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PubMed1996

Tween 80 effect on bacteriocin synthesis by Lactococcus lactis subsp. cremoris J46.

Sorbitan polyoxyethylene monooleate (Tween 80) suppressed bacteriocin cell adhesion. Within the range 0-1% (v/v), there was an increase in bacteriocin production in regulated (pH 5.5 or 6.0) batch cultures with increasing Tween 80 concentration. For example, at pH 5.5 and in the presence of 1% Tween 80, bacteriocin production was about fourfold higher than in its absence. However, further increase in Tween 80 concentration did not result in a significant modification of the bacteriocin titre. It was shown that the increase was not linked to an activating effect of the surfactant on preformed enzyme, to an increase of bacteriocin availability or to a sensitization of the target cell, demonstrating that Tween 80 promoted bacteriocin production.

Bacteriocins↗

PubMed2006

Plasmid-mediated bacteriocin production by Shigella flexneri isolated from dysenteric diarrhoea and their transformation into Escherichia coli.

AIMS: To determine the production of bacteriocin by Shigella flexneri strains, to relate their production to the presence of dysenteric diarrhoea and to asses the genetic determination of the bacteriocin. METHODS AND RESULTS: One hundred and sixteen strains of Sh. flexneri were isolated from patients with diarrhoea and 49 of them produced bacteriocin active against several Escherichia coli and abacteriocinogenic Sh. flexneri strains. The extrachromosomal DNA isolated from bacteriocinogenic Sh. flexneri strains were used as a substrate to transform E. coli HB-101 cells by means of electroporation. CONCLUSIONS: Only the Sh. flexneri strains isolated from dysenteric diarrhoea produced bacteriocin. It was demonstrated that a plasmid of approx. 3 kb was responsible for the genetic determination of these anti-bacterial substances. SIGNIFICANCE AND IMPACT OF THE STUDY: A 3-kb plasmid that harboured information for the production of bacteriocin by Sh. flexneri strains was described. The production of this bacteriocin may be related to dysenteric diarrhoea produced by these bacterial strains.

Adolescent↗

PubMed2006

Bacteriocin production, plasmid content and plasmid location of enterocin P structural gene in enterococci isolated from food sources.

AIMS: To characterize bacteriocin production, antimicrobial spectrum and plasmid content in bacteriocinogenic enterococci from foods. METHODS AND RESULTS: Bacteriocinogenic Enterococcus faecium (14 isolates) and Enterococcus faecalis (three isolates) showed two different patterns of bacteriocin production in liquid broth: exponential-phase and stationary-phase production. Bacteriocin concentrates from all enterococci were inactivated by trypsin, but seldom by heat (100-117 degrees C), extremes of pH (2.0 to 9.0) or reducing agents (such as dithiothreitol). All bacteriocin concentrates were active against Listeria innocua and Listeria monocytogenes, and most were also active against many Ent. faecalis and Ent. faecium isolates. Enterococci clustered in three main groups according to their plasmid content (which included plasmids from 2.0 to 53 kb). Several isolates from different foods showed almost identical plasmid profiles. The enterocin P structural gene (entP) was detected by hybridization on plasmids of c. 19, 26 and/or 35-38 kb. CONCLUSIONS: Enterococci from food show different patterns of bacteriocin production and different plasmid content in spite of carrying similar bacteriocin-encoding genes. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides information on the diversity of bacteriocinogenic enterococci from food sources carrying apparently similar enterocin genes.

Bacteriocins↗

PubMed2001

Lactococcin MMFII, a novel class IIa bacteriocin produced by Lactococcus lactis MMFII, isolated from a Tunisian dairy product.

A novel bacteriocin, lactococcin MMFII, produced by Lactococcus lactis MMFII isolated from a Tunisian dairy product had been identified. The bacteriocin was purified to homogeneity from fresh overnight M17 broth culture by sulfate ammonium precipitation, cation-exchange chromatography, sep-pack chromatography and two steps of reverse-phase chromatography. The purified bacteriocin was heat stable, pH resistant and protease sensitive. Its amino acid sequence, obtained by Edman degradation, revealed a 37-amino acid peptide with two cysteine residues in positions 9 and 14 and a calculated mass of 4144.6 Da. Laser desorption mass spectrometry analysis gave a molecular mass of 4142.6, suggesting the presence of a disulfide bond within the purified bacteriocin. Lactococcin MMFII contains the N-terminal YGNGV consensus motif and is active against Listeria. Thus, it belongs to the class IIa bacteriocins figuring the first example of such a bacteriocin produced by a lactococcal strain.

