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PubMed1999

Identification and cloning of an Erwinia carotovora subsp. carotovora bacteriocin regulator gene by insertional mutagenesis.

Avirulent Erwinia carotovora subsp. carotovora CGE234-M403 produces two types of bacteriocin. For the purpose of cloning the bacteriocin genes of strain CGE234M403, a spontaneous rifampin-resistant mutant of this strain, M-rif-11-2, was isolated. By Tn5 insertional mutagenesis using M-rif-11-2, a mutant, TM01A01, which produces the high-molecular-weight bacteriocin but not the low-molecular-weight bacteriocin was obtained. By thermal asymmetric interlaced PCR, the DNA sequence from the Tn5 insertion site and the DNA sequence of a contiguous 1,280-bp region were determined. One complete open reading frame (ORF), designated ORF2, was identified within the sequenced fragment. The 3' end of another ORF, ORF1, was located upstream of ORF2. A noncoding region and a putative promoter were located between ORF1 and ORF2. Downstream from ORF2, the 5' end of another ORF (ORF3) was found. Deduction from the nucleotide sequence indicated that ORF2 encodes a protein of 99 amino acids, which showed high homology with Yersinia enterocolitica Yrp, a regulator of enterotoxin (Y-ST) production; Escherichia coli host factor 1, required for Qbeta-replicase; and Azorhizobium caulinodans NrfA, required for the expression of nifA. ORF2 was designated brg, bacteriocin regulator gene. A fragment containing ORF2 and its promoter was amplified and cloned into pBR322 and pHSG415r, and the recombinant plasmids, pBYL1 and pHYL1, were transferred into E. coli DH5. Plasmid pBYL1 was reisolated and transferred into the insertion mutant TM01A01. Transformants carrying the plasmid, which was reisolated and designated pBYL1, re-produced the low-molecular-weight bacteriocin.

Amino Acid Sequence↗
PubMed1984

Typing of Enterobacter spp. by bacteriocin susceptibility and its use in epidemiological analysis.

Most clinical isolates of Enterobacter cloacae are bacteriocinogenic and susceptible to bacteriocins. Both rapidly diffusing, nonsedimentable, protease-susceptible and slowly diffusing, sedimentable, protease-resistant bacteriocins are produced. A practicable system was devised for epidemiological typing of E. cloacae isolates by their patterns of susceptibility to bacteriocins. A set of eight bacteriocin-producing strains was grown on tryptic soy agar plates for 16 h. After removal of the producer lawn, the isolates to be typed were inoculated on the agar media by a multipoint inoculator. After a second 16-h period of incubation, the strains were classified into bacteriocin types according to the patterns of growth inhibition. Typability of 134 clinical isolates was 96.3%. Only 11 (8.2%) of the isolates fell into the largest group. Repeat testing of isolates from the same patients within 2 months gave identical bacteriocin types. Other species of Enterobacter (E. agglomerans and E. aerogenes) are also typable by this method.

Bacteriocins↗
PubMed1978

Typing methods for Proteus rettgeri: comparison of biotype, antibiograms, serotype, and bacteriocin production.

Two hunderd five strains of Proteus rettgeri from epidemic and nonepidemic sources were differentiated by a new biotyping scheme, agglutination in O antisera, antimicrobial resistance patterns, and a new scheme based on bacteriocin production. The P. rettgeri were divided into 10 groups by their fermentation of lactose, sucrose, D-mannitol, and salicin. These groups were then subdivided into 19 biotypes by other biochemical reactions. Bacteriocin production was tested by the cross-streak method. Thirty-four bacteriocin-sensitive indicator strains were evaluated, and 16 were selected for the final scheme and used to type the 205 P. rettgeri, which were divided into 15 bacteriocin types. Serologically, 43% of the P. rettgeri were O42, 13% were untypable, 4% were O15, and 3% each were O33, O64, and O84 in addition to 31 remaining serotypes. Strains of P. rettgeri from known outbreaks contained fewer biotypes, O groups, and bacteriocin types and were more resistant to antimicrobial agents than endemic strains. Strains with common patterns with all four marker systems were frequently associated with outbreaks. A strong correlation between multiple antibiotic resistance and bacteriocin production was shown.

