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At least 343 records · Page 19Linked to original sources
PubMed1991

Characterization of leucocin A-UAL 187 and cloning of the bacteriocin gene from Leuconostoc gelidum.

Leucocin A-UAL 187 is a bacteriocin produced by Leuconostoc gelidum UAL 187, a lactic acid bacterium isolated from vacuum-packaged meat. The bacteriocin was purified by ammonium sulfate or acid (pH 2.5) precipitation, hydrophobic interaction chromatography, gel filtration, and reversed-phase high-performance liquid chromatography with a yield of 58% of the original activity. Leucocin A is stable at low pH and heat resistant, and the activity of the pure form is enhanced by the addition of bovine serum albumin. It is inactivated by a range of proteolytic enzymes. The molecular weight was determined by mass spectrometry to be 3,930.3 +/- 0.4. Leucocin A-UAL 187 contains 37 amino acids with a calculated molecular weight of 3,932.3. A mixed oligonucleotide (24-mer) homologous to the sequence of the already known N terminus of the bacteriocin hybridized to a 2.9-kb HpaII fragment of a 7.6-MDa plasmid from the producer strain. The fragment was cloned into pUC118 and then subcloned into a lactococcal shuttle vector, pNZ19. DNA sequencing revealed an operon consisting of a putative upstream promoter, a downstream terminator, and two open reading frames flanked by a putative upstream promoter and a downstream terminator. The first open reading frame downstream of the promoter contains 61 amino acids and is identified as the leucocin structural gene, consisting of a 37-amino-acid bacteriocin and a 24-residue N-terminal extension. No phenotypic expression of the bacteriocin was evident in several lactic acid bacteria that were electrotransformed with pNZ19 containing the 2.9-kb cloned fragment of the leucocin A plasmid.

Amino Acid Sequence↗
PubMed1996

Cloning and genetic organization of the bacteriocin 31 determinant encoded on the Enterococcus faecalis pheromone-responsive conjugative plasmid pYI17.

The conjugative plasmid pYI17 (57.5 kb) isolated from Enterococcus faecalis YI717 confers a pheromone response on the host and encodes the bacteriocin 31 gene. Bacteriocin 31 is active against E. hirae 9790, E. faecium, and Listeria monocytogenes. pYI17 was mapped physically by restriction enzyme analysis and the relational clone method. Deletion mutant and sequence analyses of the EcoRI fragment B cloned from pYl17 revealed that a 1.0-kb fragment contained the bacteriocin gene (bacA) and an immunity gene (bacB). This fragment induced bacteriocin activity in E. faecalis OG1X and E. hirae 9790. The bacA gene is located on the pYI17 physical map between 3.37 and 3.57 kb, and bacB is located between 3.59 kb and 3.87 kb, bacA encodes 67 amino acids, and bacB encodes 94 amino acids. The deduced amino acid sequence of the bacA protein contained a series of hydrophobic residues typical of a signal sequence at its amino terminus. The predicted mature bacA protein (43 amino acids) showed sequence homology with the membrane-active class II bacteriocins of lactic acid bacteria. Analysis of Tn5 insertion mutants and the resulting transcripts indicated that these genes are transcribed as an operon composed of bacA, bacB, and an open reading frame located downstream of bacB designated ORF3.

Amino Acid Sequence↗
PubMed1981

Bacteriocins as tools in analysis of nosocomial Klebsiella pneumoniae infections.

Epidemiological analysis of isolates from nosocomial infections caused by Klebsiella pneumoniae was improved by the use of bacteriocins in addition to capsular serotyping. Screening for bacteriocins produced by 77 reference strains for capsular serotyping identified 39 strains, and 8 of these strains were selected as a typing set. Using this set, we found that 241 to 259 (91%) nonepidemic clinical isolates of K. pneumoniae were inhibited by one or more of the eight producers. Of the most frequent bacteriocin type there were 31 examples (12%). High reproducibility of typing patterns (83.3%) and easy practicability of typing were achieved with a streak-and-point method avoiding the use of suspensions of bacteriocins and the risk of instability. The Klebsiella bacteriocins were active also on Enterobacter and Shigella species and on Escherichia coli strains, but were ineffective on other Enterobacteriacae.

Bacteriocins↗
PubMed1976

Studies on mode of action of a bacteriocin from Clostridium septicum.

