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Bacteriocins, natural antimicrobial peptides produced by bacteria, present eco-friendly, non-toxic, and cost-effective alternatives to traditional chemical antimicrobial agents in the food industry. This review provides a comprehensive update on the classification of bacteriocins in food preservation. It highlights the significant industrial potential of pediocin-like and two-peptide bacteriocins, emphasizing chemical synthesis methods like Fmoc-SPPS to meet the demand for bioactive bacteriocins. The review details the mode of action, focusing on mechanisms such as transmembrane potential disruption and pH-dependent effects. Furthermore, it addresses the limitations of bacteriocins in food preservation and explores the potential of nanotechnology-based encapsulation to enhance their antimicrobial efficacy. The benefits of nanoencapsulation, including improved stability, extended antimicrobial spectrum, and enhanced functionality, are underscored. This understanding is crucial for advancing the application of bacteriocins to ensure food safety and quality. [ABSTRACT FROM AUTHOR]

Aims This study aimed to prospect and isolate lactic acid bacteria (LAB) from an artisanal cheese production environment, to assess their safety, and to explore their bacteriocinogenic potential against Listeria monocytogenes. Methods and results Samples were collected from surfaces of an artisanal-cheese production facility and after rep-PCR and 16S rRNA sequencing analysis, selected strains were identified as to be belonging to Lactococcus garvieae (1 strain) and Enterococcus faecium (14 isolates, grouped into three clusters) associated with different environments (worktables, cheese mold, ripening wooden shelves). All of them presented bacteriocinogenic potential against L. monocytogenes ATCC 7644 and were confirmed as safe (γ-hemolytic, not presenting antibiotic resistance, no mucus degradation properties, and no proteolytic or gelatinase enzyme activity). Additionally, cell growth, acidification and bacteriocins production kinetics, bacteriocin stability in relation to different temperatures, pH, and chemicals were evaluated. According to performed PCR analysis all studied strains generated positive evidence for the presence of ent A and ent P genes (for production of enterocins A and enterocins P, respectively). However, pediocin PA-1 associated gene was recorded only in DNA obtained from E. faecium ST02JL and Lc. garvieae ST04JL. Conclusions It is worth considering the application of these safe LAB or their bacteriocins in situ as an alternative means of controlling L. monocytogenes in cheese production environments, either alone or in combination with other antimicrobials. [ABSTRACT FROM AUTHOR]

Aims Enterocins K1 and EJ97 have specific antimicrobial activity against Enterococcus faecium and Enterococcus faecalis , respectively. The aim of this study was to investigate the utility of these enterocins for in vivo treatment of systemic enterococcal infections. Methods and results The antimicrobial effect in blood was analysed and compared against the effect in saline. Colony forming unit counts revealed that the enterocins killed all the bacteria within 1 hour. Additionally, the bactericidal effect against E. faecalis was more rapid in blood, indicating a possible synergy between EntEJ97 and blood. Importantly, no enterocin resistant mutants emerged in these experiments. Injecting the enterocins intraperitoneally in an in vivo mouse model and using fluorescence and minimum inhibitory concentration determination to estimate concentrations of the peptides in plasma, indicate that the enterocins exist in circulation in therapeutic concentrations. Alanine aminotransferase detection, and haemolysis analysis indicates that there is no detectable liver damage or haemolytic effect after injection. Conclusions The study revealed that EntK1 and EntEJ97 are able to kill all bacteria ex vivo in the presence of blood. In vivo experiments determine that the enterocins exist in circulation in therapeutic concentrations without causing liver damage or haemolysis. Future experiments should test these peptides for treatment of infection in a relevant in vivo model. [ABSTRACT FROM AUTHOR]

Aims: Bacteriocinogenic lactic acid bacteria (LAB) isolates and Croton heliotropiifolius essential oil (EO) were used to inhibit Staphylococcus aureus subsp. aureus and enhance the antioxidant action in goat coalho cheese (GCC). Methods and Results: Lactic acid bacteria isolates were selected for their inhibitory capacity against S. aureus subsp. aureus, safety, existence of bacteriocin‐encoding genes, bacteriocinogenic activity, and its antistaphylococcal action. The staphylococcal inhibition capacity of C. heliotropiifolius EO was also verified. Three cheeses were prepared containing S. aureus subsp. aureus (GCC SA), S. aureus subsp. aureus + LAB (GCC SA + LAB), and S. aureus subsp. aureus + EO (GCC SA + EO). Samples were analysed on days 0, 7, 14 and 21. Based on the screening, three LAB isolates were selected and identified as Enterococcus faecium. In GCC, the smallest population of S. aureus subsp. aureus was found until the 17th in the GCC SA + EO and from the 18th in the GCC SA + LAB. Total phenolic content and antioxidant activity increased over time in GCCs. Conclusions: Autochthonous bacteriocinogenic LAB and C. heliotropiifolius EO are natural resources of the Caatinga, an exclusively Brazilian biome that predominates in the northeast of the country, with the potential to reduce the presence of S. aureus and increase the antioxidant activity in the GCC. Significance and Impact of the Study: Goat coalho cheese is a product of cultural importance in northeastern Brazil. The process of obtaining the GCC is manual, and there is a high frequency of S. aureus in the product. Resources of the Caatinga with biofunctional properties can be tested to reduce the risk of staphylococcal toxins, and contribute to the nutritional value of the GCC, maintaining regional characteristics and respecting the local cultural tradition. LAB and C. heliotropiifolius EO contribute to the incorporation of bioactive substances and microbiological quality, generating a value‐added GCC with exclusive resources of the Caatinga. [ABSTRACT FROM AUTHOR]

Aim: Our previous study reported a strain that can detoxify Jatropha curcas L. cake (JCC), but the detoxification duration is long. This study intends to explore the efficient detoxification of JCC through multi‐strain collaborative fermentation to accelerate the detoxification process. Methods and Results: Mucor circinelloides SCYA25 strain that we previously reported can effectively degrade the toxicity of JCC, and the newly screened Bacillus megaterium SCYA10 and Geotrichum candidum SCYA23 strains were used to detoxify JCC. Different solid‐state‐fermentation (SSF) parameters were optimized by single‐factor tests and response surface methodology. A detoxification rate established by zebrafish toxicity of JCC at 96% was achieved under the following optimized conditions: the combination ratio of B. megaterium SCYA10, G. candidum SCYA23 and M. circinelloides SCYA25 at 2:3:1, a total injection amount of 15.25%, a feed to water ratio of 1:0.68, a fermentation temperature of 30.3°C and fermentation duration of 21.5 days. The protein content of fermented JCC (FJCC) increased, while the concentrations of ether extract, crude fibre and toxins were all degraded considerably. Metabolomics analysis revealed that the fermentation increased the contents of neurotransmitter receptor modulator, emulsifier, aromatic substances and insecticidal compounds, as well as decreasing the contents of oxidative stress and neurotoxic substances. A rat feeding trial showed that the growth performance of the rats provided with the FJCC diet was similar to that of the corn‐soybean meal group, and no lesions in the liver and kidney were observed. Conclusion: The co‐bio‐fermentation process can effectively detoxify JCC and improve its nutritional value, which means it could be served as a protein feed in animal husbandry. Significance: The combination of three microbial strains can detoxify JCC in a safe and effective manner to provide a great potential alternative to soybean meal. The research also suggests that metabonomics and bioinformatics are useful tools for revealing the bio‐detoxification mechanism. [ABSTRACT FROM AUTHOR]

Nisin is a bacteriocin produced by a group of Gram-positive bacteria that belongs to Lactococcus and Streptococcus species. Nisin is classified as a Type A (I) lantibiotic that is synthesized from mRNA and the translated peptide contains several unusual amino acids due to post-translational modifications. Over the past few decades, nisin has been used widely as a food biopreservative. Since then, many natural and genetically modified variants of nisin have been identified and studied for their unique antimicrobial properties. Nisin is FDA approved and generally regarded as a safe peptide with recognized potential for clinical use. Over the past two decades the application of nisin has been extended to biomedical fields. Studies have reported that nisin can prevent the growth of drug-resistant bacterial strains, such as methicillin-resistant Staphylococcus aureus, Streptococcus pneumoniae, Enterococci and Clostridium difficile. Nisin has now been shown to have antimicrobial activity against both Gram-positive and Gram-negative disease-associated pathogens. Nisin has been reported to have anti-biofilm properties and can work synergistically in combination with conventional therapeutic drugs. In addition, like host-defence peptides, nisin may activate the adaptive immune response and have an immunomodulatory role. Increasing evidence indicates that nisin can influence the growth of tumours and exhibit selective cytotoxicity towards cancer cells. Collectively, the application of nisin has advanced beyond its role as a food biopreservative. Thus, this review will describe and compare studies on nisin and provide insight into its future biomedical applications.

