Isolation of Two Bacteriocin
Isolation of two bacteriocin-producing lactic acid bacteria from alfalfa seeds.
Institute of Food Technologists Annual Meeting, New Orleans, Jun 29 2008 Guoping Feng, Cornell University, Geneva, NY; John J. Churey, Cornell University, Geneva, NY; Randy W. Worobo, Cornell University, Geneva, NY.
While alfalfa seeds are notorious as a vehicle for food-borne pathogens, primarily Salmonella spp. and Escherichia coli O157:H7, they harbor a diverse microbial background biota that include lactic acid bacteria which can serve as protective cultures to prevent foodborne pathogen growth.Two different strains of lactic acid bacteria were isolated from alfalfa sprouts and were found to produce antimicrobial compounds. Both strains showed high antimicrobial activity against a broad spectrum of spoilage and pathogenic bacteria. 16S RNA gene homology analysis revealed the two producers are Lactococcus lactis and Enterococcus spp.. The compound produced by Lactococcus lactis was shown to be inactivated by proteinase K and pronase E while the antimicrobial compound produced by Enterococcus spp. was inactivated by proteinase K, suggesting both compounds are proteinaceous in nature. Tricine-SDS-PAGE analysis of these two bacteriocins showed molecular mass of approximately 3k Da and 5k Da, from Lactococcus lactisand Enterococcus spp., respectively. Deferred inhibition tests against a range of indicator bacteria suggest that the bacteriocin produced by L. lactis may be a Type I lantibiotic while the Enterococcus bacteriocin appears to have a spectrum of activity similar to many of the different enterocins identified to date.