A bacteriocin was found in the supernatant fluid of Clostridium septicum strain Ovinus. Sensitivity to the bacteriocin was confined to other strains of C. septicum and to strains of C. chauvoei; the other Gram-positive and Gram-negative bacteria tested for sensitivity were unaffected by the bacteriocin. The bacteriocin killed sensitive cells rapidly but cell lysis did not appear to be involved. The bacteriocin inhibited protein and RNA synthesis immediately after its addition to sensitive cells; DNA synthesis was inhibited 10 min later.

Bacteria↗
PubMed1976

Bacteriocins of Streptococcus bovis.

Forty-seven strains of Streptococcus bovis were tested for bacteriocin production. Fourteen were found to produce bacteriocins, while all 47 were sensitive to at least one of these bacteriocins. The bacteriocins, on the basis of their host range on S. bovis strains, formed six groups. A representative of each group was selected and characterized by temperature stability, sensitivity to trypsin and lipase, sedimentation by centrifugation, ability to pass through dialysis tubing, host range on other bacterial species, and conditions for production in liquid media. A correlation between mannitol fermentation and bacteriocin production was noted.

Bacteriocins↗
PubMed2003

Butyrivibriocin AR10, a new cyclic bacteriocin produced by the ruminal anaerobe Butyrivibrio fibrisolvens AR10: characterization of the gene and peptide.

The gene (bviA) encoding the ruminal bacteriocin butyrivibriocin AR10 was cloned from an EcoRI library by using an oligonucleotide probe based on a partial peptide sequence of the previously isolated peptide. The gene encoded an 80 amino acid prebacteriocin that demonstrated significant identity with the cyclic bacteriocin gassericin A. Negative ion time of flight mass spectroscopic analysis (ESI/MS) indicated a mass of 5981.5 Da for the isolated bacteriocin, a molecular mass that could not be generated by removal of a leader peptide alone. However, an N- to C-terminal cyclization of the predicted mature bacteriocin resulted in a peptide that conformed to the determined mass and charge characteristics. Northern blotting confirmed that expression of bviA mirrored the production of the bacteriocin in both liquid and solid media.

Amino Acid Sequence↗
PubMed2006

Plasmid content and bacteriocin production by five strains of Lactococcus lactis isolated from semi-hard homemade cheese.

In this study, the plasmid content and bacteriocin production of natural isolates of lactococci were investigated. Five bacteriocin producing lactococcal strains (Lactococcus lactis subsp. lactis BGMN1-2, BGMN1-3, BGMN1-5, BGMN1-6, and BGMN2-7) were isolated as nonstarter microflora of semi-hard homemade cheese and characterized. All isolates contained a number of plasmids. It was shown that lcnB structural genes for bacteriocin lactococcin B were located on large plasmids in all isolates. In the strains BGMN1-3 and BGMN1-5 proteinase prtP genes collocated with lcnB. Furthermore, these strains produced two additional bacteriocins (LsbA and LsbB) with genes responsible for their production and immunity located on the small rolling circle-replicating plasmid pMN5. Using deletion experiments of pMN5, minimal replicon of the plasmid and involvement of a bacteriocin locus in plasmid maintenance were identified. In addition, plasmid curing experiments showed that genes for catabolism or transport of 10 carbohydrates in the strain BGMN1-5 were plasmid located.

Bacteriocins↗
PubMed2000

Primary amino acid and DNA sequences of gassericin T, a lactacin F-family bacteriocin produced by Lactobacillus gasseri SBT2055.

A broad-spectral bacteriocin, named gassericin T, produced by Lactobacillus gasseri SBT 2055 (from human feces) was isolated to homogeneity from the culture supernatant by hydrophobic chromatography. By SDS-PAGE and in situ activity assay, the purified gassericin T migrated as a single band with bacteriocin activity and molecular size of 5,400. A 2.9-kbp HindIII-HindIII fragment of chromosome DNA was hybridized with the oligonucleotide probe designed from the partial N-terminal amino acid sequence of gassericin T and was cloned. Six ORFs including the structural gene of gassericin T were deduced by computer analysis and the data bases. The structural gene of gassericin T (gatA) was identified as the fourth ORF, which encoded a protein composed of 75 amino acids that included the GG motif of the cleavage site. Chemical sequencing analysis of the complete amino acid sequence showed that gassericin T (57 amino acids) had a disulfide bond in the molecule and no modified amino acid residues, making it a class II bacteriocin. The gassericin T had 60% sequence similarity to mature LafA (57 amino acids, lactacin F, bacteriocins produced by L. johnsonii VPI11088), and the sequences around the processing site and C-terminal area were well conserved. The fifth ORF was designated as gatX, encoded as a peptide composed of 65 amino acids containing the GG motif of the putative cleavage site, however mature GatX and its antibacterial activity were not detected in the culture supernatant. GatX has higher similarity with LafX than with lactobin A (50 amino acids) belonging to the first lactacin F-family. These results indicated that gassericin T belongs to the hydrophobic class II bacteriocins and the most vicinal lactacin F-family.

