Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “BACTERIOCINS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources
PubMed1996

Mutational analysis and chemical modification of Cys24 of lactococcin B, a bacteriocin produced by Lactococcus lactis.

Using site-directed mutagenesis the single cysteine residue at position 24 of lactococcin B was replaced by all other possible amino acids. Most of these mutant molecules retained bacteriocin activity, with the exception of those in which cysteine was replaced by a positively charged amino acid. This would seem to be in agreement with the authors' earlier observation that treatment of the wild-type molecule with HgCl2 resulted in its inactivation. The factor that causes inactivation of lactococcin B seems to be the introduction of a positive charge at position 24 by HgCl2 rather than oxidation of this residue, as treatment of the bacteriocin with other oxidative chemicals did not interfere with the ability of lactococcin B to dissipate the membrane potential of sensitive cells. Results are also reported which imply that inactive lactococcin B can still bind to its receptor. It can be replaced by an active bacteriocin molecule, resulting in dissipation of the membrane potential.

Bacteriocins↗
PubMed2003

Bacteriocin-like inhibitory substance (BLIS) production by the normal flora of the nasopharynx: potential to protect against otitis media?

The normal bacterial flora of the upper airways provides an important barrier to invading pathogens. This study investigated the production of bacteriocin-like inhibitory substances (BLIS) by streptococci isolated from the nasopharyngeal flora of children who either do or do not experience recurrent acute otitis media (AOM). Twenty children with recurrent AOM and 15 controls were tested. Swabs from the nasopharynx were evaluated for streptococci having BLIS activity against two representative strains of each of the AOM pathogens Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae and Moraxella catarrhalis. Streptococci displaying strong BLIS activity were characterized further and tested for known streptococcal bacteriocin structural genes. Sixty-five per cent of children had nasopharyngeal streptococcal isolates that were inhibitory to strains of one or more of the AOM pathogens. Six children (17 %) had streptococci that demonstrated strong BLIS activity against strains of at least three of the pathogenic species. Three of these inhibitory isolates were Streptococcus salivarius, two were S. pneumoniae and one was S. pyogenes. The inhibitory S. salivarius and S. pyogenes were shown to have structural genes for known streptococcal bacteriocins. No statistically significant difference was found between the two groups of children with respect to the presence of inhibitory streptococci in their nasopharyngeal floras. The finding of S. salivarius with strong inhibitory activity against several AOM pathogens in the nasopharyngeal flora of children is unique. Although there is no clear evidence from the present study that these organisms protect against AOM, their low pathogenicity and strong in-vitro BLIS production capability indicate that they should be incorporated in future trials of bacteriotherapy for recurrent AOM.

Acute Disease↗
PubMed2003

Biphasic kinetics of growth and bacteriocin production with Lactobacillus amylovorus DCE 471 occur under stress conditions.

Micro-organisms used during the production of fermented foods are subjected to several abiotic stresses. Microbial survival during these processes strongly depends on the ability of the cells to adapt and become more tolerant to the environmental conditions. Cultivation of Lactobacillus amylovorus DCE 471, a potential strain for use during type II sourdough fermentations, at low temperatures, unfavourable pH and high salt concentrations resulted in biphasic growth patterns. In addition, two separate bacteriocin peaks, as well as a dramatic change in cellular morphology, were observed. In general, an increase of the specific bacteriocin production occurred during the second growth phase. Finally, the observed sugar consumption profiles were affected by the applied fermentation temperature. Moreover, the highest bacteriocin activity occurred during maltose consumption at a low constant temperature of 28 degrees C and a constant pH of 5.4. Plate counts from both growth phases revealed the existence of two colony types. Irregular colonies were found to outnumber smoother colonies during the first growth phase, while the second growth phase was characterized by a greater number of smooth colonies. Electron microscopy was used to investigate the observed morphological switch at the single-cell level. Single, rod-shaped cells changed into elongated cells that grew in chains. Colony and cell morphology changes coincided with the biphasic growth pattern.

Bacterial Typing Techniques↗
PubMed2004

Expression of mptC of Listeria monocytogenes induces sensitivity to class IIa bacteriocins in Lactococcus lactis.

Sensitivity to class IIa bacteriocins from lactic acid bacteria was recently associated with the mannose phosphotransferase system (PTS) permease, in Listeria monocytogenes. To assess the involvement of this protein complex in class IIa bacteriocin activity, the mptACD operon, encoding, was heterologously expressed in an insensitive species, namely Lactococcus lactis, using the NICE double plasmid system. Upon induction of the cloned operon, the recombinant Lc. lactis became sensitive to leucocin A. Pediocin PA-1 and enterocin A also showed inhibitory activity against Lc. lactis cultures expressing mptACD. Furthermore, the role of the three genes of the mptACD operon was investigated. Derivative plasmids containing various combinations of these three genes were made from the parental mptACD plasmid by divergent PCR. The results showed that expression of mptC alone is sufficient to confer sensitivity to class IIa bacteriocins in Lc. lactis.

