MODE OF ACTION OF A LYSOSTAPHIN-LIKE BATERIOLYTIC AGENT PRODUCED BY STREPTOCOCCUS-ZOOEPIDEMICUS-4881

Electron microscopy of zoocin A-treated sensitive streptococcus cells revealed cytoplasmic disruption and ultimately complete rupture of the cell wall. Culture viability and optical density were shown to decrea se rapidly and simultaneously in Streptococcus pyogenes FF22 but less quickly in the relatively more resistant Streptococcus mutans 10449. Z oocin A was shown to cleave hexaglycine in a colorimetric cell-free mi crotiter assay system, and it is concluded that the killing action of zoocin A, like that of lysostaphin, is most probably the result of dir ect cleavage of the peptidoglycan cross-links in the cell wall. The re lationship between sensitivity to zoocin A and the peptidoglycan cross -linkage structure of Streptococcus zooepidemicus, Lactococcus spp. S. pyogenes, Streptococcus gordonii, Streptococcus oralis, S. mutans, an d Streptococcus rattus has been evaluated.