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PubMed2004

The contribution of bacteriocin to inhibition of Listeria monocytogenes by Carnobacterium piscicola strains in cold-smoked salmon systems.

AIMS: To study the importance of bacteriocin production for the antilisterial effect of a bacteriocinogenic Carnobacterium piscicola strain A9b on growth of Listeria monocytogenes in broth and cold-smoked salmon systems. METHODS AND RESULTS: Acriflavin treatment of strain A9b resulted in loss of bacteriocin production and of immunity to carnobacteriocin B2. Two plasmids present in the wild-type were lost in the variant that was also more sensitive to bavaricin and leucocin A than the wild-type indicating cross-resistance to class IIa bacteriocins. The growth rate of the bac- mutant was higher than that of the wild-type at 5 and 37 degrees C but not at 25 or 30 degrees C. In salmon juice the maximum cell density of L. monocytogenes was suppressed 3 and 6 log by co-culture with C. piscicola A9b bac- and bac+, respectively, as compared with the control. Sterile filtered cultures of C. piscicola A9b bac- caused a limited suppression of the maximum cell density of L. monocytogenes similar to that observed when sterile buffer was added in equal amounts. Semi-purified carnobacteriocin B2 caused a 3.5 log decline in viable cell count after 6 day of incubation in cold-smoked salmon juice at 5 degrees C. High resistance level to carnobacteriocin B2 was observed for L. monocytogenes cells exposed to semi-purified and in situ produced carnobacteriocin B2. CONCLUSIONS: The presence of bacteriocin production in C. piscicola enhances its inhibition of L. monocytogenes. SIGNIFICANCE AND IMPACT OF THE STUDY: Due to the emergence of resistance, a bacteriocin negative lactic acid bacteria may be more suited for practical use as a bioprotective agent against L. monocytogenes in ready-to-eat foods.

Animals↗
PubMed2000

Functional analysis of promoters involved in quorum sensing-based regulation of bacteriocin production in Lactobacillus.

Bacteriocin production in Lactobacillus sake LTH673 involves at least four operons: a regulatory operon (sppIPKR); two operons encoding bacteriocins and their immunity proteins (sppAiA and orfX); and an operon needed for secretion (sppTE). We show here that the response regulator encoded by sppR in L. sake LTH673, as well as the homologous response regulators encoded by plnC and plnD in Lactobacillus plantarum C11, bind to characteristic repeats found in the -80 to -40 regions of spp operons. The promoters controlling bacteriocin operons are strictly regulated, and their activity is increased more than 1000-fold upon activation. Constitutive expression for the regulatory and transport operons is driven, at least in part, by promoters upstream of the -80 to -40 regions. Peak promoter activity of the regulatory and transporter operons precedes that of the two bacteriocin operons. The results reveal how promoters involved in quorum sensing-based regulation of bacteriocin production in Lactobacillus differ in strength, leakiness and timing of their activity.

Bacteriocins↗
PubMed1998

Plantaricin D, a bacteriocin produced by Lactobacillus plantarum BFE 905 ready-to-eat salad.

Lactobacillus plantarum BFE 905 isolated from 'Waldorf' salad produced a bacteriocin termed plantaricin D which was active against Lact. sake and Listeria monocytogenes strains. Plantaricin D was heat stable, retaining activity after heating at 121 degrees C. The bacteriocin was inactivated by alpha-chymotrypsin, trypsin, pepsin and proteinase K, but not by papain and other non-proteolytic enzymes tested. Plantaricin D was stable at pH values ranging from 2.0 to 10.0. The bacteriocin inhibited growth of L. monocytogenes in automated turbidity assays. Although Lact. Plantarum BFE 905 harboured plasmids ranging in size from 3 to 55 kilobase pairs, loss of bacteriocin production could not be correlated with plasmid loss. A role for bacteriocin-producing Lact. plantarum of vegetable origin in assuring the safety of vegetable foods is suggested.

Bacteriocins↗
PubMed2003

Alternatives to antibiotics: bacteriocins, antimicrobial peptides and bacteriophages.

