Optimization of sterilization of Escherichia coli in milk by surfactin and fengycin using a response surface method

In this paper, the sensitivity of Escherichia coli to surfactin and fengycin was observed, and the optimization of the antimicrobial activity of surfactin and fengycin to E. coli in milk by a response surface methodology was studied. Results showed that E. coli had high sensitivity to these antibiotics, whose minimal inhibitory concentrations were 15.625 mu g center dot mL(-1) and 31.25 mu g center dot mL(-1), respectively. The optimization result indicated that E. coli could be sterilized by 5 orders of magnitude when the temperature was 5.5 degrees C, the action time was 15.8 h, and the concentration (surfactin/fengycin weight ratio 1:1) was 14.63 mu g center dot mL(-1).