Anti-Bacterial Agents↗
PubMed1979

Bacteriocins of phytopathogenic Corynebacterium species.

The majority (85% of all strains tested) of 12 phytopathogenic Corynebacterium species produced bacteriocin(s) on nutrient broth--yeast extract (NBY) medium. All C. nebraskense, C. michiganense, C. insidiosum, C. oortii, and C. iranicum strains produced bacteriocin(s). The optimal conditions for production of 23 distinct bacteriocins by eight species of Corynebacterium generally were 20 degrees C and 4 days of incubation on NBY or on modified Burkholder's agar that lacked peptone (MBAL). Production in liquid was marginal and not augmented by adding mitomycin C. Bacteriocins generally had little effect on other strains within a species but were inhibitory to other species. Most bacteriocins appeared to be bactericidal proteins resistant to heat (75 to 80 degrees C, 30 min) but sensitive to proteolytic enzymes. Some strains of C. nebraskense, C. michiganense, C. insidiosum, and C. flaccumfaciens produced two bacteriocins which were clearly differentiated by varying or testing one or more of the following: conditions for production, the indicator, heat stability, and susceptibility to proteolysis. Within certain limitations, a convenient and reproducible typing scheme was devised for strain and species differentiation of most phytopathogenic corynebacteria.

Bacteria↗
PubMed1982

Response of Clostridium perfringens and its L form to bacteriocins of C. perfringens.

Clostridium perfringens strain No. 28 and its penicillin-induced stable L form were treated with 10 different bacteriocins of C. perfringens. Viable count and labelled amino acid incorporation experiments revealed that the L form was sensitive to two and possibly three bacteriocins to which the bacillus was not, while both forms were commonly sensitive to two other bacteriocins and resistant to five others. Adsorption of bacteriocin, immunity factors, or perhaps uptake of bacteriocin might be proposed to explain the responses of these organisms to bacteriocins.

Bacterial Proteins↗
PubMedDate not supplied

Similarity of bacteriocin activity profiles of mutans streptococci within the family when the children acquire the strains after the age of 5.

It has been shown that there is a window of infectivity for mutans streptococci between the ages of 19 and 31 months, when many children acquire mutans streptococci transmitted from their mothers. Part of the children that escape this window acquire mutans streptococci at a later age. In this group, maternal transmission is expected to be less prevalent. The present study compared the bacteriocin activity profiles of mutans streptococci isolated from mothers, fathers and children when the children acquired the mutans streptococci between the ages of 5 and 11. Twelve families were randomly selected from a group of 11-year-old children who were known to have acquired mutans streptococci during this age period. From the saliva of the mothers (n = 12), fathers (n = 8) and children (n = 12) approximately 30 mutans streptococci strains were isolated. All isolates were tested twice for bacteriocin activity against 21 indicator strains with a double-layer technique. Bacteriocin activity of strains was considered to be different when the number of strains against which bacteriocin was produced differed >1 or when the width of one or more inhibition zones differed > or =4 mm. In 7/12 mother-child pairs similar profiles were found. In the 8 father-child pairs similar profiles were only found on 2 occasions. In these 2 families, all 3 ( mother, father and child) harboured strains with a similar profile. In 4/8 father-mother pairs similar profiles were found. There was no correlation between the prevalence of mutans streptococci strains, the number of indicator strains against which the strains made bacteriocin, nor the mean size of the inhibition zones and the presence of similarity of bacteriocin activity profiles of mutans streptococci within the family members. The results show that even when a child acquires mutans streptococci after the age of 5, there may be similarity between mutans streptococci in mother, father and child, indicating that transmission between the family members occurs.

Age Factors↗
PubMed2004

Purification of bacteriocins produced by lactic acid bacteria.

