Growth responses of Staphylococcus aureus and Streptococcus agalactiae to Corynebacterium bovis metabolites.

Staphylococcus aureus and Streptococcus agalactiae growth responses to metabolites of Corynebacterium bovis cultured in media containing polyoxyethylenesorbitan monolaurate, monooleate, or trioleate and milk were determined. Filter sterilized metabolites of 48-h C. bovis cultures in synthetic media were added to cultures of Staph. aureus and Strep. agalactiae. Staphylococcus aureus and Strep. agalactiae were inoculated into 12-h C. bovis milk cultures. Growth responses of Staph. aureus and Strep. agalactiae were not affected by C. bovis metabolites of synthetic media. Staphylococcus aureus growth was inhibited during logarithmic and stationary phases in milk containing mixed cultures of C. bovis compared with growth in pure Staph. aureus cultures. Streptococcus agalactiae growth curves were similar in pure and C. bovis mixed cultures. Fatty acid compositions were not different in sterile milk and milk containing bacterial cultures. Growth responses of Staph. aureus and Strep. agalactiae were not related to concentration of C. bovis metabolites or fatty acid content of media in which C. bovis were cultured.