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PubMed1995

Partial purification and characterization of bacteriocin from Yersinia kristensenii.

A raw milk bacterial isolate, identified as Yersinia kristensenii was found to produce a bacteriocin which was inhibitory to Yersinia enterocolitica but not to other selected species of Yersinia or Gram-negative bacteria. Maximum production of bacteriocin was obtained when the organism was grown in shake culture at 28 degrees C. Mitomycin C at a concentration of 0.5 micrograms ml-1 induced bacteriocin production. The bacteriocin was partially purified and characterized by ammonium sulphate fractionation and gel filtration. The bacteriocin was completely inactivated when treated with proteolytic enzymes (trypsin and chymotrypsin). Bacteriocin activity was heat-resistant and it retained some of its activity after 5 min at boiling temperature. A total of 15 bacteriocin sensitive-suspected food isolates were further identified biochemically as Yersinia enterocolitica and a non-sensitive isolate was identified as Yersinia intermedia.

Animals↗
PubMed1996

Antimicrobial activity of lactic acid bacteria isolated from goat's milk and artisanal cheeses: characteristics of a bacteriocin produced by Lactobacillus curvatus IFPL 105.

A total of 203 lactic acid bacteria isolated from raw goat's milk and artisanal cheese were tested for antibacterial activity. Only two strains of Lactococcus lactis, one strain of Enterococcus faecalis and one strain of Lactobacillus curvatus were shown to produce a bacteriocin-like substance. Lactobacillus curvatus IFPL105 produced a heat-stable bacteriocin, which was hydrolysed by alpha-chymotrypsin, proteinase K and pancreatin and exhibited a broad spectrum of inhibitory activity. The bactericidal activity of the bacteriocin was more potent when sensitive strains were in the logarithmic growth phase, inducing cell lysis, as observed by decreases in optical density and release of intracellular marker enzymes. Curing experiments resulted in variants that lacked both bacteriocin activity and immunity to the bacteriocin. Plasmid profile analysis of the parental strain and the bacteriocin-negative variants indicated that a plasmid of about 46 kbp may be involved in bacteriocin production and immunity to this antibacterial compound.

Ammonium Sulfate↗
PubMed2005

Purification, amino acid sequence and characterization of Bacthuricin F4, a new bacteriocin produced by Bacillus thuringiensis.

AIMS: Purification and characterization of a new bacteriocin, Bacthuricin F4 of Bacillus thuringiensis. METHODS AND RESULTS: A newly isolated B. thuringiensis subsp. kurstaki strain BUPM4, was shown to produce a novel bacteriocin named Bacthuricin F4. The highest bacteriocin activity was found in the growth medium and evidenced in the late exponential growth phase. Bacthuricin F4 could be purified by a two-step procedure: ammonium sulphate precipitation of protein from culture supernatant followed by a reverse phase chromatography. Upon purification, the specific activity was increased 100-fold. This bacteriocin was heat-stable up to 70 degrees C and resisted up to pH 3.0. Bacthuricin F4 was sensitive to proteases demonstrating its proteinaceous nature. Its molecular mass, determined by mass spectrometry was 3160.05 Da. Direct N-terminal sequencing of Bacthuricin F4 revealed the following sequence: DWTXWSXL. The latter was unique in the databases. Bacthuricin F4 was active against Bacillus species while it had little or no effect on Gram-negative bacteria. CONCLUSIONS: A strain BUPM4 of B. thuringiensis subsp. kurstaki, was shown to produce a new bacteriocin named Bacthuricin F4 of both new molecular mass (3160.05 Da) and new amino acid terminal sequence. This is, to our knowledge, the first bacteriocin exhibiting such characteristics reported to be produced by B. thuringiensis. SIGNIFICANCE AND IMPACT OF THE STUDY: The bacteriocin produced by the B. thuringiensis strain BUPM4 respond to both criteria of thermostability and stability to low pHs. Thus, it could be used for the control of the related species of Bacillus harmful for agricultural products.