Bacteriocins are antibacterial substances of a proteinaceous nature that are produced by different bacterial species. Lactic acid bacteria (LAB) produce biologically active peptides or protein complexes that display a bactericidal mode of action almost exclusively toward Gram-positive bacteria and particularly toward closely related species. Generally they are active against food spoilage and foodborne pathogenic microorganisms including Bacillus cereus, Clostridium perfringens, Staphylococcus aureus, and Listeria monocytogenes. There is an increased tendency to use natural occurring metabolites to prevent the growth of undesirable flora in foodstuffs. These metabolites could replace the use of chemical additives such as sorbic acid, sulfur dioxide, nitrite, nitrate, and others. For instance, bacteriocins produced by LAB may be promising for use as bio-preservaties. Bacteriocins of lactic acid bacteria are typically cationic, hydrophobic peptides and differ widely in many characteristics including molecular weight, presence of particular groups of amino acids, pI, net positive charge, and post-translational modifications of certain amino acids. This heterogeneity within the LAB bacteriocins may explain the different procedures for isolation and purification developed so far. The methods most frequently used for isolation, concentration, and purification involve salt precipitation of bacteriocins from culture supernatants, followed by various combinations of gel filtration, ion-exchange chromatography, and reverse-phase high-performance liquid chromatography (RP-HPLC). In this chapter, a protocol is described that combines several methods used in our laboratory for the purification of two cationic bacteriocins, Lactocin 705AL and Enterocin CRL10, produced by Lactobacillus casei CRL705 and Enterococcus mundtii CRL10, respectively.

Bacteriocins↗
PubMed2004

Isolation and characterization of lactobacilli from some traditional fermented foods and evaluation of the bacteriocins.

Lactic acid bacteria (LAB) commonly used in food as starter cultures are known to produce antimicrobial substances such as bacteriocins and have great potential as food biopreservatives. LAB isolated from traditional fermented foods (appam batter and pickles) were screened for bacteriocin production. Two lactobacilli, LABB and LABP (one from each source) producing bacteriocins were characterized. Both the bacilli were homo-fermentative, catalase negative and micro-aerophilic in nature. LABB was found to be a thermobacterium growing at 45 degrees C while LABP was a streptobacterium growing at 15 degrees C. Both were able to grow at pH 4.5-8.6 but were intolerant to high salt concentration. They failed to produce gas from glucose as well as ammonia from arginine. Among the sugars examined they could not ferment arabinose, raffinose, rhamnose or xylose. Additionally, LABB could not ferment esculin, gluconate or mannose. LABB is identified as Lactobacillus acidophilus while LABP as Lb. casei. Their bacteriocins showed a broad inhibitory spectrum against the indicator organisms tested. They were active below pH 8.0 and after autoclaving as well. There was a complete loss of activity when treated with proteolytic enzymes such as trypsin indicating the proteinaceous nature of the active molecules. SDS-PAGE of partially purified bacteriocins indicated the molecular mass of the bacteriocin as 3.8 and 4.5 kDa for LABB and LABP respectively.

Bacteria↗
PubMed1993

Antibiosis revisited: bacteriocins produced by dairy starter cultures.

Well before the existence of starter bacteria was recognized, their activities were instrumental in preserving dairy foods. During growth in fermented products, dairy starters, including lactobacilli, lactococci, leuconostocs, streptococci, and propionibacteria, produce inhibitory metabolites. Inhibitors include broad-spectrum antagonists, organic acids, diacetyl, and hydrogen peroxide. Some starters also produce bacteriocins or bactericidal proteins active against species that usually are related closely to the producer culture. Several bacteriocins have been biochemically and genetically characterized. Evaluating properties of the Lactobacillus acidophilus bacteriocin, lactacin B, led to a new purification protocol. Purified lactacin B migrates in SDS-PAGE as a single 8100-Da band with inhibitory activity after Coomassie blue staining. Production of lactacin B is enhanced by cultivation of the producer with the sensitive indicator, Lactobacillus delbrueckii ssp. lactis 4797; understanding this interaction may increase knowledge of production of bacteriocins in heterogeneous cultures. Bacteriocins have been recently identified in dairy propionibacteria. Jenseniin G, a bacteriocin produced by Propionibacterium jensenii P126, has narrow activity; propionicin PLG-1 produced by Propionibacterium thoenii P127 inhibits propionibacteria, some fungi, Campylobacter jejuni, and additional pathogens. Better understanding of these antagonists may lead to targeted biocontrol of spoilage flora and foodborne pathogens.

