Bacteriocins of gram-positive bacteria

Glutamicin CBII, a bacteriocin-like substance produced by Corynebacterium glutamicum

Corynebacterium glutamicum CBII, in the stationary phase of growth, was found to produce spontaneously a substance resembling bacteriocins by its bactericidal properties. This substance designated glutamicin CBII was observed to exhibit bactericidal activity against coryneform bacteria (12 species tested) but not against unrelated gram-positive (3) and gram-negative (3) bacteria, while its action on bacteria with no quite known relatedness to the coryneform group (14) was found to be variable. Glutamicin CBII was partially purified by precipitation with ammonium sulphate (70% saturation), selective heat precipitation and gel chromatography on Sephadex G-50. The antibacterial substance diffused through cellophane membrane with an approximate cut-off of 10,000 dalton and its sedimentation coefficient was determined to be 1.1 S by ultracentrifugation. Heating at 100 degrees C for 30 min had no effect on its activity. Glutamicin CBII was proved to be resistant to chloroform, trypsin, chymotrypsin, pronase, and subtilisin. According to its staining behaviour and 1H NMR spectra it probably represents a glycoprotein containing only a minor protein component.

Effect of mutacin administration on Streptococcus mutans-induced dental caries in rats

A bacteriocin from serotype c Streptococcus mutans strain C3603 was examined for its inhibitory effect on experimental dental caries in rats infected with S. mutans MT8148R (serotype c). Significant reduction in the incidence of dental caries was found only when bacteriocin was incorporated both in the drinking water and in the diet at a high concentration. However, caries reduction was not as great as expected and the addition of bacteriocin to drinking water alone had no effect on the recovery of S. mutans, plaque deposition or caries incidence. The bacteriocin activity must have been reduced in the oral cavity of rats, and the reasons were examined. Bacteriocin-resistant mutants were not detected and the bacteriocin was not inactivated by saliva. Whereas the bacteriocin did not kill the S. mutans cells grown in a sucrose-containing medium, it completely killed the cells grown in a sucrose-free medium.

Classification and pathogenesis of vulvovaginal candidiasis

Although candidiasis of the female genital tract is one of the most common of the vaginitides, it is a poorly understood disease entity. Vulvovaginal candidiasis is a monoetiologic disease, but the pathways by which pathogenic expression is attained are sufficiently divergent to constitute a classification schema that influences therapy. For selection of appropriate therapy, the following three broad categories are proposed: (1) primary candidiasis, (2) antibiotic-induced candidiasis, and (3) systemically induced candidiasis.

The growth of micro-organisms in intravenous fluids

The growth of four micro-organisms in 12 different intravenous fluids at room temperature was studied. Gram-negative organisms grew better than Gram-positive, and lipid solutions were most favourable to microbial growth. Microbial growth was inhibited in solutions with osmolalities over 500 mosmol/l; Staphylococcus epidermidis was inhibited by inocula with Gram-negative bacilli, while the growth of Gram-negative bacilli generally was not affected. Candida albicans was inhibited by Gram-negative bacilli in lipid and 5% dextrose solutions.

New bacteriophage-like particles in Corynebacterium glutamicum

Three new phage-like particles (CG1, CG2, and CGK1) were isolated from Corynebacterium glutamicum CBII. Particles CG1 and CG2 are DNA phages with long, noncontractile tails, CGK1 is a killer particle according to electron microscopy. A heat-stable low-molecular-weight bacteriocidal substance affecting various coryneform bacteria was observed to be joined to the killer particle CGK1.

