Design and optimization of fermentation medium for enhanced bacteriocin production by probiotic bacterium enterococcus faecium MC13

Statistics-based experimental designs were used to develop a cost-effective medium for enhanced production of viable cells and bacteriocin by probiotic Enterococcus faecium MC13. Carbon, nitrogen, and mineral sources were first screened by one-variable-at-a-time (OVAT) methods. In order to increase yield production, the selected variables were further statistically optimized using response-surface methodology (RSM) with central composite design (CCD). The maximum and minimum levels of the selected variables were determined and a set of 34 experimental runs was performed. The optimum concentrations of the tested variables for production of viable cells (12.24 log CFU mL^-1) and bacteriocin activity (25,600AU mL^-1) were tryptone (10.0g/L), peptone (6.0g/L), maltose (3.0g/L), glucose (9.0g/L), NaCl (15.0g/L), sodium citrate (2.5g/L), sodium acetate (1.0g/L), and dipotassium PO4 (0.1g/L). Threefold increased yield of bacteriocin was achieved in optimized medium compared to the unoptimized counterpart, and this was two times less cost than commercial MRS medium.