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PubMed2001

Nutritional factors affecting the production of two bacteriocins from lactic acid bacteria on whey.

The ability of Lactococcus lactis subsp. lactis CECT 539 and Pediococcus acidilactici NRRL B-5627 to produce bacteriocins on both diluted and concentrated whey was investigated in batch fermentations. Both strains produced the higher amounts of biomass and bacteriocin titres on diluted whey. Luedeking and Piret expression was able to model the production of nisin, which was produced as a primary metabolite on both culture media. However, the pediocin production could not be typified in any case due to the negligible growth of P. acidilactici. Although the whey supported the growth and bacteriocin production by the two strains, both biomass and bacteriocin productions were lower than those obtained on MRS broth. The effect of total sugar, nitrogen, phosphorous and buffer concentrations on the production of nisin and pediocin was studied in diluted whey using factorial experiments and empirical modelling. The production of nisin was greatly inhibited by the increase in nitrogen, buffer, and to a lesser extent, sugar concentration in the medium, nevertheless, the used phosphorous source produced a light stimulatory effect on bacteriocin synthesis. In addition, the growth of Lc 1.04 was mainly affected by the nitrogen source used. On the other hand, pediocin was inhibited by the increase in buffer, phosphorous, and to a lesser degree, by the sugar and nitrogen concentration. The inhibitory activity of pediocin disappeared almost totally after 15 min of treatment with trypsin, papain, subtilisin and pepsin. The activity of nisin was drastically reduced by treatment with trypsin, subtilisin and pepsin. Nevertheless, 50% of the initial activity was retained when nisin was treated with papain. Both bacteriocins showed the highest heat stability at acidic pH and short incubation times.

Bacteriocins↗
PubMed2004

Viability loss and morphology change of foodborne pathogens following exposure to hydrostatic pressures in the presence and absence of bacteriocins.

Cell suspensions of three pathogens were exposed to hydrostatic pressure (HP), bacteriocin mixture (nisin and pediocin) or a combination of HP+bacteriocins and changes in colony forming units (cfu) and cell-morphology by scanning electron microscopy (SEM) were studied. Cell viability loss, as determined from the reduction in cfu before and after a treatment, occurred in Listeria monocytogenes by all three treatments and in Salmonella typhimurium and Escherichia coli O157:H7 by HP and HP+bacteriocin combination. Cell wall and cell membrane collapse and cell lysis was indicated in L. monocytogenes exposed to bacteriocin or HP+bacteriocin and in Salmonella and E. coli exposed to HP or HP+bacteriocin.

Anti-Bacterial Agents↗
PubMed1998

Bacteriocin production and competitiveness of Lactobacillus plantarum LPCO10 in olive juice broth, a culture medium obtained from olives.

A culture medium, named olive juice broth, which resembles the natural environment of Lactobacillus plantarum in the traditional Spanish-style green olive fermentation was obtained from green olives. In this medium, the bacteriocin-producing L. plantarum LPCO10 strain was able to produce bacteriocin throughout the incubation time (15 days). Bacteriocin purification from olive juice broth was achieved by a protocol including ammonium sulphate precipitation of cell-free, L. plantarum LPCO10 culture supernatants, and cation-exchange, hydrophobic-interaction and reversed-phase chromatographies. In a series of mixed cultures in olive juice broth, L. plantarum LPCO10 was able to dominate the bacteriocin-sensitive L. plantarum 128/2 strain, whereas the non-bacteriocin-producing, LPCO10 strain derivative, L. plantarum 55-1 strain did not show such capability. These results indicated that olive juice broth may be a valuable experimental substitute for olive fermentation brine in gaining more knowledge about the role of the bacteriocin-producing L. plantarum strains in the control of the Spanish-style green olive fermentation.

Bacteriocins↗
PubMedDate not supplied

Mode of action of modified and unmodified bacteriocins from Gram-positive bacteria.