A bacteriocin produced by certain M-type 49 Streptococcus pyogenes strains when incubated anaerobically

Bacteriocin production (P)-typing of 75 M-type 49 group-A streptococci obtained from a variety of epidemiological incidents in different countries gave no evidence of production under the usual aerobic test conditions. However, with anaerobic incubation, 28% of the strains gave a pattern of inhibitory activity against the indicator strains which was indistinguishable from that previously attributed to the bacteriocin, streptococcin A-FF22 (SA-FF22). Isolation and partial purification of the M type 49 bacteriocin (SA-M49) by freeze-thaw elution from anaerobically grown lawn cultures, followed by ammonium sulphate precipitation and Sephadex chromatography, showed the activity to be associated with a heat-stable proteinaceous molecule of molecular weight approximately 8000 - properties similar to those of SA-FF22. SA-FF22 and SA-M49 were found to have identical inhibitory spectra including immunity of the producer strains to the inhibitory activity of both the homologous and heterologous bacteriocin preparations. SA-M49 production occurred in some strains of phage subtypes II, III and provisional VI and, since it was a consistent property for all isolates from single outbreaks of infection, it provides a means of discriminating between strains of each of these three phage subtypes. There was no evidence of any increased incidence of SA-M49 production in M-type 49 strains associated with nephritic sequelae.

Production and properties of a bacteriocin from Myxococcus coralloides D

Myxococcus coralloides D was found to produce a substance with a narrow range of antibacterial activity. This substance was produced during the exponential growth phase and was not inducible by ultraviolet light or mitomycin C treatment. The bacteriocin was precipitable by ammonium sulphate, and showed resistance to heat (100 degrees C for 10 min), trypsin, lysozyme, beta-glucuronidase, DNase, RNase, acetone, ethyl ether, urea and mercaptoethanol; it was partially destroyed by pronase and inactivated at extreme pH values. Electron microscopy did not reveal any phage-like particles associated with bacteriocin activity.

Bacteriocin-like activity of group B and group C streptococci of human and of animal origin

An inhibitor "fingerprinting' technique was used to test 120 group B and 50 group C streptococcus strains for production of inhibitory activity. The incidence of inhibitor production was low. Five of 70 group B streptococci of animal origin and one of 50 from human sources consistently produced inhibitory activity. Six of 20 animal strains and three of 30 human strains of group C streptococci were inhibitor producers. These included two Streptococcus dysgalactiae, three S. equisimilis and four S. zooepidemicus. The temperature of incubation and species of origin of the blood used in the culture medium were critical determinants of inhibitor production. Investigation of inhibitors for their spectrum of activity, heat stability, sensitivity to trypsin, dialysability and mode of action indicated that five of the group B and seven of the group C streptococci produced inhibitors that had bacteriocin-line properties. Three bovine strains of group B streptococci produced very similar inhibitory activity. A greater variety of bacteriocin-like substances was detected in the group C streptococcus strains. Two of the S. zooepidemicus strains were each found to produce more than one inhibitory substance.

On the mode of action of the bacteriocin butyricin 7423. Effects on membrane potential and potassium-ion accumulation in Clostridium pasteurianum

1. The apparent transmembrane bulk-phase electrical potential (delta psi) of Clostridium pasteurianum was determined from the distribution ratio of the membrane-permeable cation butyltriphenylphosphonium (BuPh3P+). In glycolysing cells the highest value of delta psi, calculated on the assumption that there was no energy-dependent binding of BuPh3P+ to the organisms, was recorded in media containing only 2-3 mM K+ ions and, even so, was only 100-110 mV. 2. Efrapeptin, a BF1-directed inhibitor of the membrane H+-ATPase of Cl. pasteurianum, abolished the membrane potential (delta psi) and caused complete efflux of actively-transported K+ ions. Thus protonmotive hydrolysis of ATP generated by substrate level phosphorylation is the sole means of membrane energisation in this anaerobe. 3. At low (sublethal) concentrations, butyricin 7423 stimulated K+ efflux from Cl. pasteurianum without measurably affecting its membrane potential. At lethal and supralethal concentrations of this bacteriocin, both delta psi and active K+ uptake were abolished. 4. Whilst the addition of valinomycin to cells of Cl. pasteurianum suspended in media of low K+ concentration generated a diffusion potential to which BuPh3P+ would respond, addition of butyricin 7423 in place of valinomycin caused no such effect. Also, unlike valinomycin, butyricin 7423 did not increase the rate of K+ efflux from non-glycolysing cells of Cl. pasteurianum. Valinomycin stimulated, but butyricin 7423 inhibited, the uptake of 86Rb+ ions by glycolysing cells of Cl. pasteurianum. 5. A mutant strain of Cl. pasteurianum (viz. strain DC3) which possessed a H+-ATPase with diminished sensitivity both to N,N'-dicyclohexylcarbodiimide and to butyricin 7423, exhibited a negligible decrease in delta psi and in K+ accumulation ratio in response to concentrations of butyricin 7423 that were bactericidal to the wild-type, parent organism. Even so, the bactericidal action of butyricin 7423 on Cl. pasteurianum is not adequately explained by its ability in vitro to inhibit the membrane H+-ATPase of this organism. 6. Bactericidal concentrations of butyricin 7423 neither provoked efflux of Na+ ions from Cl. pasteurianum nor exhibited any protonophorous activity. However, at artificially high concentration, butyricin 7423 catalysed the passage of Na+ ions as well as of K+ ions through multilayer lipid membranes. 7. As a non-protonophorous uncoupler, butyricin 7423 appears to act in a similar manner to that of the membrane-active colicins. Yet no evidence was obtained that butyricin 7423 at its minimum lethal concentration might form a gated ion channel in the cytoplasmic membrane of the target cell, or act as a classic ionophore.

