Detection and characterization of a bacteriocin, garviecin L1-5, produced by Lactococcus garvieae isolated from raw cow's milk

Abstract

Aims: The identification of a bacteriocin-producing lactococcal strain isolated from raw cow's milk is reported, along with production conditions, physical and chemical properties, and mode of action of the bacteriocin.

Methods and results: On the basis of resistance to clindamycin, species-specific PCR and amplification of the 16S-23S rDNA spacer region, the strain was identified as Lactococcus garvieae. Its bacteriocin, designated garviecin L1-5, was bactericidal against closely related species and strains of species from different genera, including Listeria monocytogenes and Clostridium spp. Garviecin L1-5 was shown to be proteinaceous by protease inactivation and was unaffected by heat treatments, also at low pH values. When amplifying known lactococcal bacteriocin genes using DNA from strain L1-5 as template, no amplification products were observed on the agarose gel. The molecular weight of garviecin L1-5 was about 2.5 kDa. As far as is known, no bacteriocins have been detected from Lactococcus garvieae.

Conclusion: The general properties of garviecin L1-5 are characteristic of the low-molecular-weight bactericidal peptide group.

Significance and impact of the study: The survey of micro-organisms for novel antimicrobial substances provided valuable information on their physiology, ecology and practical application.