Table 1.

Strains used in this study

Strain	Relevant characteristics, source, and plasmids	Reference
Staphylococcus aureus
A70	Aureocin A70 producer; pRJ6 (7.9 kb)	[6]
A70 Bac−	Strain cured of pRJ6 and, therefore, of aureocin A70 production	[6]
4181	Aureocin 4181 producer; pRJ80 (8.3 kb)	[13]
4181 Bac−	Strain cured of pRJ80 and, therefore, of aureocin 4181 production	This work
30 Strains isolated from 15 different herds	Involved in bovine mastitis	This work
Micrococcus luteus ATCC 4698	Indicator of bacteriocin production	[14]
Streptococcus spp.
30 strains isolated from 15 different herds	Involved in bovine mastitis	This work

Bac, bacteriocin

Sign –, absence of the phenotype