Aims: Phytopathogens are a global threat to the world's food supply. The use of broad‐spectrum bactericides and antibiotics to limit or eliminate bacterial infections is becoming less effective as levels of resistance increase, while concurrently becoming less desirable from an ecological perspective due to their collateral damage to beneficial members of plant and soil microbiomes. Bacteria produce numerous antimicrobials in addition to antibiotics, such as bacteriocins with their relatively narrow activity spectra, and inhibitory metabolic by‐products, such as organic acids. There is an interest in developing these naturally occurring antimicrobials for use as alternatives or supplements to antibiotics. Methods and Results: In this study, we investigate the inhibitory potential of 217 plant‐associated bacterial isolates from 44 species including plant pathogens, plant growth promoting rhizobacteria and plant commensals. Over half of the isolates were found to produce antimicrobial substances, of which 68% were active against phytopathogens. Even more intriguing, 98% of phytopathogenic strains were sensitive to the compounds produced specifically by plant growth promoting rhizobacteria. Conclusion: These data argue that plant‐associated bacteria produce a broad range of antimicrobial substances, and that the substances produced preferentially target phytopathogenic bacteria. Significance and Impact of Study: There is a need for novel antimicrobials for use in agriculture. The methods presented here reveal the potential for simple phenotypic screening methods to provide a broad range of potential drug candidates. [ABSTRACT FROM AUTHOR]

Aims: Worldwide, studies regarding antimicrobial resistance in rabbits are scarce. In addition, it seems that rearing conditions have important impact on emergence and spread of antimicrobial‐resistant bacteria. Thus, the authors sought to (1) assess the role of rabbits residing across diverse ecosystems as potential reservoirs of antimicrobial‐resistant enterococci and (2) investigate the genetic background of detected resistances. Methods and Results: Faecal samples from 60 healthy farmed rabbits (one farm), 35 laboratory rabbits and 31 wild rabbits were analysed. Overall, 97 enterococci isolates were accumulated, as follows: 44 E. faecium, 37 E. faecalis, 7 E. gallinarum, 5 E. durans and 4 E. avium. E. faecalis isolates were statistically associated with farm rabbits and wild rabbits (p < 0.05). High rates of resistance were observed for tetracycline (60.8%; tetM [n = 48; 81.3%], tetO [n = 7; 11.8%] and tetL [n = 1; 1.7%]), erythromycin (43.3%; msr(A) [n = 14; 33.3%] and ermB [n = 13; 31%]), ampicillin (29.9%), streptomycin (26.8%; ant(6)‐Ia [n = 3, 11.5%]) and vancomycin (21.6%; vanA [one E. faecium + one E. faecalis; 9.5%]). Low frequencies of resistance were observed for teicoplanin (9.2%), linezolid (8.2%), ciprofloxacin (7.2%) and gentamicin (1%; aac(6′)‐Ie‐aph(2″)‐Ia). Resistance to ampicillin and vancomycin was associated with laboratory rabbits (p < 0.05). Int‐Tn (Tn916/1545) was detected in 27 (27.8%) isolates, of which 10 isolates co‐harboured tetM and ermB genes, while 16 comprised tetM. Conclusion: Findings indicate that clinically relevant enterococci species isolated from rabbits are frequently resistant to antimicrobials and harbour a range of genes associated with the Tn916/1545 family. Significance and Impact of the study: This study highlights the high rates of antimicrobial‐resistant enterococci from rabbits and the occurrence of both vancomycin‐ and linezolid‐resistant isolates, potentially representing a very serious threat to human and animal health. [ABSTRACT FROM AUTHOR]

Aims: The objective of this study was to isolate multifunctional bacteriocin‐producing strains; to characterize the expressed bacteriocin for the control of Listeria monocytogenes and vancomycin‐resistant Enterococcus; to evaluate the safety of studied strains; and to explore their antifungal activity. Methods and Results: Two Pediococcus strains were isolated from silage samples obtained from an organic farm in Belogradchik, Bulgaria. The strains were identified by 16S rRNA sequencing analysis and characterized as bacteriocins producers. Strong antimicrobial activity was detected against more than 74 different strains of Listeria monocytogenes, 27 different vancomycin‐resistant Enterococcus strains. In addition, studied strains were able to inhibit the growth of strains of Alternaria alternate, Aspergillus flavus, Aspergillus niger, Cladosporium sphaerospermum, Penicillium chrysogenum and Penicillium expansum. Some aspects of the antimicrobial mode of action were evaluated, including killing curves and aggregation properties. Both strains generated positive PCR results for the presence of pediocin PA‐1, but not for other bacteriocins evaluated in this screening process. Metabolomic analysis of the cell‐free supernatants from both strains was performed in order to explain the observed antifungal activity against different moulds. According to PCA and PLS‐DA score plot, P. acidilactici ST3522BG and P. pentosaceus ST3633BG were clearly clustered from control (MRS). Increases in the production of benzoic acid, 2‐hydroxyisocaproic acid, β‐phenyl‐lactic acid, α‐hydroxybutyric acid and 1,3‐butanediol were recorded, these metabolites were previously described as antifungal. Conclusions: Pediococcus acidilactici ST3522BG and P. pentosaceus ST3633BG were evaluated as producing bacteriocin strains with high specificity against Listeria and vancomycin‐resistant Enterococcus species. In addition, both investigated Pediococcus strains were evaluated as producer of effective antifungal metabolites with potential for the inhibition of mycotoxin‐producing moulds. Significance and Impact of the Study: To the best of our knowledge, this report is a pioneer in the evaluation of Pediococcus strains isolated from silage with highly specific bacteriocinogenic antimicrobial activity against Listeria spp. and vancomycin‐resistant Enterococcus spp., and antifungal activity against mycotoxin‐producing moulds. [ABSTRACT FROM AUTHOR]

Aims: Increases in antimicrobial resistance have meant that the antimicrobial potential of lantibiotics is now being investigated irrespective of the nature of the producing organism. The aim of this study was to investigate whether natural nisin variants produced by non‐Generally Recognized as Safe (GRAS) strains, such as nisin H, nisin J and nisin P, could be expressed in a well‐characterized GRAS host. Methods and Results: This study involved cloning the nisin A promoter and leader sequence fused to nisin H, nisin J or nisin P structural gene sequences originally produced by Streptococcus hyointestinalis DPC 6484, Staphylococcus capitis APC 2923 and Streptococcusagalactiae DPC 7040, respectively. This resulted in their expression in Lactococcus lactis NZ9800, a genetically modified strain that does not produce nisin A. Conclusions: Induction of the nisin controlled gene expression system demonstrates that these three nisin variants could be acted on by nisin A machinery provided by the host strain. Significance and Impact of the Study: Describes the first successful heterologous production of three natural nisin variants by a GRAS strain, and demonstrates how such systems could be harnessed not only for lantibiotic production but also in the expansion of their structural diversity and development for use as future biotherapeutics. [ABSTRACT FROM AUTHOR]

Aims: To investigate the inhibitory activity and the distribution of biosynthetic genes encoding bovicin‐like bacteriocins among ruminal Streptococcus isolated from beef and dairy cattle. Methods and Results: Most isolates were classified as Streptococcus equinus and Streptococcus lutetiensis based on 16S rRNA sequencing. The antimicrobial activity of 150 ruminal streptococci isolated from beef and dairy cattle were tested by deferred inhibition assays and their genetic diversity was characterized by BOX‐PCR. The frequency of biosynthetic genes associated with the biosynthesis of bovicin‐like bacteriocins (bovicin HC5 and bovicin 255) was investigated by PCR screening. Approximately 33% of the ruminal streptococci isolated from Nellore heifers showed inhibitory activity in vitro with the majority harbouring genes for bacteriocin biosynthesis. In contrast, streptococci from Holstein cows showed limited inhibitory activity and a lower frequency of bacteriocin biosynthetic genes. Conclusions: Streptococcus from the rumen of beef and dairy cattle exhibit remarkable differences in inhibitory activity and distribution of genes associated with the biosynthesis of prototypical bovicins (bovicin HC5 and bovicin 255). Significance and Impact of the Study: Our findings demonstrate that bovicin HC5 is distributed among ruminal streptococci from different breeds of cattle. The high degree of conservation of the bovicin HC5 structural gene among strains of ruminal streptococci suggests that random genetic drift is not a dominant force in the evolution of this bacteriocin. [ABSTRACT FROM AUTHOR]

