ANTIBIOTIC PRODUCTION BY COAGULASE-NEGATIVE STAPHYLOCOCCI ISOLATED FROM THE SKIN OF PIGS

Seven coagulase-negative staphylococci isolated from pig skin were previously found to inhibit gram-positive organisms when tested by direct and deferred antagonism. Crude and chemically semipurified extracts of the isolates also had antibacterial activity against a selection of both gram-positive and gram-negative bacteria. The inhibitory substances were probably peptide antibiotics with molecular weights in the range 856-1400 Da. They were chromatographically similar to the peptide classes III and IV of Betina. Their electrophoretic migration pattern resembled that of other peptide antibiotics such as bacitracin, novobiocin and polymyxin. There were some differences between antibiotics from different staphylococcal species. These antibiotics were not destroyed by temperatures of 40-100-degrees-C, nor by changes of pH of 2-12 units, but were inactivated by some enzymes.