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PubMed1978

Interactions between Neisseria sicca and viridin B, a bacteriocin produced by Streptococcus mitis.

Viridin B, a bacteriocin produced by Streptococcus mitis (mitior), is bactericidal to Neisseria sicca. Oxygen consumption by actively growing N. sicca cultures ceased immediately upon exposure to viridin B. Adenosine triphosphate production was slightly enhanced within 1 h of exposure to the bacteriocin but was subsequently repressed. The uptake and incorporation of glucose was prevented in the presence of viridin B. The bacteriocin also blocked uptake of an amino acid mixture in chloramphenicol-pretreated cells. Pretreatment or concomitant treatment with a variety of antibiotics known to inhibit specific synthetic pathways did not alter the inhibition of macromolecular synthesis produced by the bacteriocin. Although viridin B blocks protein and nucleic acid syntheses, no degradation of such macromolecules was observed. The inhibitory effects of viridin B on macromolecular synthesis and on viability required the presence of sufficient nutrients to allow active metabolism of N. sicca. The bacteriocin did not inhibit viability or macromolecular synthesis in anaerobically incubated N. sicca. Thus, active, oxidative metabolism by N. sicca cells is essential for viridin B action. A model for viridin B action is proposed.

Adenosine Triphosphate↗
PubMed1979

Bacteriocin production by Clostridium acetobutylicum in an industrial fermentation process.

High titers of a noninducible bacteriocin were produced by Clostridium acetobutylicum in a molasses fermentation medium used for the industrial production of solvents. Release of the bacteriocin towards the end of the exponential growth phase was accompanied by lysis of the culture and inhibition of the production of solvents. The producer cells were sensitive to the bacteriocin, which only affected other C. acetobutylicum strains and a Clostridium felsineum strain. The thermolabile bacteriocin was not inactivated by protease enzymes and had no optimum stability between pH 4 and 5. The sedimentation coefficient of the bacteriocin was 6S.

Bacteriocins↗
PubMed1975

Self-transferable plasmids determining the hemolysin and bacteriocin of Streptococcus faecalis var. zymogenes.

Strains of Streptococcus faecalis var. zymogenes, designated JH1 and JH3, produced a hemolysin and a bacteriocin. Hemolytic activity was lost from a low percentage of cells grown in broth at either 37 or 45 C. All nonhemolytic (Hly-) variants had lost bacteriocin activity (Ben-), and those from strain JH3 had also lost resistance to the bacteriocin (Bnr-). The majority of Hly-, Ben- variants from JH1 retained bacteriocin resistance (Bnrplus). Strains JH1 and JH3 contained a plasmid deoxyribonucleic acid species of molecular weight 38 times 10-6 (plasmids pJH2 and pJH3, respectively), and strain JH1 also contained a 50 times 10-6 molecular weight plasmid (pJH1) which has previously been shown to carry the genes determining resistance to the antibiotics kanamycin, neomycin, streptomycin, erythromycin, and tetracycline. Hly-, Bcn-, Bnr- variants of strain JH3 had completely lost plasmid pJH3. Hly-, Bcn-, Bnr- variants of strain JH1 had completely lost plasmid pJH2 and retained plasmid pJH1, but Hly-, Bcn-, Bnrplus variants had retained both plasmids pJH2 and pJH1. The Hlyplus, Bcnplus, Bnrplus traits from both parental strains were transferable to nonhemolytic S. faecalis strains during mixed incubation in broth at 37 C, and hemolytic recipient strains were found to have received plasmid pJH2 from strain JH1 and pJH3 from JH3. We conclude that the Hlyplus, Bnrplus traits are borne on plasmid pJH2 in strain JH1 and pJH3 in strain JH3 and that, in Hly-, Bcn-, Bnrplus variants of strain JH1, plasmic pJH2 has suffered a mutation affecting hemolysin and bacteriocin expression. We infer that the plasmids transfer by conjugation. Beta-hemolytic activity is the only property distinguishing the zymogenes variety from S. faecalis. Since we have shown that this activity is plasmid borne in strains JH1 and JH3, we endorse the view that the varietal status of zymogenes should be dropped.

