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PubMed2006

Data mining and characterization of a novel pediocin-like bacteriocin system from the genome of Pediococcus pentosaceus ATCC 25745.

The genome of Pediococcus pentosaceus ATCC 25745 contains a gene cluster that resembles a regulated bacteriocin system. The gene cluster has an operon-like structure consisting of a putative pediocin-like bacteriocin gene (termed penA) and a potential immunity gene (termed peiA). Genetic determinants involved in bacteriocin transport and regulation are also found in proximity to penA and peiA but the so-called accessory gene involved in transport and the inducer gene involved in regulation are missing. Consequently, this bacterium is a poor bacteriocin producer. To analyse the potency of the putative bacteriocin operon, the two genes penA-peiA were heterologously expressed in a Lactobacillus sakei host that contains the complete apparatus for gene activation, maturation and externalization of bacteriocins. It was demonstrated that the heterologous host expressing penA and peiA produced a strong bacteriocin activity; in addition, the host became immune to its own bacteriocin, identifying the gene pair penA-peiA as a potent bacteriocin system. The novel pediocin-like bacteriocin, termed penocin A, has an isotopic mass [M+H]+ of 4684.6 Da as determined by mass spectrometry; this value corresponds well to the expected size of the mature 42 aa peptide containing a disulfide bridge. The bacteriocin is heat-stable but protease-sensitive and has a calculated pI of 9.45. Penocin A has a relatively broad inhibition spectrum, including pathogenic Listeria and Clostridium species. Immediately upstream of the regulatory genes reside some features that resemble remnants of a disrupted inducer gene. This degenerate gene was restored and shown to encode a double-glycine leader-containing peptide. Furthermore, expression of the restored gene triggered high bacteriocin production in P. pentosaceus ATCC 25745, thus confirming its role as an inducer in the pen regulon.

Amino Acid Sequence↗
PubMed1978

Comparative study of ten bacteriocins of Clostridium perfringens.

Bacteriocins of Clostridium perfringens were prepared by ammonium sulfate precipitation of supernatant broth from 10 bacteriocinogenic strains. These bacteriocins were compared with respect to their ability to produce spheroplasts in a sensitive indicator strain; their inducibility; sensitivity to pH, proteolytic enzymes, and boiling; and their effect on macromolecular synthesis. Two bacteriocins were stable over a wide range of pH values and resisted boiling, and three bacteriocins were resistant to trypsin. Five bacteriocins shut down DNA, RNA, and protein synthesis; three bacteriocins had varying effects on DNA and RNA synthesis; and two bacteriocins had little effect on macromolecular synthesis. Antiserum prepared against one bacteriocin highly neutralized three bacteriocins with partial neutralization of five others; two bacteriocins were unaffected. Mutant strains selected for resistance to bacteriocin 28 also demonstrated coresistance to two other closely related bacteriocins and partial resistance to five others.

Bacteriocins↗
PubMed1995

Protection against bacteriocin 28b in Serratia marcescens is apparently not related to the expression of an immunity gene.

The gene encoding bacteriocin 28b from Serratia marcescens N28b (bss gene) has been cloned in Escherichia coli and its nucleotide sequence has been determined. The genetic determinants coding for other well-characterized bacteriocins from enterobacteria (colicins) are located in plasmids and they have always been shown to contain a gene responsible for immunity located downstream from the bacteriocin structural gene. In some cases there is another gene located downstream from the immunity gene, which is responsible for bacteriocin release. Analysis of bacteriocin 28b release and the sensitivity to this bacteriocin of E. coli strains harbouring recombinant plasmids containing the bss gene showed that bacteriocin 28b is not released from the cell in these strains and that their phenotypic insensitivity is not associated with any region close to the structural gene. The nucleotide sequence of the region downstream from the bss gene contains two putative open reading frames transcribed in the opposite direction to the bss gene. These open reading frames apparently encode proteins that seem not to be involved in bacteriocin immunity or release. Moreover, a S. marcescens N28b genomic library was screened and no immunity gene was found. Therefore, bacteriocin 28b differs greatly from the bacteriocins from other enterobacteria, and in the following senses it is unique: firstly, the gene encoding bacteriocin 28b seems to be located on the chromosome, and secondly, insensitivity to this bacteriocin in S. marcescens N28b is not associated with the expression of an immunity gene.

