Studies on antagonism between porcine skin bacteria

Strains of Staphylococcus warneri, Staph. epidermidis and Aerococcus viridans isolated from porcine skin were shown to produce substances that inhibited the growth of Staph. hyicus. Studies of interactions between the inhibitor-producing bacteria and Staph. hyicus on cellulose acetate membranes demonstrated a significant reduction (P less than 0.001) of the Staph. hyicus population at various stages of its growth cycle, depending on the inhibitor used. Inhibitor production profiles in batch culture showed a change in production with culture growth. Trypsin and an extracellular substance from Staph. hyicus had similar effects in reducing inhibitor production. Staphylococcus hyicus was shown to produce varying amounts of a proteolytic enzyme during growth in batch culture. Such in vitro models of bacterial interaction enable potential mechanisms of disease control using inhibitor-producing organisms to be investigated and provide a basis for studies in vivo.