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

Aims: The identification of a bacteriocin-producing lactococcal strain isol ated from raw cow's milk is reported, along with production conditions, phy sical and chemical properties, and mode of action of the bacteriocin. Methods and Results: On the basis of resistance to clindamycin, species-spe cific PCR and amplification of the 16S-23S rDNA spacer region, the strain w as identified as Lactococcus garvieae. Its bacteriocin, designated garvieci n L1-5, was bactericidal against closely related species and strains of spe cies from different genera, including Listeria monocytogenes and Clostridiu m spp. Garviecin L1-5 was shown to be proteinaceous by protease inactivatio n and was unaffected by heat treatments, also at low pH values. When amplif ying known lactococcal bacteriocin genes using DNA from strain L1-5 as temp late, no amplification products were observed on the agarose gel. The molec ular weight of garviecin L1-5 was about 2.5 kDa. As far as is known, no bac teriocins have been detected from Lactococcus garvieae. Conclusions: 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 nov el antimicrobial substances provided valuable information on their physiolo gy, ecology and practical application.