a concentration of 40 g L-1 and urea as nitrogen source at a concentration of 5.5 g L-1. The optimal conditions were 33 °C temperature, pH 7.5, an agitation of 175 rpm and 2.5% inoculum size. Utilizing the predicted optimized conditions, the maximum lipopeptides yield of 4.7 g L-1 was reached which accord well with the predicted value.