Aims: The objective of this study was to isolate a bacteriocin‐producing strain and to characterize the expressed bacteriocin for the control of Listeria monocytogenes with aim of biopreservation application. Methods and Results: Soil samples from a Korean organic farm were subjected to microbiological analysis for isolation of potential bacteriocinogenic LAB, based on a three‐level approach, using L. monocytogenes ATCC 15313 as an indicator test micro‐organism. From a total of 17 isolates with inhibitory potential, seven were confirmed to be bacteriocin producers. The selected isolates were differentiated based on their morphology, catalase reaction, sugar fermentation profile obtained by API50CHL and by RAPD‐PCR generating two unique profiles. One of the isolates, ST110LD, a specific strong producer of anti‐Listeria bacteriocins (12 800 AU ml−1) was identified as Leuconostoc citreum. The proteinaceous nature of the inhibitory compound produced by Leuc. citreum ST110LD was confirmed through treatment with pepsin and α‐chymotrypsin. Bacteriocin activity was observed to be not affected by the presence of milk, NaCl, SDS, Tween 80 or glycerol. Bacteriocin ST110LD effectively inhibited the growth of exponentially growing L. monocytogenes ATCC 15313 during a 10‐h incubation period in BHI at 37°C. In addition, this bacteriocin showed specific inhibition of only Listeria spp., but did not inhibit the growth of beneficial cultures included in the microbial test panel for assessment of the spectrum of activity. Conclusions: Leuconostoc citreum ST110LD was evaluated as safe bacterium strain, producing bacteriocin with high specificity against listerial and enterococcal species. Specificity of producer strain and expressed bacteriocin can be explored in biopreservation of different fermented food products or applied in biotherapy of antibiotic resistant listerial or enterococcal infections. Significance and Impact of the Study: To the best of our knowledge, this is the first report of bacteriocin produced by Leuc. citreum strain with highly specific antimicrobial activity against Listeria sp. and Enterococcus sp. [ABSTRACT FROM AUTHOR]

Aim: Bacteriocins with antimicrobial activity are considered as potential natural bio‐preservatives to control the growth of food spoilage bacteria. The aim of this work was to characterize a novel bacteriocin BM1029 discovered from Lactobacillus crustorum MN047 and evaluate its antibacterial mechanism. Methods and Results: Bacteriocin BM1029 was purified by cation‐exchange chromatography and reversed‐phase chromatography. Antibacterial activity assay showed that BM1029 is antagonistic against both Gram‐positive and Gram‐negative bacteria. Furthermore, it was found that BM1029 showed low haemolysis with high stability to the pretreatment with different temperatures, pH and surfactants. Moreover electron microscopy and flow cytometry suggested that BM1029 inhibit indicator strains by damaging the cell envelope integrity. Cell cycle assay suggested that BM1029 arrested cell cycle in R‐phase. Conclusion: The novel bacteriocin BM1029 showed high bactericidal activity against Escherichia coli and Staphylococcus aureus through a cell envelope‐associated mechanism. Significance and Impact of the Study: Application of BM1029 inhibited the growth of indicator strains on beef meat storage at 4°C suggesting that this bacteriocin is promising to be used as a novel preservative in food processing and preservation. [ABSTRACT FROM AUTHOR]

Aims: We aimed to evaluate some specific conditions for growth of Pediococcus pentosaceus ST65ACC and its bacteriocin expression through ABC transporters; to purify the bacteriocin and determine its sequence; and to evaluate the cytotoxicity potential of the purified bacteriocin(s). Methods and Results: The results presented for growth behaviour of P. pentosaceus ST65ACC showed that the bacterial growth was slightly influenced when cultured in MRS broth with different amounts of inoculum: 1, 2, 5 and 10%. The bacteriocin activity increased when 5 and 10% inocula were used. The carbon source (glucose) used in different amounts (1, 2, 3 or 4%) had no significant effect on growth and bacteriocin production. The studied strain P. pentosaceus ST65ACC was able to metabolize xylooligosaccharide (XOS) as the sole carbon source, resulting in the production of an antimicrobial peptide. The genes involved in the ABC transport system and sugar metabolism of P. pentosaceus ST65ACC were expressed at different levels. The bacteriocin produced by P. pentosaceus ST65ACC was partially purified by precipitation with ammonium sulphate (40% saturation), followed by reversed‐phase liquid chromatography, resulting in the identification of an active bacteriocin. Tandem mass spectrometry was used to identify the partial sequence KYYGNGVTCGKHSCSVDWGK sharing high similarity to coagulin A. The semi‐purified bacteriocin had low cytotoxicity based on estimated values for maximal nontoxic concentration (MNC) and cytotoxicity concentration (CC50). Conclusions: The bacteriocin produced by P. pentosaceus ST65ACC is similar to coagulin, with low cytotoxicity, strong antimicrobial activity and possible additional metabolite routes in the producer cell. In addition to MRS broth, bacteriocin was produced also in medium containing XOS (as the single carbon source). Significance and Impact of the Study: To the best of our knowledge, this is the first report of evaluation of the role of ABC transporters in the expression of bacteriocin by P. pentosaceus, cultured in MRS and XOS. [ABSTRACT FROM AUTHOR]

Aims: The control of Listeria monocytogenes biofilm formation using lactocin AL705 bacteriocin at sub‐minimum inhibitory concentrations (MICs) through an antiquorum sensing strategy, was preliminarily investigated. Methods and Results: The screening for biofilm formation of different Listeria species at 10°C allowed selecting L. monocytogenes FBUNT for its use as biofilm producer. MIC and minimum bactericidal concentration of lactocin AL705 purified extract against the pathogen was determined. Bacteriocin sub‐MICs were used to evaluate biofilm reduction. Concentrations between 2·5–20 AU ml−1 of lactocin AL705 produced significant decreases in biofilm formation without affecting the growth of the pathogen after 3 days of incubation. When bacteriocin concentrations (5–20 arbitrary units per millilitre (AU ml−1)) were investigated as quorum sensing (QS) inhibitors using Vibrio harveyi as reporter strain, a significant reduction in luminescence by lactocin AL705 (20 AU ml−1) was observed. Even when L. monocytogenes produced AI‐2 like molecules as recognized by the reporter strain, bacteriocins did not interfere with this compound. Conclusion: Antilisterial lactocin AL705 used to disrupt QS through a signal molecule inactivation was able to control L. monocytogenes FBUNT biofilm formation. Other molecule(s) different from the AI‐2 involved during biofilm formation could be acting as target of the bacteriocin. Significance and Impact of the Study: The use of bacteriocins derived from food‐grade micro‐organisms as a QS inhibition represents an effective strategy to control pathogens as well as an environmentally friendly sanitation method to mitigate postprocessing food contamination. [ABSTRACT FROM AUTHOR]

Aims: To determine the characteristics of the novel phage tail‐like bacteriocin (PTLB) produced by Stenotrophomonas maltophilia S16. Methods and Results: A screen to identify novel bacteriocins from a panel of 86 S. maltophilia strains was performed. We found that 62 tested S. maltophilia strains were sensitive to a PTLB, designated maltocin S16. In addition, 8 of 14 tested Escherichia coli strains were also susceptible to maltocin S16. Minimum inhibitory concentration determination confirmed that maltocin S16 had rather high bactericidal activity against both S. maltophilia and E. coli. Maltocin S16 was resistant to trypsin and proteinase K. Furthermore, lipopolysaccharide was found to be involved in the adsorption of maltocin S16. The gene cluster of maltocin S16 was consisted of 23 putative open reading frames. Phylogenetic analysis indicated that maltocin S16 represents a new class of PTLB in S. maltophilia. Conclusion: Maltocin S16 was a novel PTLB with broad‐spectrum and high bactericidal activity against S. maltophilia and E. coli. Significance and Impact of the Study: Stenotrophomonas maltophilia is a multidrug‐resistant opportunistic pathogen with increasing contributions to infectious disease morbidity and mortality. Maltocin S16 could be a promising alternative for antibiotics against S. maltophilia and E. coli infections. [ABSTRACT FROM AUTHOR]