The antibiotic activity of bacteriocins from Gram-positive bacteria, whether they are modified (class I bacteriocins, lantibiotics) or unmodified (class II), is based on interaction with the bacterial membrane. However, recent work has demonstrated that for many bacteriocins, generalised membrane disruption models as elaborated for amphiphilic peptides (e.g. tyriodal pore or carpet model) cannot adequately describe the bactericidal action. Rather, specific targets seem to be involved in pore formation and other activities. For the nisin and epidermin family of lantibiotics, the membrane-bound cell wall precursor lipid II has recently been identified as target. The duramycin family of lantibiotics binds specifically to phosphoethanolamine which results in inhibition of phospholipase A2 and various other cellular functions. Most of the class II bacteriocins dissipate the proton motive force (PMF) of the target cell, via pore formation. The subclass IIa bacteriocin activity likely depends on a mannose permease of the phosphotransferase system (PTS) as specific target. The subclass IIb bacteriocins (two-component) also induce dissipation of the PMF by forming cation- or anion-specific pores; specific targets have not yet been identified. Finally, the subclass IIc comprises miscellaneous peptides with various modes of action such as membrane permeabilization, specific inhibition of septum formation and pheromone activity.

Amino Acid Sequence↗
PubMed2001

Proteolysis and formation of volatile compounds in cheese manufactured with a bacteriocin-producing adjunct culture.

Hispánico cheese, a semi-hard Spanish variety, was manufactured from a mixture of pasteurized cows' and ewes' milks (4:1) using a commercial mesophilic LD-type starter comprising Lactococcus lactis subsp. cremoris, Lc. lactis subsp. lactis, Lc. lactis subsp. lactis var diacetylactis and Leuconostoc mesenteroides subsp. cremoris. Varying amounts (0-1.0 g/kg) of an Enterococcus faecalis INIA 4 culture in milk were added as a bacteriocin-producing adjunct. Differences in pH between cheeses manufactured with and without the bacteriocin producer did not exceed 0.11 pH units. Starter lactococci lost viability more rapidly in cheeses made with the bacteriocin producer, which reached counts of up to 6 x 10(7) cfu/g during ripening. Aminopeptidase activity in 1-d-old cheese made from milk inoculated with 1.0 g bacteriocin-producing culture/kg was twice that in control cheese. Degrees of overall proteolysis and levels of total free amino acids in 45-d-old cheese made with 1.0 g bacteriocin-producing culture/kg were 1.80-fold and 2.17-fold those in control cheese of the same age. Inoculating milk with 1.0 g/kg bacteriocin-producing culture reduced the level of hydrophobic peptides in the resultant cheese, increased the concentrations of 3-methyl-1-butanal, diacetyl and acetoin, and resulted in the highest scores for flavour quality and flavour intensity throughout ripening.

Aminopeptidases↗
PubMed1985

The assessment and application of a bacteriocin typing scheme for Clostridium perfringens.

A collection of 50 bacteriocins was assembled and used to type 802 isolates of Clostridium perfringens from food poisoning outbreaks and a variety of other sources. It was found that strains of the same serotype within an outbreak showed similar patterns of susceptibility to bacteriocins, and the use of "one difference' rule is proposed for interpretation of the typing patterns of epidemiologically related strains. Isolates of different serotype or of the same serotype isolated from different sources produced many variations in bacteriocin susceptibility patterns. Two computer programs were developed to assist in the interpretation of bacteriocin typing patterns. Their use showed that related and unrelated strains formed different clusters and enabled a range of the 20 most discriminatory bacteriocins to be selected. Isolates of C. perfringens from a wide range of sources were screened for their ability to produce bacteriocins. A much greater proportion of the strains from food poisoning outbreaks was bacteriocinogenic than were isolates from human and animal infections, various foods and the environment. The relevance of these findings to the occurrence of C. perfringens food poisoning is discussed.

Bacteriocins↗
PubMed1998

Plantaricin A is an amphiphilic alpha-helical bacteriocin-like pheromone which exerts antimicrobial and pheromone activities through different mechanisms.

