Characterization of lactococcin BZ produced by Lactococcus lactis subsp. lactis BZ isolated from boza

Abstract

A bacterium isolated from boza produced in Turkey was identified, and the physico-chemical and microbiological properties of its inhibitory compound were characterized. The isolate was identified as Lactococcus lactis subsp. lactis, based on morphology, physiology, carbohydrate fermentation, the fatty acid profile, and 16S rDNA gene sequence homology. The antimicrobial compound produced by the microorganism, lactococcin BZ, was sensitive to papain, pepsin, trypsin, and β- mercaptoethanol, but was resistant to catalase, amylase, lipase, organic solvents (methanol, chloroform, etc.), detergents (SDS, urea, Tween-80, Triton X-100), and EDTA. Lactococcin BZ was active against several gram-positive and gram-negative foodborne pathogens and food spoilage bacteria. Lactococcin BZ maintained its activity after high-heat treatment (90 °C for 30 min), at acidic and neutral pHs (2.0-7.0), and after storage at -20 to -80 °C for 3 months in lyophilized form. Lactococcin BZ was produced at the maximum level in MRS broth with an inoculum volume of 0.1%, an initial pH of 7.0, and an incubation temperature of 25 °C. Bacteriocin production began during the logarithmic phase and reached the maximum level during the early stationary phase. Its mode of action against Listeria monocytogenes was bactericidal and its molecular weight was about 5500 Da, as determined using tricine SDS-PAGE. Lactococcus lactis subsp. lactis BZ or its bacteriocin, which has a wide inhibitory spectrum, has the potential for use as a biopreservative in food products. © TÜBİTAK.