Bacteriocins↗
PubMed2004

Cell-surface alterations in class IIa bacteriocin-resistant Listeria monocytogenes strains.

Strains of the food-borne pathogen Listeria monocytogenes, showing either intermediate or high-level resistance to class IIa bacteriocins, were investigated to determine characteristics that correlated with their sensitivity levels. Two intermediate and one highly resistant spontaneous mutant of L. monocytogenes B73, a highly resistant mutant of L. monocytogenes 412, and a highly resistant, defined (mptA) mutant of L. monocytogenes EGDe were compared with their respective wild-type strains in order to investigate the contribution of different factors to resistance. Decreased mannose-specific phosphotransferase system gene expression (mptA, EIIAB(Man) component) was implicated in all levels of resistance, confirming previous studies by the authors' group. However, a clear correlation between d-alanine content in teichoic acid (TA), in particular the alanine : phosphorus ratio, and a more positive cell surface, as determined by cytochrome c binding, were found for the highly resistant strains. Furthermore, two of the three highly resistant strains showed a significant increase in sensitivity towards d-cycloserine (DCS). However, real-time PCR of the dltA (d-alanine esterification), and dal and ddlA genes (peptidoglycan biosynthesis) showed no change in transcriptional levels. The link between DCS sensitivity and increased d-alanine esterification of TA may be that DCS competes with alanine for transport via the alanine transporter. A possible tendency towards increased lysinylation of membrane phospholipid in the highly resistant strains was also found. A previous study reported that cell membranes of all the resistant strains, including the intermediate resistant strains, contained more unsaturated phosphatidylglycerol, which is an indication of a more fluid cell membrane. The results of that study correlate with the possible lysinylation, decreased mptA expression, d-alanine esterification of TA and more positive cell surface charge found in this study for resistant strains. The authors' findings strongly indicate that all these factors could contribute to class IIa bacteriocin resistance and that the combination and contribution of each of these factors determine the level of bacteriocin resistance.

Alanine↗
PubMed2006

Dysgalacticin: a novel, plasmid-encoded antimicrobial protein (bacteriocin) produced by Streptococcus dysgalactiae subsp. equisimilis.

Dysgalacticin is a novel bacteriocin produced by Streptococcus dysgalactiae subsp. equisimilis strain W2580 that has a narrow spectrum of antimicrobial activity directed primarily against the principal human streptococcal pathogen Streptococcus pyogenes. Unlike many previously described bacteriocins of Gram-positive bacteria, dysgalacticin is a heat-labile 21.5 kDa anionic protein that kills its target without inducing lysis. The N-terminal amino acid sequence of dysgalacticin [Asn-Glu-Thr-Asn-Asn-Phe-Ala-Glu-Thr-Gln-Lys-Glu-Ile-Thr-Thr-Asn-(Asn)-Glu-Ala] has no known homologue in publicly available sequence databases. The dysgalacticin structural gene, dysA, is located on the indigenous plasmid pW2580 of strain W2580 and encodes a 220 aa preprotein which is probably exported via a Sec-dependent transport system. Natural dysA variants containing conservative amino acid substitutions were also detected by sequence analyses of dysA elements from S. dysgalactiae strains displaying W2580-like inhibitory profiles. Production of recombinant dysgalacticin by Escherichia coli confirmed that this protein is solely responsible for the inhibitory activity exhibited by strain W2580. A combination of in silico secondary structure prediction and reductive alkylation was employed to demonstrate that dysgalacticin has a novel structure containing a disulphide bond essential for its biological activity. Moreover, dysgalacticin displays similarity in predicted secondary structure (but not primary amino acid sequence or inhibitory spectrum) with another plasmid-encoded streptococcal bacteriocin, streptococcin A-M57 from S. pyogenes, indicating that dysgalacticin represents a prototype of a new class of antimicrobial proteins.

Amino Acid Sequence↗
PubMed1994

Antimicrobial activity of lactobacilli: preliminary characterization and optimization of production of acidocin B, a novel bacteriocin produced by Lactobacillus acidophilus M46.