Amino Acid Sequence↗

PubMed1995

Bacteriocin release proteins: mode of action, structure, and biotechnological application.

The mechanism by which Gram-negative bacteria like Escherichia coli secrete bacteriocins into the culture medium is unique and quite different from the mechanism by which other proteins are translocated across the two bacterial membranes, namely through the known branches of the general secretory pathway. The release of bacteriocins requires the expression and activity of a so-called bacteriocin release protein and the presence of the detergent-resistant phospholipase A in the outer membrane. The bacteriocin release proteins are highly expressed small lipoproteins which are synthesized with a signal peptide that remains stable and which accumulates in the cytoplasmic membrane after cleavage. The combined action of these stable, accumulated signal peptides, the lipid-modified mature bacteriocin release proteins (BRPs) and phospholipase A cause the release of bacteriocins. The structure and mode of action of these BRPs as well as their application in the release of heterologous proteins by E. coli is described in this review.

Amino Acid Sequence↗

PubMed2006

Isolation of a Lactobacillus salivarius strain and purification of its bacteriocin, which is inhibitory to Campylobacter jejuni in the chicken gastrointestinal system.

We evaluated anti-Campylobacter jejuni activity among >1,200 isolates of different lactic acid bacteria. Lactobacillus salivarius strain NRRL B-30514 was selected for further study. The cell-free, ammonium sulfate precipitate from the broth culture was termed the crude antimicrobial preparation. Ten microliters of the crude preparation created a zone of C. jejuni growth inhibition, and growth within the zone resumed when the crude preparation was preincubated with proteolytic enzymes. Bacteriocin OR-7, derived from this crude preparation, was further purified using ion-exchange and hydrophobic-interaction chromatography. The determined amino acid sequence was consistent with class IIa bacteriocins. Interestingly, OR-7 had sequence similarity, even in the C-terminal region, to acidocin A, which was previously identified from L. acidophilus and had activity only to gram-positive bacteria, whereas OR-7 had activity to a gram-negative bacterium. Bacteriocin activity was stable following exposure to 90 degrees C for 15 min, also consistent with these types of antibacterial peptides. The purified protein was encapsulated in polyvinylpyrrolidone and added to chicken feed. Ten day-of-hatch chicks were placed in each of nine isolation units; two groups of birds were challenged with each of four C. jejuni isolates (one isolate per unit). At 7 days of age, one group of birds was treated with bacteriocin-emended feed for 3 days, and one group was left untreated. At 10 days of age, the birds were sacrificed and the challenge strain was enumerated from the bird cecal content. Bacteriocin treatment consistently reduced colonization at least one millionfold compared with levels found in the untreated groups. Nonchallenged birds were never colonized by C. jejuni. Bacteriocin from L. salivarius NRRL B-30514 appears potentially very useful to reduce C. jejuni in poultry prior to processing.

Amino Acid Sequence↗

PubMed1979

Purification, properties, and cytotoxic effect of a bacteriocin from Mycobacterium smegmatis.

The bacteriocin produced by Mycobacterium smegmatis ATCC 14468 was isolated, and a study was made of its chemical, physical, and biological properties. No appreciable bacteriocin activity was found in the culture supernatant fluids, but it was released in appreciable quantities after disruption of the cells. The material was purified 49-fold by means of chromatography on diethylaminoethyl-cellulose, ammonium sulfate fractionation, gel filtration on Sephadex G-200, and chromatography on diethylaminoethyl-Sephadex A-50. Its molecular weight was determined to be approximately 75,000 from the elution profile on Sephadex G-200 chromatography. The bacteriocin was resistant to deoxyribonuclease, ribonuclease, lipase, ultraviolet irradiation, and freeze-thawing, whereas it was relatively less thermostable and was sensitive to proteolytic enzymes. The lethal effect of the bacteriocin was demonstrated by the decrease in viable counts of the bacteriocin-sensitive indicator strain, M. diernhoferi ATCC 19340. The bacteriocin preparation inhibited the growth of HeLa-S3 cells.

Antineoplastic Agents↗

PubMed1981

Inhibition of ribonucleic acid polymerase by a bacteriocin from Bacteroides fragilis.