Bacteriocins, antimicrobial peptides, and bacteriophage have attracted attention as potential substitutes for, or as additions to, currently used antimicrobial compounds. This publication will review research on the potential application of these alternative antimicrobial agents to poultry production and processing. Bacteriocins are proteinaceous compounds of bacterial origin that are lethal to bacteria other than the producing strain. It is assumed that some of the bacteria in the intestinal tract produce bacteriocins as a means to achieve a competitive advantage, and bacteriocin-producing bacteria might be a desirable part of competitive exclusion preparations. Purified or partially purified bacteriocins could be used as preservatives or for the reduction or elimination of certain pathogens. Currently only nisin, produced by certain strains of Lactococcus lactis subsp. lactis, has regulatory approval for use in certain foods, and its use for poultry products has been studied extensively. Exploration of the application of antimicrobial peptides from sources other than bacteria to poultry has not yet commenced to a significant extent. Evidence for the ability of chickens to produce such antimicrobial peptides has been provided, and it is likely that these peptides play an important role in the defense against various pathogens. Bacteriophages have received renewed attention as possible agents against infecting bacteria. Evidence from several trials indicates that phage therapy can be effective under certain circumstances. Numerous obstacles for the use of phage as antimicrobials for poultry or poultry products remain. Chiefly among them are the narrow host range of many phages, the issue of phage resistance, and the possibility of phage-mediated transfer of genetic material to bacterial hosts. Regulatory issues and the high cost of producing such alternative antimicrobial agents are also factors that might prevent application of these agents in the near future.

Animals↗
PubMed1994

Characteristics and genetic determinant of a hydrophobic peptide bacteriocin, carnobacteriocin A, produced by Carnobacterium piscicola LV17A.

Carnobacteriocin A is a hydrophobic nonlantibiotic bacteriocin that is detected early in the growth cycle of Carnobacterium piscicola LV17A and encoded by a 49 MDa plasmid. The bacteriocin was purified using hydrophobic interaction and gel filtration chromatography, and reversed-phase HPLC. Three different active peaks (A1, A2 and A3) were detected, but the purified samples had identical N-terminal amino acid sequences for the first 15 amino acids as determined by Edman degradation analysis. Only a 2.4 kb fragment of the EcoRI digest of the plasmid pCP49 hybridized with a 23-mer oligonucleotide probe derived from amino acids 5 to 13 of the amino acid sequence. The structural gene for carnobacteriocin A is located 600 base pairs into the 2.4 kb EcoRI fragment, but no other genetic information was detected on this unit. The structural gene includes an 18 amino acid N-terminal extension of the bacteriocin, ending with Gly-Gly residues in the -2, -1 positions with respect to the cleavage site. The bacteriocin consists of 53 amino acids that differ markedly from the majority of hydrophobic peptide bacteriocins characterized to date. Based on the amino acid sequence derived from the nucleotide sequence a molecular mass of 5052.85 Da was calculated. Mass spectrometric analysis showed that the molecular mass of the major component (A3) was 2 Da lower, thereby indicating the presence of a disulphide bridge between Cys 22 and Cys 51. Carnobacteriocin A2 has a similar structure except that Met 52 is oxidized to a sulphoxide, whereas A1 appears to be a mixture of peptides derived proteolytically from A3 or A2.

Amino Acid Sequence↗
PubMed1999

Antibodies to a synthetic 1-9-N-terminal amino acid fragment of mature pediocin PA-1: sensitivity and specificity for pediocin PA-1 and cross-reactivity against Class IIa bacteriocins.

Polyclonal antibodies specific for pediocin PA-1 (PedA1) were generated by immunization of rabbits with a chemically synthesized 1-9-N-terminal amino acid fragment of this bacteriocin (PH1) conjugated to the carrier protein keyhole limpet haemocyanin (KLH). The PH1 fragment holds a highly conserved amino acid sequence with closely related Class IIa bacteriocins. The sensitivity and specificity of the PH1-KLH-generated rabbit polyclonal antibodies were evaluated by the development of various ELISAs, such as a non-competitive indirect ELISA (NCI-ELISA), a competitive indirect ELISA (CI-ELISA), a competitive direct ELISA (CD-ELISA) and a sandwich ELISA (S-ELISA), and by protein slot-blotting and Western blotting. NCI- and CI-ELISA were valuable for detecting the existence of PedA1-specific antibodies in the sera of immunized rabbits. The limit of detection of PedA1 in MRS medium was found to be 0.5 microg ml(-1) in NCI-ELISA, while CI-ELISA on plates coated with purified PedA1 increased the affinity of the PH1-KLH-generated antibodies for PedA1; the limit of detection of PedA1 was less than 0.01 microg ml(-1) and 50% binding inhibition was achieved with 0.1 microg PedA1 ml(-1). Similarly, the limits of detection of PedA1 in MRS medium were found to be 5 microg ml(-1) by protein slot-blotting and 0.01 microg ml(-1) by Western blotting. Most importantly, PH1-KLH-generated polyclonal antibodies detected the presence of PedA1 in the supernatants of the producing strains of Pediococcus acidilactici 347, Z102, A172, X13 and P20, with no reactivity or negligible immunoreactivity with the supernatants of other lactic acid bacteria producing or not producing closely related or different bacteriocins. The approaches taken for the selection of the bacteriocin peptide fragment, the generation of antibodies and the development of immunoassays could prove useful for the generation and evaluation of antibodies of adequate specificity for other bacteriocins of interest in the food industry.