A study on bacteriocin typing of avian strains of Pasteurella multocida

In two groups, each containing 56 Pasteurella multocida strains of avian origin, the percentage of multicin-producing strains was 80.4 and 71.4. In two groups containing 46 and 58 isolates tested for sensitivity to multicins, 82.6% and 62.1% respectively were listed as indicators. P. multocida strains producing bacteriocins were active on a range of 1-33 indicators. A preliminary multicin typing system was set up with the use of eight selected indicators; 52% of multicin-producing strains acted on one indicator only. P. multocida serotypes and serologically untypable strains were subdivided into multicin types.

Honey and other environmental risk factors for infant botulism

Infant botulism results from the in vivo production of toxin by Clostridium botulinum after it has colonized the infant's gut. Epidemiologic and laboratory investigations of this recently recognized disease were undertaken to identify risk factors and routes by which C. botulinum spores might reach susceptible infants. Clostridium botulinum organisms, but no preformed toxin, were identified in six different honey specimens fed to three California patients with infant botulism, as well as from 10% (9/90) of honey specimens studied. By food exposure history, honey was significantly associated with type B infant botulism (P = 0.005). In California, 29.2% (12/41) of hospitalized patients had been fed honey prior to onset of constipation; worldwide, honey exposure occurred in 34.7% (28/75) of hospitalized cases. Of all food items tested, only honey contained C. botulinum organisms. On household vacuum cleaner dust specimens and five soil specimens (three from case homes, two from control homes) contained Clostridium botulinum. The known ubiquitous distribution of C. botulinum implies that exposure to its spores is universal and that host factors contribute importantly to the pathogenesis of infant botulism. However, honey is now an identified and avoidable source of C. botulinum spores, and it therefore should not be fed to infants.

Lactostrepcins--acid bacteriocins produced by lactic streptococci

All 47 non-nisin producing strains of Streptococcus lactis and 12/13 strains of Str. lactis subsp. diacetylactis examined produced bacteriocins, for which the term lactostrepcins is suggested. Seven strains of Str. cremoris examined produced no bacteriocins active against 3 lactic streptococci strains used as indicators. The strains examined were divided into 3 groups: I, those producing lactostrepcins active against only one streptomycin resistant mutant of Str. lactis 60 indicator strain; II, those producing lactostrepcins active against all 3 indicator strains; III, those not producing lactostrepcins active against the indicator strains employed. The lactostrepcins were sensitive to various proteolytic enzymes and to phospholipase D, but retained full or partial activity after dialysis. Most of the bacteriocins studied were fully active only within the pH range 4.2--5.0 and were reversibly inactivated at pH 7.0 or 8.0. Results suggested occurrence of 4 different lactostrepcins. The lactostrepcins produced by all group I strains were the same, but there were differences among the lactostrepcins produced by group II strains. Lactostrepcins killed some beta-haemolytic streptococci and some strains of Lactobacillus helveticus. One of the lactostrepcins was also active against certain Leuconostoc strains, but not against other Leuconostoc strains, nor against L. helveticus or other Gram-positive bacteria.