Proteomics of foes and friends adapted to milk environment: focus on Gram-positive bovine mastitis bacteria and probiotics

The evolutionary success of bacteria depends on their excellent genetic flexibility that promotes adaptation in diverse environmental niches and different host organisms. The economically important group of bacteria well-adapted to milk-environment include species of the genera like Staphylococcus, Streptococcus and Lactobacillus. Some of these species are important causative agents of infectious diseases such as bovine mastitis, while many are able to form commensal relationship with the host or even able to positively affect the health. Bovine mastitis is most frequently caused by Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus uberis strains and it is a major economic burden in the dairy industry world-wide. It is still the most common reason for antibiotic use in dairy farms, which has raised concerns on development of antimicrobial resistance and residues in the food chain. In most bacteria, the activation of SOS response has been considered the major driving force in increasing genomic fitness and adaptation (via mutagenesis, acquisition pathogenic islands, prophages or drug resistance genes, etc.).