Amino Acid Sequence↗
PubMed2005

Characterization of bacteriocins produced by lactic acid bacteria isolated from spoiled black olives.

Bacteriocin-producing strains of Lactobacillus plantarum ST23LD and ST341LD, Enterococcus faecium ST311LD and Leuconostoc mesenteroides subsp. mesenteroides ST33LD were isolated from the brine of spoiled black olives. The bacteriocins produced by all four strains inhibited the growth of Gram-positive bacteria (E. faecalis, L. casei and Streptococcus pneumoniae), but also Escherichia coli and Pseudomonas aeruginosa. Strain ST23LD produced two bacteriocins (ST23LDa and ST23LDb of approximately 3.0 and 14.0 kDa, respectively), with a combined maximum level of activity of 25,600 AU/ml after 18 h of growth. The same level of activity was recorded for bacteriocin ST341LD (approximately 3.0 kDa), but after 16 h. Bacteriocins ST311LD (ca. 2.3 kDa) and ST33LD (ca. 2.7 kDa) were produced at much lower levels (6400 AU/ml), and only after 20 h of growth. Bacteriocin activity was destroyed after treatment with proteolytic enzymes and Triton X, but not when treated with alpha-amylase, SDS, Tween 20, Tween 80, urea and EDTA, or when heated for 20 min at 121 degrees C. Addition of bacteriocins ST23LD, ST341LD and ST311LD to cells of Lactobacillus casei LHS in logarithmic phase resulted in growth inhibition for one hour, followed by a slight increase in optical density over the next seven hours. Bacteriocin ST33LD also inhibited the growth of strain LHS, but to a lesser extent. Bacteriocins ST23LD, ST341LD and ST33LD remained at the same level of activity for 6 h at pH<4.0. However, the activity of bacteriocin ST311LD decreased by 50% within 2 h at pH 4.4. The possibility of the bacteriocin adsorbing to the producer cell and proteolytic degradation is unlikely.

Bacteria↗
PubMed1980

Rifampin and bacteriocin resistance in Bacteroides fragilis.

A low-molecular-weight bacteriocin produced by a Bacteroides fragilis strain inhibited ribonucleic acid polymerase activity in crude extracts of a susceptible B. fragilis indicator strain. A total of 10 rifampin-resistant mutants of the indicator strain were isolated. Nine of the rifampin-resistant mutants were resistant to the bacteriocin, and the other mutant was hypersusceptible. The rifampin- and bacteriocin-resistant mutants all adsorbed approximately the same amount of the bacteriocin as the indicator strain. Two of these rifampin- and bacteriocin-resistant mutants were investigated further, and the polymerase activity in crude extracts of the two mutants was not affected by either rifampin or the bacteriocin. The in vitro ribonucleic acid polymerase activity of the hypersusceptible strain was more susceptible to the bacteriocin than the parent indicator strain was. The bacteriocin-producing strain was susceptible to rifampin but was resistant to its own bacteriocin in vivo. The in vitro ribonucleic acid polymerase activity of the producer strain was only slightly affected by 64 arbitrary units of the bacteriocin. Increasing concentrations of the bacteriocin inhibited ribonucleic acid polymerase extracts of the producer strain.

Bacteriocins↗
PubMed2001

Identification of a new plasmid-encoded sec-dependent bacteriocin produced by Listeria innocua 743.

