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PubMed2003

Plant lectin-like bacteriocin from a rhizosphere-colonizing Pseudomonas isolate.

Rhizosphere isolate Pseudomonas sp. strain BW11M1, which belongs to the Pseudomonas putida cluster, secretes a heat- and protease-sensitive bacteriocin which kills P. putida GR12-2R3. The production of this bacteriocin is enhanced by DNA-damaging treatment of producer cells. We isolated a TnMod mutant of strain BW11M1 that had lost the capacity to inhibit the growth of strain GR12-2R3. A wild-type genomic fragment encompassing the transposon insertion site was shown to confer the bacteriocin phenotype when it was introduced into Escherichia coli cells. The bacteriocin structural gene was identified by defining the minimal region required for expression in E. coli. This gene was designated llpA (lectin-like putidacin) on the basis of significant homology of its 276-amino-acid product with mannose-binding lectins from monocotyledonous plants. LlpA is composed of two monocot mannose-binding lectin (MMBL) domains. Several uncharacterized bacterial genes encoding diverse proteins containing one or two MMBL domains were identified. A phylogenetic analysis of the MMBL domains present in eukaryotic and prokaryotic proteins assigned the putidacin domains to a new bacterial clade within the MMBL-containing protein family. Heterologous expression of the llpA gene also conveyed bacteriocin production to several Pseudomonas fluorescens strains. In addition, we demonstrated that strain BW11M1 and heterologous hosts secrete LlpA into the growth medium without requiring a cleavable signal sequence. Most likely, the mode of action of this lectin-like bacteriocin is different from the modes of action of previously described Pseudomonas bacteriocins.

Amino Acid Motifs↗
PubMed2005

Regulation of bacteriocin production in Streptococcus mutans by the quorum-sensing system required for development of genetic competence.

In Streptococcus mutans, competence for genetic transformation and biofilm formation are dependent on the two-component signal transduction system ComDE together with the inducer peptide pheromone competence-stimulating peptide (CSP) (encoded by comC). Here, it is shown that the same system is also required for expression of the nlmAB genes, which encode a two-peptide nonlantibiotic bacteriocin. Expression from a transcriptional nlmAB'-lacZ fusion was highest at high cell density and was increased up to 60-fold following addition of CSP, but it was abolished when the comDE genes were interrupted. Two more genes, encoding another putative bacteriocin and a putative bacteriocin immunity protein, were also regulated by this system. The regions upstream of these genes and of two further putative bacteriocin-encoding genes and a gene encoding a putative bacteriocin immunity protein contained a conserved 9-bp repeat element just upstream of the transcription start, which suggests that expression of these genes is also dependent on the ComCDE regulatory system. Mutations in the repeat element of the nlmAB promoter region led to a decrease in CSP-dependent expression of nlmAB'-lacZ. In agreement with these results, a comDE mutant and mutants unable to synthesize or export CSP did not produce bacteriocins. It is speculated that, at high cell density, bacteriocin production is induced to liberate DNA from competing streptococci.

Amino Acid Sequence↗
PubMed1969

Properties and characteristics of a bacteriocin from Serratia marcescens.

A strain of Serratia marcescens was found to produce a bacteriocin that inhibits the growth of certain Escherichia coli strains. This inhibition was bacteriocidal rather than bacteriostatic and was not caused by a bacteriophage. Whereas the bacteriocin was inactive on the 7 Serratia strains tested, it killed 11 of the 20 E. coli strains tested for sensitivity. A relationship of the bacteriocin to a possible colicin cannot as yet be excluded, although E. coli mutants resistant to 1 or 2 of 15 different colicins remained sensitive to the bacteriocin. The bacteriocidal effect by the bacteriocin could be interrupted in a substantial fraction of the treated cell population by the addition of trypsin. The synthesis of the bacteriocin was inducible by ultraviolet light or by starvation for thymidine. Both procedures led to a similar increase in maximum bacteriocin titer relative to noninduced cultures.

Bacteriocins↗
PubMed1995

Bacteriocins of gram-positive bacteria.

