Expression of the hemolysin trait in a proteolytic transconjugant of Streptococcus faecalis.

Streptococcus faecalis 31H-1 is a proteolytic transconjugant of strain 31B, that harbors the 38.5 Mdal plasmid which codes for hemolysin in strain X14. It fails to express the hemolytic character in broth due to its proteolytic character. Hemolytic activity can be demonstrated when the proteolytic activity is inhibited by 10(-4) M EDTA. The effect of erythromycin (on the donor cells) and of proteinase K during conjugation suggests that the conjugation system involving the 38.5 Mdal plasmid of S. faecalis strain X14 is sex-pherormone mediated.

Genetic loci of hemolysin production in Streptococcus faecalis subsp. zymogenes.

Two plasmids corresponding to molecular weights of 38.5 X 10(6) and 3.6 X 10(6) have been identified in Streptococcus faecalis subsp. zymogenes strain X-14. The larger plasmid is required for hemolysin-bacteriolysin production. Strain L2, a nonlytic nitrosoquanidine 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.

Dependence of protease secretion by Streptococcus faecalis var. liquefaciens on arginine and its possible relation to site of synthesis.

Washed cells of Streptococcus faecalis var. liquefaciens, when harvested from media that supported protease biosynthesis, continued to release this extracellular enzyme in phosphate buffer. The addition of ethylenediaminetetraacetic acid (EDTA) halted the secretion. If zinc ions were added to the EDTA-treated cells before 45 to 60 min had elapsed, a fraction of the anticipated enzyme activity was observed. After 60 min, arginine and phosphate, in addition to zinc, were necessary for the demonstration of proteolytic activity. The enzyme that was released was newly formed, because chloramphenicol, puromycin, or actinomycin D prevented its appearance. Energy for this synthetic reaction was obtained, apparently, from arginine; lactose could not be substituted for arginine. This last point is interpreted to mean that extracellular protease biosynthesis occurs in a localized area or cellular compartment into which the adenosine triphosphate derived from the fermentation of lactose cannot diffuse. No evidence was found for a protease zymogen, although this possibility is not completely precluded.

Production of Hemolysin and Bacteriolysin in a Synthetic Medium by Streptococcus faecalis var. zymogenes.

A synthetic medium has been developed in which Streptococcus faecalis var. zymogenes X-14 elaborates a lysin. The medium consists of 18 amino acids, lactose, six vitamins, adenine, guanine, uracil, and six salts. Glucose, and K(2)HPO(4) in excess of 0.5% (wt/vol), were inhibitory to lysin production; increasing concentrations of l-arginine-hydrochloride gave increasing yields of lytic activity.

Plasmid-borne resistance to ultraviolet light and phage in Streptococcus faecalis ssp. zymogens.

A plasmid of molecular weight 38.5 X 10(6) that is found in a number of enterococci and carries genetic markers for lysin production was found also to carry genes for resistance to bacteriophage SFL as well as to ultraviolet light.

Stimulation of proteinase biosynthesis by canavanine in streptococcus faecalis var. liquefaciens.

l-Canavanine, an analogue of arginine, was found to stimulate the synthesis of an extracellular proteinase in Streptococcus faecalis var. liquefaciens. Cells grown in a synthetic medium containing 10(-4)m arginine and 10(-4)m canavanine produced almost twice as much proteinase as cells grown in 2 x 10(-3)m arginine alone; total growth was the same in both media. Hydrolyzed proteinase samples were analyzed for arginine and canavanine by means of paper chromatography and electrophoresis. Arginine, but not canavanine, was detected in the purified enzyme sample.