Production of bacteriocins by lactic acid bacteria is in some cases regulated by a quorum sensing mechanism that involves a secreted bacteriocin-like peptide pheromone. In the case of Lactobacillus plantarum C11, this pheromone, the 26-mer plantaricin A (PlnA), has the interesting property of having both bacteriocin and pheromone activities. To gain insight into how PlnA functions as a pheromone and as a bacteriocin, the L- and D-enantiomers of an N-terminally truncated form of PlnA were synthesized (PlnA-22L and PlnA-22D; PlnA-22L has full biological activity). With circular dichroism, it was shown that the two peptides are unstructured in aqueous solution, but they adopt mirror-image amphiphilic helical structures in the presence of trifluoroethanol and membrane-mimicking entities such as micelles of dodecylphosphocholine and negatively charged Ole2GroPGro liposomes, but not in the presence of zwitterionic Ole2GroPCho liposomes. Thus, the negative charge on the membrane is important for structuring of the (positively charged) PlnA peptides. In terms of in vivo antimicrobial activity, PlnA-22L and PlnA-22D behaved almost identically. Likewise, the peptides dissipated the membrane potential and the transmembrane pH gradient in sensitive cells equally effectively. PlnA-22L induced bacteriocin production in L. plantarum C11 (i.e., displayed pheromone activity), the level of induction being clearly dose-dependent. PlnA-22D did not display pheromone activity, but, at high concentrations, was able to inhibit the pheromone activity of PlnA-22L. The results indicate that the antimicrobial activity of PlnA does not require chiral interactions and is mediated through the formation of a strongly amphiphilic alpha-helical structure. In contrast, PlnA's pheromone activity is dependent on a chiral interaction between the amphiphilic helix (PlnA-22L) and a receptor protein. One may speculate that PlnA is an evolutionary intermediate between a true bacteriocin and a pheromone.

Amino Acid Sequence↗
PubMed2000

Preliminary characterization of bacteriocins produced by Enterococcus faecium and Enterococcus faecalis isolated from pig faeces.

A total of 92 enterococci, isolated from the faeces of minipigs subjected to an in vivo feeding trial, were screened for the production of antimicrobial substances. Bacteriocin production was confirmed for seven strains, of which four were identified as Enterococcus faecalis and three as Enterococcus faecium, on the basis of physiological and biochemical characteristics. The bacteriocins produced by the Ent. faecalis strains showed a narrow spectrum of activity, mainly against other Enterococcus spp., compared with those from the Ent. faecium strains showing a broader spectrum of activity, against indicator strains of Enterococcus spp., Listeria spp., Clostridium spp. and Propionibacterium spp. The bacteriocins of all seven Enterococcus strains were inactivated by alpha-chymotrypsin, proteinase K, trypsin, pronase, pepsin and papain, but not by lipase, lysozyme and catalase. The bacteriocins were heat stable and displayed highest activity at neutral pH. The molecular weight of the bacteriocins, as determined by tricine SDS-PAGE, was approximately 3.4 kDa. Only the strains of Ent. faecalis were found to contain plasmids. PCR detection revealed that the bacteriocins produced by Ent. faecium BFE 1170 and BFE 1228 were similar to enterocin A, whereas those produced by Ent. faecium BFE 1072 displayed homology with enterocin L50A and B.

Animals↗
PubMed1973

Group A streptococcal bacteriocin. Production, purification, and mode of action.

A bacteriocin, streptocin A, was isolated from the supernatant fluid of tryptic soy broth cultures of Group A streptococcus strain FF-22. Evidence was obtained which supports the view that the failure to recover active streptocin A after growth of the producer strain in certain fluid media is due to the inactivation of the bacteriocin by concomitantly synthesized streptococcal proteinase. The bacteriocin was purified 139-fold and the active product appeared to be of uniform size, having a molecular weight of approximately 8,000. Streptocin A was bactericidal, but not lytic, for a susceptible Group A streptococcus and the lethal effect was markedly temperature dependent. The bacteriocin inhibited the synthesis of DNA, RNA, and protein, and also prevented the uptake and incorporation of glucose by the sensitive cells. Degradation of RNA occurred, but appeared to be less than that produced by a staphylococcal bacteriocin. This effect may be due to differences in the killing potency of the two bacteriocins in preparations having similar inhibitory activity when measured by lawn culture assays.