Listeria innocua 743 produces an inhibitory activity demonstrating broad-spectrum inhibition of Listeria monocytogenes isolates. Gel-electrophoretic analysis of culture supernatants indicated that two inhibitors with different molecular weights were produced by this strain. Insertion of Tn917 into a 2.9 Kb plasmid (pHC743) generated mutants with either an impaired ability or a loss in ability to produce one of the inhibitors. Sequence analysis of the transposon insertion regions revealed the presence of two continuous open reading frames, the first encoding a new pediocin-like bacteriocin (lisA) and the second encoding a protein homologous with genes involved in immunity toward other bacteriocins (lisB). Translation of the bacteriocin gene (lisA) initiates from a noncanonical start codon and encodes a 71-amino-acid prebacteriocin which lacked the double glycine leader peptidase processing site common in other type II bacteriocins. Alignment of the sequence with the processed N termini of related bacteriocins suggests that the mature bacteriocin consists of 43 amino acids, with a predicted molecular mass of 4,484 Da. Mutants containing insertions into lisA were sensitive to the inhibitor, indicating that lisAB forms a single operon and that lisB represents the immunity protein. Cloning of an amplicon containing the lisAB operon into Escherichia coli resulted in expression and export of the bacteriocin. This finding confirms that the phenotype is dependent on the structural and immunity gene only and that export of this bacteriocin is sec dependent. This is the first confirmation of bacteriocin production in a Listeria spp., and it is of interest that this bacteriocin is closely related to the pediocin family of bacteriocins produced by lactic acid bacteria.

Amino Acid Sequence↗
PubMed2006

Bacteriocins as oral and gastrointestinal antibiotics: theoretical considerations, applied research, and practical applications.

Bacteriocins, specific and highly potent protein antibiotics, have been long been expected to enter the working pharmacopeia. Despite laboratory experiments demonstrating their effectiveness against a wide range of gastrointestinal pathogens, attempts to reproduce such killing activity by using live bacteriocin-producing bacteria in animal gastrointestinal systems repeatedly failed. This raised doubts about the potential of the bacteriocins as in vivo antibiotics. Thus, though some bacteriocins have been employed in food preservation and processing, none have been applied directly as medicine. Recent experiments, based on an improved theoretical understanding of microbial ecology, demonstrate the in vivo activity of bacteriocins, the potential importance of bacteriocins as antibiotics, and the role that bacteriocins play in antibiotic resistance. Meanwhile, several kinds of bacteriocins have been proposed for applications in gastrointestinal microbiology, as well as for the use of probiotics to reduce dental caries and improve oral hygiene. Unfortunately, much of the probiotic-oriented research appears to be pursued without reference to resistance and the role of the bacteriocins in a community of bacteria. This leads to continued confusion regarding the interpretation of experimental results and mistaken assessments, positive and negative, of bacteriocins' therapeutic potential. A study of microbial ecology should be incorporated in the drug development process in order to apply bacteriocins most effectively.

Animals↗
PubMed2004

Optimization of bacteriocin production by Lactobacillus plantarum ST13BR, a strain isolated from barley beer.

The cell-free supernatant containing bacteriocin ST13BR, produced by Lactobacillus plantarum ST13BR, inhibits the growth of L. casei, Pseudomonas aeruginosa, Enterococcus faecalis, Klebsiella pneumoniae and Escherichia coli. Based on tricine-SDS-PAGE, bacteriocin ST13BR is 10 kDa in size. Complete inactivation or significant reduction in bacteriocin activity was observed after treatment with Proteinase K, trypsin and pronase, but not with catalase or alpha-amylase. Low bacteriocin activity (200 AU/ml) was recorded in BHI medium, M17 broth, 10% (w/v) soy milk, and 2% and 10% (w/v) molasses, despite good growth. Maximal bacteriocin activity (6,400 AU/ml) was recorded after 23 h in MRS broth, but only at 30 degrees C. Tween 80 in MRS broth increased bacteriocin production by more than 50%. Meat extract or yeast extract as sole nitrogen source, or a combination of the two (1 : 1) in MRS broth, stimulated bacteriocin production (6,400 AU/ml). Only 50% activity (3,200 AU/ml) was recorded with tryptone as sole nitrogen source, whereas a combination of tryptone, meat extract and yeast extract yielded 6,400 AU/ml. Bacteriocin production was not stimulated by the addition of glucose at 2.0% w/v (3,200 AU/ml), nor 2% (w/v) fructose, sucrose, lactose or mannose, respectively (800 AU/ml). Activity levels less than 200 AU/ml were recorded in the presence of 0.05% to 0.5% (w/v) maltose. Maximal bacteriocin production (6,400 AU/ml) was recorded in the presence of 2% (w/v) maltose. Maltose at 4.0% (w/v) led to a 50% reduction of bacteriocin activity. The presence of 1.0% (w/v) and higher KH(2)PO(4), or glycerol at 0.2% (w/v) suppressed bacteriocin production.