Anaerobiosis↗
PubMed1977

Synthesis of bacteriocins in liquid cultures of Streptococcus mutans.

Strains of Streptococcus mutans synthesized bacteriocins in agar plates, but synthesis of detectable bacteriocins in liquid media took place only under certain culture conditions. The composition of the medium proved to be crucial. Trypticase Soy Broth with 4% Yeast Extract meeting the requirements. The effect of the Yeast Extract is obscure, for some strains also formed detectable bacteriocins in a special Trypticase medium without this agent. It was noted that the broth should be filter-sterilized rather than autoclaved and only a few days old. Attempts at liberating cell-bound bacteriocins from washed cells were unsuccessful, even when they were treated with ultrasound, EDTA, or various chemicals followed by ultrasound. On the basis of size and sensitivity to heat the bacteriocins could be divided into two groups, while their resistance to ether and chloroform and to trypsin did not follow this pattern. Dependence on plasmids could not be demonstrated by attempts at curing with acridine orange or ethidium bromide; and the involvement of phages was unlikely, since the inhibition was not transmissible and phage-like structures were not observed in the electron microscope.

Bacteriocins↗
PubMed1977

[Differentiation of several species of lactobacilli of the subgenus Thermobacterium according to their bacteriocin sensitivity spectra].

The method of retarded antagonism was applied to the study of L. acidophilus (187 cultures), L. salivarius (65 cultures), L. jugurti (16 cultures), L. helveticus (4 cultures) sensitivity to the action of 39 bacteriocines produced by various lactobacilli species. By the sensitivity spectra to bacteriocines L. ècidophilus cultures were divided into 76, L. salivarius--22, L. jugurti--15, and L. helveticus into 2 bacteriocines. By bacteriocine typing it was possible to differentiate into a number of bacteriocine types L. acidophilus and L. salivarius variants with the same biochemical and physiological properties.

Bacteriocins↗
PubMed1976

[Bacteriocin typing of lactobacilli of the Streptobacterium subgenus].

Sensitivity of 144 L. casei cultures and 23 L. plantarum cultures to the action of 39 bacteriocins produced by lactobacillae of different species was studied by the method of delayed antagonism. By the bacteriocin sensitivity the L. casei cultures were subdivided into 37 and L. plantarum cultures--into 7 bacteriocin types. The method of bacteriocin typing permitted differentiation of the L. casei and L. plantarum cultures, which had the same biochemical and physiological properties, as a number of bacteriocin types.

Bacteriocins↗
PubMed1979

Bacteriocin typing of Serratia marcescens. A simplified system.

The authors describe a simplified system for the detection of bacteriocin production by Serratia marcescens with the use of six indicator strains, which include Escherichia coli, Klebsiella pneumoniae, Citrobacter diversus, Enterobacter aerogenes (two strains), and Serratia rubidaea grown on arabinose minimal medium plates. Of the 64 possible bacteriocin types, 11 were observed; 66% of the isolates tested were found to be one of three types. Occasionally more than one bacteriocin type was observed in an individual specimen; however, serotyping or antibiograms, or both, also indicated this was a different strain. The marcescin types were stable markers. With the use of this technic, different endemic strains of Serratia were shown to predominate in various areas of the hospital. In addition, when urinary tract isolates were compared with respiratory tract isolates, significant differences were found in the predominate types. The typing of these isolates by bacteriocin production was supported by serotype and antibiotype findings. The results suggest that this simple system may be a useful tool in a general hospital.

Bacteriocins↗
PubMed1976

Activity of two Streptococcus mutans bacteriocins in the presence of saliva, levan, and dextran.

