Genetic loci of hemolysin production in Streptococcus faecalis subsp. zymogenes

Abstract

Two plasmids corresponding to molecular weights of 38.5 x 106 and 3.6 x 106 have been identified in Streptococcus faecalis subsp. zymogenes strain X-14. The larger plasmid is required for hemolysin-bacteriolysin production. Strain L2, a nonlytic nitrosoguanidine mutant of strain X-14, still harbors the hemolytic plasmid and produces the lysin component, but not the activator component, of the lytic system. Conjugal transfer of this plasmid from strain L2 to plasmid-free strains and strains cured of the 38.5-megadalton plasmid gives rise to hemolytic recipients. This implicates a gene in hemolysin production at a site other than the 38.5-megadalton plasmid.

Genetic and physical studies of Streptococcus faecalis hemolysin plasmids

“…All wild-type strains (Table 1) transferred the Hly trait into the S. faecalis recipients (JH2-2, BM 118 and UV202) at a similar high frequency (10-i to 10-3). Comparable results were obtained by Jacob et al [1] and Frasier and Zimmerman [12]. Retransfer of the Hly trait from transconjugants into BM133 also occurred at a high frequency (10-2 to l0 -3) after 18h of mating contact.…”