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PubMed2006

Bacteriocins Pep5 and epidermin inhibit Staphylococcus epidermidis adhesion to catheters.

Pep5 and epidermin bacteriocins were tested on clinical strains of Staphylococcus epidermidis and S. aureus isolated from catheter-related infections. These bacteriocins were inhibitory to several isolates at a concentration of 640 activity units mL(-1). The ability of bacteriocins in inhibiting adhesion of S. epidermidis to silicone catheters was evaluated. When Pep5 and epidermin were added to in vitro catheter colonization experiments, there was a significant decrease in the cell number of S. epidermidis adhered to silicone catheters. Bacteriocins used to decrease bacterial attachment to medical devices may represent a novel strategy to control catheter-related infections.

Anti-Bacterial Agents↗
PubMed2005

Purification and characterization of Warnericin RB4, anti-Alicyclobacillus bacteriocin, produced by Staphylococcus warneri RB4.

In this study we characterized a bacteriocin, warnericin RB4, produced by Staphylococcus warneri RB4. Warnericin RB4 activity was completely inactivated by trypsin and actinase E. The activity was stable at 100 degrees C for 15 min, and had a pH range of 2 to 6. S. warneri RB4 showed antibacterial activity against only Alicyclobacillus acidoterrestris, A. acidocaldarius, and Micrococcus luteus, among 34 bacterial species tested. The amino acid sequence of the purified bacteriocin contained 27 amino acid residues (K-K-K-S-G-V-I-P-X-V-X-H-D-X-H-M-N-X-F-Q-F-V-F-X-X-X-S). The molecular mass of the bacteriocin was estimated to be 2,958.2 Da by ESI-MS. These results show that the Warnericin RB4 exhibiting specific antibacterial activity against thermo-acidophiles, Alicyclobacillus spp., is a Nukacin ISK-1 or closely related bacteriocin, classified with class IA (Lacticin 481 types). This is the first report that Warnericin RB-4 is effective to inhibit the growth of causative microorganisms of spoilage in various acidic drinks. Warnericin RB4 might prove useful in fruit juices and fruit juice-containing drinks.

Anti-Bacterial Agents↗
PubMed2005

Thermophilin 110: a bacteriocin of Streptococcus thermophilus ST110.

A screen of thermophilic lactic acid bacteria identified Streptococcus thermophilus strain ST110 as the putative producer of a bacteriocin with high level of activity against pediococci. Thermophilin 110 was isolated from culture supernatant after 16 h of growth and partially purified by a chloroform extraction procedure. The bacteriocin inhibited the growth of several lactic acid bacteria and in the case of Pediococcus acidilactici, it induced cell lysis with the concomitant release of OD260-absorbing material and intracellular enzymes. SDS-PAGE analysis revealed two components with estimated sizes between 4.0 kDa and 4.5 kDa, respectively, with possible involvement in bacteriocin activity as indicated by agar overlay assays with P. acidilactici as the target organism. Thermophilin 110 was inactivated by several proteolytic enzymes and also by alpha-amylase, which indicated the putative requirement of a glycosidic component for activity. The bacteriocin produced by S. thermophilus may be especially useful in the food processing industries to control spoilage caused by pediococci.

Anti-Bacterial Agents↗
PubMed2006

Comparison of bacteriocins produced by lactic-acid bacteria isolated from boza, a cereal-based fermented beverage from the Balkan Peninsula.

Boza is a low-pH and low-alcohol cereal-based beverage produced in the Balkan Peninsula. From a total population of 9 x 10(6) colony-forming units ml(-1), four isolates (JW3BZ, JW6BZ, JW11BZ, and JW15BZ) produced bacteriocins active against a broad spectrum of Gram-positive bacteria. Bacteriocin JW15BZ inhibited the growth of Klebsiella pneumoniae. The producer strains were identified as Lactobacillus plantarum (strains JW3BZ and JW6BZ) and L. fermentum (strains JW11BZ and JW15BZ). The spectrum of antimicrobial activity, characteristics, and mode of action of these bacteriocins were compared with bacteriocins previously described for lactic-acid bacteria isolated from boza.

