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 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.