Animals↗
PubMed1979

Effect of a bacteriocin produced by Mycobacterium smegmatis on growth of cultured tumor and normal cells.

Growth-inhibitory effects of a partially purified bacteriocin derived from Mycobacterium smegmatis ATCC 14468 on various animal cells transformed by tumor viruses, human malignant cells, and normal cells in the same species were studied. A growth-inhibitory effect of the bacteriocin on these cultured cells was determined by counting the residual cells. The bacteriocin inhibited virally transformed animal cells (mKS-A TU-7, 155-4 T2, and XC cells) and human malignant cells (AS-II and HGC-27 cells). The inhibitory effect increased with an increase in the bacteriocin activity. The bacteriocin sensitivities of transformed animal cells were relatively higher than were those of human malignant cells, while normal cells in the same species were practically insensitive to the bacteriocin. Differences in the degree of bacteriocin sensitivity were observed among tumor cell lines. Simian virus (SV) 40-transformed hamster cells (TSV-5 cells), which grow rapidly, were less sensitive to the bacteriocin. The cell membrane of SV40-transformed BALB/c mouse cells (mKS-A TU-7 cells) adsorbed the bacteriocin much more than did the cell membrane of nontransformed BALB/3T3 cells. The results seem to indicate that the inhibitory effect of bacteriocin 14468 on cultured mammalian cells probably depends on the binding sites for the bacteriocin which appear or increase by malignant transformation on cytoplasmic membrane.

Adsorption↗
PubMed1985

Characterization and mode of action of a purified bacteriocin from the oral bacterium Streptococcus mutans RM-10.

The purified bacteriocin was sensitive to proteolytic enzymes such as trypsin, alpha-chymotrypsin and pronase, but resistant to papain and pepsin. Lowering the pH of the bacteriocin caused precipitation, and the Abs280 of the supernatant reached a minimum at pH 3.6, suggesting that this is the isoelectric point. Such a pH value coincides with minimum bacteriocin activity. The effect of the bacteriocin was bactericidal rather than bacteriolytic and concentration dependent. Treatment of Streptococcus faecalis ODU with Rm-10 bacteriocin led rapidly to the cessation of biosynthesis of macromolecules, DNA, RNA and protein. Electron microscopy showed bacteriocin fibres attached in aggregated bundles to target cells; after ultra-sonication or detergent treatment they were individually attached to the cell surface and, at the same time, the apparent bacteriocin activity had doubled. Bacteriocin activity was not altered by filter-sterilized saliva components. Oral rinsing with Rm-10 bacteriocin reduced the number of viable salivary bacteria after 20 min, suggesting a possible therapeutic use for Rm-10 bacteriocin.

Animals↗
PubMed2003

Enterococcus faecium RZS C5, an interesting bacteriocin producer to be used as a co-culture in food fermentation.