Aims: The aim of this study was to characterize Lactobacillus strains for their biological properties and amensalistic activities against genital and nongenital pathogens. Methods and Results: For the purpose, some special characteristics (H2O2, biofilm and antimicrobial substances production) as well as safety properties of 112 lactobacilli were evaluated. All the strains had good amensalistic characteristics, in particular cell‐free supernatants of 10 strains showed antibacterial activity against bacteria, as well as Candida sp. Moreover, these 10 strains were excellent biofilm producers. Conclusions: These results provide evidence for the possible use as probiotics for vaginal co‐therapy in case of dysbiosis. Significance and Impact of the Study: Recently, the problem of antibiotic resistance is constantly increasing, even though resources and energy are invested in order to increase knowledge on the mechanisms of action. Bacteriocins have a rapid mechanism of action, act at extremely low concentrations, are generally sensitive to proteases and they usually have a narrow killing spectrum; these characteristics reduce the possibility of the bacterium to develop resistance. This study is focused on the feasibility of a high production of antimicrobial substances and their characterization in order to be exploited as a therapeutic alterative or in co‐therapy with antibiotics in case of vaginal dysbiosis. [ABSTRACT FROM AUTHOR]

Aims: This study aimed to explore the possibility of using the Gluconacin from Gluconacetobacter diazotrophicus strain PAL5 in the biological control of diverse sugarcane phytopathogenic bacteria. Methods and Results: An in silico analysis was first employed to determine the phylogenetic relationship between Gram‐negative/positive bacteriocin producers and Gluconacin. The analysis showed that this trait is widespread among tested bacterial species and a well‐conserved gene within the Acetobacteraceae family. The bacteriocin gene (GDI_0415) present in the genome of strain PAL5 was than cloned in pDEST™17 and expressed in Escherichia coli BL21‐AI™. A bioassay showed growth inhibition of Xanthomonas albilineans by the recombinant bacteriocin. Subsequent bioassays indicated different levels of antagonistic activity against the majority of the sugarcane phytopathogenic bacteria (Xanthomonas axonopodis pv. vasculorum, Acidovorax avenae subsp. avenae, Pseudomonas syringae pv. syringae, Xanthomonas vasicola pv. vasculorum). In addition, the bacteriocin was also antagonistic to some beneficial bacterial strains belonging to G. diazotrophicus and endophytic Bacillus species, which also colonize sugarcane plants. Conclusions: The GDI_0415 gene, responsible for the production of Gluconacin, is well conserved within the Acetobacteraceae family and presented antagonistic activity against phytopathogenic and a few beneficial sugarcane bacteria. Significance and Impact of the Study: The production of a recombinant protein, named Gluconacin, opens new avenues for the agro‐biotechnology application in agriculture, mainly with regard to the sugarcane crop. [ABSTRACT FROM AUTHOR]

Aims Characterization of the biosynthesis (secretion and immunity) of lactococcin Z. Methods and Results Lactococcin Z is produced by Lactococcus lactis QU 7. DNA sequence analysis revealed that the lactococcin Z gene cluster ( c. 5·1 kb) includes four genes encoding putative biosynthetic proteins, LczB (self-immunity protein), LczC (an ABC transporter) and LczD (a transport accessory protein), besides the previously identified LczA. LczB showed 25·5% identity to LciA, the lactococcin A immunity protein, while LczC and LczD had 93·7 and 95·3% identities, respectively, to corresponding proteins of lactococcin A. Heterologous expression of various combinations of the four genes indicated that lczB confers self-immunity against lactococcin Z, and that the four genes are necessary to produce lactococcin Z. However, LczB and LciA showed no cross-immunity to lactococcins A and Z respectively. Conclusions The results verified that LczB is the lactococcin Z immunity protein, and LczC is responsible for lactococcin Z secretion in a manner dependent on LczD expression. Significance and Impact of the Study The biosynthesis (secretion and immunity) of a new Lactococcus-specific bacteriocin, lactococcin Z, was characterized. Moreover, the results suggested that lactococcin Z has different immunity and action mechanisms from other Lactococcus-specific bacteriocins. [ABSTRACT FROM AUTHOR]

Aims To analyse the function of a putative lantibiotic gene cluster of Paenibacillus polymyxa E681 and to characterize its product, paenilan. Methods and Results Comparative analysis of the lantibiotic gene cluster of E681 revealed that the cluster, consisting of 11 open reading frames, is involved in the biosynthesis of a class I lantibiotic. The pnlA gene encoding the prepeptide PnlA was identified and P. polymyxa strain EPT14 producing only paenilan was constructed by knockout of the other five antibiotic biosynthetic gene clusters of E681. Paenilan was purified from EPT14 culture by solvent partitioning, ODS silica gel chromatography and reversed-phase preparative HPLC. The molecular mass (2510·10 Da) and structure of paenilan analysed by Nanoelectrospray ionization mass spectrometry ( MS) and MS/ MS showed that paenilan is a novel class I lantibiotic. Paenilan exhibited antimicrobial activity against Gram-positive bacteria such as Bacillus cereus, Micrococcus luteus and Paenibacillus durus. The paenilan gene is well-conserved in different Paenibacillus sp. isolated from globally distant places. Conclusions The lantibiotic gene cluster of P. polymyxa E681 was analysed and its product, a novel and useful lantibiotic named paenilan that inhibits the growth of some Gram-positive bacteria, was characterized. Significance and Impact of the Study Paenibacillus species are a good source of new lantibiotics, and the conservation of the paenilan gene among Paenibacillus sp. implies paenilan has an important function(s) for their survival. [ABSTRACT FROM AUTHOR]

Aims The aim of this study was the coproduction in a single strain of the Gram-negative bacteriocin colicin V with other bacteriocins from lactic acid bacteria (LAB). Methods and Results Colicin V was expressed in Lactococcus and Enterococcus strains by replacing the colicin V leader peptide by the leader peptide and promoter of d-alanyl- d-alanine carboxypeptidase from Lactobacillus reuteri CECT925 in pNZ8048 ( pNZ: LR-colV). The antimicrobial activity of colicin V against the indicator organism Escherichia coli DH5α in transformed strains was checked by agar diffusion assay and SDS- PAGE analysis. Conclusions Lactococcus and Enterococcus transformed with pNZ: LR-colV were able to coproduce colicin V at high levels together with other LAB bacteriocins such as nisin A, nisin Z, lacticin 481 or enterocins A and B, obtaining broad-spectrum activity strains with large potential applications. Significance and Impact of the study The construction showed in this work could be used for the heterologous expression of other bacteriocins active against Gram-negative bacteria or wide-spectrum bacteriocins from LAB. [ABSTRACT FROM AUTHOR]

Aims This study was designed to investigate the ability of naturally occurring bacteria isolated from mushroom substrate to prevent biofilm formation by Listeria monocytogenes or to remove existing biofilms in mushroom production facilities. Methods and Results It is generally recognized that L. monocytogenes forms biofilms that can facilitate its survival in food-processing environments. Eleven bacteriocin-producing isolates were identified and the bacteriocins characterized based on heat and enzyme inactivation studies. Further characterization was undertaken by MALDI- TOF mass spectrometry, PCR and sequencing. Production of nisin Z (by Lactococcus lactis isolates), subtilomycin (by Bacillus subtilis isolates) and lichenicidin (by Bacillus licheniformis and Bacillus sonorensis isolates) was detected. In co-culture with L. monocytogenes, the bacteriocin-producing strains could prevent biofilm formation and reduce pre-formed biofilms. Conclusions Mushroom substrate can be a source of bacteriocin-producing bacteria that can antagonize L. monocytogenes. Significance and Impact of the Study The results highlight the potential of bacteriocin-producing strains from mushroom substrate to reduce L. monocytogenes biofilm in food production environments, contributing to a reduction in the risk of food contamination from the environment. [ABSTRACT FROM AUTHOR]