Amino Acid Sequence↗
PubMed2000

Production kinetics of acidophilin 801, a bacteriocin produced by Lactobacillus acidophilus IBB 801.

Lactobacillus acidophilus IBB 801 produces a small bacteriocin, designated acidophilin 801. Studying the relationship between growth and bacteriocin biosynthesis revealed primary metabolite kinetics of bacteriocin production with a peak activity at the end of the exponential growth phase followed by a decrease during the stationary phase. Both microbial growth and bacteriocin production was inhibited by lactic acid. Whereas volumetric bacteriocin production (activity units (AU) ml(-1)) was favoured under pH-controlled conditions, bacteriocin titres rapidly decreased because of strong adsorption of the bacteriocin molecules to the producing cells under less acidic conditions.

Bacteriocins↗
PubMed1979

Characterization and mode of action of a bacteriocin produced by a Bacteroides fragilis strain.

A Bacteroides fragilis strain produces a low-molecular-weight (13,500 to 18,700), proteinaceous bacteriocin during the stationary growth phase. The extracellular bacteriocin is not inducible by ultraviolet light or mitomycin C and is stable between pH 7.5 and 8.2. The majority of the bacteriocin is thermolabile, but a small proportion (3%) of the bacteriocin is stable after autoclaving at 121 degrees C for 15 min. Killing of sensitive bacteroides cells follows single-hit kinetics, and the interaction of a single molecule of bacteriocin with a target cell occurs in two stages. The killing of susceptible cells is affected by temperature and the growth state of the susceptible cells. The bacteriocin is unusual in that the primary event in its mode of action is the inhibition of RNA synthesis. The bacteriocin inhibits RNA synthesis immediately but has no effect on DNA synthesis or intracellular ATP levels. Protein synthesis is inhibited after a delay of 20 min, presumably as a result of the initial inhibition of RNA synthesis.

Adenosine Triphosphate↗
PubMed1975

Binding of bacteriocin Clo DF13 to Clo DF13 plasmid deoxyribonucleic acid in vivo and in vitro.

The bacteriocinogenic plasmid Clo DF13 is present in Escherichia coli to the extent of 10 copies per cell. A complex of Clo DF13 plasmid deoxyribonucleic acid (DNA) and protein can be isolated from cells. Treatment of the complex with ionic detergents or proteases dissociates the complex but does not convert any supercoiled Clo DF13 DNA to the open circular form, indicating that this complex is not a relaxation complex. The complex is stable in 0.5 M NaCl and contains one polypeptide species. The protein, present in the complex, appeared to be bacteriocin Clo DF13 for the following reasons: (i) the protein is de novo synthesized in Clo DF13-harboring minicells, indicating that this protein is Clo DF13 specific; (ii) this protein shows bacteriocinogenic activity on a bacteriocin Clo DF13-susceptible indicator strain; (iii) this protein has the same molecular weight (60,000) as bacteriocin Clo DF13. DNA-protein binding experiments, involving QAE-Sephadex column chromatography and nitrocellulose membrane filters, demonstrate that bacteriocin Clo DF13 has also affinity in vitro for Clo DF13 DNA. Membrane filter binding experiments revealed that bacteriocin Clo DF13 does not interact with other DNA species, such as ColE1 DNA, yeast DNA, calf thymus DNA, phiX174 DNA, and also not with denatured Clo DF13 DNA. In addition no binding to Clo DF13 DNA of a related bacteriocin, colicin E3, could be detected. These results indicate that the binding of bacteriocin Clo DF 13 to double-stranded Clo DF13 DNA is very specific.

Bacterial Proteins↗
PubMed1999

Temperature and pH conditions that prevail during fermentation of sausages are optimal for production of the antilisterial bacteriocin sakacin K.