The Bacteroides fragilis bacteriocin which inhibits ribonucleic acid (RNA) polymerase activity had a narrow activity spectrum in vivo and only inhibited the growth of certain B. fragilis strains. In vitro the bacteriocin was not specific and inhibited RNA polymerases from widely diverse bacterial genera. RNA polymerases from rifampin-resistant strains of Bacteroides thetaiotaomicron and Clostridium acetobutylicum were resistant to the bacteriocin in vitro. Purified bacteriocin bound to partially purified RNA polymerase, and both proteins were cosedimented in a glycerol gradient. In the RNA polymerase reaction, the bacteriocin acted as a competitive inhibitor for adenosine, cytidine, and uridine 5'-triphosphates and as a noncompetitive inhibitor for guanosine 5'-triphosphate. The bacteriocin did not inhibit RNA polymerase from chicken embryos.

Bacteriocins↗

PubMed1996

Analysis of Lactobacillus phages and bacteriocins in American dairy products and characterization of a phage isolated from yogurt.

Yogurt and acidophilus milk that contain Lactobacillus acidophilus could promote human health because L. acidophilus can inhibit enteric and food-borne microbial pathogens. To evaluate the stability of diary L. acidophilus cultures, we studied whether some diary lactobacilli could be inhibited by phages or bacteriocins released by other dairy lactobacilli. From 20 yogurts and two acidophilus milks purchased at local food markets, 38 Lactobacillus strains were isolated. Eight Lactobacillus type strains were used as controls. With mitomycin induction and agar spot assay, phages and bacteriocins were isolated from these strains and their activities were analyzed. Lactobacillus strains from 11 yogurts released phages, while the strains from most of the remaining products released bacteriocins. One phage, designated phi y8, was characterized. It was spontaneously released from its host strain L. acidophilus Y8, at a rate of about 10(4)/ml. This phage lysed nine other dairy Lactobacillus strains tested. It had a burst size of 100, an elongated prolate head of 39 by 130 nm, a long, flexible but noncontractile tail of 300 nm, and a 54.3-kb linear double-stranded DNA. DNA fingerprinting analysis indicated that L. acidophilus phages of nine yogurts in this study belonged to the same type as phi y8. Although they may be sensitive to bacteriocins, all lysogens resisted further phage attacks, whereas most nonlysogens were sensitive to both phages and bacteriocins. Therefore, Lacotbacillus cultures of some American yogurts and acidophilus milks may be unstable or unsafe because they can either be inhibited by phages or bacteriocins or release them to inhibit lactobacilli or other diary products.

Animals↗

PubMed1997

Application and evaluation of the phage resistance- and bacteriocin-encoding plasmid pMRC01 for the improvement of dairy starter cultures.

The conjugative 63-kb lactococcal plasmid pMRC01 encodes bacteriophage resistance and production of and immunity to a novel broad-spectrum bacteriocin, designated lacticin 3147 (M.P. Ryan, M.C. Rea, C. Hill, and R.P. Ross, Appl. Environ. Microbiol. 62:612-619, 1996). The phage resistance is an abortive infection mechanism which targets the phage-lytic cycle at a point after phage DNA replication. By using the genetic determinants for bacteriocin immunity encoded on the plasmid as a selectable marker, pMRC01 was transferred into a variety of lactococcal starter cultures to improve their phage resistance properties. Selection of resulting transconjugants was performed directly on solid media containing the bacteriocin. Since the starters exhibited no spontaneous resistance to the bacteriocin as a selective agent, this allowed the assessment of the transfer of the naturally occurring plasmid into a range of dairy starter cultures. Results demonstrate that efficient transfer of the plasmid was dependent on the particular recipient strain chosen, and while high-frequency transfer (10(-3) per donor) of the entire plasmid to some strains was observed, the plasmid could not be conjugated into a number of starters. In this study, transconjugants for a number of lactococcal starter cultures which are phage resistant and bacteriocin producing have been generated. This bacteriocin-producing phenotype allows for control of nonstarter flora in food fermentations, and the phage resistance property protects the starter cultures in industry. The 63-kb plasmid was also successfully transferred into Lactococcus lactis MG1614 cells via electroporation.

Bacteriocins↗

PubMed1999

The presence of salt and a curing agent reduces bacteriocin production by Lactobacillus sakei CTC 494, a potential starter culture for sausage fermentation.