Aims The purpose of this study was to isolate, characterize and determine the structure and the antibacterial activities of a bacteriocin produced by Carnobacterium maltaromaticum CPN, a strain isolated from unpasteurized milk Camembert cheese. Methods and Results This bacteriocin, termed maltaricin CPN, was produced at higher amounts in MRS broth at temperatures between 15°C and 25°C. It was purified to homogeneity from culture supernatant by using a simple method consisting of cation-exchange and reversed-phase chromatographies. Mass spectrometry showed that maltaricin was a 4427·29 Da bacteriocin. Its amino acid sequence was determined by Edman degradation which showed that it had close similarity with bacteriocins of the class IIa. Maltaricin CPN consisted in fact of 44 unmodified amino acids including two cysteine residues at positions 9 and 14 linked by a disulphide bond. The antimicrobial activity of maltaricin CPN covered a range of bacteria, with strong activity against many species of Gram-positive bacteria, especially the food-borne pathogen Listeria monocytogenes, but no activity against Gram-negative ones. Conclusions In the studied conditions, C. maltaromaticum CPN produced a new class IIa bacteriocin with strong anti- Listeria activity. Significance and Impact of the Study The study covers the purification and the structural characterization of a new bacteriocin produced by strain C. maltaromaticum CPN isolated from Camembert cheese. Its activity against strains of L. monocytogenes and higher production rates at relatively low temperatures show potential technological applications to improve the safety of refrigerated food. [ABSTRACT FROM AUTHOR]

Escherichia coli biofilm consists of a bacterial colony embedded in a matrix of extracellular polymeric substances (EPS) which protects the microbes from adverse environmental conditions and results in infection. Besides being the major causative agent for recurrent urinary tract infections, E. coli biofilm is also responsible for indwelling medical device-related infectivity. The cell-to-cell communication within the biofilm occurs due to quorum sensors that can modulate the key biochemical players enabling the bacteria to proliferate and intensify the resultant infections. The diversity in structural components of biofilm gets compounded due to the development of antibiotic resistance, hampering its eradication. Conventionally used antimicrobial agents have a restricted range of cellular targets and limited efficacy on biofilms. This emphasizes the need to explore the alternate therapeuticals like anti-adhesion compounds, phytochemicals, nanomaterials for effective drug delivery to restrict the growth of biofilm. The current review focuses on various aspects of E. coli biofilm development and the possible therapeutic approaches for prevention and treatment of biofilm-related infections. [ABSTRACT FROM AUTHOR]

Aims The biofilm produced by Staphylococcus aureus isolates involved in clinical or subclinical bovine mastitis and the activity of nisin and lysostaphin against the preformed biofilm produced by these strains were investigated. Methods and Results Eighteen strains were tested and all produced biofilm. Eight strains with distinct biofilm composition were selected for the antimicrobial activity assays. The minimal inhibitory concentration of each bacteriocin was determined against the planktonic cells and ranged from 15·6 to 500 μg ml−1 for nisin, and from 3·9 to 50 μg ml−1, for lysostaphin. Lysostaphin treatment (0·4 μg ml−1) for 4 h caused a strong Staph. aureus 4181 biofilm detachment and death of the majority of the sessile cells, while nisin treatment (100 μg ml−1) for the same time caused only a great reduction in cell viability. Additionally, combination of both bacteriocins for 4 h resulted in significant death of the sessile cells but no biofilm detachment. Conclusions The treatment with lysostaphin alone or in combination with nisin was effective in killing most biofilm sessile cells. Significance and Impact of the Study The action of lysostaphin, either alone or in combination with nisin, against established staphylococcal biofilm may represent an alternative to bovine mastitis control. However, the duration of the treatment should be considered for its application so that the best effectiveness can be achieved. [ABSTRACT FROM AUTHOR]

Aim: To analyse nutrition-adaptive multiple-bacteriocin production by Weissella hellenica QU 13. Methods and Results: Weissella hellenica QU 13 produces two leaderless bacteriocins, weissellicins Y and M. Their production was studied in MRS and APT media by quantification analyses with liquid chromatography mass spectrometry (LC/MS), while transcriptional analysis of biosynthetic genes was performed by real-time reverse transcription (RT)-PCR. Weissellicin Y production was higher in MRS culture than in APT culture, while weissellicin M production was higher in APT culture than in MRS culture. APT medium contains a higher amount of thiamine than MRS medium, to enhance the growth of heterofermentative lactic acid bacteria. Therefore, thiamine addition to MRS culture enhanced the growth of W. hellenica QU 13; consequently, weissellicin Y production was decreased, while weissellicin M production was not affected. Furthermore, real-time RT-PCR analyses indicated that the transcriptional trends of their respective structural genes, welY and welM, were different from each other, and that these two genes' transcriptions responded to nutrition conditions. Conclusion: Weissella hellenica QU 13 was demonstrated to control weissellicins Y and M production based on nutrition conditions. In addition, differential expression behaviour of weissellicins Y and M indicates that each of them would have separate roles to adapt to different environmental situations. Significance and Impact of the Study: This is the first report that describes nutrition-adaptive multiple-bacteriocin production, in which thiamine inhibits bacteriocin production while it enhances the growth of the producer strain. [ABSTRACT FROM AUTHOR]

Aims To investigate the safety and technological traits of previously isolated bacteriocinogenic enterococci strains for potential use as starter/adjunct cultures in foods. Methods and Results Fifty-five bacteriocinogenic enterococci strains previously isolated from different origins in Tunisia were screened for safety. Twenty-two strains did not harbour the genes coding for virulence traits, were susceptible to relevant antibiotics such as vancomycin, and tested negative for haemolysis, histamine production, gelatinase activity and DNase activity. These strains were further assessed for some technological properties, demonstrating low milk-acidifying ability, low proteolytic activity, high peptidolytic activity and diacetyl production in milk. Conclusions This study revealed that 22 bacteriocinogenic enteroccoci strains did not present virulence features and could be safely applied in food preservation. Some strains also showed good technological potential as adjunct/protective cultures in milk fermentation and cheese production. Significance and Impact of the Study This is one of very few studies that identified safe Enterococcus strains capable of producing a wide variety of enterocins against different spoilage and pathogenic micro-organisms that have good potential for application as adjunct/protective cultures in foods. [ABSTRACT FROM AUTHOR]

Aims The aim of this study was to evaluate the potential application of bacteriocins against Gram-negative bacteria when associated with others food preservation methods. Methods and Results Salmonella was subjected to heat, cold, acid and chemical (with ethylenediaminetetracetate and trisodium phosphate) stresses. Then, the cells were recovered and subjected to treatment with bacteriocins (500 AU ml−1) for 6 h. Heat and cold stress were those that promoted more sensitization to bactericidal activity of nisin. Under the same conditions, bovicin HC5 acted more rapidly than nisin reducing the number of viable cells to undetectable levels after 20 min of treatment. Similar results with use of nisin only were observed after 6 h of treatment. Conclusions Stress conditions used in food industry, such as temperature and pH, and use of chelating agents or membrane disruptors, sensitized Salmonella Typhimurium cells to bacteriocins produced by lactic acid bacteria, such as nisin and bovicin HC5. Significance and Impact of the Study Food preservation methods sensitized Gram-negative bacteria to bacteriocins activity, which demonstrate the potential of nisin and bovicin HC5 to inhibit the growth of Salmonella. [ABSTRACT FROM AUTHOR]

Aims To screen and identify wine-isolated LAB strains for bacteriocin production, and to identify and characterize bacteriocins. Methods and Results One hundred and fifty-five LAB strains isolated from South African red wines undergoing spontaneous malolactic fermentation were screened for bacteriocin production. Eight isolates were identified to be bacteriocin producers and were identified as Enterococcus faecium. All eight isolates had the same phenotypic and genotypic profiles. The peptides were preliminarily identified as enterocin P using mass spectrometry and further confirmed by PCR-amplifying enterocin P gene. The enterocin activity was inhibited by α-Chymotrypsin, papain and proteinase K treatments. It was heat stable at 37, 60, 80 and 100°C and showed activity over a broad pH range of 2-10. The production of the enterocin followed that of primary metabolite kinetics and, it showed bactericidal effect to some wine spoilage LAB strains. Conclusions Our study identified the presence of the enterocin-producing Enterococcus in wine. The enterocin was heat stable; with broad pH range and bactericidal effects to sensitive strains. Significance and Impact of the Study This is one of very few studies that isolated Enterococcus species from wine. It is, however, the first to report presence of bacteriocin-producing Enterococcus in wine fermentation. [ABSTRACT FROM AUTHOR]

