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Biomedical subjects

J R Tagg

Publications and source records attributed to J R Tagg.

At least 73 records · Page 4Linked to original sources
PubMed1981

Bacteriocin production by Streptococcus salivarius strain P.

A bacteriocin, streptococcin sal-P, was isolated by freeze-thaw elution from cultures of Streptococcus salivarius strain P grown on tryptic soy agar plus 1% neopeptone. The inhibitor could also be extracted with either 7 M urea of 1 M NaCl from cells grown on this medium, but little activity was recovered from cells grown in liquid media of from the supernatants of these cultures. Streptococcin sal-P was found to be a proteinaceous substance of molecular weight approximately 8000. It was remarkably stable at extremes of pH or temperature and appeared to adsorb nonspecifically to both sensitive and resistant bacterial cells and also to cellulose membranes. The range of its inhibitory activity was almost entirely against Gram-positive bacteria, particularly streptococci, including strains of S. pyogenes and S. sanguis, but not S. mutans or group D streptococci. Streptococcin sal-P was bactericidal for actively metabolizing susceptible strains.

Bacteriocins↗
PubMed1979

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

A scheme for the "fingerprinting" of streptococci according to their production of (P typing) and sensitivity to (S typing) bacteriocine-like inhibitory substances has been developed. P typing of 450 beta-haemolytic streptococci by their action on a set of nine standard indicator strains revealed that 80% of strains produced one or more detectable inhibitors, and that 17 different P types could be recognised. Production of some inhibitors seemed to be a property of strains of a particular serological group or type. Bacteriocine-like substances were produced by streptococci of serological groups, A, B, C, D, E, F and G. Nine strains were selected as standard producers for S typing. These strains differed in their spectra of inhibition, but all seemed to be active only against gram-positive bacteria. One producer, a group-F streptococcus, specifically inhibited group-A streptococci. The conditions of incubation were critical for demonstration of inhibitor production. A requirement for blood and for incubation at 32 degrees C were important factors. None of the inhibitors was induced by ultraviolet irradiation. The observed inhibitory effects were not attributable to either hydrogen peroxide or low pH, but to the production of a variety of substances having diverse physicochemical properties and production requirements. Most of the inhibitors do not seem to be produced in liquid media. The "fingerprinting" procedure is simple and inexpensive, and provides a reliable means of subdividing streptococcal strains that may find application as a supplement to the existing serological typing schemes.

Bacteriocins↗
PubMed1979

Production of a bacteriocine-like substance by group-A streptococci of M-type 4 and T-pattern 4.

A unique and characteristic bacteriocine-like inhibitor elaborated by M-type 4, T-pattern 4, group-A streptococci was isolated and partially purified. This inhibitor was found to be produced optimally in Todd-Hewitt broth; after extraction and concentration, was shown to be protein in nature, and to have a m.w. of c. 8000. It was extremely heat stable and acid tolerant, but was quickly inactivated in alkaline conditions. It could be demonstrated in cell-bound form, but 99.5% was found in culture supernates. It was specifically adsorbed by viable sensitive cells, and its mode of action was bacteristatic.

Antigens, Bacterial↗
PubMed1978

Streptococcin A-FF22: nisin-like antibiotic substance produced by a group A streptococcus.

Streptococcin A-FF22 (SA) was shown to occur as both a cell-associated (SA-CA) and an extracellular (SA-EX) component of cultures of the producer bacterium, group A streptococcus strain FF22. SA-CA was solubilized by chemical, enzymatic, and mechanical procedures, similar to those used to release M protein. The independence of SA and M protein in strain FF22 was established by chromatographic separation of the two proteins on the basis of molecular weight and isoelectric point differences between the two substances. Media supporting optimal growth of strain FF22 did not necessarily favor SA production. SA was not produced either at elevated temperatures (39 degrees C) or if the culture was maintained at pH 7 or higher. The release of SA from producer cells was enhanced at lower culture pH values. Much of the SA-CA activity seemed associated with the cell walls of the producer strain, and the nature of the binding appeared to be largely nonspecific in nature and attributable to electrostatic interaction.

Anti-Bacterial Agents↗
PubMed1976

Transduction of bacteriocin determinants in group A streptococci.

Determinants of streptococcin A-FF22 (SA) production and host cell immunity have been transduced to three serologically distinct Group A streptococci. Streptomycin resistance markers were not cotransducible with bacteriocin determinants. SA+ transductants of strains unrelated to the parent SA+ strain were unstable but SA+ transductants of a spontaneous SA- derivative of the parent appeared to be stable.

Bacteriocins↗
PubMed1976

Genetic basis of streptococcin A-FF22 production.