In recent years, a group of antibacterial proteins produced by gram-positive bacteria have attracted great interest in their potential use as food preservatives and as antibacterial agents to combat certain infections due to gram-positive pathogenic bacteria. They are ribosomally synthesized peptides of 30 to less than 60 amino acids, with a narrow to wide antibacterial spectrum against gram-positive bacteria; the antibacterial property is heat stable, and a producer strain displays a degree of specific self-protection against its own antibacterial peptide. In many respects, these proteins are quite different from the colicins and other bacteriocins produced by gram-negative bacteria, yet customarily they also are grouped as bacteriocins. Although a large number of these bacteriocins (or bacteriocin-like inhibitory substances) have been reported, only a few have been studied in detail for their mode of action, amino acid sequence, genetic characteristics, and biosynthesis mechanisms. Nevertheless, in general, they appear to be translated as inactive prepeptides containing an N-terminal leader sequence and a C-terminal propeptide component. During posttranslational modifications, the leader peptide is removed. In addition, depending on the particular type, some amino acids in the propeptide components may undergo either dehydration and thioether ring formation to produce lanthionine and beta-methyl lanthionine (as in lantibiotics) or thio ester ring formation to form cystine (as in thiolbiotics). Some of these steps, as well as the translocation of the molecules through the cytoplasmic membrane and producer self-protection against the homologous bacteriocin, are mediated through specific proteins (enzymes). Limited genetic studies have shown that the structural gene for such a bacteriocin and the genes encoding proteins associated with immunity, translocation, and processing are present in a cluster in either a plasmid, the chromosome, or a transposon. Following posttranslational modification and depending on the pH, the molecules may either be released into the environment or remain bound to the cell wall. The antibacterial action against a sensitive cell of a gram-positive strain is produced principally by destabilization of membrane functions. Under certain conditions, gram-negative bacterial cells can also be sensitive to some of these molecules. By application of site-specific mutagenesis, bacteriocin variants which may differ in their antimicrobial spectrum and physicochemical characteristics can be produced. Research activity in this field has grown remarkably but sometimes with an undisciplined regard for conformity in the definition, naming, and categorization of these molecules and their genetic effectors. Some suggestions for improved standardization of nomenclature are offered.

Amino Acid Sequence↗
PubMed2004

The circular bacteriocins gassericin A and circularin A.

Gassericin A, a bacteriocin produced by Lactobacillus gasseri LA39, shows antibacterial activity against a number of Gram-positive food-borne pathogenic bacteria. Circularin A produced by Clostridium beijerinckii ATCC25752 is active against C. tyrobutyricum, a known cheese-spoilage bacterium. Both bacteriocins were purified to homogeneity from culture supernatants by reverse-phase chromatography and the subsequently determined amino acid sequences were used to clone the bacteriocin structural genes. Mature gassericin A and circularin A are class V circular bacteriocins comprised of 58 and 69 amino acid residues, respectively. Both bacteriocins are resistant to several peptidases and proteases, as are other cyclic bacteriocins. Heterologous expression of gassericin A in Escherichia coli was used to produce a non-cyclic mature peptide, which was shown to have a specific activity 173-fold lower than the circular molecule. The minimal region for production and secretion of active circularin A is comprised of five genes, as was deduced by heterologous gene expression in Enterococcus faecalis. Gassericin A and circularin A have limited mutual similarity in their primary sequences. Unlike most bacteriocins, including gassericin A, circularin A has a three-amino-acid-leader sequence.

Animals↗
PubMed2006

Factors affecting the adsorption of bacteriocins ST194BZ and ST23LD to Lactobacillus sakei and Enterococcus sp.

Bacteriocins ST194BZ and ST23LD, produced by Lactobacillus plantarum, inhibit Gram-positive and Gram-negative bacteria. Images obtained by atomic force microscopy showed clear signs of membrane damage of Lactobacillus sakei, accompanied by the leakage of DNA and beta-galactosidase. Adsorption of the bacteriocins to cells was increased when cells were treated with buffers at pH values above neutral. An increase in bacteriocin ST194BZ adsorption to cells of Enterococcus sp. and L. sakei was observed with an increase in incubation temperatures, but at different rates for the two species. Treatment of the two species with various inorganic salts and solvents gave different results regarding the adsorption of the two bacteriocins. In general, pre-treatment of the two sensitive cells with Triton X-100, Triton X-114 and chloroform increased the adsorption of the two bacteriocins. Increased adsorption of bacteriocin ST23LD to L. sakei was recorded when the cells were pre-treated with Tris and NH4-citrate. Treatment of Enterococcus sp. and L. sakei with Na-EDTA and SDS decreased the adsorption of the two bacteriocins. Variable results were recorded with inorganic salts.

Adsorption↗
PubMed1994

Bacteriocins produced by Leuconostoc species.

