PARTIAL CHARACTERIZATION OF THE COHEMOLYTIC FACTOR PRODUCED BY STREPTOCOCCUS-UBERIS AND COMPARISON WITH THE CAMP-FACTOR

Exosubstances (cohemolysins) produced by Streptococcus agalactiae (CAM P-factor) and Streptococcus uberis (Uberis-factor) showing hemolytic s ynergism with beta-lysin produced by Staphylococcus aureus were compar ed. Cohemolytic activity was evaluated in the supernatants of bacteria l cultures, before and after ammonium sulfate precipitation, Sheep ery throcytes sensitized with beta-lysin were used as substrate. The assay s were performed in microtiter plates and results were expressed as co hemolytic units/ml. Maximum cohemolytic activity was detected, respect ively, after 8 h and 14 h of growth in Columbia broth in S. uberis and S. agalactiae cultures. Cohemolytic activities of both microorganisms showed similarities when submitted to various physical and chemical t reatments. They were significantly decreased by heating at 60 degrees C and 100 degrees C, or in presence of trypsin, and were abolished in the presence of Tween 20. Activities were found to be stable in crude supernatants and concentrated preparations maintained at - 20 degrees C for 3 months. Differences were related to levels of activity and kin etics of detection during the growth cycle. The results indicate the p roteic nature, at least in part, of the Uberis factor. Analysis by PAG E in the presence or absence of SDS allowed us to correlate Uberis act ivity with a protein band with apparent molecular mass of 42 kDa, whil e CAMP activity was associated with a protein band of 27 kDa.