Sakacin K is an antilisterial bacteriocin produced by Lactobacillus sake CTC 494, a strain isolated from Spanish dry fermented sausages. The biokinetics of cell growth and bacteriocin production of L. sake CTC 494 in vitro during laboratory fermentations were investigated by making use of MRS broth. The data obtained from the fermentations was used to set up a predictive model to describe the influence of the physical factors temperature and pH on microbial behavior. The model was validated successfully for all components. However, the specific bacteriocin production rate seemed to have an upper limit. Both cell growth and bacteriocin activity were very much influenced by changes in temperature and pH. The production of biomass was closely related to bacteriocin activity, indicating primary metabolite kinetics, but was not the only factor of importance. Acidity dramatically influenced both the production and the inactivation of sakacin K; the optimal pH for cell growth did not correspond to the pH for maximal sakacin K activity. Furthermore, cells grew well at 35 degrees C but no bacteriocin production could be detected at this temperature. L. sake CTC 494 shows special promise for implementation as a novel bacteriocin-producing sausage starter culture with antilisterial properties, considering the fact that the temperature and acidity conditions that prevail during the fermentation process of dry fermented sausages are optimal for the production of sakacin K.

Bacteriocins↗
PubMed1999

Cloning and characterization of a Rhizobium leguminosarum gene encoding a bacteriocin with similarities to RTX toxins.

A 3-kb region containing the determinant for bacteriocin activity from Rhizobium leguminosarum 248 was isolated and characterized by Tn5 insertional mutagenesis and DNA sequencing. Southern hybridizations showed that this bacteriocin was encoded on the plasmid pRL1JI and that homologous loci were not found in other unrelated R. leguminosarum strains. Tn5 insertional mutagenesis showed that mutations in the C-terminal half of the bacteriocin open reading frame apparently did not abolish bacteriocin activity. Analysis of the deduced amino acid sequence revealed that, similarly to RTX proteins (such as hemolysin and leukotoxin), this protein contains a characteristic nonapeptide repeated up to 18 times within the protein. In addition, a novel 19- to 25-amino-acid motif that occurred every 130 amino acids was detected. Bacteriocin bioactivity was correlated with the presence of a protein of approximately 100 kDa in the culture supernatants, and the bacteriocin bioactivity demonstrated a calcium dependence in both R. leguminosarum and Sinorhizobium meliloti. A mutant of strain 248 unable to produce this bacteriocin was found to have a statistically significant reduction in competitiveness for nodule occupancy compared to two test strains in coinoculation assays. However, this strain was unable to compete any more successfully with a third test strain, 3841, than was wild-type 248.

Amino Acid Sequence↗
PubMed2000

Biochemical and genetic characterization of propionicin T1, a new bacteriocin from Propionibacterium thoenii.

A collection of propionibacteria was screened for bacteriocin production. A new bacteriocin named propionicin T1 was isolated from two strains of Propionibacterium thoenii. This bacteriocin shows no sequence similarity to other bacteriocins. Propionicin T1 was active against all strains of Propionibacterium acidipropionici, Propionibacterium thoenii, and Propionibacterium jensenii tested and also against Lactobacillus sake NCDO 2714 but showed no activity against Propionibacterium freudenreichii. The bacteriocin was purified, and the N-terminal part of the peptide was determined with amino acid sequencing. The corresponding gene pctA was sequenced, and this revealed that propionicin T1 is produced as a prebacteriocin of 96 amino acids with a typical sec leader, which is processed to give a mature bacteriocin of 65 amino acids. An open reading frame encoding a protein of 424 amino acids was found 68 nucleotides downstream the stop codon of pctA. The N-terminal part of this putative protein shows strong similarity with the ATP-binding cassette of prokaryotic and eukaryotic ABC transporters, and this protein may be involved in self-protection against propionicin T1. Propionicin T1 is the first bacteriocin from propionibacteria that has been isolated and further characterized at the molecular level.

Amino Acid Sequence↗
PubMed2000

Bacteriocin production with Lactobacillus amylovorus DCE 471 is improved and stabilized by fed-batch fermentation.