Aims To assess the antimicrobial properties of lactic acid bacteria from Tunisian raw bovine milk. Methods and Results A bacteriocin-producing Enterococcus faecium strain was isolated from raw cow milk with activity against Gram-positive and Gram-negative bacteria. Antimicrobial substances produced by this strain were sensitive to proteolytic enzymes and were thermostable and resistant to a broad range of pH (2-10). Mode of action of antimicrobial substances was determined as bactericidal. Maximum activity was reached at the end of the exponential growth phase when checked against Listeria ivanovii BUG 496 (2366·62 AU ml−1). However, maximum antimicrobial activity against Pseudomonas aeruginosa 28753 was recorded at the beginning of the exponential growth phase. Enterococcus faecium GGN7 was characterized as free from virulence factors and was susceptible to tested antibiotics. PCR analysis of the micro-organism's genome revealed the presence of genes coding for enterocins A and B. Mass spectrometry analysis of RP-HPLC active fractions showed molecular masses corresponding to enterocins A (4835·77 Da) and B (5471·56 Da), and a peptide with a molecular mass of 3215·5 Da active only against Gram-negative indicator strains. The latter was unique in the databases. Conclusions Enterococcus faecium GGN7 produces three bacteriocins with different inhibitory spectra. Based on its antimicrobial properties and safety, Ent. faecium GGN7 is potentially useful for food biopreservation. Significance and Impact of the Study The results suggest the bacteriocins from GGN7 strain could be useful for food biopreservation. [ABSTRACT FROM AUTHOR]

Aims To compare the action of nisin and bovicin HC5 in combination with EDTA on Salmonella Typhimurium under different environmental conditions. Methods and Results Salmonella Typhimurium was treated in BHI broth containing EDTA (1·5 mmol l−1) and nisin or bovicin HC5 (200 AU ml−1) under different pH and temperature conditions, and according to a central composite design with two factors (temperature and pH). Cell viability was evaluated on plate count agar for 48 h. The combination of nisin or bovicin HC5 with EDTA was able to inhibit the growth of Salmonella, but the temperature and pH conditions promoting inhibition were distinct for each bacteriocin. Nisin was bactericidal over a broad range of temperature and pH, while bovicin HC5 was bacteriostatic in most conditions and bactericidal only in specific conditions ( pH >6·0 and temperature >30°C). Salmonella Typhimurium did not show tolerance to bovicin HC5 or cross-tolerance between these lantibiotics. Conclusions Nisin and bovicin HC5 both inhibited the growth of Salmonella, but the activity of each bacteriocin was differently influenced by environmental conditions. Significance and Impact of the Study Nisin and bovicin HC5 have the potential to inhibit the growth of Salmonella, but environmental conditions should be considered to establish optimal conditions for its application. [ABSTRACT FROM AUTHOR]

Aims Microcin Mcc PDI-producing Escherichia coli have a fitness advantage in dairy calves. For this project, we determined whether Mcc PDI is responsible for the in vivo fitness advantage, which is a necessary condition before Mcc PDI strains can be considered viable candidates for inhibiting pathogenic serovars of E. coli. Methods and Results Neonatal calves were coinoculated with either Mcc PDI-producing E. coli or Mcc PDI-knockout mutants in conjunction with a susceptible strain. After 6 days, the Mcc PDI-producing E. coli-25 strain clearly dominated the E. coli-186 susceptible strain in the inoculated calves ( P = 0·003). Mcc PDI-producing E. coli composed a higher log percentage of the total population of lactose-fermenting bacteria in the faeces (5·51 log CFU per 8·03 log CFU) compared with the knockout strain (2·6 log CFU per 8·23 log CFU) ( P = 0·01), and it was more consistently recovered from the lower gastrointestinal tract at the time of necropsy ( P = 0·01). Conclusion Our findings support the hypothesis that Mcc PDI is functional in vivo and it is most likely responsible for a fitness advantage in vivo. Significance and Impact of the Study Mcc PDI-producing E. coli strongly inhibit pathogenic E. coli strains in vitro. We show herein that Mcc PDI functions in vivo, and thus, these strains may be candidate probiotics against pathogenic strains of E. coli. [ABSTRACT FROM AUTHOR]

Aims To explore antibacterial activities of coagulase-negative staphylococci (Co NS) from teat apices of dairy cows towards mastitis-causing pathogens. Methods and Results Of 254 Co NS, 38 displayed bacteriocin-like activity after a first screening. Seven of these strains displayed activity against at least one mastitis-related pathogen ( Streptococcus uberis, Streptococcus dysgalactiae and Staphylococcus aureus). Staphylococcus chromogenes L217 displayed the strongest inhibitory effect, being active against all tested mastitis-related pathogens and most tested Co NS. Based on cation exchange and reversed-phase chromatography, in addition to N-terminal Edman degradation and PCR, the antibacterial peptide was identified as a nukacin-type bacteriocin and named nukacin L217. Although staphylococcal bacteriocins are generally found in the cell-free supernatants of liquid cultures, Staph. chromogenes L217 only led to detectable activity when grown on agar medium. Conclusions Bacteriocin-like activities are not uncommon among Co NS from teat apices and may inhibit mastitis-causing pathogens, as found for nukacin L217 production by Staph. chromogenes L217. Significance and Impact of the Study Nukacin L217 is the first identified bacteriocin of the species Staph. chromogenes and displays unusual production kinetics, that is, requiring surface growth of its producer. The fact that nukacins are produced by different Co NS species suggests a role in the teat skin ecosystem. [ABSTRACT FROM AUTHOR]

Aims The study aimed at determining the biochemical characteristics of the bacteriocin produced by Lactobacillus sakei MBSa1, isolated from salami, correlating the results with the genetic features of the producer strain. Methods and Results Identification of strain MBSa1 was performed by 16 S rDNA sequencing. The bacteriocin was tested for spectrum of activity, heat and p H stability, mechanism of action, molecular mass and amino acid sequence when purified by cation-exchange and reversed-phase HPLC. Genomic DNA was tested for bacteriocin genes commonly present in Lact. sakei. Bacteriocin MBSa1 was heat-stable, unaffected by pH 2·0 to 6·0 and active against all tested Listeria monocytogenes strains. Maximal production of bacteriocin MBSa1 (1600 AU ml−1) in MRS broth occurred after 20 h at 25°C. The molecular mass of produced bacteriocin was 4303·3 Da, and the molecule contained the SIIGGMISGWAASGLAG sequence, also present in sakacin A. The strain contained the sakacin A and curvacin A genes but was negative for other tested sakacin genes (sakacins T- α, T- β, X, P, G and Q). Conclusions In the studied conditions, Lact. sakei MBSa1 produced sakacin A, a class II bacteriocin, with anti- Listeria activity. Significance and Impact of the Study The study covers the purification and characterization of the bacteriocin produced by a lactic acid bacteria isolated from salami ( Lact. sakei MBSa1), linking genetic and expression information. Its heat-resistance, p H stability in acid conditions (p H 2·0-6·0) and activity against L. monocytogenes food isolates bring up a potential technological application to improve food safety. [ABSTRACT FROM AUTHOR]

Aim Evaluate technologically relevant properties from bacteriocin-producing strains to use as starter/adjunct cultures in cheese making. Methods and Results Eight isolates obtained from Pico cheese produced in Azores ( Portugal) were found to produce bacteriocins against Listeria monocytogenes and three isolates against Clostridium perfringens. They were identified as Lactococcus lactis and Enterococcus faecalis and submitted to technological tests: growth at different conditions of temperature and salt, acid production, proteolysis, lipolysis, coexistence, enzymatic profile and autolytic capacity. Safety evaluation was performed by evaluating haemolytic, gelatinase and DNase activity, resistance to antibiotics and the presence of virulence genes. Some isolates presented good technological features such as high autolytic activity, acid and diacetyl production. Lactococcus lactis was negative for all virulence genes tested and inhibit the growth of all Lactic acid bacteria ( LAB) isolates. Enterococci were positive for the presence of some virulence genes, but none of the isolates were classified as resistant to important antibiotics. Conclusions The bacteriocin-producing Lc. lactis present good potential for application in food as adjunct culture in cheese production. The study also reveals good technological features for some Enterococcus isolates. Significance and Impact of the Study Bacteriocin-producing strains presented important technological properties to be exploited as new adjunct culture for the dairy industry, influencing flavour development and improve safety. [ABSTRACT FROM AUTHOR]