Enterocins, bacteriocins produced by enterococci, are gaining interest because of their industrial potential. Due to its bacteriocin production, Enterococcus faecium RZS C5, a natural cheese isolate, has a strong activity towards Listeria monocytogenes. For this reason, the strain may be applicable as a bacteriocin-producing co-culture in food fermentation in order to reduce the risk on Listeria outgrowth. The strain displays remarkable bacteriocin production kinetics. Whereas most lactic acid bacteria produce bacteriocin in a growth-associated way until the beginning of the stationary phase, bacteriocin production by E. faecium RZS C5 in MRS broth at controlled pH values below 7.5 is characterised by a boost of bacteriocin activity levels in the very early growth phase. In addition, bacteriocin production kinetics are closely linked to the environmental and cultural conditions. However, no straightforward statement about the effect of environmental stress on bacteriocin production can be made since the effect is dependent on the type of stress applied. Kinetic experiments in milk and on pilot scale, applying Cheddar cheese-making conditions, have indicated that the strain may be effective as a bacteriocin-producing co-culture. Further research is needed to evaluate the use of E. faecium RZS C5 as a co-culture for the production of fermented sausage.

Animals↗
PubMed2005

A versatile system for the expression of nonmodified bacteriocins in Escherichia coli.

AIMS: To develop a method and plasmid vectors suitable for expression of class II bacteriocins from Escherichia coli. METHODS AND RESULTS: The expression vector pSuV1 was constructed by inserting the PelB secretion signal coding sequence and a number of restriction endonuclease sites for cloning, into pTYB1. Codon optimized genes encoding the active mature region of each bacteriocin were constructed and inserted into pSuV1. Transfer of these constructs to a host expressing T7 RNA polymerase allowed for expression of secreted mature or fusion forms of the bacteriocins. Generation of the fusion, to the adjacent intein-chitin-binding domain gene, was achieved by removal of a small intervening BseRI fragment. The bacteriocins BacR1, divercin V41, enterocin P, pediocin PA-1 and piscicolin 126 were expressed from this system. For piscicolin 126, expression levels of 200 microg l(-1) in the mature form and 1100 microg l(-1) when cleaved from the fusion partner were achieved. All expressed bacteriocins displayed antimicrobial activity. CONCLUSIONS: Several class II bacteriocins have been expressed in E. coli using purpose designed plasmid vectors described here. SIGNIFICANCE AND IMPACT OF THE STUDY: This method provides a common expression system capable of producing a range of different class II bacteriocins. It allows researchers to study class II bacteriocins without access to the original producer strain, the native bacteriocin gene, or highly specific heterologous producing strains. Resulting expression levels are as high or higher than those previously reported for related bacteriocins.

Bacteriocins↗
PubMed2005

Characterization of a bacteriocin produced by Enterococcus faecium GM-1 isolated from an infant.

AIM: To partially characterize the bacteriocin produced by the GM-1 strain of Enterococcus faecium, isolated from the faeces of a newborn human infant. METHODS AND RESULTS: The bacteriocin produced by E. faecium GM-1 showed a broad spectrum of activity against indicator strains of Escherichia coli, Staphylococcus aureus, Vibrio spp., Salmonella typhimurium, Listeria monocytogenes, Lactobacillus acidophilus, and Streptococcus thermophilus. Treatment of the GM-1 bacteriocin with proteolytic enzymes reduced its inhibitory activities. The bacteriocin was stable at 100 degrees C for 20 min and displayed inhibitory activity at neutral pH. The optimal production of bacteriocin from E. faecium GM-1 was obtained when the culture conditions were pH 6.0-6.5 and 35-40 degrees C. The inhibitory activity of the bacteriocin was not substantially changed by the use of different carbon sources in the media, except when galactose was substituted for glucose. The use of a sole nitrogen source caused a decrease in inhibitory activity. A bacteriocin gene similar to enterocin P was identified from the total DNA of E. faecium GM-1 by PCR and direct sequencing methods. CONCLUSION: E. faecium GM-1, which was isolated from the faeces of a newborn baby, produces an enterocin P-like bacteriocin with inhibitory activity against Gram-positive and Gram-negative bacteria, including food-borne pathogens. SIGNIFICANCE AND IMPACT OF THE STUDY: E. faecium GM-1, isolated from infant faeces, produces a new bacteriocin that is similar to enterocin P. This bacteriocin is heat stable and has a broad antibacterial spectrum that includes both Gram-positive and Gram-negative bacteria.

