Group a Streptococcal Bacteriocin

Abstract

The bacteriocins are an intriguing potpourri of bactericidal antibiotics, having a wide range of different genetic determinants, physicochemical properties, and killing mechanisms (1). Bacteriocinogeny seems an almost universal property of bacteria and various strains of most species have now been shown to produce bacteriocins. Although there have been several reports of bacteriocin-like inhibition produced by Group A streptococci on solid media (2-4), progress in this field has been hampered by the inability to demonstrate the active bacteriocin in broth cultures.A streptococcal bacteriocin was recently obtained in cell-free form following "freeze-thaw" extraction of the liquor from cultures grown on Oxoid ToddHewitt agar (4, 5). The producer organism was a Group A beta-hemolytic streptococcus (strain FF-22) and the bacteriocin was correspondingly named streptocin A. The present communication is concerned with the isolation and purification of streptocin A from broth cultures of this same producer strain and an investigation of the mode of action of the bacteriocin against a susceptible Group A streptococcus. Several properties of the bacteriocin are compared with those of a bacteriocin produced by a strain of phage type 71 Staphylococcus aureus. Materials and MethodsBacterial Strains.--Group A streptococcus strain FF-22 (5) and S. aureus strain C55 (6) were the organisms used for the production of the streptococcal and staphylococcal bacteriocins. Various other strains were utilized as indicators in studies of the specificity of the range of bactericidal activity of these bacteriocins. Group A streptococcus strain PF 1643 (6) is an indicator sensitive to both streptocin A and staphylococcin. S. aureus strain 502A (6)

"Fingerprinting" -haemolytic streptococci by their production of and sensitivity to bacteriocine-like inhibitors

“…Recently, Farkas-Himsley and Page1 (1 977) have attempted to make bacteriocine typing more quantitative by mixing suspensions of test strains with standardised bacteriocine preparations and detecting the presence of leaked ultravioletlight-absorbing material. Similar principles might eventually be applicable to the inhibitor typing of streptococci, but so far it has been possible to make cell-free preparations only of the inhibitors produced by strains P1 (Johnson et al, 1979), P2 (Tagg et al, 1973b) and P3 (Tagg et al, 1975). Similar difficulties have been encountered in other investigations of inhibitor production by gram-positive bacteria .…”

Group H Streptococcal Bacteriocins Having No Relation to Bacterial Transformation

“…The identity of the Challis and 36658 bacteriocins and their autolysins was not established in this study, the possibility remaining that they are products of essential the same origin modified by the different media. Bacteriocin activity without lysis was reported for streptococci of group A by Tagg et al (14) and of group H strain Challis by Schlegel and Slade (12,13), and for staphylococci by Lanchowicz and Walczak (3). This phenomenon was interpreted as being due to the inhibition of synthesis of DNA, RNA or protein.…”

“…The lawn assay is unsuitable for detecting sensitivity to the Challis bacteriocin. Tagg et al (14) stated that several bacteriocins show stronger activity on agar plates than in broth, which is the usual method for examining bacteriocin activity. Possible interpretations of this phenomenon are: 1) too small quantity of bacteriocin in the filtrate to form a growth inhibition zone, and/or 2) adsorption and inactivation of the bacteriocin to the agar medium.…”

“…Since the bacteriocins were prepared in neutral pH and at normal ion concentration, then may correspond to the latter phase of streptocin STH l . Streptocin A (14) and staphylococcin (3) are reported to be low-molecular weight polymer of about 10,000 daltons. Whether the bacteriocins in our study have polymerized structures is not known.…”

Factors affecting production of the group A streptococcus bacteriocin SA-FF22

“…' Proteinase production by strain FF22 is promoted by growth in BHI. 4 In some cases production of group A streptococcal bacteriocins is favoured by conditions that promote proteinase production. 2 3 Since purified streptococcal proteinase inactivates SA-FF22 (results not shown), inhibition of proteinase production should increase the yield of SA-FF22.…”