Amino Acid Sequence↗
PubMed1991

Isolation and purification of bacteriocin from Prevotella intermedia (Bacteroides intermedius).

Thirty-three out of 46 strains of Prevotella intermedia (Bacteroides intermedius) isolated from gingival deposits of patients with adult periodontitis possessed the ability to inhibit growth of P. intermedia strain ATCC 25611, and 6 of the 33 showed strong inhibitory activity. Thirteen isolates did not have the ability to inhibit the growth of P. intermedia strain ATCC 25611. An inhibition factor from one of the isolates, P. intermedia TH14 which had strong inhibition, was purified and characterized. Bacteriocin TH14 activity was effective against only P. intermedia ATCC 25611 and Fusobacterium nucleatum, but not against other crevicular bacteria, including P. intermedia ATCC 33563, Porphyromonas gingivalis (Bacteroides gingivalis), Capnocytophaga sputigena and Actinobacillus actinomycetemcomitans. Streptococci, actinomyces, and veillonellas were not inhibited by bacteriocin TH14. Bacteriocin TH14 was heat sensitive, proteinaceous with molecular weight of 1,700 daltons and inhibited the growth of strain ATCC 25611 in 15 minutes. The growth inhibition of P. intermedia ATCC 25611 by bacteriocin TH14 was found to be due to the bactericidal activity of the bacteriocin.

Adult↗
PubMed2006

Searching for bacteriocin-producing lactic acid bacteria in soil.

A survey was conducted on the isolation and characterization of bacteriocin-producing lactic acid bacteria in soil. Forty-two acid-producing bacterial strains were isolated from 55 soil samples collected in Yamanashi prefecture, Japan. Investigation of antibacterial activities of isolates revealed that three isolates, Lactobacillus animalis C060203, Enterococcus durans C102901 and Leuconostoc mesenteroides subsp. mesenteroides C060204, showed antibacterial activities against the indicator strain of Lactobacillus sakei JCM 1157T. Bacteriocin from Enterococcus durans C102901 showed different characteristics from the known durancin L28-1A, produced by Enterococcus durans L28-1. Furthermore, this is the first report of a bacteriocin being produced by Lactobacillus animalis. Viewing from the species, bacteriocins from strains C102901 and C060203 showed high possibilities for the novel substances. These significant findings suggest that soil may be a common source for the isolation of novel bacteriocin-producing lactic acid bacteria.

Anti-Bacterial Agents↗
PubMed2003

Streptococcus thermophilus 580 produces a bacteriocin potentially suitable for inhibition of Clostridium tyrobutyricum in hard cheese.

A strain of Streptococcus thermophilus that inhibits Clostridium tyrobutyricum has been isolated from raw milk. The active compound produced disappears after a treatment with protease. However, unlike most bacteriocins, it is not thermoresistant, and the activity is completely lost after 1 h at 60 degrees C. Its inhibitory spectrum is limited to other thermophilic streptococci, Brochothrix, and sporulated gram-positive rods. So this bacteriocin could be different from those already described. This bacteriocin-producing strain could be used in thermophilic starter for hard cheese making because the bacteriocin is not active against thermophilic lactobacilli. It is produced in M17 medium during the decreasing temperature phase of the hard cheese-making process temperature cycle and is also produced in milk. Moreover, when Streptococcus thermophilus was cocultured with a Lactobacillus delbrueckii subsp. lactis starter strain, it seems to enhance the bacteriocin production. However the level of activity always decreases drastically during the stationary phase. But inhibition of Clostridium tyrobutyricum spores can be obtained in small-scale curds.

Animals↗
PubMed2006

Effect of high-pressure treatment and a bacteriocin-producing lactic culture on the proteolysis, texture, and taste of Hispánico cheese.

