Bacteriocins: Biological tools for bio-preservation and shelf-life extension

Combating antibiotic resistance in a one health context: a plethora of frontiers

One of the most significant medical advancements of the 20th century was the discovery of antibiotics, which continue to play a vital tool in the treatment and prevention of diseases in humans and animals. However, the imprudent use of antibiotics in all fields of One-Health and concerns about antibiotic resistance among bacterial pathogens have raised interest in antibiotic use restrictions on a global scale. Despite the failure of conventional antimicrobial agents, only about 15 new antibiotics have been introduced clinically since year 2000 to date. Moreover, there has been reports of resistance to some of these new antibiotics. This has necessitated a need to search for alternative strategies to combat antimicrobial resistant pathogens. Thus, this review compiles and evaluates the approaches-natural compounds, phage treatment, and nanomaterials-that are being used and/or suggested as the potential substitutes for conventional antibiotics.

Fermentation starters and bacteriocins as biocontrol strategies for table olives preservation: a mini-review

Biopreservation is a powerful strategy to prolong the shelf life of food products by applying naturally occurring microorganisms and/or their metabolites. Current food trends emphasise the need to develop alternatives for chemical or thermal preservation methods. In this line, different fermentation starters from table olives present the potential to control spoilage or pathogen-occurring microorganism in table olives storage. One of the most interesting family used as biopreservative culture is Lactobacillaceae and it has also been used in combination with yeasts as olive fermentation starter. Lactic acid bacteria, from Lactobacillaceae family, are characterised by the production of bacteriocins, proteins with the potential for preserving food by changing the organisation of the membrane of spoilage microorganisms. These bacteriocins-producing bacteria can be directly inoculated, although nanosystem technology is the most promising incorporation strategy. In table olives, the most commonly used starters are Lactiplantibacillus plantarum, Lactiplantibacillus pentosus, Saccharomyces cerevisiae, Wickerhamomyces anomalus, among others. These strains with biopreservation characteristics, inoculated alone or in mixed cultures, ensure food safety by conferring the product added value and prolonging product shelf life. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Influence of different culture media on the antimicrobial activity of Pediococcus pentosaceus ST65ACC against Listeria monocytogenes

Pediococcus pentosaceus ST65ACC is a bacteriocinogenic lactic acid bacteria (LAB) isolated from Brazilian artisanal cheese that is capable of inhibiting different food pathogens, mainly Listeria monocytogenes. The production of bacteriocins can be influenced by several growth conditions, such as temperature, pH, and medium composition. This study aimed to evaluate the effect of different culture media on the production of bacteriocins and antimicrobial activity of P. pentosaceus ST65ACC on L. monocytogenes Scott A. The strains were inoculated alone and in coculture in four different media: BHI broth, MRS broth, meat broth, and reconstituted skim milk (RSM) 10% (w/v). The culture media were then incubated at 37 °C for 96 h, and count analysis, pH measurement, and bacteriocin production were performed at 0, 24, 48, 72 and 96 h. L. monocytogenes was inhibited to nondetectable levels in coculture with P. pentosaceus ST65ACC in MRS broth within 96 h, consistent with the high production of bacteriocin throughout the analysis period (3,200-12,800 AU/mL). However, lower inhibitory activities of P. pentosaceus ST65ACC on L. monocytogenes Scott A were recorded in BHI, RSM, and meat broth, with low or no production of bacteriocins at the analyzed times. The composition of these culture media may have repressed the production and activity of bacteriocins and, consequently, the antagonist activity of P. pentosaceus ST65ACC on L. monocytogenes Scott A. The results showed that the antimicrobial activity was more effective in MRS broth, presenting greater production of bacteriocins and less variability when compared to the other media analyzed.

Genomic Modifications of Lactic Acid Bacteria and Their Applications in Dairy Fermentation

Lactic Acid Bacteria (LAB) have a long history of safe use in milk fermentation and are generally recognized as health-promoting microorganisms when present in fermented foods. LAB are also important components of the human intestinal microbiota and are widely used as probiotics. Considering their safe and health-beneficial properties, LAB are considered appropriate vehicles that can be genetically modified for food, industrial and pharmaceutical applications. Here, this review describes (1) the potential opportunities for application of genetically modified LAB strains in dairy fermentation and (2) the various genomic modification tools for LAB strains, such as random mutagenesis, adaptive laboratory evolution, conjugation, homologous recombination, recombineering, and CRISPR (clustered regularly interspaced short palindromic repeat)- Cas (CRISPR-associated protein) based genome engineering. Lastly, this review also discusses the potential future developments of these genomic modification technologies and their applications in dairy fermentations.