Leuconostoc spp. are lactic acid bacteria that are commonly associated with foods and that are used as starter bacteria in some dairy fermentations. Lactic acid bacteria are inhibitory to other bacteria because of pH, organic acids, hydrogen peroxide, and other chemicals produced during their growth, including bacteriocins. Bacteriocin production by Leuconostoc spp. was first observed in the 1950s, but only since 1984, when antagonistic activity of Leuconostoc spp. was reported, have more extensive studies of bacteriocins produced by Leuconostoc spp. been conducted, including mesentericin Y105, produced by Leuconostoc mesenteroides spp. mesenteroides; leucocin A-UAL 187, produced by Leuconostoc gelidum; carnosin 44A, produced by Leuconostoc carnosum; and leuconocin S, produced by Leuconostoc paramesenteroides. Bacteriocins produced by leuconostocs may or may not be active against other lactic acid bacteria, but all include Listeria in their activity spectra. Mesentericin Y105 is reported to be exclusively active against Listeria spp. The amino acid sequences for leucocin A and mesentericin Y105 have been determined. Despite considerable differences in antibacterial spectra, only two amino acids differ between these bacteriocins. The prevalence of leuconostocs in many adventitious fermentations of food and the use of leuconostocs as starter bacteria in controlled fermentations make the bacteriocins produced by these bacteria of interest as possible food preservatives by addition of the bacteriocin or its producer organism to foods.

Amino Acid Sequence↗
PubMed2005

Paenibacillus polymyxa purified bacteriocin to control Campylobacter jejuni in chickens.

Campylobacter spp. cause numerous foodborne diseases. Poultry is thought to be a significant source of this zoonosis. Although many interventions designed to control this agent have been researched, none have succeeded. We evaluated a bacteriocin-based treatment to reduce Campylobacter jejuni colonization in poultry. A previously described purified bacteriocin (class IIa; molecular mass, 3,864 Da), secreted by Paenibacillus polymyxa NRRL-B-30509, was microencapsulated in polyvinylpyrrolidone, and 0.25 g of the purified bacteriocin was incorporated into 1 kg of chicken feed. One-day-old chickens were orally challenged and colonized with one of four isolates of C. jejuni, then reared in isolation facilities. Birds were provided ad libitum access to standard broiler starter feed and water for 7 days until 3 days before sampling, when only the treated groups of birds were provided the bacteriocin-emended feed described. In each of the eight (four by two replicates) trials, significant reductions in colonization by C. jejuni were observed (P < or = 0.05). As an example of this highly consistent data, in the first trial, 10 untreated 10-day-old chickens were colonized at a mean log 7.2 + 0.3 CFU/g of feces, whereas none of the 10 bacteriocin-treated 10-day-old chickens were colonized with detectable numbers of C. jejuni. Bacteriocin treatment dramatically reduced both intestinal levels and frequency of chicken colonization by C. jejuni. Feeding bacteriocins before poultry slaughter appears to provide control of C. jejuni to effectively reduce human exposure. This advance is directed toward on-farm control of pathogens, as opposed to the currently used chemical disinfection of contaminated carcasses.

Animal Feed↗
PubMed2006

Isolation and preliminary characterization of a bacteriocin produced by Lactobacillus plantarum N014 isolated from nham, a traditional Thai fermented pork.

Lactobacillus plantarum N014 was isolated from nham, a traditional Thai fermented pork, and exhibited antimicrobial activity against Listeria monocytogenes. Its bacteriocin had a broad inhibitory spectrum toward both gram-positive and gram-negative bacteria. The bacteriocin activity was sensitive to all proteolytic enzymes used in this study, including papain, pepsin, pronase E, proteinase K, and trypsin, but was resistant to the other enzymes, such as alpha-amylase, lipase A, and lysozyme. Furthermore, activity was stable over various heat treatments and pH values. The bacteriocin exerted a bacteriolytic mode of action. It was produced during the exponential growth phase and reached its highest level as producer cells entered the stationary phase. Adsorption of the bacteriocin onto producer cells was pH-dependent. No bacteriocin adsorption was detected at pH 1 to 3, whereas 100% bacteriocin adsorption was found at pH 7. Plasmid isolation revealed that L. plantarum N014 contained no plasmids. From Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis and growth inhibition testing against L. monocytogenes, the estimated molecular mass of L. plantarum N014 bacteriocin was 8 kDa.

Adsorption↗
PubMed2001

Symbiotic effectiveness of bacteriocin producing and non-producing strains of Rhizobium in green gram (Vigna radiata).