The extracellular dextrans produced from sucrose by Streptococcus mutans strains BHT and GS-5 did not prevent the synthesis or release of active bacteriocins by these two strains. In addition, several streptococci that were genetically sensitive to these bacteriocins, and that could synthesize a variety of extracellular dextrans and levans from sucrose, remained phenotypically sensitive when grown in the presence of sucrose. Bacteriocin activity was not altered by treatment with high-molecular-weight dextran or by human saliva. The bacteriocins produced by, and active against, S. mutans thus appear to be capable of acting in vivo and may play a role in regulating the bacterial ecology of the oral cavity.

Bacteriocins↗
PubMed1979

Effect of bacteriocin production by Streptococcus mutans on the plaque of gnotobiotic rats.

The effect of bacteriocins produced by strains of Streptococcus mutans on the microbial composition of dental plaque was studied in gnotobiotic rats. In one set of tests, using S. mutans strains T2 and SW31, rats were simultaneously infected with the bacteriocinogenic parent (bac(+)) and corresponding bac(-) mutants, and the relative proportions of each strain present in three different tooth sites were determined at various time intervals after inoculation. Some animals were monoinfected with bac(+) and bac(-) strains, and in vivo properties, such as plaque fermentation end products, amount of plaque formed, and cariogenicity, were measured. In another series of tests with strains T2 bac(+) and T2 bac(-), animals were sequentially inoculated with a time interval of 1 week. On simultaneous inoculation, the bac(-) mutant, which was sensitive in vitro to the bacteriocin produced by the parent, was totally unable to establish in a plaque consisting of the bac(+) strain even when the challenging dose was increased 100-fold. In contrast, the bac(+) strain was successful not only in invading an established bac(-) plaque but also in eventually almost eliminating the mutant. In monoinfected animals, there were no significant differences in plaque-forming ability, fermentation end products, or cariogenicity between the two strains. Also, bacteriocin activity was detected in plaque harboring the bac(+) but not the bac(-) strain. The results not only indicate that bacteriocin activity can occur in vivo but also suggest that bacteriocinogeny might confer an ecological advantage upon a strain attempting to establish itself in an ecosystem.

Acetates↗
PubMed1978

Bacteriocin typing of Clostridium perfringens in human feces.

Three hundred and ninety-nine isolates of Clostridium perfringens from enriched stool specimens of 51 individuals (about eight colonies per person) were typed by bacteriocins. Forty-nine percent of these persons carried more than one bacteriocin type in their stool, and some had three or four different stains as determined by bacteriocin typing. Weekly stool specimens obtained from seven positive volunteers over a period of 5 weeks were screened for C. perfringens, and several colonies from each person were typed. This survey demonstrated that the number of types fluctuated with time, several types could be carried simultaneously, and the isolation of the organism was variable. Nine new bacteriocin types of C. perfringens were isolated in this study.

Bacteriocins↗
PubMed1978

Typing of fluorescent phytopathogenic pseudomonads by bacteriocin production.

Several phytopathogenic fluorescent Pseudomonas species, primarily P. syringae, could be grouped into 16 bacteriocin producer groups, including new and previously described groups. At least 86% of the P. syringae strains could be typed by bacteriocin production. There was poor correlation between bacteriocin type and host plant origin. No correlation was detected between syringomycin (a phytotoxin) production and bacteriocin type.

Bacterial Toxins↗
PubMed1978

Bacteriocin typing of some Lactobacillus species of the subgenus betabacterium.

One hundred and forty cultures of L. fermenti, L. brevis, and L. buchneri were tested by the method of delayed antagonism for sensitivity to 39 bacteriocins produced by lactobacillus strains of different species. According to their bacteriocin sensitivity patterns, 84 L. fermenti, 43 L. brevis and 13 L. buchneri cultures were differentiated into 26, 18 and 10 bacteriocin types, respectively. Bacteriocin typing allows not only intraspecific differentiation of L. fermenti, L. brevis and L. buchneri cultures but also a subdivision of their biochemical-physiological variants.

Bacteriocins↗
PubMed1978

Bacteriocine typing of Providencia isolates.

