Growth parameters influencing the production of Lactobacillus rhamnosus bacteriocins ST461BZ and ST462BZ
Bacteriocins ST461BZ (2.8 kDa) and ST462BZ (8.0 kDa), produced by two strains of Lactobacillus rhamnosus isolated from boza, a beverage produced from different cereals by yeast and lactic acid bacteria, inhibits the growth of Lactobacillus casei, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa. Maximum bacteriocin activity (12 800 AU/ml) was recorded after 15 h in MRS broth. No increase in the production of the two bacteriocins was recorded in MRS broth supplemented with tryptone (20 g/l), D-glucose (20 g/l) and sucrose (20 g/l). Glycerol at 1 g/l and higher inhibited the production of both bacteriocins. Bacteriocin ST461BZ production increased to 25 600 AU/ml in MRS broth supplemented with 20 g/l or 50 g/l K2HPO4. Bacteriocin ST462BZ activity increased to 51 200 AU/ml in MRS broth supplemented with 20 g/l to 100 g/l KH2PO4.