Purification and amino acid sequence of lactocin 705, a bacteriocin produced by Lactobacillus casei CRL 705

Lactobacillus casei CRL 705, isolated from a dry fermented sausage, produce s an antibacterial peptide which is active against Lister ia monocytogenes. Previous studies have shown that this compound is potentially useful to co ntrol food-borne pathogens in ground meat. in view of the potential applica tion of this antimicrobial substance in food fermentation, a detailed bioch emical analysis of this peptide is required, in this work, the purification and amino acid sequence of this bacteriocin is presented. The adsorption-d esorption pH-dependent property of lactocin 705 was exploited for purificat ion. The active extract was further subjected to RP-HPLC and SDS-PAGE. The active antimicrobial band was electroeluted from an SDS-PAGE gel and its am ino acid sequence determined. Lactocin 705 had an estimated molecular weigh t of 3357.80 and an isoelectric point of 10.03. The peptide contains a high ratio of glycine residues and does not show any modified amino acids, like lanthionine or beta-methyllanthionine. The sequence was unique when compar ed to several databases.