The effects of high-pressure treatment, by itself or in combination with a bacteriocin-producing culture added to milk, on the proteolysis, texture, and taste of Hispánico cheese were investigated. Two vats of cheese were manufactured from a mixture of cow and ewe milk. Milk in one vat was inoculated with 0.5% Lactococcus lactis ssp. lactis INIA 415, a nisin Z and lacticin 481 producer; 0.5% L. lactis ssp. lactis INIA 415-2, a bacteriocin-nonproducing mutant; and 2% of a commercial Streptococcus thermophilus culture. Milk in the other vat was inoculated with 1% L. lactis ssp. lactis INIA 415-2 and 2% S. thermophilus culture. After ripening for 15 d at 12 degrees C, half of the cheeses from each vat were treated at 400 MPa for 5 min at 10 degrees C. Ripening of high-pressure-treated and untreated cheeses continued at 12 degrees C until d 50. High-pressure treatment of cheese made from milk without the bacteriocin producer accelerated casein degradation and increased the free AA content, but it did not significantly influence the taste quality or taste intensity of the cheese. Addition of the bacteriocin producer to milk lowered the ratio of hydrophobic peptides to hydrophilic peptides, increased the free AA content, and enhanced the taste intensity. The combination of milk inoculation with the bacteriocin producer and high-pressure treatment of the cheese resulted in higher levels of both hydrophobic and hydrophilic peptides but had no significant effect on the free AA content, taste quality, or taste intensity.

Amino Acids↗
PubMed2002

Behavior of Listeria monocytogenes and Staphylococcus aureus in yogurt fermented with a bacteriocin-producing thermophilic starter.

Streptococcus salivarius subsp. thermophilus B producing a bacteriocin active against Listeria monocytogenes ATCC 7644 and Staphylococcus aureus SAD 30 was isolated from bakery yeast. The bacteriocin was partially purified by an adsorption/desorption technique, and its spectrum of action was compared to that of a neutralized cell-free supernatant (CFS). Although the CFS inhibited a number of gram-positive and -negative bacteria of health and spoilage significance, the spectrum of action of the partially purified bacteriocin was limited to gram-positive bacteria. L. monocytogenes was the most sensitive to both preparations. The bacteriocin-producing streptococcal strain was used in combination with a Bac- Lactobacillus delbrueckii subsp. bulgaricus CY strain isolated from commercial yogurt to assess the effectiveness of the resulting thermophilic starter in controlling L. monocytogenes and S. aureus in yogurt during fermentation and storage at refrigeration (ca. 7 degrees C) or abuse (ca. 22 degrees C) temperature. Yogurt samples were contaminated with L. monocytogenes or S. aureus to the approximate levels of 10(3) and 10(6) CFU/ml of milk, respectively. The results showed that in situ bacteriocin production was more active against L. monocytogenes than against S. aureus in vitro and in contaminated samples. While L. monocytogenes leveled off below the detectable limit in a 1-ml sample of yogurt within 24 h of processing, S. aureus survived in Bac+ and Bac- samples during 10 days of storage at room temperature (ca. 22 degrees C). Use of a Bac+ starter resulted in a 5-day extension of the shelf life.

Bacteriocins↗
PubMed2003

Antagonism of Helicobacter pylori by bacteriocins of lactic acid bacteria.

Antimicrobial activity of seven bacteriocins produced by lactic acid bacteria against Helicobacter pylori strains (ATCC 43504, Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH [DSM] 4867, DSM 9691, and DSM 10242) was investigated in vitro using a broth microdilution assay. The bacteriocins chosen for the study were nisin A; lacticins A164, BH5, JW3, and NK24; pediocin PO2; and leucocin K. Antimicrobial activity of the bacteriocins varied among the H. pylori strains tested, of which strain ATCC 43504 was the most tolerant. Among the bacteriocins tested, lacticins A164 and BH5 produced by Lactococcus lactis subsp. lactis A164 and L. lactis BH5, respectively, showed the strongest antibacterial activity against H. pylori strains. MICs of the lacticins against H. pylori strains, when assessed by the critical dilution micromethod, ranged from 0.097 to 0.390 mg/liter (DSM strains) or from 12.5 to 25 mg/liter (ATCC 43504), supporting the strain-dependent sensitivity of the pathogen. Pediocin PO2 was less active than the lacticins against four strains of H. pylori, and leucocin K was the least active peptide, with no inhibition toward H. pylori ATCC 43504. Anti-Helicobacter activity of lacticin A164 was dependent on initial inoculum size as well as concentration of the bacteriocin added.

Antibiosis↗
PubMed2005

Isolation of Bacillus circulans and Paenibacillus polymyxa strains inhibitory to Campylobacter jejuni and characterization of associated bacteriocins.