Amino Acid Sequence↗
PubMed2005

Characterization of minimal bacteriocin operon from Prevotella nigrescens ATCC 25261.

AIMS: To characterize a minimal bacteriocin operon of Prevotella nigrescens ATCC 25261. METHODS AND RESULTS: A genomic DNA library of Pr. nigrescens ATCC 25261 was constructed and screened for bacteriocin production by an agar overlay assay. Sequence analysis of the bacteriocin-producing recombinant plasmid, pGP2, has shown that the insert DNA consists of 4868 base pairs, termed nig locus. There is a cluster of four genes within the nig locus, respectively designated nigA, B, C and D. Deleting 160 nucleotides at the 3'-end of nigAB resulted in loss of bacteriocin production, indicating that nigAB may belong to a bacteriocin operon. nigA is thought to be the bacteriocin gene, while nigB may encode an immunity protein. Escherichia coli containing pGP2 expressed the bacteriocin, which is similar in size, antimicrobial activity, and biochemical properties to that purified from Pr. nigrescens ATCC 25261. CONCLUSION: nig Locus is a chromosomal fragment of Pr. nigrescens ATCC 25261, consisting of 4868 base pairs, and has been proved to be important for bacteriocin production. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of the successful cloning and expression of the bacteriocin from Pr. nigrescens ATCC 25261 into E. coli. This will facilitate the construction of bacteriocin analogues and permit investigation of their structure/function relationships.

Bacterial Proteins↗
PubMed1977

Bacteriocin production by strains of Bacteroides isolated from human feces and the role of these strains in the bacterial ecology of the colon.

Several human fecal isolates of Bacteroides have been found to produce bacteriocins. The bacteriocin-producing strain T1-1 was studied in the most detail. Strain T1-1 belongs to the 0061-1 deoxyribonucleic acid (DNA) homology group of Bacteroides. This homology group phenotypically resembles Bacteroides thetaiotaomicron but has little DNA homology with it. The bacteriocin-producing strains T1-12 and T1-48 belong to the 3452-A DNA homology group. This group has DNA homology with B. thetaiotaomicron and Bacteroides ovatus. The bacteriocin-producing strain T1-42 remains unidentified in that it does not belong to any recognized DNA homology group of the saccharolytic intestinal bacteroides. The extracellular bacteriocin produced by strain T1-1 was specifically bactericidal for other bacteria within the genus Bacteroides. The highest bacteriocin titers (32 to 64) were produced in complex media, with only trace amounts being produced in a defined medium. The bacteriocin appeared to have a high molecular weight (>/=300,000) and was unusual because it was stable from pH 1 to 12 and only a 50% reduction in activity resulted after 15 min at 121 degrees C in an autoclave. It was inactivated by trypsin and Pronase. Strain T1-1 was isolated from all three fecal samples obtained over a 25-week period from an individual who was part of a National Aeronautics and Space Administration mock Skylab flight. Strains T1-12, T1-48, and T1-42 were isolated only from the first fecal sample. Each of these strains was immune to the bacteriocins produced by the others. These strains were found to coexist in the colon with a larger population of non-bacteriocin-producing, bacteriocin-susceptible strains of Bacteroides.

Bacteriocins↗
PubMed2006

Genetic analysis of bacteriocin 43 of vancomycin-resistant Enterococcus faecium.