Alanine↗
PubMed1980

Passive bacteriocin typing of strains of Clostridium perfringens type A causing food poisoning for epidemiologic studies.

A passive bacteriocin typing system was developed for use as an epidemiologic tool to study outbreaks of food poisoning caused by Clostridium perfringens type A. The 90 strains tested were from England, the United States, India, Japan, France, and Canada. Forty of 74 strains produced bacteriocin when irradiated with ultraviolet light for 40-90 sec. Eight bacteriocins were concentrated with ammonium sulfate and titrated on a common indicator strain. These bacteriocins were found to be specific for C. perfringens type A. All of the 90 strains were typable, with 16 distinct bacteriocin types. Most (85.56%) of the strains were types 1-6. Strains of C. perfringens type A clustered into certain patterns of bacteriocin types according to their country of origin and source of isolation.

Bacteriocins↗
PubMed1992

Cloning and DNA sequence analysis of a bacteriocin gene of Serratia marcescens.

Serratia marcescens N28b synthesized and secreted a bacteriocin, with a molecular mass of 45 kDa, which was capable of inhibiting the growth of Escherichia coli. The expression of this bacteriocin was negligible unless induced with mitomycin C. The genes encoding the bacteriocin were cloned in plasmid pBR328. E. coli harbouring recombinant plasmid pBA189 or pBA289 expressed the Serratia marcescens N28b bacteriocin. The nucleotide sequence of the bss gene (Serratia marcescens N28b bacteriocin structural gene) was determined. The predicted amino acid sequence of the carboxy-terminal part of the bacteriocin 28b had a high degree of similarity to the pore-forming domains of colicins A, E1, B, N, Ia and Ib.

Amino Acid Sequence↗
PubMed1999

Characterization and production of amylovorin L471, a bacteriocin purified from Lactobacillus amylovorus DCE 471 by a novel three-step method.

The strongly hydrophobic bacteriocin amylovorin L471 from Lactobacillus amylovorus DCE 471 was isolated and purified to homogeneity from complex culture broth by a novel, rapid and simple three-step protocol including (i) ammonium sulphate precipitation, (ii) chloroform/methanol extraction/precipitation and (iii) reversed-phase HPLC, the only chromatographic step involved. The molecular mass of the peptide was determined to be 4876.9 Da by electrospray mass spectrometric analysis. N-terminal amino acid sequencing identified 35 amino acid residues as being identical to the N-terminal sequence of lactobin A, a bacteriocin from another L. amylovorus strain. These non-identical strains produce bacteriocins that display small differences in molecular mass and inhibitory spectrum. The amino acid sequence of amylovorin L471 shared significant homology with lactacin X, one of the two bactericidal peptides produced by Lactobacillus johnsonii VPI11088. A purified amylovorin L471 preparation permitted confirmation of the inhibitory spectrum previously established with a crude extract. It displayed a bactericidal mode of action on lactobacilli after an extremely rapid adsorption to the target cells. Two Listeria spp. were only weakly sensitive. Amylovorin L471 appears to be produced constitutively. Ethanol not only stimulated specific bacteriocin production but also prevented adsorption of the bacteriocin molecules to the producer cells upon prolonged fermentation. The latter result supports the hypothesis that the apparent inactivation of bacteriocin observed during the stationary phase of batch fermentations is due to adsorption.

Amino Acid Sequence↗
PubMed1982

A bacteriocin typing scheme for Bacteroides.