Amylovorin L471 is a small, heat-stable, and hydrophobic bacteriocin produced by Lactobacillus amylovorus DCE 471. The nutritional requirements for amylovorin L471 production were studied with fed-batch fermentations. A twofold increase in bacteriocin titer was obtained when substrate addition was controlled by the acidification rate of the culture, compared with the titers reached with constant substrate addition or pH-controlled batch cultures carried out under the same conditions. An interesting feature of fed-batch cultures observed under certain culture conditions (constant feed rate) is the apparent stabilization of bacteriocin activity after obtaining maximum production. Finally, a mathematical model was set up to simulate cell growth, glucose and complex nitrogen source consumption, and lactic acid and bacteriocin production kinetics. The model showed that bacterial growth was dependent on both the energy and the complex nitrogen source. Bacteriocin production was growth associated, with a simultaneous bacteriocin adsorption on the producer cells dependent on the lactic acid accumulated and hence the viability of the cells. Both bacteriocin production and adsorption were inhibited by high concentrations of the complex nitrogen source.

Bacteriocins↗
PubMed2000

Requirement of autolytic activity for bacteriocin-induced lysis.

The bacteriocin produced by Lactococcus lactis IFPL105 is bactericidal against several Lactococcus and Lactobacillus strains. Addition of the bacteriocin to exponential-growth-phase cells resulted in all cases in bacteriolysis. The bacteriolytic response of the strains was not related to differences in sensitivity to the bacteriocin and was strongly reduced in the presence of autolysin inhibitors (Co(2+) and sodium dodecyl sulfate). When L. lactis MG1363 and its derivative deficient in the production of the major autolysin AcmA (MG1363acmADelta1) were incubated with the bacteriocin, the latter did not lyse and no intracellular proteins were released into the medium. Incubation of cell wall fragments of L. lactis MG1363, or of L. lactis MG1363acmADelta1 to which extracellular AcmA was added, in the presence or absence of the bacteriocin had no effect on the speed of cell wall degradation. This result indicates that the bacteriocin does not degrade cell walls, nor does it directly activate the autolysin AcmA. The autolysin was also responsible for the observed lysis of L. lactis MG1363 cells during incubation with nisin or the mixture of lactococcins A, B, and M. The results presented here show that lysis of L. lactis after addition of the bacteriocins is caused by the resulting cell damage, which promotes uncontrolled degradation of the cell walls by AcmA.

Bacteriocins↗
PubMed2002

Role of acetate in production of an autoinducible class IIa bacteriocin in Carnobacterium piscicola A9b.

Carnobacterium piscicola strain A9b isolated from cold smoked salmon inhibits growth of the food-borne pathogen Listeria monocytogenes partly due to the production of a proteinaceous compound (L. Nilsson, L. Gram, and H. H. Huss. J. Food Prot. 62:336-342, 1999). The purpose of the present study was to purify the compound and describe factors affecting its production, with particular emphasis on food-relevant factors. Amino acid sequencing showed that the compound is a class IIa bacteriocin with an N-terminal amino acid sequence identical to that of carnobacteriocin B2. The production of the bacteriocin was autoinducible, and the threshold level for induction was 9.6 x 10(-10) M. We also report, for the first time, that acetate acts as an induction factor, with a threshold concentration of 0.3 to 12 mM. Acetate could not act as an inducer during the late exponential phase of C. piscicola A9b. The induction of bacteriocin production showed a dose-dependent relationship at acetate concentrations of up to 10 to 20 mM (depending on the growth medium) and at a concentration of 1.9 x 10(-8) M for the bacteriocin itself; a saturation level of bacteriocin specific activity was reached at these concentrations of induction factors. The combined use of both inducers did not enhance the saturation level of bacteriocin production compared to that seen with the use of each inducer alone. Increasing NaCl and glucose concentrations negatively influenced the efficiency of acetate as an induction factor. Based on the results, carnobacteriocin B2 was used as an induction factor to manipulate the production of bacteriocin in cold smoked salmon juice and thus improve the ability to inhibit L. monocytogenes.