Antibiosis↗
PubMed1999

Spray-drying of bacteriocin-producing lactic acid bacteria.

Cell survival, cellular damage, and antagonistic activity were investigated after spray-drying of four bacteriocin-producing strains of lactic acid bacteria: Lactococcus lactis subsp. lactis 140, isolated from natural whey culture and producing a narrow-inhibitory spectrum bacteriocin); L. lactis subsp. lactis G35, isolated from pizza dough and producing nisin; Lactobacillus curvatus 32Y and Lactobacillus sp. 8Z, isolated from dry sausages. Trials were performed with bacteria suspended in skimmed milk or directly grown in whey. Three air temperatures at the inlet of the drier (160, 180, and 200 degrees C) and three flow rates (10, 13, and 17 ml/min) were assayed. Cell viability and bacteriocin activity of the dried materials were determined immediately after the process and after 5, 15, 30, and 60 days of storage at 4 degrees C. There was no significant difference between the two feeding suspensions in cell survival, always decreasing with the increase of inlet-air temperature. No loss of bacteriocin activity was detected in reconstituted powders, nor was any loss of ability to produce bacteriocin found after drying. Investigations of sensitivity to NaCl revealed only temporary damage to dried bacteria. During storage for 2 months at 4 degrees C, all samples, but mainly the lactococcal strains, displayed a gradual decrease in cell survival. Bacteriocin activity remained at the same level, allowing powders to be considered as effective biopreservatives.

Aerosols↗
PubMed2005

Production, purification, and characterization of micrococcin GO5, a bacteriocin produced by Micrococcus sp. GO5 isolated from kimchi.

Strain GO5, a bacteriocin-producing bacterium, was isolated from green onion kimchi and identified as Micrococcus sp. The bacteriocin, micrococcin GO5, displayed a broad spectrum of inhibitory activity against a variety of pathogenic and nonpathogenic microorganisms, as tested by the spot-on-lawn method; its activity spectrum was almost identical to that of nisin. Micrococcin GO5 was inactivated by trypsin (whereas nisin was not) and was completely stable at 100 degrees C for 30 min and in the pH range of 2.0 to 7.0. Micrococcin GO5 exhibited a typical mode of bactericidal activity against Micrococcus flavus ATCC 10240. It was purified to homogeneity through ammonium sulfate precipitation, ultrafiltration, and CM-Sepharose column chromatography. The molecular mass of micrococcin GO5 was estimated to be about 5.0 kDa by tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis and in situ activity assay with the indicator organism. The amino acid sequence of micrococcin GO5 lacks lanthionine and beta-methyllanthionine and is rich in hydrophobic amino acids and glycine, providing the basis for the high heat stability of this bacteriocin. The N-terminal amino acid sequence of micrococcin GO5 is Lys-Lys-Ser-Phe-Cys-Gln-Lys, and no homology to bacteriocins reported previously was observed in the amino acid composition or N-terminal amino acid sequence. Based on the physicochemical properties, small molecular size, and inhibition of Listeria monocytogenes, micrococcin GO5 has been placed with the class II bacteriocins, but its broad spectrum of activity differs from that of other bacteriocins in this class.

Amino Acid Sequence↗
PubMed2005

Interactions of meat-associated bacteriocin-producing Lactobacilli with Listeria innocua under stringent sausage fermentation conditions.

