Purpose: To purify and characterize the antimicrobial protein produced by Leuconostoc mesenteroides subsp. mesenteroides SJRP55.
Methods: The production of bacteriocin was studied at 25°C and 30°C. Influence of enzymes, detergents, pH and temperature on bacteriocin was evaluated. Bacteriocin effect on Listeria spp. and Enterococcus spp. and other foodborne pathogens was determined. The bacteriocin was purified using affinity column and reversed-phase chromatography. Molecular mass of the expressed bacteriocins have been determined by mass spectrometry. DNA from strain SJRP55 have been evaluated by PCR with primers targeting mesenterocin B105 and Y105, leucocins K, A, B and A-TA33a.
Results: Cell-free supernatant of strain SJRP55 showed inhibition activity against Listeria spp. and Enterococcus spp., but not affected Lactobacillus spp. Antimicrobial compound was resistant to high temperatures, low pH, and chemical compounds; was not affected by α-amylase, lipase and catalase, confirming its proteinaceous nature. The optimal temperature for bacteriocin production was 25°C. Bacteriocin showed a bacteriostatic effect against several Listeria species and Enterococcus faecalis. Mass spectrometry and amino acids analyses showed that the bacteriocin produced by strain SJRP55 was similar to mesenterocin Y105 and mesenterocin B105. PCR reactions generated positive results for mesenterocin Y105 and B105 genes and after sequencing, a 100% homology have been recorded.
Significance: The bacteriocins showed high similarity to other bacteriocins produced by Leuconostoc species. Different environmental matrices, conditions and geographical regions seem do not affect the genes encoding bacteriocins. Probably these genes are very well conserved during the evolution of Leuconostoc genus. The bacteriocin produced by Leuconostoc mesenteroides subsp. mesenteroides SJRP55 showed potential as a biopreservative to be applied as a tool of a system of multiple preservative principles.