Abstract:

The production of bacteriocin-like substances by Enterococcus faecium BC-3 fermentation was optimized with respect to the effects of various fermentation culture medium components. Plackett-Burman (PB) design was employed to evaluate the importance of 10 factors affecting the production of bacteriocin-like substances, and peptone, beef extract and dibasic ammonium citrate were selected as the most significant affecting factors. Subsequently, path of steepest ascent was coupled with response surface analysis based on central composite design to investigate the optimal values of the selected factors. The optimal fermentation culture medium for the production of bacteriocin-like substances was composed of 33.1 g/L peptone, 55.6 g/L beef extract and 4.9 g/L dibasic ammonium citrate. A maximum diameter of inhibition zone of 17.13 mm obtained using such a medium, 50.79% higher than before the optimization.

Key words: Enterococcus faecium, bacteriocin-like substance, Plackett-Burman design, response surface methodology, optimization