Antibacterial activities of coagulase‐negative staphylococci from bovine teat apex skin and their inhibitory effect on mastitis‐related pathogens

Aims To explore antibacterial activities of coagulase‐negative staphylococci (Co NS ) from teat apices of dairy cows towards mastitis‐causing pathogens. Methods and Results Of 254 Co NS , 38 displayed bacteriocin‐like activity after a first screening. Seven of these strains displayed activity against at least one mastitis‐related pathogen ( S treptococcus uberis , S treptococcus dysgalactiae and S taphylococcus aureus ). S taphylococcus chromogenes L 217 displayed the strongest inhibitory effect, being active against all tested mastitis‐related pathogens and most tested C o NS . Based on cation exchange and reversed‐phase chromatography, in addition to N ‐terminal E dman degradation and PCR , the antibacterial peptide was identified as a nukacin‐type bacteriocin and named nukacin L 217. Although staphylococcal bacteriocins are generally found in the cell‐free supernatants of liquid cultures, S taph. chromogenes L 217 only led to detectable activity when grown on agar medium. Conclusions Bacteriocin‐like activities are not uncommon among C o NS from teat apices and may inhibit mastitis‐causing pathogens, as found for nukacin L 217 production by S taph. chromogenes L 217. Significance and Impact of the Study Nukacin L 217 is the first identified bacteriocin of the species S taph. chromogenes and displays unusual production kinetics, that is, requiring surface growth of its producer. The fact that nukacins are produced by different Co NS species suggests a role in the teat skin ecosystem.