A method of typing isolates of Providencia is described based on the sensitivities of the organisms to bacteriocines. Twelve standard bacteriocine producing strains were selected from a large number of isolates tested and from these liquid bacteriocine preparations were obtained. The activities of these preparations on over 300 isolates were determined and from this information a bacteriocine typing system has been developed.

Bacteriocins↗
PubMed1976

[Sensitivity of the lactobacilli of the subgenus Streptobacterium to bacteriocins of lactobacilli of different species].

Sensitivity of 167 cultures of Lactobacilli of Streptobacterium to 39 bacteriocins produced by L. acidophilus, L. jugurti, L. salivarius, L. lactis, L. helveticus, L. casei, L. plantarum, L. fermenti, L. brevis and L. buchneri was studied. It was found that the cultures of L. casei were sensitive to 30 types of bacteriocins, while the cultures of L. plantarum were sensitive to 9 bacteriocin types. 89.6 per cent of the cultures of L. casei and all cultures of L. plantarum were sensitive to one or several bacteriocins produced by Lactobacilli of different species.

Bacteriocins↗
PubMed2026

Bacteriocin-mediated intraspecies competition driven by acquired Bac41 operon in epidemic Enterococcus faecalis ST179.

Enterococcus faecalis is a common gut commensal and an opportunistic pathogen causing hospital-acquired infections. Despite its clinical importance, comprehensive global genomic and epidemiological data remain limited. Here, we analyzed 5,895 E. faecalis genomes collected between 2000 and 2020 and identified ST179, a human-derived single-operon variant of the high-risk CC16 clonal complex, as an emerging epidemic clone in China. Spot-killing assays revealed that ST179 strongly inhibited other clinical E. faecalis sequence types. Biochemical purification and proteomic analyses identified BacL1 as a key effector associated with this species-specific antibacterial activity. Functional assays confirmed its inhibitory phenotype, providing ST179 with a lineage-specific, bacteriocin-mediated competitive advantage. The high prevalence of the Bac41 operon likely contributed to the epidemiological success and ecological fitness of ST179. These findings highlight the role of bacteriocin-mediated intraspecies competition in shaping E. faecalis population dynamics and suggest that ST179 might become an emerging high-risk lineage in China.IMPORTANCEEnterococcus faecalis is a common gut bacterium and an opportunistic pathogen. We identify ST179 as an emerging epidemic clone in China and show that it outcompetes other strains via the bacteriocin Bac41. This competitive advantage helps explain its rapid spread. Our findings highlight how bacterial competition shapes population dynamics and provide insights into the emergence of high-risk E. faecalis lineages, informing strategies for monitoring and infection control.

Enterococcus faecalis↗
PubMed1977

Bacteriocins from Myxococcus fulvus (Myxobacterales).

Bacteriocin-like activities were found in several Myxococcus fulvus strains. One strain, Mx f16, exerted strong inhibitory effects on several myxobacterial strains. Synthesis of its bacteriocinic activity could not be induced by mitomycin. Electrophoresis and molecular sieve chromatography revealed at least three different bacteriocinic substances of low molecular weight.

Bacteriocins↗
PubMed1978

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.

Bacteriocins↗
PubMed1975

Properties of some bacteriocins produced by Rhizobium trifolii.

Bacteriocins produced by six strains of Rhizobium trifolii were found to be of the relatively low molecular weight, non-phage type. The molecular weights ranged from approximately 1-8 X 105 to 2-0 X 105. All were of protein composition, as indicated by buoyant density (1-32 to 1-34 g/cm3) in CsC1 and by sensitivity to proteolytic enzymes. They were resistant to RNAase but sensitive to DNAase. The six bacteriocins could further be separated into two subgroups on the basis of sensitivity to extremes of pH, binding to filter membranes, activity spectrum on sensitive strains of R. trifolii, and possibly mode of action on sensitive bacteria. Bacteriocin production occurred spontaneously during the early-to mid-exponential phase of bacterial growth in broth culture.

Bacteriocins↗