Anti-Bacterial Agents↗
PubMed2000

Natural variation in susceptibility of Listeria strains to class IIa bacteriocins.

Thirty-one Listeria strains were tested for sensitivity to four class IIa bacteriocins, namely, enterocin A, mesentericin Y105, divercin V41, and pediocin AcH, and to nisin A. Class IIa bacteriocins displayed surprisingly similar antimicrobial patterns ranging from highly susceptible to fully resistant strains, whereas nisin A showed a different pattern in which all Listeria strains were inhibited. Particularly, it was observed that the strain Listeria monocytogenes V7 could not be inhibited by any of the class lIa bacteriocins tested. These observations suggest that Listeria strains resistant to the whole range of class IIa bacteriocins may occur in natural environments, which could be of great concern with regard to the use of these peptides as food preservatives.

Bacteriocins↗
PubMed2000

The rpoN gene of Enterococcus faecalis directs sensitivity to subclass IIa bacteriocins.

The final sigma 54 factor has been previously described to be involved in Listeria monocytogenes sensitivity to mesentericin Y105, a subclass IIa bacteriocin. Here, we identified the rpoN gene, encoding final sigma 54, of Enterococcus faecalis JH2-2 and showed that its interruption leads to E. faecalis resistance to different subclass IIa bacteriocins. Moreover, this rpoN mutant remained sensitive to nisin, a class I bacteriocin, suggesting that final sigma 54 is especially involved in sensitivity to subclass IIa bacteriocins.

Bacteriocins↗
PubMed2001

Influence of physico-chemical factors on the oligomerization and biological activity of bacteriocin AS-48.

Bacteriocin AS-48 forms a mixture of monomers and oligomers in aqueous solutions. Such oligomers can be clearly differentiated by SDS-PAGE after formaldehyde crosslinking, and we have verified that these associates are stable to acid treatment after fixation. In addition, they show antimicrobial activity and are recognized by anti-AS-48 antibodies. AS-48 oligomers can be dissociated by the detergents SDS and Triton X-100. The degree of oligomerization of AS-48 depends on the pH of the solution and the protein concentration. At pH below 5, AS-48 is in the monomeric state at protein concentrations below 0.55.mg ml(-1), but it also forms dimers above this protein concentration. This bacteriocin forms oligomers at pH values above 5, in agreement with the observation that it is also more hydrophobic at neutral pH. AS-48 is stable to mild heat treatments irrespectively of pH. At 120 degrees C it is more heat resistant under acidic conditions, but it inactivates at neutral pH. Activity of AS-48 against E. faecalis is highest at neutral pH, but it is highest at pH 4 for E. coli. The influence of pH on bacteriocin activity could be owing to changes in the conformation/oligomerization of the bacteriocin peptide as well as to changes in the surface charge of the target bacteria.

Bacteriocins↗
PubMed2001

Classification and mode of action of membrane-active bacteriocins produced by gram-positive bacteria.

Bacteriocins are ribosomally synthesized antimicrobial peptides produced by microorganisms belonging to different eubacterial taxonomic branches. Most of them are small cationic membrane-active compounds that form pores in the target cells, disrupting membrane potentials and causing cell death. The production of small cationic peptides with antibacterial activity is a defense strategy found not only in bacteria, but also in plants and animals. Bacteriocins are classified according to different criteria by different authors; in this review, we will summarize the principal bacteriocin classifications, highlight their main physical and chemical characteristics, and describe the mechanism of some selected bacteriocins that act at the membrane level.

Bacteriocins↗
PubMed1992

Identification and characterization of two bacteriocin-producing strains of Lactococcus lactis isolated from vegetables.