Approximately 1000 lactobacillus strains were isolated and screened for the production of antimicrobial activity, using a target panel of spoilage organisms and pathogens. Only eight positive strains were found; two of these were studied in more detail. Lactobacillus salivarius M7 produces the new broad spectrum bacteriocin salivaricin B which inhibits the growth of Listeria monocytogenes, Bacillus cereus, Brochothrix thermosphacta, Enterococcus faecalis and many lactobacilli. A new atypical bacteriocin produced by Lact. acidophilus M46, acidocin B, combines the inhibition of Clostridium sporogenes with a very narrow activity spectrum within the genus Lactobacillus and was selected for further characterization. Acidocin B is sensitive to trypsin, heat-stable (80 degrees C for 20 min) and can be extracted from the culture supernatant fluid with butanol. Native acidocin B occurs as a large molecular weight complex (100 kDa), while with SDS-PAGE the partly purified activity migrates as a peptide of 2.4 kDa. Optimization of the cultivation conditions resulted in an eightfold increase of the amount of acidocin B produced during growth. Growth is not necessary for acidocin B production; washed producer cells can synthesize the bacteriocin in a chemically defined production medium. The application potential of acidocin B is discussed.

Bacteriocins↗
PubMed1996

Adsorption of bacteriocins by ingestible silica compounds.

Bacteriocins including nisin, pediocin PO2, brevicin 286 and piscicolin 126 were adsorbed from culture supernates by various food-grade porous silica anti-caking agents and the food colourant, titanium dioxide. All the porous silica (calcium silicate or silicon dioxide) materials showed substantial capacity in adsorbing bacteriocin activities from the culture supernate and biological activity was recovered in the adsorbents. In contrast, the food colourant titanium dioxide adsorbed most of the bacteriocin activity from the supernate, with minimal biological activity retained in the adsorbent. Experiments with piscicolin 126 showed that optimum adsorption could be achieved with Micro-Cel E within 30 min, independent of the supernate pH (2.0-10.0). Piscicolin activity of up to 5 x 10(7) AU g(-1) of Micro-Cel E was obtained after adsorption from culture supernates and the adsorbed piscicolin demonstrated substantial biological activity against Listeria monocytogenes in both broth and a milk growth medium.

Adsorption↗
PubMed2005

Antimicrobial activity of lactic acid bacteria isolated from Tenerife cheese: initial characterization of plantaricin TF711, a bacteriocin-like substance produced by Lactobacillus plantarum TF711.

AIMS: The screening and initial characterization of bacteriocins produced by lactic acid bacteria (LAB) from raw Tenerife goats' cheese with possible application as biopreservatives or ripening accelerators for Tenerife cheese. METHODS AND RESULTS: One hundred and eighty LAB of the genera Lactobacillus (95), Leuconostoc (64) and Lactococcus (21) isolated from raw Tenerife goats' cheese were screened for the production of antimicrobial substances. Lactobacillus plantarum TF711, which had the broadest spectrum of antimicrobial activity, was selected for further characterization. The antimicrobial compound was determined as a proteinaceous substance, as it was sensitive to proteases. The bacteriocin-like substance, which we called plantaricin TF711, was active against the Gram-positive bacteria Bacillus cereus, Clostridium sporogenes and Staphylococcus aureus; and against the Enterobacteriaceae Shigella sonnei and Klebsiella pneumoniae. It was stable to heat and to treatment with surfactants and organic solvents. Highest antimicrobial activity was found between pH 1 and 9. Plantaricin TF711 exhibited primary metabolite kinetics, a bacteriostatic mode of action and a molecular mass of c. 2.5 kDa as determined by tricine SDS-PAGE. CONCLUSIONS: Lact. plantarum TF711 produces a low molecular mass bacteriocin-like compound with a wide spectrum of activity and interesting technological properties (thermostability, good pH stability and stability against surfactants and organic solvents). SIGNIFICANCE AND IMPACT OF THE STUDY: Plantaricin TF711 was found to have potential for use as a biopreservative in the food industry.

Anti-Bacterial Agents↗
PubMed2006

A novel bacteriocin, thuricin 17, produced by plant growth promoting rhizobacteria strain Bacillus thuringiensis NEB17: isolation and classification.