Acetic Acid↗
PubMed2002

Optimization of bacteriocin production by batch fermentation of Lactobacillus plantarum LPCO10.

Optimization of bacteriocin production by Lactobacillus plantarum LPCO10 was explored by an integral statistical approach. In a prospective series of experiments, glucose and NaCl concentrations in the culture medium, inoculum size, aeration of the culture, and growth temperature were statistically combined using an experimental 2(3)(5-2) fractional factorial two-level design and tested for their influence on maximal bacteriocin production by L. plantarum LPCO10. After the values for the less-influential variables were fixed, NaCl concentration, inoculum size, and temperature were selected to study their optimal relationship for maximal bacteriocin production. This was achieved by a new experimental 3(2)(3-1) fractional factorial three-level design which was subsequently used to build response surfaces and analyzed for both linear and quadratic effects. Results obtained indicated that the best conditions for bacteriocin production were shown with temperatures ranging from 22 to 27 degrees C, salt concentration from 2.3 to 2.5%, and L. plantarum LPCO10 inoculum size ranging from 10(7.3) to 10(7.4) CFU/ml, fixing the initial glucose concentration at 2%, with no aeration of the culture. Under these optimal conditions, about 3.2 x 10(4) times more bacteriocin per liter of culture medium was obtained than that used to initially purify plantaricin S from L. plantarum LPCO10 to homogeneity. These results indicated the importance of this study in obtaining maximal production of bacteriocins from L. plantarum LPCO10 so that bacteriocins can be used as preservatives in canned foods.

Bacteriocins↗
PubMed2003

Functional characterization of a composite bacteriocin locus from malt isolate Lactobacillus sakei 5.

Lactobacillus sakei 5, isolated from malted barley, produces three bacteriocins. Genetic and functional analysis of the purified bacteriocins showed that this strain produces a plasmid-encoded bacteriocin that is identical to sakacin P, as well as two novel, chromosomally encoded bacteriocins, which were designated sakacin T and sakacin X. The structural genes specifying sakacin T and sakacin X are part of the sakacin TX locus, which consists of two adjacent but divergently oriented gene clusters. The first gene cluster includes stxP, stxR, stxK, and stxT, which, based on functional and comparative sequence analysis, are believed to encode an inducing peptide and proteins involved in regulation and secretion of these bacteriocins. The second gene cluster includes the structural and immunity genes for sakacin T, a class IIb two-peptide bacteriocin composed of SakTalpha and SakTbeta, and sakacin X, a class IIa bacteriocin. Interestingly, a so-called transport accessory protein was absent from the locus, and based on our results it appears that a dedicated accessory protein is not required for processing and transport of sakacin T and sakacin X.

Amino Acid Sequence↗
PubMed2003

The curing agent sodium nitrite, used in the production of fermented sausages, is less inhibiting to the bacteriocin-producing meat starter culture Lactobacillus curvatus LTH 1174 under anaerobic conditions.

Curvacin A is a listericidal bacteriocin produced by Lactobacillus curvatus LTH 1174, a strain isolated from fermented sausage. The response of this strain to an added curing agent (sodium nitrite) in terms of cell growth and bacteriocin production was investigated in vitro by laboratory fermentations with modified MRS broth. The strain was highly sensitive to nitrite; even a concentration of 10 ppm of curing agent inhibited its growth and both volumetric and specific bacteriocin production. A meat simulation medium containing 5 ppm of sodium nitrite was tested to investigate the influence of the gas phase on the growth and bacteriocin production of L. curvatus LTH 1174. Aerating the culture during growth had no effect on biomass formation, but the oxidative stress caused a higher level of specific bacteriocin production and led to a metabolic shift toward acetic acid production. Anaerobic conditions, on the other hand, led to an increased biomass concentration and less growth inhibition. Also, higher maximum volumetric bacteriocin activities and a higher level of specific bacteriocin production were obtained in the presence of sodium nitrite than in fermentations under aerobic conditions or standard conditions of air supply. These results indicate that the inhibitory effect of the curing agent is at least partially masked under anaerobic conditions.