Rhizobium strains nodulating green gram [Vigna radiata (L.) Wilczek] were found to produce bacteriocin on modified Bergersen's medium and inhibited the growth of homologous Rhizobium strains. Four bacteriocin producing and four bacteriocin non-producing strains were compared for their effect on nodulation, in planta nitrogenase activity and plant dry weight of green gram. The bacteriocin producers formed more nodules in comparison to non-bacteriocin producers. However, the symbiotic effectiveness of bacteriocin producers was less in terms of plant dry weight in comparison to non-bacteriocin producers.

Bacteriocins↗
PubMedDate not supplied

Effects of the bacteriocin PsVP-10 produced by Pseudomonas sp. on sensitive bacterial strains.

The bacteriocin PsVP-10 is a 2.6 Kda peptide which was isolated and purified from Pseudomonas sp. This bacteriocin possesses lethal activity over Enterococcus faecalis, Salmonella typhimurium and Shigella flexneri. The experimental assays showed that the bacteriocin is able to be adsorbed by all cells of these bacterial species and also by their isolated cell walls. It was observed that the resistant mutants and their respective cell walls are unable to adsorb the bacteriocin. Assays performed with spheroplasts obtained from sensitive bacterial species and their resistant mutants show a rapid lethal effect of the bacteriocin PsVP-10. This results indicated furthermore, it is also shown that the optimal pH and temperature for the adsorption were 7.2 and 37 degrees C, respectively. The study carried out with organic solvents like methanol, ethanol, isopropanol and the detergents sodium dodecyl sulfate and triton X-100 showed a moderate inhibition of the bacteriocin lethal action for the Gram negative cells. The enzymes lysozime, protease XIV and trypsine type III-S did not present any effect over the adsorption capacity of the bacteriocin with any of the bacterial species studied.

Adsorption↗
PubMed1990

Production of bacteriocins and siderophore-like activity by Azospirillum brasilense.

Sixty Azospirillum strains were tested for their bacteriocin production ability; twenty-seven (45%) were able to produce bacteriocins and inhibited the growth of one or more indicator strains in solid medium. Mitomycin C treatment enhanced the proportion to 80%. Sometimes large growth inhibition zones were formed, but not when FeCl3 was added in the medium. These inhibition zones probably result from the activity of siderophores. Partially purified bacteriocins produced by four strains were inactivated at pH 4, but were very stable between pH 5 to 10; bacteriocins produced by three strains lost their activity between 55 and 80 degrees C. Loss or decrease in the bacteriocin activity was observed with pronase E treatment; trypsin, lysozyme and alpha-amylase did not have an effect on bacteriocin activity. These findings show that the antagonism among azospirilla was due principally to the bacteriocins and sometimes probably due to siderophores, but not to bacteriophages or other substances.

Alkylating Agents↗
PubMed1981

The significance of bacteriocin typing of Klebsiella strans.

Out of three different methods used for bacteriocin sensitivity typing of Klebsiella strains, the "scarpe and streak" method was the most appropriate tool for its routine use in epidemiologic studies. The method is quite simple, reliable and does not imply any special requirements. Out of 533 Klebsiella strains tested by our set of seven bacteriocins 453 (85%) strains proved to be typable and 100 (15%) nontypable. The number of strains typable by bacteriocins was higher than of those typable by phages. In 14 of 19 outbreaks, the predominance of 1-2 distinct patterns of bacteriocin sensitivity was observed. Two large geographical areas have been delineated by two predominant distinct bacteriocin types of Klebsiella strains, each being observed in a high number of outbreaks as well as in sporadic cases belonging to the same area. Although it was not possible to establish any clear correlation between the pattern of bacteriocin sensitivity and the lysotype or serotype of the strains, The present findings offer strong reason to allow recommendation of the bacteriocin sensitivity pattern as a marker of high epidemiologic significance in monitoring Klebsiella cross-infections. Medical and auxiliary workers could play the role of reservoir to Klebsiella strains and for this reason the hospital personnel has to follow carefully strict procedures for ensuring a valid protection of patients especially when coming into direct contact with neonates, infants and debilitated patients.

Bacteriocins↗
PubMed1997

Isolation and partial amino acid sequence of bacteriocins produced by Lactobacillus acidophilus.