The kinetics of the antilisterial effect of meat-associated lactobacilli on Listeria innocua LMG 13568 were investigated during laboratory batch fermentations. During these fermentations, which were performed in a liquid meat simulation medium, a combination of process factors typical for European-style sausage fermentations was applied, such as a temperature of 20 degrees C and a representative pH and salting profile. Two bacteriocin-producing sausage isolates (Lactobacillus sakei CTC 494 and Lactobacillus curvatus LTH 1174), which have already proven efficacy in sausage trials, and one nonbacteriocinogenic, industrial strain (Lactobacillus sakei I), were evaluated. Staphylococcus carnosus 833 was included in the experiment because of its role in flavor and color development. When grown as a monoculture or upon cocultivation with L. sakei I and S. carnosus 833, L. innocua LMG 13568 developed slightly, despite the stress of low temperature, pH, lactic acid, salt, and nitrite. In contrast, when either of the bacteriocin producers was used, the L. innocua LMG 13568 population was rapidly inactivated with more than 3 log CFU ml(-1) after 2 days of fermentation. A bacteriocin-tolerant L. innocua LMG 13568 subpopulation (4 X 10(-4)) remained after bacteriocin inactivation. Thus, when the initial level of L. innocua LMG 13568 equaled 3 log CFU ml(-1), all cells were inactivated and no bacteriocin-tolerant cells were detected, even after 7 days of incubation. S. carnosus was not inactivated by the Lactobacillus bacteriocins and displayed slight growth.

Animals↗
PubMedDate not supplied

Bacteriocins: mechanism of membrane insertion and pore formation.

Lactic acid bacteria produce several types of pore forming peptides. Class I bacteriocins are lantibiotics that contain (methyl)lanthionine residues that may form intramolecular thioether rings. These peptides generally have a broad spectrum of activity and form unstable pores. Class II bacteriocins are small, heat stable peptides mostly with a narrow spectrum of activity. Most bacteriocins interact with anionic lipids that are abundantly present in the membranes of gram-positive bacteria. 'Docking molecules' may enhance the conductivity and stability of lantibiotic pores, while 'receptors' in the target membrane may determine specificity of class II bacteriocins. Insertion into the membrane of many bacteriocins is proton motive force driven. Lantibiotics may form pores according to a 'wedge-like' model, while class II bacteriocins may enhance membrane permeability either by the formation of a 'barrel stave' pore or by a 'carpet' mechanism.

Amino Acid Sequence↗
PubMedDate not supplied

Developing applications for lactococcal bacteriocins.

While much of the applied research carried out to date with bacteriocins has concerned nisin, lactococci produce other bacteriocins with economic potential. An example is the two component bacteriocin lacticin 3147, which is active over a wide pH range and has a broad spectrum of activity against gram-positive bacteria. Since the genetic determinants for lacticin 3147 are encoded on a large self-transmissible plasmid, the bacteriocin genes may be conveniently transferred to different lactococcal starters. The resulting food-grade strains can then be used to make a significant impact on the safety and quality of a variety of fermented foods, through the inhibition of undesirable microflora. The bacteriocin is heat stable so it can also be used as an ingredient in a powdered form such as a spray-dried fermentate. Given the observation that lacticin 3147 is effective at physiological pH, there is also considerable potential for biomedical applications. Field trials have demonstrated its efficacy in the prevention of mastitis infections in dairy cows. In contrast to lacticin 3147, the lactococcin bacteriocins A, B and M have a narrow spectrum of activity limited to lactococci. Strains which produce these inhibitors can be exploited in the acceleration of cheese ripening by assisting the premature lysis of starter cultures.

Animals↗
PubMed2002

The bacteriocins of ruminal bacteria and their potential as an alternative to antibiotics.