Amino Acid Sequence↗
PubMed1991

In-vitro bacteriocin-mediated antagonism by oral streptococci against human carrier strains of staphylococci.

All strains of oral streptococci tested and specially those of Streptococcus mutans, Strep. sanguis and Strep. mitior produced more than one distinct bacteriocin-like substance with variable inhibitory activity on 20 indicator staphylococci. Inhibitory activity was comparatively higher on nasal strains of Staph. aureus and Staph. epidermidis than on strains of both species isolated from the mouth. Nineteen of 20 staphylococcal indicators were inhibited by 1-12 of the 12 effector streptococci. Sensitivity of nasal staphylococci to bacteriocins (frequency of positive inhibitory tests and total inhibition zone diameters) was significantly higher (P less than 0.001, chi 2 test and P less than 0.05, t test respectively) than that of oral ones. The sensitivity of nasal over oral Staph. aureus (P less than 0.001 and P less than 0.01) and of oral Staph. epidermidis over oral Staph. aureus (P less than 0.01 and P less than 0.05) was also significantly higher. The evaluation of variability of inhibitory patterns of bacteriocins produced by streptococci (p-typing), of sensitivity patterns of staphylococci to bacteriocins (s-typing) and of the significantly higher sensitivity of nasal over oral staphylococci to bacteriocins from the epidemiological and ecological viewpoints are discussed.

Adult↗
PubMed2007

Partial characterization of bacteriocins produced by human Lactococcus lactis and Pediococccus acidilactici isolates.

AIMS: The aim of this study was to isolate bacteriocin-producing lactic acid bacteria (LAB) from human intestine. METHODS AND RESULTS: A total of 111 LAB were isolated from human adult stool and screened for their bacteriocin production. Neutralized cell-free supernatants from Lactococcus lactis subsp. lactis MM19 and Pediococcus acidilactici MM33 showed antimicrobial activity. The antimicrobials in the supernatant from a culture of L. lactis inhibited Enterococcus faecium, various species of Lactobacillus and Staphylococcus aureus; while those in the supernatant from a culture of P. acidilactici inhibited Enterococcus spp., some lactobacilli and various serotypes of Listeria monocytogenes. The antimicrobial metabolites were heat-stable and were active over a pH range of 2-10. The antimicrobial activities of the supernatants of both bacteria were inhibited by many proteases but not by catalase. The plate overlay assay allowed an approximation of size between 3.5 and 6 kDa for both antimicrobial substances. CONCLUSIONS: As the antagonistic factor(s) produced by L. lactis MM19 and P. acidilactici MM33 were sensitive to proteolytic enzymes, it could be hypothesized that bacteriocins were involved in the inhibitory activities. Inhibition spectrum and biochemical analysis showed that these bacteria produced two distinct bacteriocins. SIGNIFICANCE AND IMPACT OF THE STUDY: We are the first to isolate bacteriocin-producing strains of Pediococcus and Lactococcus from human intestine. These strains might be useful for control of enteric pathogens.

Anti-Bacterial Agents↗
PubMed1994

Bacteriocin production by Enterococcus faecium NA01 from 'wara'--a fermented skimmed cow milk product from west Africa.

An Enterococcus faecium strain from Nigerian fermented skimmed cow milk ('wara') produced bacteriocin inhibitory towards Lactobacillus, Enterococcus and Listeria strains. The bacteriocin (designated enterocin 01) was inactivated by proteases, heat-stable at 100 degrees c and active at pH 2.0-6.0. The Ent. faecium isolate harboured plasmids of ca 36.3 and 23.1 kb. Curing experiments with ethidium bromide resulted in a bacteriocin-negative mutant which had not lost immunity to the bacteriocin. Slight differences in plasmid profiles between wild-type and mutant indicated a possible plasmid-coded bacteriocin production.

Africa↗
PubMed1998

A system for heterologous expression of bacteriocins in Lactobacillus sake.

A system for efficient heterologous expression of class II bacteriocins is described that is based on introducing two plasmids in a bacteriocin-negative Lactobacillus sake strain. The first plasmid (pSAK20) contains the genes necessary for transcriptional activation of the Sakacin A promoter as well as export and processing of bacteriocin precursors. The second plasmid (a pLPV111 derivative) contains the structural and immunity genes for the bacteriocin of interest fused to the sakacin A promoter. Using this system, various bacteriocins were produced at levels equal to or higher than those obtained with the corresponding wild-type producer strains.