Isolated from mixed salad and fermented carrots, 123 strains of lactic acid bacteria were screened for bacteriocin production. Two strains, D53 and 23, identified as Lactococcus lactis by DNA-DNA hybridizations, produced heat stable bacteriocins which were resistant to trypsin and pepsin, but were inactivated by alpha-chymotrypsin and proteinase K. The bacteriocins were active from pH 2 to 9 and inhibited species of Listeria, Lactobacillus, Lactococcus, Pediococcus, Leuconostoc, Carnobacterium, Bacillus and Staphylococcus. Strain D53 produced bacteriocin at pH values of 4.5-8.0 and from 10 to 37 degrees C.

Anti-Bacterial Agents↗
PubMed1993

Detection, identification and characterization of bacteriocin-producing lactic acid bacteria from retail food products.

Forty bacteriocin-producing (Bac+) lactic acid bacteria (LAB) were isolated from food samples purchased from retail supermarkets and local farms. Of the 40 Bac+ isolates, 18 were isolated from 85 food samples by enrichment (21% isolation rate) whereas eight were obtained from 63 samples by direct plating (13% isolation rate). By direct plating, Bac+ LAB were detected at levels up to 2.4 x 10(5) cfu/g in ready-to-eat meats. The Bac+ isolates were identified by carbohydrate fermentation patterns, SDS-PAGE protein patterns, and other biochemical characteristics; SDS-PAGE proved invaluable in identifying strains that could not be identified by other means. Differential inhibitory spectra against indicator microorganisms assisted in the identification of 19 unique Bac+ isolates. Bac+ LAB included Enterococcus faecalis, Lactobacillus curvatus, Lb. delbrueckii, Lb. plantarum, Lactococcus lactis, and Pediococcus acidilactici. Lb. curvatus (four strains) and Lc. lactis (nine strains) were the only isolates inhibitory to foodborne pathogens including Listeria monocytogenes, Bacillus cereus, Clostridium perfringens and Staphylococcus aureus. Some Lc. lactis isolates inhibited as many as nine Gram-positive genera. Lb. curvatus FS47 and FS65 grew to high cell densities and produced bacteriocin at 6 degrees C; however, Lc. lactis FS56 produced greater levels of bacteriocin at lower cell densities. The high incidence of Bac+ LAB detected in retail foods indicates that the public is consuming a wide variety of Bac+ LAB that occur as natural contaminants. These data suggest a greater role for bacteriocins as biopreservatives in food.

Animals↗
PubMed1994

Scanning electron microscopy of target cells and molecular weight determination of a bacteriocin produced by Lactococcus lactis D53.

A bacteriocin, lactococcin D53, from Lactococcus lactis strain D53 was partially purified by precipitation with ammonium sulfate and dialysis against deionized water, at which time it precipitated from solution. A native molecular weight was determined by gel filtration, where bacteriocin was detected in two fractions which were measured at 104 and 6.7 kDa. A molecular weight of 7.0 kDa under denaturing conditions was determined by Tricine-SDS-polyacrylamide gel electrophoresis. The molecular weight determinations implied that lactococcin D53 complexed with other macromolecules in its native state in solution. Scanning electron micrographs of Lactobacillus D17 target cells treated with lactococcin D53 showed considerable differences from untreated control cells. The bacteriocin-treated cells had rougher, more granular-looking outer surfaces than untreated cells, which appeared smooth. Counts of viable cells in buffer solution rapidly declined by about one log in target cells treated with bacteriocin.

Ammonium Sulfate↗
PubMed1988

Antibacterial activity of plantaricin SIK-83, a bacteriocin produced by Lactobacillus plantarum.

Lactobacillus plantarum SIK-83 produces a bacteriocin, designated plantaricin SIK-83, which inhibits 66 of 68 lactic acid bacteria from the genera Lactobacillus, Leuconostoc, Pediococcus and Streptococcus. A 500-fold dilution of L. plantarum SIK-83 MRS culture supernatant with phosphate buffer was sufficient to kill 10(5) cells/ml of Pediococcus pentosaceus within 120 s. The killing of a sensitive population followed exponential kinetics. It was shown that the bacteriocin binds specifically to sensitive cells but not to nonsensitive lactic acid bacteria, the producer strain or Gram-negative bacteria. Sensitive cells, after exposure to the bacteriocin, could be rescued by treatment with proteolytic enzymes. In buffer, plantaricin SIK-83 was adsorbed to the cell surface almost immediately, and morphological lesions were observed within 2 h after the cells were exposed to the bacteriocin. The lethal mode of action appeared to be due to damage to the cell membrane, resulting in cell lysis, which was detected by electron microscopy and by determination of released intracellular components.