Spontaneous, low-frequency loss of ability to produce streptococcin A-FF22 (SA) by group A streptococcus strain FF22 was observed. The proportion of non-SA-producing (SA(-)) derivatives occurring in strain FF22 cultures grown in Todd Hewitt broth supplemented with 1% of yeast extract (THBY) was increased on treatment with ethidium bromide, acriflavin, or rifampin. The highest incidence of SA(-) organisms, however, was found in untreated THBY cultures that had been aging by incubation at 37 degrees C for several months. The possibility of selective effects in these experiments, operating to enhance the apparent frequency of SA(-) bacteria, was discounted. The survival of SA(-) derivatives in association with populations of SA(+) bacteria was dependent upon the use of culture conditions inimical to SA activity, since a consistent finding was that the loss of ability to produce SA was associated with loss of immunity to the killing action of this bacteriocin. Whereas selective killing of SA(-) derivatives was evident in mixed cultures of SA(+) and SA(-) strains in tryptic soy broth, no such effect was demonstrable in THBY. In these experiments, elimination of SA(-) cells seemed directly related to the presence of active SA. Purified clones of SA(-) substrains did not seem revertible to SA production, either spontaneously or on treatment with nitrosoguanidine. It is suggested that the property of production of SA by group A streptococcus strain FF22, together with that of host cell immunity to the homologous bacteriocin, may be mediated by plasmid-borne genetic determinants.

Bacteriocins↗
PubMed1976

Bacteriocin production by group a streptococcal L-forms.

L-forms induced from a bacteriocin-producing strain of group A streptococcus retained both the ability to produce the streptococcin and producer strain immunity to the homologous bacteriocin. L-forms of a spontaneously cured (bacteriocin negative) derivative of this same strain failed to produce streptococcin but were sensitive to its action.

Bacteriocins↗
PubMed1975

Bacteriocin of a group B streptococcus: partial purification and characterization.

The production of bacteriocin-like inhibition by two of 135 strains of group B streptococci was demonstrated during the growth of these organisms on solid nutrient media. Although a variety of gram-positive organisms was susceptible, none of a wide range of different gram-negative strains was inhibited. The active substance produced by one of these strains was extracted from cultures grown on solid media (Todd-Hewitt agar) and was shown to be bactericidal in action. This bacteriocin (streptocin B(1)) was partially purified by ammonium sulfate precipitation followed by gel filtration and ion-exchange chromatography. Production of the bacteriocin was repressed by addition of certain fermentable carbohydrates to the basic medium and enhanced by the addition of yeast extract. The bacteriocin was shown to exist in two distinct and interconvertible physical forms: a basic unit of molecular weight 10,000 and an aggregate having a molecular weight of over 200,000. The bacteriocin was inactivated by proteolytic enzymes and, although labile in alkali, it was stable to boiling in mild acids.

Bacteriocins↗
PubMed1973

Group A streptococcal bacteriocin. Production, purification, and mode of action.

A bacteriocin, streptocin A, was isolated from the supernatant fluid of tryptic soy broth cultures of Group A streptococcus strain FF-22. Evidence was obtained which supports the view that the failure to recover active streptocin A after growth of the producer strain in certain fluid media is due to the inactivation of the bacteriocin by concomitantly synthesized streptococcal proteinase. The bacteriocin was purified 139-fold and the active product appeared to be of uniform size, having a molecular weight of approximately 8,000. Streptocin A was bactericidal, but not lytic, for a susceptible Group A streptococcus and the lethal effect was markedly temperature dependent. The bacteriocin inhibited the synthesis of DNA, RNA, and protein, and also prevented the uptake and incorporation of glucose by the sensitive cells. Degradation of RNA occurred, but appeared to be less than that produced by a staphylococcal bacteriocin. This effect may be due to differences in the killing potency of the two bacteriocins in preparations having similar inhibitory activity when measured by lawn culture assays.

Alanine↗
PubMed1973

Bacteriocin of a group A streptococcus: partial purification and properties.

The production of bacteriocin-like inhibition by certain strains of group A streptococci was demonstrated during the growth of these organisms on solid nutrient media. Active bacteriocin could not be recovered from broth cultures, possibly because of its inactivation by streptococcal proteinase. The bacteriocin, streptocin A, produced by Streptococcus pyogenes strain FF-22 was partially purified by chemical precipitation and chromatography on carboxymethyl-cellulose. Streptocin A inhibited the growth of various gram-positive organisms but none of a wide range of different gram-negative strains. The bacteriocin was inactivated by proteolytic enzymes and, although labile in alkali, it was extremely stable to heating in mild acids.

Bacteriocins↗