Aim To isolate and characterize bacteriocin, licheniocin 50.2, from soil bacteria identified as Bacillus licheniformis. Methods and Results The strain B. licheniformis VPS50.2 was identified as bacteriocin producer, effective against Gram-positive bacteria, including Listeria monocytogenes, methicillin-resistant Staphylococcus aureus ( MRSA) and β-haemolytic streptococci. The start of bacteriocin production coincides with the beginning of sporulation. Ammonium sulfate precipitation, chloroform extraction and ultrafiltration were used for bacteriocin purification. MALDI TOF/ TOF mass spectrometry of purified sample detected the protein with molecular mass of 3253·209 Da. N-terminal sequencing recognized first 15 amino acids with the sequence: W E E Y N I I X Q L G N K G Q. We named the newly characterized bacteriocin as subclass II.3 bacteriocin, licheniocin 50·2. The bacteriocin activity was insensitive to lysozyme and proteinase K, heat stable after incubation at 100°C for 30 min and over wide range of p H (2-12). MICs of crude bacteriocin extract were determined for L. monocytogenes and MRSA. Time-kill study showed that licheniocin had bactericidal effect to L. monocytogenes. Conclusion A novel, thermostable, p H-tolerant bacteriocin active against Gram-positive bacteria was isolated. Significance and Impact of the Study Attributes of new, stable licheniocin 50.2 make it a promising agent for application as biopreservative in food industry. [ABSTRACT FROM AUTHOR]

Aims Purification and characterization of a novel bacteriocin produced by strain Enterococcus faecium D081821. Methods and Results Enterococcus faecium D081821, isolated from the traditional Taiwanese fermented food dochi (fermented black beans), was previously found to produce a bacteriocin against Listeria monocytogenes and some Gram-positive bacteria. This bacteriocin, termed enterocin TW21, was purified from culture supernatant by ammonium sulfate precipitation, Sep- Pak C18 cartridge, ion-exchange and gel filtration chromatography. Mass spectrometry analysis showed the mass of the peptide to be approximately 5300·6 Da. The N-terminal amino acid sequencing yielded a partial sequence NH2- ATYYGNGVYx NTQK by Edman degradation, and it contains the consensus class IIa bacteriocin motif YGNGV in the N-terminal region. The open reading frame ( ORF) encoding the bacteriocin was identified from the draft genome sequence of Enterococcus faecium D081821, and sequence analysis of this peptide indicated that enterocin TW21 is a novel bacteriocin. Conclusions Enterococcus faecium D081821 produced a bacteriocin named enterocin TW21, the molecular weight and amino acid sequence both revealed it to be a novel bacteriocin. Significant and Impact of Study A new member of class IIa bacteriocin was identified. This bacteriocin shows great inhibitory ability against L. monocytogenes and could be applied as a natural food preservative. [ABSTRACT FROM AUTHOR]

Aim The current study aimed to visualize the damage caused by enterolysin A to the cells of sensitive strains and to find out cleavage site within the peptidoglycan moiety of bacterial cell walls. Methods and Results Enterolysin A produced by a local isolate, Enterococcus faecalis B9510 was found to rapidly kill cells of the sensitive strain Lactococcus lactis ssp. cremoris 2144 during 120 min of treatment as compared to the untreated control where no such effect was observed. Transmission electron microscopy of the enterolysin A-treated cells revealed leaking of the cytoplasmic contents ultimately resulting in complete lysis of cell walls. To find the cleavage site, purified cell walls of L. lactis ssp. cremoris 2144, Pediococcus pentosaceus 43201 and Lactobacillus delbrueckii ssp. bulgaricus ATCC 11842 were treated with enterolysin A, and liberated amino acids were derivatized for N and C terminals and analysed using thin layer chromatography on silica gel with isopropanol as solvent. The results showed that enterolysin A cleaves the peptide bonds at two locations within peptidoglycan subunits. The first location is between L-alanine and D-glutamic acid of the stem peptide and the other location is between L-lysine of the stem peptide and D-aspartic acid of the interpeptide bridge. Conclusions Enterolysin A cleaves the peptide bonds within the stem peptide as well as in the interpeptide bridge of Gram-positive bacterial cell walls. This gives a possible reason for the broad spectrum of enterolysin A activity. Significance and Impact of the Study This is the first report identifying the cleavage site of enterolysin A within the cell walls of sensitive bacteria. This will help in identifying potential applications for enterolysin A. [ABSTRACT FROM AUTHOR]

Aim To characterize novel multiple bacteriocins produced by Lactobacillus sakei D98. Methods and Results Lactobacillus sakei D98 isolated from Shubo (rice malt) produced at least three bacteriocins. Using three purification steps, three novel antimicrobial peptides termed sakacin D98a, sakacin D98b and sakacin D98c were purified from the culture supernatant. Amino acid and DNA sequencing analysis revealed that the sakacins D98a, D98b and D98c are novel class IIa-like or class IId bacteriocins. In particular, sakacin D98b has a variant pediocin-box sequence, YANGVXC (with Ala instead of Gly), and a different location for the disulfide bridge (Cys11 and Cys18) from that found in other class IIa bacteriocins. Conclusions Three novel bacteriocins were identified from Lactobacillus sakei D98. Their antimicrobial spectra and intensities indicate that these sakacins would have different modes of action. In addition, sakacin D98b showed low inhibitory activity against Listeria, probably due to the differences in amino acids and position of the disulfide bridge compared with the other class IIa bacteriocins. Significance and Impact of Study Sakacins D98a and D98c are novel bacteriocins belonging to class IId bacteriocins. On the other hand, sakacin D98b, a class IIa-like bacteriocin, has a unique internal structure and activity spectrum. [ABSTRACT FROM AUTHOR]

Aim To identify and characterize novel bacteriocins from Weissella hellenica 4-7. Methods and Results Weissella hellenica 4-7, isolated from the traditional Taiwanese fermented food sian-sianzih (fermented clams), was previously found to produce a bacteriocin active against Listeria monocytogenes and some other Gram-positive bacteria. Bacteriocin activity decreased slightly after autoclaving (121°C for 15 min), but was inactivated by protease K and trypsin. Mass spectrometry analysis revealed the bacteriocin mass to be approximately 3205·6 Da. N-terminal amino acid sequencing yielded a partial sequence, NH2- KGFLSWASKATSWLVGP, by Edman degradation. The obtained partial sequence showed high homology with leucocin B- TA33a; however, at least two different residues were observed. No identical peptide or protein was found, and this peptide was therefore considered to be a novel bacteriocin produced by W. hellenica 4-7 and termed weissellicin L. Conclusions The findings obtained in the current study suggest a novel bacteriocin produced by W. hellenica 4-7. Significance and Impact of the Study Bacteriocins from Weissella remain rare, and this study is the second report of a bacteriocin produced by W. hellenica. [ABSTRACT FROM AUTHOR]

Aims To purify and primarily characterize an anti- Alicyclobacillus bacteriocin produced by Bifidobacterium animalis subsp. animalis CICC 6165, suggested to be named bificin C6165. Methods and Results During purification of the bificin C6165, optimal recovery was achieved with ammonium sulfate precipitation followed by two chromatographic steps. Mass spectrometry analyses revealed a distinctive peak corresponding to a molecular mass of 3395·1 Da. This bacteriocin was heat stable, effective after refrigerated storage and freeze-thaw cycles. The primary mode of action of bificin C6165 is most probably due to pore formation, as indicated by the efflux of K+ from metabolically active cells of Alicyclobacillus acidoterrestris. In the presence of 10 mmol l−1 gadolinium, bificin C6165 did not affect cells of Alicyclobacillus acidoterrestris. This suggests that the mode of action of bificin C6165 relies on a net negatively charged cell surface. Conclusions Bificin C6165 is indeed a novel bacteriocin and it exhibited remarkable potency for Alicyclobacillus control. Significance and Impact of the Study Application of bacteriocins in preservation of fruit juices has seldom been studied. Bificin C6165 may be an alternative method to control juice spoilage by this Alicyclobacillus acidoterrestris and meet increasing consumer demand for nature and artificial chemical additive-free food products. [ABSTRACT FROM AUTHOR]