The specific conditions in the batter of raw fermented sausages may reduce the efficiency of bacteriocin-producing starter cultures. In this work, using in vitro fermentation, we found that sodium chloride and sodium nitrite interfere with the growth of Lactobacillus sakei CTC 494, an organism which produces the antilisterial bacteriocin sakacin K. Because sakacin K production follows primary metabolite kinetics, a decrease in cell formation resulted in a decrease in sakacin K production as well. Sodium chloride dramatically influenced bacteriocin production by decreasing both biomass production and specific bacteriocin production. Sodium nitrite, however, had no effect on specific bacteriocin production and decreased bacteriocin production only because of its effect on cell growth. Moreover, sodium nitrite enhanced the toxic effect of lactic acid on bacterial growth.

Bacteriocins↗

PubMed2004

Molecular and genetic characterization of propionicin F, a bacteriocin from Propionibacterium freudenreichii.

This work describes the purification and characterization of propionicin F, the first bacteriocin isolated from Propionibacterium freudenreichii. The bacteriocin has a bactericidal activity and is only active against strains of P. freudenreichii. Propionicin F appears to be formed through a processing pathway new to bacteriocins. The mass of the purified bacteriocin was determined by mass spectrometry, and the N-terminal amino acid sequence was determined by Edman degradation. Sequencing of pcfA, the bacteriocin structural gene, revealed that propionicin F corresponds to a 43-amino-acid peptide in the central part of a 255-amino-acid open reading frame, suggesting that mature propionicin F is excised from the probacteriocin by N- and C-terminal proteolytic modifications. DNA sequencing and Northern blot hybridizations revealed that pcfA is cotranscribed with genes encoding a putative proline peptidase and a protein from the radical S-adenosylmethionine family. A gene encoding an ABC transporter was also identified in close proximity to the bacteriocin structural gene. The potential role of these genes in propionicin F maturation and secretion is discussed.

Amino Acid Sequence↗

PubMed2004

Structural and functional differences in two cyclic bacteriocins with the same sequences produced by lactobacilli.

Lactobacillus gasseri LA39 and L. reuteri LA6 isolated from feces of the same human infant were found to produce similar cyclic bacteriocins (named gassericin A and reutericin 6, respectively) that cannot be distinguished by molecular weights or primary amino acid sequences. However, reutericin 6 has a narrower spectrum than gassericin A. In this study, gassericin A inhibited the growth of L. reuteri LA6, but reutericin 6 did not inhibit the growth of L. gasseri LA39. Both bacteriocins caused potassium ion efflux from indicator cells and liposomes, but the amounts of efflux and patterns of action were different. Although circular dichroism spectra of purified bacteriocins revealed that both antibacterial peptides are composed mainly of alpha-helices, the spectra of the bacteriocins did not coincide. The results of D- and L-amino acid composition analysis showed that two residues and one residue of D-Ala were detected among 18 Ala residues of gassericin A and reutericin 6, respectively. These findings suggest that the different D-alanine contents of the bacteriocins may cause the differences in modes of action, amounts of potassium ion efflux, and secondary structures. This is the first report that characteristics of native bacteriocins produced by wild lactobacillus strains having the same structural genes are influenced by a difference in D-amino acid contents in the molecules.

Amino Acid Sequence↗

PubMed1972

Epidemiological differentiation of Serratia marcescens: typing by bacteriocin production.

A new method for comparing and differentiating strains of S. marcescens is described which has proved useful in determining the epidemiology of hospital infections. Strains were grown in Trypticase soy broth, and bacteriocin production was induced with mitomycin C for 5 hr. The bacteriocin lysates were then spotted onto nine standard indicator strains, which were chosen with the aid of computer analysis from the 118 indicators tested. After 24 hr at 37 C, zones of inhibition due to bacteriocins were recorded. One hundred twentynine strains were differentiated into 72 different bacteriocin production patterns, but 11 strains were nontypable. None of the 45 other strains of Enterobacteriaceae produced bacteriocins. Bacteriocin production was a stable epidemiological marker. Colonial mutants always had identical patterns, as did the same strain which has passed from patient to patient through cross-infection. The new technique does not require any specialized equipment and can be used in laboratories with limited budgets. The applications of the new method in cross-infection studies and as a supplement to serological typing are discussed.

Bacteriocins↗

PubMed1985

Distinct bacteriocin groups correlate with different groups of Streptococcus mutans plasmids.