Biosynthesis, classification, properties, and applications of Weissella bacteriocins

This review aims to comprehensively chronicle the biosynthesis, classification, properties, and applications of bacteriocins produced by Weissella genus strains, particularly emphasizing their potential benefits in food preservation, human health, and animal productivity. Lactic Acid Bacteria (LAB) are a class of microorganisms well-known for their beneficial role in food fermentation, probiotics, and human health. A notable property of LAB is that they can synthesize antimicrobial peptides known as bacteriocins that exhibit antimicrobial action against both closely related and other bacteria as well. Bacteriocins produced by Weissella spp. are known to exhibit antimicrobial activity against several pathogenic bacteria including food spoilage species, making them highly invaluable for potential application in food preservation and food safety. Importantly, they provide significant health benefits to humans, including combating infections, reducing inflammation, and modulating the gut microbiota. In addition to their applications in food fermentation and probiotics, Weissella bacteriocins show promising prospects in poultry production, processing, and improving animal productivity. Future research should explore the utilization of Weissella bacteriocins in innovative food safety measures and medical applications, emphasizing their potential to combat antibiotic-resistant pathogens, enhance gut microbiota composition and function, and synergize with existing antimicrobial therapies.

Discovering Potential Bacteriocins Against Pseudomonas fragi: a Subtractive Proteomics and Molecular Dynamic Simulation Study for Food Preservation

Food preservation is a schematic and scientific procedure employed for the maintenance and improvement of food's quality, shelf life, and nutritional value. Although, on one hand, ancient conventional methods such as freezing, pasteurization, canning, and chemical methods have the potential to lengthen the shelf life of edible substances, but on the other hand, they can deteriorate its nutritional value as well. Present research focuses on the identification of promising bacteriocins against Pseudomonas fragi via subtractive proteomics pipeline as an alternative approach for food preservation. Bacteriocins are small peptides produced by certain microbes to naturally defend themselves by destroying other closely related bacteria residing in their neighborhood. P. fragi lies among the most notable microbes responsible for the elicitation of food spoilage. Due to increasing emergence and prevalence of multidrug resistance bacteria, there is a need to unravel novel drug targets, crucially involved in food decay process. Based on subtractive scrutinization, UDP-N-acetylglucosamine O-acyltransferase (LpxA) was chosen as promising therapeutic protein target that could play a significant role in progression of food spoilage. Subtilosin A, thuricin-CD, and mutacin B-NY266 were found as the most robust inhibitors of LpxA according to the molecular docking assay results. Molecular dynamic simulations and binding energy calculations via MM/PBSA method of LpxA and three top hit docked complexes, i.e., LpxA-subtilosin A, LpxA-thuricin-CD, and LpxA-mutacin B-NY266, revealed stability throughout simulations and ensured that shortlisted bacteriocins had strong affinity for LpxA.

Bacteriocins: potentials and prospects in health and agrifood systems

Bacteriocins are highly diverse, abundant, and heterogeneous antimicrobial peptides that are ribosomally synthesized by bacteria and archaea. Since their discovery about a century ago, there has been a growing interest in bacteriocin research and applications. This is mainly due to their high antimicrobial properties, narrow or broad spectrum of activity, specificity, low cytotoxicity, and stability. Though initially used to improve food quality and safety, bacteriocins are now globally exploited for innovative applications in human, animal, and food systems as sustainable alternatives to antibiotics. Bacteriocins have the potential to beneficially modulate microbiota, providing viable microbiome-based solutions for the treatment, management, and non-invasive bio-diagnosis of infectious and non-infectious diseases. The use of bacteriocins holds great promise in the modulation of food microbiomes, antimicrobial food packaging, bio-sanitizers and antibiofilm, pre/post-harvest biocontrol, functional food, growth promotion, and sustainable aquaculture. This can undoubtedly improve food security, safety, and quality globally. This review highlights the current trends in bacteriocin research, especially the increasing research outputs and funding, which we believe may proportionate the soaring global interest in bacteriocins. The use of cutting-edge technologies, such as bioengineering, can further enhance the exploitation of bacteriocins for innovative applications in human, animal, and food systems.

Genome-Based Identification and Characterization of Bacteriocins Selectively Inhibiting Staphylococcus aureus in Fermented Sausages

The bacteriocin-producing Lactiplantibacillus plantarum SL47 was isolated from conventional fermented sausages, and the bacteriocin SL47 was purified using ethyl acetate, Sephadex G-25 gel chromatography, and reversed-phase high-performance liquid chromatography (RP-HPLC). Bacteriocin SL47 was identified by HPLC-MS/MS combined with whole-genome sequencing, and the results showed it consisted of plantaricin A, J, K, and N. Further characterization analysis showed that the bacteriocin SL47 was highly thermostable (30 min, 121 °C), pH stable (2-10), sensitive to protease and exhibited broad-spectrum antibacterial ability against Gram-positive and Gram-negative bacteria. The mechanism of action showed that the bacteriocin SL47 increased cell membrane permeability, and 2 × minimum inhibitory concentration (MIC) treatment for 40 min caused apoptosis of Staphylococcus aureus F2. The count of S. aureus in the sausage that was inoculated with L. plantarum SL47 and bacteriocin SL47 decreased by about 64% and 53% of that in the initial stage, respectively. These results indicated the potential of L. plantarum SL47 and bacteriocin SL47 as a bio-preservative in meat products.

