Friend, Patric L. (Northwestern University Medical School, Chicago, Ill.), and Hutton D. Slade . Characteristics of group A streptococcal bacteriophages. J. Bacteriol. 92: 148–154. 1966.—A medium for the growth of group A streptococcal phages is described, consisting of Brain Heart Infusion broth supplemented with 0.2% yeast extract, 10 −4 m CaCl 2 , and 10 μg/ml of dl -tryptophan. Cell and phage growth in this medium was excellent, and did not require the addition of serum or other proteins as indicated by other workers. Growth of one phage has also been achieved in a completely synthetic medium. The adsorption characteristics of two group A phages in protein broth and synthetic broth were studied, and the initial adsorption of phage was found to be more extensive in synthetic broth. However, the final amounts of adsorption in both were similar. The addition of purified group A carbohydrate antigen to the adsorption mixture in synthetic broth had no effect on the adsorption, and cells containing type-specific M protein adsorbed phage at the same rate as those lacking M protein. It was concluded that neither the group antigen nor the type antigen was the primary site of phage adsorption. One-step growth curves of the two phages showed a second step or burst occurring. Sonic oscillation of the bacterial cultures, which broke up the chains to single cells, abolished the second step of the growth curve. It appears that the second step is a function of the chain formation of streptococcal cells.
Several phage hosts of group A streptococci became resistant to lysis by bacteriophage as a consequence of having acquired the ability to grow in the presence of chloramphenicol. The phage was adsorbed to the streptococcal cell, and P 32 -labeling of the phage showed that the phage genome penetrated the chloramphenicol (CM)- resistant cells as it did the parent cells. However, artificial lysis of the infected CM-resistant cells with chloroform or enzymes revealed no intracellular mature phage particles. Lysates of infected CM-resistant cells contained no phage-related antigenic materials which possessed serum-blocking power, although they were readily detected in lysates of infected parent cells. The CM-resistant cells were not lysogenized by the phage. Only cells resistant to more than 10 μg/ml of chloramphenicol were resistant to phage, and this threshold effect was taken as an indication of at least two different loci of chloramphenicol resistance on the streptococcal genome. Strains resistant to high levels of other antibiotics, such as streptomycin and erythromycin, showed no resistance to lysis by phage. Evidence indicated that the mutant cells were deficient in an essential function associated with the phage genome.
FRIEND, P. L. 1971. Association of chloran~phenicol resistance of group A streptococci with hostcontrolled restriction and modification of bacteriophages. Can. J. Microbial. 17: 1573-1576. Bacteriophages grown on chloran~phenicol (CM)-sensitive group A streptococci plate efficiently only on other CM-sensitive strains, while phages propagated on CM-resistant strains plate well only on CMresistant hosts. Data are presented showing that the phages are subject to host-controlled modification and restriction, and that these processes are related to the CM resistance level of the host.Des bacteriophages multipliCs sur des streptocoques du groupe A sensibles au chloramphenicol (CM) et Ctudies d'apres la methode de 1'Ctalement cornparatif, sont reproduits sans perte seulement sur d'autres souches CM-sensibles. Des phages propages sur des souches CM-resistantes se multiplient bien seulement sur des h6tes CM-resistants. Les resultats indiquent que les phages sont sujets a une modification et une restriction contr6lCes par l'h6te et que ces phtnonlenes sont reliCs au niveau de la resistance au chloramphenicol de l'h6te.Previous studies have reported alterations in picked and transferred, three were selected for the phage sensitivity of group A streptococci when the cells acquired chloramphenicol (CM) resistance (7). CM-sensitive cells were sensitive to phage while CM-resistant mutants derived from them were not lysed, although both types of host adsorbed the phage equally well and were equally sensitive to killing by it. Both cell types were apparently penetrated by the phage DNA, as shown by Waring Blendor treatment of cells infected with 32P-labeled phage. However, no phage antigens or progeny phage could be found in infected CM-resistant cells; thus, the block in phage production occurred after phage DNA penetration and before phage antigen synthesis. It seemed desirable to pursue the relationship between CM resistance and phage sensitivity more thoroughly.If a large number of phage A6 plaque-forming units (pfu) were plated on strain S43CM39, a CM-resistant derivative of A6 host strain S43, an occasional plaque would arise, with a frequency of about one plaque per 104 plaqueforming units. Some of these plaques were picked with sterile toothpicks and propagated in Pbroth (6) on S43CM39. Of about 20 plaques f~~r t h e r study, on the basis of their consistently higher titers and greater stability to storage. These three phages were termed A6.S43CM39 isolates a, b, and c (= cpa, cpb, and cpc). It was found that cpa, cpb, and cpc would now form plaques only on S43CM39 and not on S43. Using techniques described previously (6), it was found that phages A6, cpa, cpb, and cpc all adsorbed to S43 and S43CM39 at the same rate, about 90% of the input phage adsorbed in 9 min, and that all phages were neutralized with similar kinetics by antisera prepared in rabbits against phage A6. The K values of the serum against A6 and cpc were 435 and 460, respectively.One-step growth curves of the three isolates on S43CM39 in P-broth at 37C sh...
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