AIMS: The aim of this study was to identify and characterize a compound produced by the plant growth promoting bacterium, Bacillus thuringiensis non-Bradyrhizobium Endophytic Bacterium 17. METHODS AND RESULTS: The bacterial peptide was analysed and purified via HPLC. Using the disk diffusion assay this peptide inhibited the growth of 16/19 B. thuringiensis strains, 4/4 Bacillus cereus strains, among others, as well as a Gram-negative strain Escherichia coli MM294 (pBS42). Both bactericidal and bacteristatic effects were observed on B. cereus ATCC 14579 and bactericidal effects were observed on B. thuringiensis ssp. thuringiensis Bt1267. The molecular weight of the peptide was estimated via SDS-PAGE and confirmed with Matrix Assisted Laser Desorption Ionization Quadrapole Time of Flight mass spectrometry; its weight is 3162 Da. The peptide is biologically active after exposure to 100 degrees C for 15 min, and within the pH range 1.00-9.25. Its activity disappeared when treated with proteinase K and protease, but not with alpha-amylase or catalase. CONCLUSIONS: We conclude that this is the first report of a bacteriocin produced by a plant growth promoting rhizobacteria (B. thuringiensis) species and have named the bacteriocin thuricin 17. SIGNIFICANCE AND IMPACT OF THE STUDY: Our work has characterized a bacteriocin produced by a plant growth promoting bacterium. This strain is previously reported to increase soya bean nodulation.

Anti-Bacterial Agents↗
PubMed2006

Inhibition of Vibrio parahaemolyticus by a bacteriocin-like inhibitory substance (BLIS) produced by Vibrio mediterranei 1.

AIMS: The aim of this research was to identify and partially purify new bacteriocin-like substances from strains of halophilic 'non-cholera' vibrios isolated from food sources. METHODS AND RESULTS: Forty-five halophilic Vibrio spp. strains were screened for antimicrobial production. Vibrio mediterranei 1, a nonpathogenic strain, showed antimicrobial activity towards Vibrio parahaemolyticus spp. and related species. The bacteriocin-like inhibitory substance (BLIS), released by the bacteria into growth media, was concentrated by ultrafiltration and characterized. BLIS was sensitive to proteinase K, was stable in the pH range 5-9, was resistant to organic solvents and was heat stable up to 75 degrees C. Initial purification of BLIS by size exclusion chromatography showed an apparent molecular mass of 63-65 kDa. CONCLUSIONS: This study reports the ability of V. mediterranei 1 to produce a bacteriocin-like substance inhibiting growth of V. parahaemolyticus spp. and other closely related bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: The strong activity of BLIS towards the human and fish pathogen V. parahaemolyticus and the persistence of antimicrobial properties under a variety of different conditions suggest its potential application in food microbiology.

Antibiosis↗
PubMed2005

Studies of the efficacy of Enterocoliticin, a phage-tail like bacteriocin, as antimicrobial agent against Yersinia enterocolitica serotype O3 in a cell culture system and in mice.

The efficacy of enterocoliticin, a phage tail-like bacteriocin, as antimicrobial compound against infections with pathogenic Yersinia enterocolitica serotype O3 strains was assessed. In cell cultures, which were infected with the Y. enterocolitica strains 13 169 or 6471/76, bactericidal activity of enterocoliticin was found for bacteria adhering to the surface of eukaryotic cells, whereas bacteria, which had invaded the eukaryotic cells, were not accessible to the bacteriocin. The interaction of enterocoliticin with Y. enterocolitica was further examined in animals. Female BALB/c mice were experimentally infected with the two Y. enterocolitica strains and enterocoliticin was applied as antimicrobial compound by the oral route. Experimental variations concerning the infectious doses of the Y. enterocolitica strains and the time points of application of the bacteriocin were investigated. The increase of the Yersinia CFU titre in animals was retarded at time points shortly after the application of enterocoliticin indicating that the particles were effective on recently introduced Yersinia. The repeated application of enterocoliticin, however, did not prevent the colonization of the gastrointestinal tract by Yersinia.

Animals↗
PubMed2006

Inhibition of Listeria innocua and Brochothrix thermosphacta in vacuum-packaged meat by addition of bacteriocinogenic Lactobacillus curvatus CRL705 and its bacteriocins.

AIMS: To evaluate the inhibition effectiveness of Lactobacillus curvatus CRL705 used as a bioprotective culture and of its bacteriocins, lactocin 705 and lactocin AL705, against Listeria innocua, Brochothrix thermosphacta and indigenous lactic acid bacteria (LAB) in vacuum-packaged meat stored at 2 degrees C. METHODS AND RESULTS: The live culture of Lact. curvatus CRL705 as well as synthetic lactocin 705 and purified lactocin AL705 were shown to be similarly effective in preventing the growth of B. thermosphacta and L. innocua in meat discs in contrast to control samples in which these micro-organisms grew rapidly, their numbers increasing by 3.0- and 2.1-log cycles respectively. In addition, indigenous LAB population showed a lower growth rate in the presence of lactocin 705. Bacteriocin activity was detected in the meat discs during 36 days at 2 degrees C irrespective of the biopreservation strategy applied. Changes in pH were not significantly different in meat discs treated with the protective culture when compared with control samples. CONCLUSIONS: Lactobacillus curvatus CRL705 and the produced bacteriocins, lactocin 705 and lactocin AL 705, were effective in inhibiting L. innocua and B. thermosphacta. The use of the bioprotective culture in refrigerated vacuum-packaged fresh meat would be more feasible from an economic and legal point of view. SIGNIFICANCE AND IMPACT OF THE STUDY: Establishment of biopreservation as a method to ensure the microbiological safety of vacuum-packaged fresh meat at 2 degrees C.