Epidemiological studies of Bacteroides spp. have been hindered because a suitable typing method is not available. In preliminary studies, 50 strains of Bacteroides were screened against each other for bacteriocin production and sensitivity; 54% of them produced bacteriocin(s) and more than 90% were sensitive to at least one bacteriocin. After calculation of similarity values for these 50 isolates, a typing set of six bacteriocinogenic strains was selected for a typing method based on bacteriocin sensitivity. With this typing set c. 90% of strains could be typed and tests of reproducibility suggested that acceptable accuracy and discrimination could be obtained without applying any one-reaction or two-reaction difference rules. Isolates from four hospitals gave a similar spectrum of typing patterns with 18 bacteriocin types being demonstrated. There was not correlation between bacteriocin type and species of Bacteroides.

Bacteriocins↗
PubMed1998

Production and sensitivity of bacteriocin-like activity among Porphyromonas gingivalis, Prevotella intermedia and Pr. nigrescens strains isolated from periodontal sites.

The production of and sensitivity to bacteriocin-like activity among 44 strains of black-pigmented anaerobes isolated from periodontal sites were evaluated by both an overlay and an agar diffusion method. The species studied were Porphyromonas gingivalis, Prevotella intermedia and the closely related species Pr. nigrescens. Pr. intermedia strains (90%) produced bacteriocin-like activity against Pr. nigrescens and all Pr. nigrescens were active against Pr. intermedia. Both species showed a high degree of activity against P. gingivalis, whereas only one P. gingivalis strain produced bacteriocin-like activity against either of the other two species. Both Pr. nigrescens and Pr. intermedia showed some activity (40% and 20%, respectively) against other strains of the same species. Such bacteriocin production might be expected to influence the distribution of these black-pigmented species in vivo. Of 224 periodontal sites sampled, only 2.6% yielded mixed cultures of black-pigmented species and of these only one strain, a P. gingivalis isolate, produced bacteriocin-like activity against any of the other strains isolated from these sites. These data support the concept that local production of bacteriocin-like activity in vivo may contribute to the selection of the black-pigmented bacterial profile in subgingival sites.

Adult↗
PubMed1991

Characterization of two bacteriocins produced by Clostridium perfringens.

Two types of bacteriocins were shown to be produced in succession by a strain of Clostridium perfringens SN-17. They were separated by diethylaminoethyl cellulose (DEAE) column chromatography at pH 8.5 with a linear concentration gradient of NaCl. One type of bacteriocin (named SN-a) was eluted at 0.07 M and the other type (named SN-b) was at 0.12 M. Each of these was partially purified in a series of column chromatographies: DEAE, Sephadex G-200 (or Bio Gel P-150), and hydroxyapatite. Specific activities of SN-a and SN-b after the last chromatography were at most 30- to 50-fold that of culture filtrate of the organisms. Chromatographed SN-a migrated as a single zone in polyacrylamide gel electrophoresis (PAGE) and the zone showed high biological activity. On the other hand, PAGE pattern of SN-b revealed the presence of a few contamination materials. The activity of SN-b after the last chromatography was hardly recovered from the gel but inactivated SN-b was identified in the gel by examining bacteriocin activity of the DEAE fractions recovered from the gel. The molecular weight of the SN-a and SN-b was determined to be about 70,000 and 100,000, respectively, by molecular sieve chromatography. These bacteriocins were very sensitive to protease but insensitive to DNase and RNase. Bacteriocins were both completely inactivated at 55 C and they were more stable in alkaline pH than in acidic pH. SN-a and SN-b were adsorbed in different ways on the surface of the producer and insensitive strains. Several differences and similarities between these 2 bacteriocins are discussed with special reference to the relationship between them.

Bacteriocins↗
PubMed2004

Characterization and purification of acidocin CH5, a bacteriocin produced by Lactobacillus acidophilus CH5.