Bacteriocins produced by Lactobacillus acidophilus JCM 1023, JCM 1028, JCM 1021, JCM 1229, and JCM 5342 were active against closely related lactobacilli. These bacteriocins were purified and partial sequenced. Bacteriocin activities of L. acidophilus JCM 1023 and JCM 1028 were associated with two components. On the basis of N-terminal amino acid sequencing and the molecular masses, it is interpreted that these two-component bacteriocins are identical to acidocin J1132, a bacteriocin from L. acidophilus JCM 1132 [Tahara et al., Appl. Environ. Microbiol., 62, 892-897 (1996)]. Other bacteriocins were single-peptide bacteriocins.

Amino Acid Sequence↗
PubMed1996

Bacteriocin typing of Klebsiella spp. isolated from different sources.

To evaluate whether clinical Klebsiella isolates differ from nonclinical strains with respect to bacteriocin susceptibility patterns, a total of 452 Klebsiella pneumoniae and K. oxytoca strains isolated from different sources were examined. Bacteriocin typing was done by a modification of the scrape-and-point method, using a set of eight producer strains. 96% of the strains were typable. Forty-one different bacteriocin susceptibility patterns were observed. While two thirds of the K. oxytoca isolates belonged to only three different bacteriocin types, the K. pneumoniae strains showed a more heterogeneous distribution of patterns. No differences in pattern distribution were observed between isolates from clinical, fecal, or environmental sources. Certain bacteriocins showed a very broad spectrum of activity; e.g. 93% of all isolates were susceptible to bacteriocin type 3. The results suggest that nonclinical Klebsiella strains do not show other bacteriocin susceptibility types than clinical isolates do.

Bacteriocins↗
PubMed1983

Bacteriocin and flow cytometry in laboratory diagnosis of leukemic peripheral blood lymphocytes and bone marrow cells.

The bacteriocin, colicin HSC10, produced by Escherichia coli HSC10, was studied as a laboratory tool for detection and differentiation of leukemic from normal lymphocytes in human peripheral blood. Flow cytometry studies detected DNA loss in bacteriocin-affected cells by computerized histograms. Differential analysis is given for the peripheral blood of 26 individuals using bacteriocin, cytochemistry and surface markers. Sensitivity to colicin was detected in 10 (83%) of the 12 patients with chronic lymphocytic leukemias and other leukemias with morphologically immature lymphocytes. Cells were lost from the G0/G1 phase and accumulated in the 'pre-G1' channels of the histogram, indicative of cells with reduced DNA content. The lymphocytes of 14 normals, however, were not or only slightly affected by the bacteriocin (P less than 0.001). Similarly, normal bone marrow cells exposed to bacteriocin remained unaffected (P greater than 0.2). Thus, immaturity per se was not recognized by bacteriocin. The bacteriocin effect was more discriminatory than other laboratory tests reported here and in most cases differentiated malignant from normal cells.

Aged↗
PubMed1999

Class IIa bacteriocins from lactic acid bacteria: antibacterial activity and food preservation.

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 various fundamental aspects of biology and biochemistry such as bacteriocin processing and secretion, mechanisms of cell immunity, and structure-function relationships. In parallel, there has been a growing awareness that bacteriocins may be developed into useful antimicrobial food 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 significant biological activities and potential applications. The present review provides an overview of the knowledge available for class IIa bacteriocins and discusses common features and recent findings concerning these substances. The activity and potential food applications of class IIa bacteriocins are a major focus of this review.

Journal Article↗
PubMed1996

Prevention of histamine formation in cheese by bacteriocin-producing lactic Acid bacteria.

The susceptibility of 13 amine-forming lactobacilli to several bacteriocins was investigated by an agar diffusion assay. All strains were susceptible to nisin and to five bacteriocins of enterococcal origin. Pediocin PA-1, bavaricin A, lactococcin A, and a bacteriocin from Enterococcus faecalis 1061 did not show inhibitory activity. Two bacteriocin-producing enterococci and a nisin-producing Lactococcus lactis strain were employed as starters in separate cheese-making experiments. Outgrowth of histamine producer Lactobacillus buchneri St2A, which was added to the milk at levels of up to 190 CFU/ml, was almost completely inhibited. No histamine formation was detected in the cheeses made with bacteriocin-producing starters. In the control cheese without bacteriocin, St2A reached levels of 1.1 x 10(sup8) CFU/g, and 200 mg of histamine per kg was found after 4 months of ripening. To our knowledge, this is the first report of bacteriocin-mediated inhibition of histamine formation in foods.

Journal Article↗