Adsorption↗
PubMed1995

Utilization of the leucocin A export system in Leuconostoc gelidum for production of a Lactobacillus bacteriocin.

The lactacin F complex, composed of LafA and LafX peptides, is produced by Lactobacillus johnsonii VPI 11088 (ATCC 11506) and is active against various lactobacilli and Enterococcus faecalis. The genetic determinants encoding the lactacin F peptides, LafA and LafX, are organized in a chromosomal operon comprised of genes lafA, lafX, and ORFZ. The lactacin F operon was introduced into Leuconostoc (Lc.) gelidum UAL187-22 which produces leucocin A. Leucocin A, a plasmid-encoded bacteriocin, inhibits E. faecalis, Listeria monocytogenes, and other lactic acid bacteria. The culture supernatant of the Leuconostoc transformant containing the lactacin F operon inhibited both lactacin F-and leucocin A-sensitive indicators. Concurrent expression of both bacteriocins did not alter the production of native leucocin A. Additive inhibitory effects due to the presence of both bacteriocins were not observed. An isogenic derivative of UAL187-22, which has lost the leucocin-encoding plasmid, was unable to produce active lactacin F when transformed with the appropriate recombinant plasmid. The ability of Lc. gelidum UAL187-22 to produce lactacin F demonstrates that the export system for leucocin A is capable of producing both bacteriocins simultaneously.

Amino Acid Sequence↗
PubMed2005

Streptococcus rattus strain BHT produces both a class I two-component lantibiotic and a class II bacteriocin.

Streptococcus rattus strain BHT is a species representative and strong bacteriocin producer. Here we report that S. rattus BHT produces two quite different types of bacteriocin activity, named BHT-A and BHT-B. The two bacteriocins were purified and analysed for activity and by MALDI-TOF mass spectrophotometry. BHT-A was found to be a variant of the two-component lantibiotic, Smb. BHT-B is a non-modified 5195Da peptide with some similarity to the tryptophan-rich Staphylococcus aureus bacteriocin, aureocin A53. Six S. rattus and two S. mutans strains were found to contain both the BHT-A and BHT-B genetic loci.

Amino Acid Sequence↗
PubMed2004

Purification, characterization and amino acid sequencing of divergicin M35: a novel class IIa bacteriocin produced by Carnobacterium divergens M35.

Carnobacterium divergens M35, isolated from a commercial sample of frozen smoked mussels, produces a new bacteriocin, divergicin M35, a class IIa bacteriocin. Divergicin M35 is sensitive to pronase-E, alpha-chymotrypsin and proteinase K, but not to trypsin and withstands thermal treatments up to 121 degrees C for 30 min. Divergicin M35 was extracted from the culture supernatant of C. divergens M35 using an SP-Sepharose cation-exchange column, desalted and purified on a C18 Sep-Pack column and further purified by reverse phase-high pressure liquid chromatography. This procedure allowed the recovery of 10% of the bacteriocin present in the culture supernatant with purity higher than 99%. Divergicin M35 had a molecular mass of 4518.75 Da as determined by mass spectrometry, a pI value of 8.3 and positive net charge (+3). The amino acid sequence of divergicin M35 was found to consist of 43 amino acid with four cysteine residues (Cys10, 15, 25, 43) and showed 80.5% homology with divercin V41 (80.5%) and 80.0% with bavaricin MN. Divergicin M35 showed powerful antilisterial activity, especially against Listeria monocytogenes and was also active against carnobacteria but not against strains of Lactococcus, Lactobacillus, Enterococcus, Bifidobacteria and Escherichia. Divergicin M35 production began in late exponential phase and reached a maximum activity of 65,000 AU/ml in early stationary phase. Initial broth pH, Tween 80 and acetate did not affect C. divergens M35 growth or divergicin production. This bacteriocin may be a potential tool for inhibiting L. monocytogenes in seafood products that do not usually undergo an adequate heat treatment.

