CULTURAL CONDITIONS FOR THE PRODUCTION OF BACTERIOCIN BY A NATIVE ISOLATE OF LACTOBACILLUS-DELBRUECKI SSP. BULGARICUS CFR 2028 IN MILK MEDIUM

The effect of growth parameters and the molecular basis for antibacter ial activity by a natural isolate of Lactobacillus delbruecki ssp. bul garicus CFR 2028 was studied. The inhibition was tested against a toxi genic strain of Bacillus cereus F 4810. When grown in milk medium, the activity was highest at an incubation temperature of 37 degrees C in 48 h. The antibacterial activity appeared to be produced between late logarithmic and early stationary phases. The active principle was prot einaceous in nature (bacteriocin) and stable to low pH (3.8-5.0) and h eat (75 degrees C for 30 min). There was also the possible role of hyd rogen peroxide in bringing about inhibition. The strain of Lact. delbr uecki ssp. bulgaricus CFR 2028 revealed the presence of plasmid DNA ba nds of 9.4 and 6.5 kbp, respectively in agarose gel electrophoresis. T he above strain has the potential to be used as a biopreservative in p opular Indian fermented foods.