We evaluated anti-Campylobacter activity among 365 Bacillus and Paenibacillus isolates from poultry production environments. One novel antagonistic Bacillus circulans and three Paenibacillus polymyxa strains were identified and further studied. Cell-free ammonium sulfate precipitate (crude antimicrobial preparation) was obtained from each candidate culture. Zones of Campylobacter growth inhibition surrounding 10 microl of this crude antimicrobial preparation were quantified using a spot test. Campylobacter growth resumed when the preparation was preincubated with selected protease enzymes, demonstrating peptide characteristics consistent with a bacteriocin. These peptides were further purified using combinations of molecular mass resolution and ion exchange chromatography. Molecular masses of the peptides were estimated at approximately 3,500 Da by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectric focusing was used to determine the pI values of the peptides. Amino acid sequences of the bacteriocins and more precise molecular masses were obtained by matrix-assisted laser desorption and ionization-time of flight (MALDI-TOF) analysis. The bacteriocin from P. polymyxa NRRL B-30507 had a pI of 4.8, that from P. polymyxa NRRL B-30509 had a pI of 7.2, that from P. polymyxa NRRL B-30508 had a pI of 4.8, and that from B. circulans NRRL B-30644 had a pI of 7.8. The amino acid sequences were consistent with those of class IIa bacteriocins. These antagonists and the corresponding bacteriocins may be useful in the control of Campylobacter infection in poultry.

Amino Acid Sequence↗
PubMed1999

Antagonistic activity of bacteriocin produced by Lactobacillus species from ogi, an indigenous fermented food.

Seven Lactobacillus species each with one or more strains were isolated from various fermented cereal gruel's (ogi). They were identified as L. plantarum (3 strains), L. delbrueckii (1 strain), L. brevis (2 strains), L. reuteri (2 strains), L. casei (1 strain), L. fermentum (1 strain) and L. acidophilus (1 strain). Bacteriocin production was observed in cell-free supernatants of 8 of these strains with L. fermentum, L. delbrueckii and L. reuteri strains (white maize ogi) being negative. The bacteriocin produced by the eight strains inhibited the growth of various target organisms with the inhibition strongly noticed using Enterococcus faecalis as indicator. While catalase treatment, pH changes and heat treatment up to 80 degrees C had no effect on the activity of bacteriocin from these isolates, treatment with trypsin and proteinase K resulted in complete loss of inhibitory activity of the bacteriocins. A reduction in the inhibitory activity of the bacteriocins was also found to occur with increasing concentrations of glucose or peptone in the cultivation medium.

Bacteriocins↗
PubMed1999

Expanded bed adsorption as a unique unit operation for the isolation of bacteriocins from fermentation media.

Expanded bed adsorption using a strong cation exchanger allowed the direct isolation of amylovorin L471, a bacteriocin from Lactobacillus amylovorus DCE 471, from the fermentation medium. The pH of the loading and elution buffer were optimised in a packed bed with cell-free culture supernatant. Bound bacteriocin was eluted with 1.0 M NaCl. The highest recovery (30%) was obtained at the lowest pH (3.6). At higher pH values the recovery was lower, namely 12%, 15% and 7% at pH 4.5, 6.5 and 8.0, respectively. In expanded bed mode, direct isolation of the bacteriocin from the fermentation medium at pH 3.6 (loading and elution) initially resulted in a recovery of 12%. After optimisation of the pH (loading and elution at pH 3.6 and 6.5, respectively), the recovery for amylovorin L471 increased up to 30% and higher. Recovery of enterocin A from Enterococcus faecium CTC 492 fermentation medium averaged 15% (loading and elution at pH 3.6 and 6.0, respectively). With pediocin, produced by Pediococcus acidilactici ATCC 8042, 26% recovery was obtained at a pH of 6.5 during loading and elution. Low recoveries can be ascribed to non-optimal operation conditions (pH of loading and elution buffer), inactivation of the bacteriocin on a cationic resin, and the formation of more insoluble and less active, strongly hydrophobic bacteriocin aggregates upon further purification.

Adsorption↗
PubMed2002

[Production of bacteriocins by gram-positive bacteria and the mechanisms of transcriptional regulation].

The mechanisms of production of bacteriocins in Gram-positive bacteria and the main distinctions of these bacteriocins from the bacteriocins of Gram-negative bacteria (colicins) are outlined. A classification of antibacterial peptides is presented, and most of known class I and II peptides are pointed out. In Gram-positive bacteria, the cases of bacteriocin-associated quorum sensing are examined. For these cases, the structure of loci containing the genes of regulatory systems, transport, immunity, processing, and posttranslational modification of antibacterial peptides are described. All known regulatory sites for class II bacteriocins are presented. A description of the putative regulatory sites found by us and their classification are provided. The evolutionary tree of transcriptional response regulators is shown to correspond to the tree of their recognition sites.

Bacteriocins↗