Amino Acid Sequence↗
PubMed2005

Characterization of a 3944 Da bacteriocin, produced by Enterococcus mundtii ST15, with activity against Gram-positive and Gram-negative bacteria.

Strain ST15, isolated from soy beans, and identified as Enterococcus mundtii, produces a 3944 Da bacteriocin that inhibits the growth of Lactobacillus sakei, Enterococcus faecalis, Bacillus cereus, Propionibacterium sp., Clostridium tyrobutyricum, Acinetobacter baumanii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus caprinus. Bacteriocin ST15 is inactivated by proteinase K, pronase, pepsin, protease and Triton X-114, but not when treated with catalase, alpha-amylase, Triton X-100, SDS, Tween 20, Tween 80, urea and EDTA. No change in activity was recorded after 2 h at pH values between 2.0 and 12.0, and after treatment at 100 degrees C for 90 min. Activity was, however, lost after treatment at 121 degrees C for 20 min. The mode of activity is bactericidal. The highest level of activity (51200 AU ml(-1)) was recorded when cells were grown in MRS broth, pH 6.5. Bacteriocin ST15 differs from other broad-spectrum bacteriocins described for Enterococcus spp. by being active against Gram-negative bacteria and by being smaller.

Adsorption↗
PubMed2005

Purification and characterisation of acidocin D20079, a bacteriocin produced by Lactobacillus acidophilus DSM 20079.

Bacteriocins are natural antimicrobial agents produced by food fermentative bacteria. Lactobacillus acidophilus DSM 20079 produces a small bacteriocin, with a molecular mass of 6.6 kDa, designated acidocin D20079. This antimicrobial peptide was extremely heat-stable (30 min at 121 degrees C) and was active over a wide pH range. It was found to be sensitive to proteolytic enzymes (trypsin, ficin, pepsin, papain, and proteinase K). Acidocin D20079 has a narrow inhibitory spectrum restricted to the genus Lactobacillus which includes L. sakei NCDO 2714, an organism known to cause anaerobic spoilage of vacuum-packaged meat. Maximum production of acidocin D20079 in MRS broth was detected at pH 6.0, and the peptide was purified by ammonium sulphate precipitation followed by sequential cation exchange and hydrophobic interaction chromatography. Purified acidocin D20079 spontaneously formed spherulite crystals during dialysis. As the N-terminus was found to be blocked for sequencing, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was used to determine a partial sequence, and the molecular mass of the bacteriocin in the formed crystals (6.6 kDa). Estimates of the molecular weight of the partially purified peptide, using tricine-SDS-PAGE, in which bacteriocin activity was confirmed by overlayer techniques were in accordance with this value.

Amino Acid Sequence↗
PubMed2006

Molecular analysis of the 21-kb bacteriocin-encoding plasmid pEF1 from Enterococcus faecium 6T1a.

The complete 21,344-bp DNA sequence of the bacteriocin-encoding plasmid pEF1 from Enterococcus faecium 6T1a was determined. Thirty-four putative open reading frames which could code for proteins longer than 42 amino acids were found. Those included the structural genes encoding for the previously described bacteriocins enterocin I and J (also named as enterocins L50A and L50B). After comparison to sequences in public databases, analysis of the gene organization of pEF1 suggests a modular structure with three different functional domains: the replication region, the bacteriocin region and the mobilization plus UV-resistance region. This genetic mosaic structure most probably evolved through recombination events promoted by transposable elements. The hypothesis that the bacteriocin cluster on pEF1 could act as a functional plasmid stabilization module in E. faecium 6T1a is discussed.

Amino Acid Sequence↗