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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↗
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↗
PubMed1977

Bacteriocin typing by leakage of ultraviolet light-absorbing material.

A rapid and reproducible method of bacteriocin typing is described based on leakage of ultraviolet light-absorbing material (UVAM), detectable in supernatants of bacteriocin-sensitive cultures, by means of a spectrophotometer. The prerequisites for reproducible results, with nonsignificant fluctuations in standard error of the mean, are: a set of standardized bacteriocins, produced under defined conditions and of determined strength. These must interact with the unknown bacterial culture in suspension and at a given ratio in order to achieve an optimal multiplicity of interaction. Pyocin and colicin typing by the "scrape and streak" technique of Gillies (J. Hyg. 62:1-10, 1963) was compared with the UVAM leakage method in 275 tests; the two tests were found to be in good agreement for the strains tested.

Bacteria↗
PubMed1978

Isolation and characterization of a Streptococcus mutans bacteriocin inhibitor from Streptococcus pyogenes.

An inhibitor of Streptococcus mutans strain GS5 bacteriocin was released from a bacteriocin-sensitive strain of S. pyogenes by sonic treatment and partly purified by gel filtration on a Sepharose 6B column. The inhibitory factor was sensitive to heat, trypsin, and periodate and possessed a molecular weight of approximately 93,000. This factor may be the receptor for the S. mutans bacteriocin.

Bacterial Proteins↗
PubMed1979

Yersinia intermedia: temperature-dependent bacteriocin production.

Yersinia enterocolitica and related Yersinia species share many temperature-dependent biological attributes. The present report documents temperature-dependent production of a bacteriocin-like substance only among Yersinia strains which ferment L-rhamnose, raffinose, and melibiose and which have been tentatively designed Y. intermedia. When tested by the "lawn-spotting" technique at 25 and 37 degrees C, 7 of 15 Y. intermedia strains produced a bacteriocin only at 25 degrees C with a uniform spectrum of activity against 2 strains of Y. enterocolitica, 1 rhamnose-positive, raffinose-negative, melibiose-negative strain tentatively designated Y. frederiksenii, 8 Y. intermedia, and 3 sucrose- and acetylmethylcarbinol-negative yersinial isolates tested. Bacteriocin-like activity was not detected among the Y. enterocolitica, Y. frederiksenii, or sucrose-negative yersinial strains tested. The exclusive activity of the Y. intermedia antibacterial substance only against yersiniae and not against other representative Enterobacteriaceae tested supports the placement of these microorganisms within the genus Yersinia and further establishes the singularity of Y. intermedia.

Bacteriocins↗
PubMed1976

Isolation and characterization of a bacteriocin produced by Bacillus stearothermophilus strain NU-10.

Broth-grown cultures of Bacillus stearothermophilus strain NU-10 produce a bacteriocin which exerts lethal activity on other strains of the bacterium. Optimal production occurs during late maximum stationary phase of growth, at neutral pH, and 55-65 degrees C. The bacteriocin can be substantially purified by a combination of precipitations, centrifugations, and gel filtrations. The thermocin is composed of protein and carbohydrate. It is partially destroyed by proteolytic enzymes but is resistant to DNase, RNase, and various chemical treatments. The bacteriocin has a small molecular weight and exhibits considerable thermostability.

Bacterial Proteins↗
PubMed1976

[Sensitivity of some Lactobacillus species of the subgenus Betabacterium to the action of bacteriocins from different species of Lactobacillus].

Sensitivity of 84 cultures of L. fermenti, 43 cultures of L. brevis, 13 cultures of L. buchneri and 2 cultures of L. cellobiosus to the effect of 39 types of bacteriocins produced by various species of lactobacilli was studied with the method of delayed antagonism. All the cultures of L. brevis, L. buchneri and L. cellobiosus and 65.5 per cent of the cultures of L. fermenti were sensitive to one or more such bacteriocins. The cultures of L. Fermenti, L. brevis, L. buchneri and L. cellobiosus were sensitive respectively to 37, 19, 16 and 9 types of the bacteriocins out of 39 types tested.

Antibiosis↗
PubMedDate not supplied

[Bacteriocins and their ecological position].

The author discusses the position of bacteriocins in ecology on the basis of the data accumulated to date in the speciality literature, referring to: (a)the great and varied number of bacteriocinogenic bacterial strains; (b)the classification of bacteriocins in terms of their structure, chemical composition and physico-chemical properties; (c)spectrum of activity; (d)elements of differentiation and similarity with other ecologic systems (virsuses, the genetic entities of other microorganisms, interrelations, bacteriocinogeny and certain genetic recombination phenomena). Bacteriocinogeny is regarded as a biologic process, the result of natural selection. Stress is laid on the importance of the bacteriocinogenic and bacteriocinosensitive properties, next to the lysogeny of bacteria, for the classification of microorganisms. It is foreseen that in the future purified bacteriocins may perhaps be used in therapy, at least in certain cases.

Bacteria↗
PubMed1975

[The mode of action of bacteriocin N5 purified from Clostridium perfringens].

The purified bacteriocin N5 produced by Clostridium perfringens BP6K inhibited simultaneously the syntheses of DNA, RNA and protein in sensitive cells, without DNA degradation. Bacteriocin N5 inhibited the accumulation of leucin and caused the exit of the previously accumulated amino acid. The effects of bacteriocin N5 are very similar to those observed for colicins E1, K, A and I.

Bacterial Proteins↗
PubMed1979

The concept of bacteriocins.

After a short description of the discovery of bacteriocins, especially the colicins in this review the following points are discussed: the classification of colicins especially with the aid of resistant mutants of sensitive indicator strains, the bacteriocin-receptors, the bacteriocin-specificity, and the possible ways of transport of colicins across the outer membrane.

Bacteriocins↗
PubMedDate not supplied

[Bacteriocin-like substances produced by Pseudomonas aeruginosa].

Cultures of Pseudomonas aeruginosa were tested for the production of bacteriocin-like substances, and differentiated with respect to three various indicator cultures. A technique was elaborated for the isolation of bacteriocin-like substances from a solid medium. Physico-chemical properties of Ps. aeruginosa were studied for the strains 8-H-3, PAO-406, and PAT-2. The molecular weight of bacteriocin-like substances was calculated for the strain 8-H-3.

Bacteriocins↗