A correlation between the presence of 5.6-kilobase plasmids and bacteriocin activity was found in human-derived strains of Streptococcus mutans. Compared with bacteriocin activity of randomly selected clinical isolates of plasmid-negative strains, bacteriocin activity of plasmid-positive strains significantly inhibited not only two laboratory strains of S. mutans, OMZ176 and AHT (P less than 0.0001 and P = 0.038, respectively), but most plasmid-negative clinical isolates as well (P = 0.0005). Comparisons of inhibition between pairs of plasmid-positive strains revealed two groups, group I and group II, that produced distinct bacteriocins we designated as mutacin I and mutacin II, respectively. Within each group, a strain produced inhibitory activity against all the members of the other group but against no members of its own group. Plasmid DNA from plasmid-positive strains of each group was isolated and analyzed by restriction endonuclease digestion. Plasmids from the two groups that were apparently identical in size differed in digestion patterns for EcoRI, HaeIII, and TaqI, even though six TaqI fragments appeared to be common to all. Based on bacteriocin profiles and restriction enzyme digests, two distinct groups of plasmid-positive S. mutans strains emerged. Although the bacteriocin activity of plasmid-positive strain LM7 (serotype e) placed it in group I, clear differences in restriction digests distinguished it from the other plasmid-containing strains.

Bacteriocins↗

PubMed1973

Kinetic studies on the interaction of bacteriophage type 71 staphylococcal bacteriocin with susceptible bacteria.

Kinetic studies on the interaction of the bacteriocin produced by phage type 71 Staphylococcus aureus with susceptible bacterial cells were undertaken. Survivors among susceptible bacteria to which the bacteriocin has been added can be rescued after trypsin treatment. The bacteriocin adsorbs very rapidly to susceptible streptococcal cells at a time when killing of the cells is only minimal. Heat-killed or mechanically disrupted cells are also effective in adsorbing the bacteriocin. Adsorption is comparable at 37 C and 25 C, but is less pronounced at 4 C. Elution of adsorbed bacteriocin could not be achieved by heating, by varying pH, or by using different concentrations of sodium chloride solutions. Surface M protein of streptococcal cells plays no role in the adsorptive process. Adsorption is specific in that only susceptible bacteria, but not resistant ones, are capable of adsorbing the bacteriocin.

Adsorption↗

PubMed1983

Purification and characterization of a bacteriocin from Bacteroides fragilis.

A bacteriocin produced by Bacteroides fragilis 1356 was purified from culture medium and characterized. The spectrum of the inhibitory activity of this bacteriocin was species specific. The bacteriocin was recovered from the initial stages of purification as a complex, greater than 2 X 10(7) daltons in mass, containing protein, lipid, and carbohydrate. The dissociation of this complex by 6.0 M guanidine hydrochloride permitted further purification of the bacteriocin by removal of lipid and carbohydrate. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the purified bacteriocin was homogeneous, with a relative molecular weight of 5,000. The activity of the purified bacteriocin was not affected by RNase, DNase, phospholipase A, pancreatic lipase, or dextranase, but was destroyed by trypsin, proteinase K, heat (80 degrees C, 30 min), or a pH below 5 or above 8. Amino acid analysis indicated a predominance of acidic and polar amino acids.

Amino Acids↗

PubMed1984

Conjugal transfer and characterization of bacteriocin plasmids in group N (lactic acid) streptococci.

Thirteen bacteriocin-producing strains of group N (lactic acid) streptococci were screened for their potential to transfer this property by conjugation to Streptococcus lactis subsp. diacetylactis Bu2-60. Bacteriocin production in three strains was plasmid encoded as shown by conjugal transfer and by analysis of cured, bacteriocin-negative derivatives of the donor strains and the transconjugants. With Streptococcus cremoris strains 9B4 and 4G6 and S. lactis subsp. diacetylactis 6F7 as donors, bacteriocin-producing transconjugants were isolated with frequencies ranging from ca. 2 X 10(-2) to 2 X 10(-1) per recipient cell. Bacteriocin-producing transconjugants had acquired a 39.6-megadalton plasmid from the donor strains 9B4 and 4G6, and a 75-megadalton plasmid from the donor strain 6F7. As shown by restriction endonuclease analysis, the plasmids from strains 9B4 and 4G6 were almost identical. The plasmid from strain 6F7 yielded some additional fragments not present in the two other plasmids. In hybridization experiments any of the three plasmids strongly hybridized with each other and with some other bacteriocin but nontransmissible plasmids from other S. cremoris strains. Homology was also detected to a variety of cryptic plasmids in lactic acid streptococci.

Bacteriocins↗