Beef cattle have been fed ionophores and other antibiotics for more than 20 years to decrease ruminal fermentation losses (e.g methane and ammonia) and increase feed efficiency, and these improvements have been explained by an inhibition of gram-positive ruminal bacteria. Ionophores are not used to treat human disease, but there has been an increased perception that antibiotics should not be used as feed additives. Some bacteria produce small peptides (bacteriocins) that inhibit gram-positive bacteria. In vitro experiments indicated that the bacteriocin, nisin, and the ionophore, monensin, had similar effects on ruminal fermentation. However, preliminary results indicated that mixed ruminal bacteria degraded nisin, and the ruminal bacterium, Streptococcus bovis, became highly nisin-resistant. A variety of ruminal bacteria produce bacteriocins, and bacteriocin production has, in some cases, been correlated with changes in ruminal ecology. Some ruminal bacteriocins are as potent as nisin in vitro, and resistance can be circumvented. Based on these results, ruminal bacteriocins may provide an alternative to antibiotics in cattle rations.

Animals↗
PubMed1979

[Bacteriocin properties of Lactobacillus fermenti, Lactobacillus brevis and Lactobacillus buchneri].

Four bacteriocins of L. fermenti, 3 bacteriocins of L. brevis and 1 bacteriocin of L. buchneri were studied with respect to morphology of the inhibition growth zones of the indicator strains, capacity for diffusion through cellophane, sensitivity to high temperature, bacterial proteases, trypsin, chymotrypsin, pepsin, papain, nucleases and lysozyme. According to the differences in their properties the bacteriocins were classified as belonging to 8 types, including 4 types of L. fermenti bacteriocins and 3 types of L. brevis bacteriocins.

Antibiosis↗
PubMed1982

[Induction of bacteriocin synthesis in Erwinia cells].

The effect of UV light and mitomycin C as inductors of bacteriocins biosynthesis by Erwinia was studied. 46 strains of Erwinia were tested and the synthesis of bacteriocins was induced by irradiation with UV light only in 14 of them. The irradiation dose providing the highest increase of the bacteriocin titer was different for every strain. The survival of the strains ranged within 0.06 to 11.3 per cent. The time course of the bacteriocin synthesis induced by UV light in 9 strains of Erwinia was studied and it was shown that the process had common similar characteristics: gradual increasing of the bacteriocin titer immediately after exposure to UV light, reaching the maximum level 5-7 hours after incubation and its persisting for the subsequent observation period. Mitomycin indices bacteriocin production by the Erwinia strains tested only in individual cases, the character of the effect being dependent on the drug concentration and exposure time.

Bacteriocins↗
PubMed1994

Chemical and genetic characterization of bacteriocins produced by Carnobacterium piscicola LV17B.

Carnobacteriocins BM1 and B2 are thermostable class II bacteriocins produced by Carnobacterium piscicola LV17B. These bacteriocins were purified by a three-step procedure that included hydrophobic interaction, size exclusion, and reversed-phase high performance liquid chromatography. The purified peptides and fragments derived by enzymatic digestion were analyzed by Edman degradation, amino acid analysis, and mass spectrometry. An oxidized form of carnobacteriocin BM1 (carnobacteriocin B1) was also purified and characterized. Probes synthesized using information from the N-terminal amino acid sequences for the purified bacteriocins were used to locate structural genes for the carnobacteriocins. A 1.9-kilobase (kb) HindIII fragment from a 61-kb plasmid (pCP40) containing the carnobacteriocin B2 structural gene and a 4.0-kb EcoRI-PstI genomic fragment containing the carnobacteriocin BM1 structural gene were cloned and fully or partially sequenced, respectively. Expression of the chromosomal bacteriocin and its immunity function requires the presence of the 61-kb plasmid. The results indicate that both bacteriocins are synthesized as prebacteriocins. Post-translational cleavage of an 18-amino acid N-terminal extension at a Gly-Gly (positions -2 and -1) site takes place in each prepeptide to yield the mature 43-amino acid carnobacteriocin BM1 (molecular mass 4524.6) and the mature 48-amino acid carnobacteriocin B2 (molecular mass 4969.9). These two peptides showed significant amino acid homology to each other and with those class II bacteriocins which contain the YGNGV amino acid motif near the N terminus.

Amino Acid Sequence↗