A total of 636 vancomycin-resistant Enterococcus faecium (VRE) isolates obtained between 1994 and 1999 from the Medical School Hospital of the University of Michigan were tested for bacteriocin production. Of the 277 (44%) bacteriocinogenic strains, 21 were active against E. faecalis, E. faecium, E. hirae, E. durans, and Listeria monocytogenes. Of those 21 strains, a representative bacteriocin of strain VRE82, designated bacteriocin 43, was found to be encoded on mobilizable plasmid pDT1 (6.2 kbp). Nine open reading frames (ORFs), ORF1 to ORF9, were presented on pDT1 and were oriented in the same direction. The bacteriocin 43 locus (bac43) consists of the bacteriocin gene bacA (ORF1) and the immunity gene bacB (ORF2). The deduced bacA product is 74 amino acids in length with a putative signal peptide of 30 amino acids at the N terminus. The bacB gene encodes a deduced 95-amino-acid protein without a signal sequence. The predicted mature BacA protein (44 amino acids) showed sequence homology with the membrane-active class IIa bacteriocins of lactic acid bacteria and showed 86% homology with bacteriocin 31 from E. faecalis YI717 and 98% homology with bacteriocin RC714. Southern analysis with a bac43 probe of each plasmid DNA from the 21 strains showed hybridization to a specific fragment corresponding to the 6.2-kbp EcoRI fragment, suggesting that the strains harbored the pDT1-like plasmid (6.2 kb) which encoded the bacteriocin 43-type bacteriocin. The bac43 determinant was not identified among non-VRE clinical isolates.

Amino Acid Sequence↗
PubMed1998

An exported inducer peptide regulates bacteriocin production in Enterococcus faecium CTC492.

Production of the bacteriocins enterocin A and enterocin B in Enterococcus faecium CTC492 was dependent on the presence of an extracellular peptide produced by the strain itself. This induction factor (EntF) was purified, and amino acid sequencing combined with DNA sequencing of the corresponding gene identified it as a peptide of 25 amino acids. The gene encodes a prepeptide of 41 amino acids, including a 16-amino-acid leader peptide of the double-glycine type. Environmental factors influenced the level of bacteriocin production in E. faecium CTC492. The optimal pH for bacteriocin production was 6.2. At pH 5.5, growth was slow, and very little bacteriocin was formed. The presence of NaCl or ethanol (EtOH) was also inhibitory to bacteriocin production, and at high concentrations of these solutes, no bacteriocin production was observed. The induction factor induced its own synthesis, and by dilution of the culture 106 times or more, nonproducing cultures were obtained. Bacteriocin production was induced in these cultures by addition of EntF. The response was linear, and low bacteriocin production could be induced by about 10(-17) M EntF. This response was attenuated by low pH or the presence of high concentrations of NaCl or EtOH, and 300 times more EntF was needed to induce detectable bacteriocin production in the presence of 6.5% NaCl. High levels of bacteriocin production in cultures grown at low pH or in the presence of high concentrations of NaCl or EtOH were obtained by addition of sufficient amounts of EntF.

Amino Acid Sequence↗
PubMed1996

Are ruminal bacteria armed with bacteriocins?

The production of toxic compounds or antibiotics is a common component of intermicrobial competitive interactions, and many of these toxins have been adopted and adapted for the control of microbial populations. One class of these toxins, the bacteriocins, is a heterogeneous group of proteinaceous antibiotics that often display a high degree of target specificity, although many have a very wide spectrum of activity. To date, only limited information is available concerning the occurrence of bacteriocins among ruminal isolates or the sensitivity of ruminal microorganisms to exogenous bacteriocins. A survey of 50 strains of Butyrivibrio spp. isolated from a variety of sources (sheep, deer, and cattle) for bacteriocin production indicated a high incidence of bacteriocin-like activity (50%). Many of these inhibitory compounds appear to have a broad spectrum of activity, which suggests that bacteriocins may have a significant impact on both the competitive fitness of individual microbial strains within the rumen and on the overall structure of the microbial population within the rumen. Selected bacteriocins from lactic acid bacteria also were shown to have activity against Butyrivibrio spp. and may have application in ruminant systems. Bacteriocins may provide an alternative group of antibiotics for the manipulation of ruminal microbial populations. Bacteriocins have significant advantages over other antibiotics in target specificity, susceptibility to proteolytic digestion, possibility of genetic transfer and manipulation, and, in the case of some bacteriocins derived from lactic acid bacteria, a long history of safe use.

Animals↗