Aerobiosis↗
PubMed2004

Sodium chloride reduces production of curvacin A, a bacteriocin produced by Lactobacillus curvatus strain LTH 1174, originating from fermented sausage.

Lactobacillus curvatus LTH 1174, a strain originating in fermented sausage, produces the antilisterial bacteriocin curvacin A. Its biokinetics of cell growth and bacteriocin production as a function of various concentrations of salt (sodium chloride) were investigated in vitro during laboratory fermentations using modified MRS medium. A model was set up to describe the effects of different NaCl concentrations on microbial behavior. Both cell growth and bacteriocin activity were affected by changes in the salt concentration. Sodium chloride clearly slowed down the growth of L. curvatus LTH 1174, but more importantly, it had a detrimental effect on specific curvacin A production (k(B)) and hence on overall bacteriocin activity. Even a low salt concentration (2%, wt/vol) decreased bacteriocin production, while growth was unaffected at this concentration. The inhibitory effect of NaCl was mainly due to its role as an a(w)-lowering agent. Further, it was clear that salt interfered with bacteriocin induction. Additionally, when 6% (wt/vol) sodium chloride was added, the minimum biomass concentration necessary to start the production of curvacin A (X(B)) was 0.90 g (cell dry mass) per liter. Addition of the cell-free culture supernatant or a protein solution as a source of induction factor resulted in a decrease in X(B), an increase in k(B), and hence an increase in the maximum attainable bacteriocin activity.

Animals↗
PubMed2005

Interactions between oral bacteria: inhibition of Streptococcus mutans bacteriocin production by Streptococcus gordonii.

Streptococcus mutans has been recognized as an important etiological agent in human dental caries. Some strains of S. mutans also produce bacteriocins. In this study, we sought to demonstrate that bacteriocin production by S. mutans strains GS5 and BM71 was mediated by quorum sensing, which is dependent on a competence-stimulating peptide (CSP) signaling system encoded by the com genes. We also demonstrated that interactions with some other oral streptococci interfered with S. mutans bacteriocin production both in broth and in biofilms. The inhibition of S. mutans bacteriocin production by oral bacteria was stronger in biofilms than in broth. Using transposon Tn916 mutagenesis, we identified a gene (sgc; named for Streptococcus gordonii challisin) responsible for the inhibition of S. mutans bacteriocin production by S. gordonii Challis. Interruption of the sgc gene in S. gordonii Challis resulted in attenuated inhibition of S. mutans bacteriocin production. The supernatant fluids from the sgc mutant did not inactivate the exogenous S. mutans CSP as did those from the parent strain Challis. S. gordonii Challis did not inactivate bacteriocin produced by S. mutans GS5. Because S. mutans uses quorum sensing to regulate virulence, strategies designed to interfere with these signaling systems may have broad applicability for biological control of this caries-causing organism.

Antibiosis↗
PubMed1972

Continued surveillance of Serratia marcescens infections by bacteriocin typing: investigation of two outbreaks of cross-infection in an intensive care unit.

During an 8.5-month period, 198 additional isolates of Serratia marcescens were typed by bacteriocin sensitivity; 154 isolates were typable and were categorized according to our current system of 54 provisional bacteriocin sensitivity patterns. Two outbreaks of nosocomial infection due to S. marcescens occurred in our intensive care unit, involving two and five patients, respectively. The latter outbreak was caused by a strain of S. marcescens which was not sensitive to any of the 10 bacteriocins normally used. Therefore we developed a supplementary procedure based on bacteriocin production rather than bacteriocin sensitivity. Bacteriocin production was induced with mitomycin C, and the crude lysates were applied to 15 provisional bacteriocin indicator strains. The reverse typing procedure was necessary to determine the spread and ultimate subsidence of this particular outbreak of cross-infection.

Bacteriocins↗