Bacteriocins↗
PubMed2006

Proteomic analysis of the bacteriocin thuricin 17 produced by Bacillus thuringiensis NEB17.

Thuricin 17 is a recently discovered bacteriocin produced by Bacillus thuringiensis NEB17. The objective of this work was to conduct a proteomic analysis of this bacteriocin. The partial N- and C-terminal amino-acid sequences of thuricin 17 have now been determined using the Edman degradation and matrix-assisted laser desorption ionization-quadrapole time of flight mass spectrometry (MS)/MS. A hydrophobic cluster analysis indicates that thuricin 17 contains a hydrophobic region, potentially corresponding to a membrane associated domain. Based on time of production, this bacteriocin may be produced as a secondary metabolite. Interestingly, thuricin 17 shares the same N-terminal sequence, DWTXWSXL, with a previously reported bacteriocin, Bacthuricin F4, produced by B. thuringiensis ssp. kurstaki strain BUPM4. This is the first time two bacteriocins from different Bacillus species have been shown to share similar N-terminal sequences.

Bacillus thuringiensis↗
PubMed2000

Class IIa bacteriocins: biosynthesis, structure and activity.

In the last decade, a variety of ribosomally synthesized antimicrobial peptides or bacteriocins produced by lactic acid bacteria have been identified and characterized. As a result of these studies, insight has been gained into fundamental aspects of biology and biochemistry such as producer self protection, membrane-protein interactions, and protein modification and secretion. Moreover, it has become evident that these peptides may be developed into useful antimicrobial additives. Class IIa bacteriocins can be considered as the major subgroup of bacteriocins from lactic acid bacteria, not only because of their large number, but also because of their activities and potential applications. They have first attracted particular attention as listericidal compounds and are now believed to be the next in line if more bacteriocins are to be approved in the future. The present review attempts to provide an insight into general knowledge available for class IIa bacteriocins and discusses common features and recent findings concerning these substances.

Amino Acid Sequence↗
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↗
PubMed1984

Purification and properties of a cell-bound bacteriocin from a Bacteroides fragilis strain.

A cell-bound bacteriocin was extracted from a Bacteroides fragilis BF-11 strain by treating the cells with a low-molarity buffer (0.01 M Tris-hydrochloride, pH 8.0). Sucrose osmotic shock experiments and ultrasonic lysis of whole cells indicated that the majority of the bacteriocin was located at the cell surface. Culture supernatants contained no significant bacteriocin activity. The bacteriocin was purified by DEAE-cellulose and Sephacryl S200 chromatography and had an apparent molecular weight of approximately 7,000. It was relatively heat stable and was inactivated by proteases. There was a delay of approximately 3.5 h before DNA, RNA, and protein synthesis were inhibited by the bacteriocin. Inhibition of macromolecular synthesis coincided with lysis of the susceptible indicator strain.

Bacterial Proteins↗
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↗
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↗
PubMed1990

Use of a bacteriocin produced by Pediococcus acidilactici to inhibit Listeria monocytogenes associated with fresh meat.

A bacteriocin produced by Pediococcus acidilactici had an inhibitory and bactericidal effect on Listeria monocytogenes associated with fresh meat. MICs were significantly lower than minimum killing concentrations. When meat was inoculated with L. monocytogenes, the bacteriocin reduced the number of attached bacteria in 2 min by 0.5 to 2.2 log cycles depending upon bacteriocin concentration. Meat treated initially with the bacteriocin resulted in attachment of 1.0 to 2.5 log cycles fewer bacteria than that attained with the control. The bacteriocin, after 28 days of refrigerated storage on meat surfaces, was stable and exhibited an inhibitory effect on L. monocytogenes.

Animals↗
PubMed1991

Detection and activity of a bacteriocin produced by Leuconostoc mesenteroides.

Leuconostoc mesenteroides UL5 was found to produce a bacteriocin, referred as mesenterocin 5, active against Listeria monocytogenes strains but with no effect on several useful lactic acid bacteria. The antimicrobial substance is a protein, since its activity was completely destroyed following protease (pronase) treatment. However, it was relatively heat stable (100 degrees C for 30 min) and partially denaturated by chloroform. The inhibitory effect of the bacteriocin on sensitive bacterial strains was determined by a critical-dilution micromethod. Mutants of L. mesenteroides UL5 which had lost the capacity to produce the bacteriocin were obtained. The mutant strain was stable and phenotypically identical to parental cells and remained resistant to the bacteriocin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to detect bacteriocin activity corresponding to an apparent molecular mass of about 4.5 kDa.

Bacteriocins↗