AIMS: To characterize and to purify a bacteriocin produced by Lactobacillus acidophilus strain with its activity restricted to Gram-positive bacteria. METHODS AND RESULTS: Native acidocin CH5, a bacteriocin produced by L. acidophilus CH5 an isolate from a dairy starter culture forms in MRS (Oxoid, Basingstoke, UK) broth high-molecular weight aggregates which can dissociate into smaller units (retained by 5 kDa membrane) with higher activity. Acidocin CH5 was purified using combinations of chromatographic methods based on hydrophobic and cation exchange principles and the N-terminal region was sequenced. CONCLUSIONS: Based on our results it is evident that acidocin CH5 belongs, according to bacteriocin classification, to the class II bacteriocins with identical N-terminal amino acid sequence described in the literature previously. SIGNIFICANCE AND IMPACT OF THE STUDY: The study has provided further data on bacteriocin acidocin CH5 from class II with wide spectrum of antimicrobial activity atypical for bacteriocins produced by L. acidophilus sharing the same homology.

Amino Acid Sequence↗
PubMed2006

Purification and characterization of two bacteriocins produced by lactic acid bacteria isolated from Mongolian airag.

AIMS: The aim of this study was to isolate and identify bacteriocin-producing lactic acid bacteria (LAB) issued from Mongolian airag (traditional fermented mare's milk), and to purify and characterize bacteriocins produced by these LAB. METHODS AND RESULTS: Identification of the bacteria (Enterococcus durans) was carried out on the basis of its morphological, biochemical characteristics and carbohydrate fermentation profile and by API50CH kit and 16S rDNA analyses. The pH-neutral cell-free supernatant of this bacterium inhibited the growth of several Lactobacillus spp. and food-borne pathogens including Escherichia coli, Staphylococcus aureus and Listeria innocua. The antimicrobial agent (enterocin A5-11) was heat stable and was not sensitive to acid and alkaline conditions (pH 2-10), but was sensitive to several proteolytic enzymes. Its inhibitory activity was completely eliminated after treatment with proteinase K and alpha-chymotrypsin. The activity was however not completely inactivated by other proteases including trypsin and pepsin. Three-step purification procedure with high recovery yields was developed to separate two bacteriocins. The applied procedure allowed the recovery of 16% and 64% of enterocins A5-11A and A5-11B, respectively, present in the culture supernatant with purity higher than 99%. SDS-PAGE analyses revealed that enterocin A5-11 has a molecular mass of 5000 Da and mass spectrometry analyses demonstrates molecular masses of 5206 and 5218 Da for fractions A and B, respectively. Amino acid analyses of both enterocins indicated significant quantitative difference in their contents in threonine, alanine, isoleucine and leucine. Their N-termini were blocked hampering straightforward Edman degradation. CONCLUSIONS: Bacteriocins A5-11A and B from Ent. durans belong to the class II of bacteriocins. SIGNIFICANCE AND IMPACT OF THE STUDY: Judging from molecular masses, amino acid composition and spectrum of activities, bacteriocins A5-11A and B from Ent. durans show high degree of similarity with enterocins L50A and L50B isolated from Enterococcus faecium (Cintas et al. 1998, 2000) and with enterocin I produced by Ent. faecium 6T1a, a strain originally isolated from a Spanish-style green olive fermentation (Floriano et al. 1998).

Amino Acids↗
PubMed1996

Comparative effectiveness of nisin and bacteriocin J46 at different pH values.

A comparative study of the inhibitory activity of nisin, the well-known lantibiotic produced by certain strains of Lactococcus lactis subsp. lactis, and of the bacteriocin produced by L. lactis subsp. cremoris J46, a strain previously isolated from fermented milk, was conducted. For both bacteriocins, the activity against L. lactis subsp. cremoris decreased with increasing pH. In addition, the bacteriocin preparations were more stable at 4 degrees than at 20 degrees C. The influence of the storage temperature was more crucial for nisin. Essentially the same activity was observed for bacteriocin J46 stored for 3 h at 4 degrees or 20 degrees C. More interesting was the observed stability of bacteriocin J46 at pH values between 5.8 and 6.8. For example, about 23% of nisin activity was lost at pH 6.4 whereas no loss of bacteriocin J46 activity was observed.

Bacteriocins↗