Staphylococcal Bacteriophage-Associated Lysin: a Lytic Agent Active Against Staphylococcus aureus

Staphylococcus aureusPS53cells. This enzyme,staphylococcal phage-associated lysin (PAL), was partially purified by ammoniumsulfate precipitation andgelfiltration through Sephadex G-200. PAL isoptimally active atpH 6.5and30C,andlytic activity isgreatly enhanced bythe addition ofreducing agents. Lytic activity was observed against allstrains ofstaphylococci tested andagainst purified staphylococcal cell walls, butno activity was notedagainst other bacterial species. PAL possessespeptidase activity andresults intheproduction ofspheroplasts which can beosmotically stabilized forextended periods bytheaddition of7.5%polyethylene glycol 4000. Bacteriophage-induced lytic enzymesactive against staphylococcal cells havebeenreported byRalston etal.(8)andDoughty andMann(2). These lysins arereleased uponlysis ofstaphylococcal cells after infection withspecific staphylococcal phages. Thelytic agentdesignated virolysin byRalston andco-workers actsonstaphylococcal cells onlyafter thecell wallhasbeen altered bytheaction ofagents suchasheatand ultraviolet irradiation orafter "sensitization" of cells withbacteriophage (9). Bothvirolysin and CWSE-80, thebacteriophage-induced lytic agent described byDoughty andMann(2), areactive insolubilizing isolated cell walls without alterationor"sensitization." Thepresent paperdescribes thepartial purification andproperties of staphylococcal phage-associated lysin (PAL), an enzymereleased uponlysis ofstaphylococcal strain PS53infected withitshomologous typing phage 53.PAL isactive insolubilizing bothisolated cell walls and-viable, actively metabolizing, wholestaphylococcal cells without thenecessity ofprior alteration orsensitization.