Anti-Bacterial Agents↗
PubMed1994

Purification and cloning of sakacin 674, a bacteriocin from Lactobacillus sake Lb674.

Sakacin 674, a bacteriocin produced by Lactobacillus sake Lb764 and which inhibits the growth of Listeria monocytogenes, was purified to homogeneity by ammonium sulphate precipitation and sequential ion exchange, hydrophobic interaction and reversed phase chromatography. The complete amino acid sequence of sakacin 674 was determined by Edman degradation. The bacteriocin consisted of 43 amino acid residues and had a calculated molecular mass of 4436.6 Da, which is in good agreement with the molecular mass of 4437.2 as determined by mass spectrometry. The structural gene encoding sakacin 674 (sakR) was located on the chromosome. This gene was cloned and sequenced. It encoded a primary translation product of 61 amino acid residues which was cleaved between amino acids 18 and 19 to yield the active sakacin 674. Sakacin 674 resembled other known bacteriocins and was very similar to sakacin P.

Amino Acid Sequence↗
PubMed2000

Streptococcus mutans strain N produces a novel low molecular mass non-lantibiotic bacteriocin.

Streptococcus mutans strain N was shown to have bacteriocin production and immunity characteristics consistent with those of Group I mutacin-producing strains of S. mutans. The bacteriocin mutacin N was purified from agar cultures of S. mutans strain N using XAD andp6 reversed phase chromatography. The molecular mass of mutacin N was 4806 Da and the entire 49 amino acid sequence was determined by N-terminal sequencing. Database searches indicate that mutacin N is a novel bacteriocin, but with some homology to the protein IIC domain of a hypothetical sugar-phosphotransferase enzyme from Acholeplasma florum.

Amino Acid Sequence↗
PubMed2000

Identification and nucleotide sequence of genes involved in the synthesis of lactocin 705, a two-peptide bacteriocin from Lactobacillus casei CRL 705.

The structural gene determinants of lactocin 705, a bacteriocin produced by Lactobacillus casei CRL 705, have been amplified from a plasmid of approximately 35 kb and sequenced. Lactocin 705 is a class IIb bacteriocin, whose activity depends upon the complementation of two peptides (705alpha and 705beta) of 33 amino acid residues each. These peptides are synthesized as precursors with signal sequences of the double-glycine type, which exhibited high identities with the leader peptides of plantaricin S and J from Lactobacillus plantarum, brochocin C from Brochotrix campestris, sakacin P from Lactobacillus sake, and the competence stimulating peptides from Streptococcus gordonii and Streptococcus mitis. However, the two mature bacteriocins 705alpha and 705beta do not show significant similarity to other sequences in the databases.

Amino Acid Sequence↗
PubMed1990

Epidemiological application of a new bacteriocin typing scheme for Streptococcus mutans.

We propose a new bacteriocin typing scheme for Streptococcus mutans (Biotype I) using nine producer strains and a numerical code with three figures. Its application in 75 unrelated S. mutans strains allowed us to type all microorganisms and to obtain a total of 15 bacteriocin types. Its epidemiological use in two family groups allowed us to obtain two bacteriocin types in each one and to show the type relations between the different family components.

Adolescent↗
PubMed1984

Inhibitory spectrum of bacteriocin-like agents from Neisseria meningitidis.

Bacteriocin-like agents from five strains of Neisseria meningitidis were active against other meningococci and some other Neisseria species. Meningococci belonging to the same serogroup or serotype could be subdivided into distinct bacteriocin types. Insensitivity to the inhibitory agents was observed more frequently among serologically groupable strains than among non-groupable. Strains belonging to serogroup B were more often insensitive to the inhibitors released by four of the donor strains (P201, P213, P241, 99/79) than other groupable strains. Insensitivity to the bacteriocin-like activity of the fifth donor strain (77/79A) seemed to be evenly distributed among strains of different groups. Strains of serotype 15 were more often insensitive to the five inhibitors than strains belonging to other types. Group B and type 15 are most frequently observed among strains isolated from clinical cases in Norway.

Bacteriocins↗