Aim This study aimed to develop a simplified chemically defined medium that could sustain the growth and bacteriocin (enterolysin A) production by Enterococcus faecalis B9510. Methods and Results The nutritional requirements of E. faecalis B9510 in a chemically defined medium were determined by single omission experiments. It was observed that eight amino acids (arginine, glycine, histidine, isoleucine, leucine, methionine, tryptophan and valine), three B vitamins (nicotinic acid, Ca-pantothenic acid and pyridoxal) and magnesium sulphate were essential for growth. Based on this information, a Simplified Defined Medium ( SDM) was formed consisting of 26 components. Comparison of SDM with M-17 showed that growth and bacteriocin production in SDM was similar to that in M-17. The bacteriocin from SDM was then purified by ultrafiltration. The retentate of ultrafiltration step was analysed by SDS- PAGE and the results showed a single active band in the gel, which was excised and analysed by mass spectrometry, which indicated that the active band was enterolysin A, a cell wall degrading bacteriocin. Conclusions A simplified defined medium can be formulated for the growth and bacteriocin production by Enterococcus faecalis, whose efficiency is comparable with that of a complex commercial medium. Significance and Impact of the Study The development of such a medium can be useful for bacteriocin production and subsequent purification in a simplified manner and, therefore, helpful in the identification of novel bacteriocins. [ABSTRACT FROM AUTHOR]

Aim To isolate and characterize bacteriocin, BL8, from the bacteria identified as Bacillus licheniformis from marine environment. Methods and Results One-hundred and twelve bacterial isolates from sediment and water samples collected off the coast of Cochin, India, were screened for antibacterial activity. Strain BTHT8, identified as Bacillus licheniformis, inhibited the growth of Gram-positive test organisms. The active component labelled as bacteriocin BL8 was partially purified by ammonium sulphate fractionation and was subjected to glycine SDS-PAGE. The band exhibiting antimicrobial activity was electroeluted and analysed using MALDI-TOF mass spectrometry, and the molecular mass was determined as 1·4 kDa. N-terminal amino acid sequencing of BL8 gave a 13 amino acid sequence stretch. Bacteriocin BL8 was stable even after boiling at 100°C for 30 min and over a wide pH range of 1-12. Conclusion A novel, pH-tolerant and thermostable bacteriocin BL8, active against the tested Gram-positive bacteria, was isolated from Bacillus licheniformis. Significance and Impact of the Study This study reports a stable, low molecular weight bacteriocin from Bacillus licheniformis. This bacteriocin can be used to address two important applications: as a therapeutic agent and as a biopreservative in food processing industry. [ABSTRACT FROM AUTHOR]

Aims To isolate and characterize bacteriocins produced by predominant species of lactic acid bacteria from faeces of elderly subjects. Methods and Results Screening over 70 000 colonies, from faecal samples collected from 266 subjects, using the indicator organisms Lactobacillus bulgaricus LMG 6901 and Listeria innocua DPC 3572, identified 55 antimicrobial-producing bacteria. Genomic fingerprinting following ApaI digestion revealed 15 distinct strains. The antimicrobial activities associated with 13 of the 15 strains were sensitive to protease treatment. The predominant antimicrobial-producing species were identified as Lactobacillus salivarius, Lactobacillus gasseri, Lactobacillus acidophilus, Lactobacillus crispatus and Enterococcus spp. A number of previously characterized bacteriocins, including ABP-118 and salivaricin B (from Lact. salivarius), enterocin B ( Enterococcus faecium), lactacin B ( Lact. acidophilus), gassericin T and a variant of gassericin A ( Lact. gasseri), were identified. Interestingly, two antimicrobial-producing species, not generally associated with intestinally derived microorganisms were also isolated: Lactococcus lactis producing nisin Z and Streptococcus mutans producing mutacin II. Conclusion These data suggest that bacteriocin production by intestinal isolates against our chosen targets under the screening conditions used was not frequent (0·08%). Significance and Impact of the Study The results presented are important due to growing evidence indicating bacteriocin production as a potential probiotic trait by virtue of strain dominance and/or pathogen inhibition in the mammalian intestine. [ABSTRACT FROM AUTHOR]

Aim To isolate and characterize bacteriocin-like inhibitory substance ( BLIS)-producing lactic acid bacteria from the intestine of grey mullet. Methods and Results Inhibitory activity against at least one or more indicator strains was observed in one Enterococcus thailandicus, one Enterococcus faecium and two Lactococcus garvieae strains. Enterococcus faecium B3-8 and Ent. thailandicus B3-22 showed the greatest inhibitory activities against Listeria monocytogenes ATCC 19111 and were therefore further characterized. The results suggested that the inhibitory substances from the two strains showed similar characteristics with respect to sensitivity to heat and proteolytic enzymes. BLIS from Ent. thailandicus B3-22 was characterized by a broader inhibitory spectrum than that from Ent. faecium B3-8. SDS- PAGE revealed that the molecular size of partially purified BLISs from Ent. faecium B3-8 and Ent. thailandicus B3-22 was c. 5 and 3 kDa, respectively. The molecular mass of purified bacteriocin from Ent. thailandicus B3-22 was further determined to be 6319 Da by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry ( MALDI- TOF MS). The results indicated that BLIS from Ent. thailandicus B3-22 can effectively inhibit the growth of all tested L. garvieae strains. Conclusions The findings obtained in this study suggest the potential use of Ent. thailandicus B3-22 as a biocontrol agent against pathogenic L. garvieae in the aquaculture. Significance and Impact of the Study This is the first report describing the characteristics of BLIS from Ent. thailandicus that showed potential for use as a biocontrol agent in the aquaculture. [ABSTRACT FROM AUTHOR]

Aim To identify enterococci from the fermentation of milk for the production of nono, an African fermented dairy product, to determine the technological properties for suitability as starter cultures and safety as probiotics. Methods and Results Enterococcus faecium CM4 and Enterococcus faecium 2 CM1 were isolated from raw cow's milk. The strains were phenotypically and genotypically identified. Technological properties, safety investigations, in vitro adherence properties and antimicrobial characteristics were carried out. Strong acidification and tolerance to bile salts were recorded. The strains were bile salts hydrolytic positive and no haemolysis. There was no resistance to clinically relevant antibiotics. The strains exhibited adherence to human collagen type IV, human fibrinogen and fibronectin. The bacteriocins were active against Bacillus cereus DSM 2301, Bacillus subtilis ATCC 6633, Micrococcus luteus and Listeria monocytogenes. Bacteriocins were stable at pH 4-9 and on treatment with lipase, catalase, α-amylase and pepsin, while their activity was lost on treatment with other proteases. The bacteriocins produced were heat stable at 100°C for 10 min. The bacteriocin produced by the strains was identified as enterocin A. Conclusions The E. faecium strains in this study exhibited probiotic activity, and the safety investigations indicate their suitability as good candidates for a starter culture fermentation process. Significance and Impact of the Study The use of bacteriocin-producing E. faecium strains as starter cultures in fermented foods is beneficial but, however, their safety investigations as probiotics must be greatly emphasized. [ABSTRACT FROM AUTHOR]

Because of the emergence of antibiotic-resistant pathogens worldwide, a number of infectious diseases have become difficult to treat. This threatening situation is worsened by the fact that very limited progress has been made in developing new and potent antibiotics in recent years. However, a group of antimicrobials, the so-called bacteriocins, have been much studied lately because they hold a great potential in controlling antibiotic-resistant pathogens. Bacteriocins are small antimicrobial peptides (AMPs) produced by numerous bacteria. They often act toward species related to the producer with a very high potency (at pico- to nanomolar concentration) and specificity. The common mechanisms of killing by bacteriocins are destruction of target cells by pore formation and/or inhibition of cell wall synthesis. Several studies have revealed that bacteriocins display great potential in the medical sector as bacteriocinogenic probiotics and in the clinic as therapeutic agents. In this review, we discuss the emerging antibiotic resistance and strategies to control its dissemination, before we highlight the potential of AMPs from bacteria as a new genre of antimicrobial agents. [ABSTRACT FROM AUTHOR]