Automated workflow for characterization of bacteriocin production in natural producers Lactococcus lactis and Latilactobacillus sakei

BACKGROUND

Lactic acid bacteria are commonly used as protective starter cultures in food products. Among their beneficial effects is the production of ribosomally synthesized peptides termed bacteriocins that kill or inhibit food-spoiling bacteria and pathogens, e.g., members of the Listeria species. As new bacteriocins and producer strains are being discovered rapidly, modern automated methods for strain evaluation and bioprocess development are required to accelerate screening and development processes.

RESULTS

In this study, we developed an automated workflow for screening and bioprocess optimization for bacteriocin producing lactic acid bacteria, consisting of microcultivation, sample processing and automated antimicrobial activity assay. We implemented sample processing workflows to minimize bacteriocin adsorption to producer cells via addition of Tween 80 and divalent cations to the cultivation media as well as acidification of culture broth prior to cell separation. Moreover, we demonstrated the applicability of the automated workflow to analyze influence of media components such as MES buffer or yeast extract for bacteriocin producers Lactococcus lactis B1629 and Latilactobacillus sakei A1608.

CONCLUSIONS

Our automated workflow provides advanced possibilities to accelerate screening and bioprocess optimization for natural bacteriocin producers. Based on its modular concept, adaptations for other strains, bacteriocin products and applications are easily carried out and a unique tool to support bacteriocin research and bioprocess development is provided.

MassArray Genotyping as a Selection Tool for Extending the Shelf-Life of Fresh Gilthead Sea Bream and European Seabass

In modern aquaculture, genomics-driven breeding programs have emerged as powerful tools for optimizing fish quality. This study focused on two emblematic Mediterranean fish species, the European seabass (Dicentrarchus labrax) and the gilthead sea bream (Sparus aurata), with a primary aim of exploring the genetic basis of white muscle/fillet degradation in fresh fish following harvest. We identified 57 and 44 missense SNPs in gilthead sea bream and European seabass, respectively, located within genes encoding for endogenous proteases responsible for fillet quality. These SNPs were cherry-picked based on their strategic location within the catalytic/regulatory domains of endogenous proteases that are expressed in the white muscle. Using MassArray technology, we successfully associated differentiated enzymatic activity of those endogenous proteases post-harvest as a phenotypic trait with genetic polymorphism of six SNPs in gilthead sea bream and nine in European seabass. These findings can be valuable attributes in selective breeding programs toward the extension of freshness and shelf life of these species. The integration of MassArray technology into breeding programs offers a cost-effective strategy for harnessing the potential of these genetic variants to enhance the overall quality of the final product. Recognizing that fresh fish perishability is a challenge, extending shelf-life is pivotal in reducing losses and production costs.

Biocontrol of L. monocytogenes with Selected Autochthonous Lactic Acid Bacteria in Raw Milk Soft-Ripened Cheese under Different Water Activity Conditions

The effect of selected autochthonous Lactic Acid Bacteria (LAB) against Listeria monocytogenes was evaluated in two elaborations of soft-ripened cheese performed under high and low relative humidity (RH) elaborations, to achieve aw ranging from 0.97 to 0.94 in ripened cheeses. Two selected autochthonous strains of Lacticaseibacillus casei 31 and 116 were used. In each elaboration, 8 batches were physicochemically and microbiologically evaluated throughout the ripening process. The aw and pH decreased during ripening to final values ranging from 0.944 to 0.972 aw and 5.0 to 5.3 pH, respectively. LAB was the only microbial group that increased throughout the ripening in high and low RH elaborations. In batches that were uninoculated with LAB strains, L. monocytogenes was either maintained at the initial inoculation level or showed a slight reduction by the end of the ripening process. However, in LAB-inoculated batches in the two elaborations, steady decreases of L. monocytogenes were observed throughout maturation. L. casei 31 alone or in combination with strain 116 provoked reductions of 2 to 4 log CFU/g in L. monocytogenes over 60 days of ripening, which could be enough as a strategy for biocontrol to deal with the usual contamination by L. monocytogenes during cheese processing.

Nisin Purification from a Cell-Free Supernatant by Electrodialysis in a Circular Economy Framework

Nisin, an antimicrobial peptide produced by Lactococcus lactis strains, is a promising natural preservative for the food industry and an alternative to antibiotics for the pharmaceutical industry against Gram-positive bacteria. Nisin purification is commonly performed using salting out and chromatographic techniques, which are characterized by their low yields, the use of solvents and the production of large volumes of effluents. In the present work, the purification of nisin from a cell-free supernatant (CFS), after the production of nisin by fermentation on a whey permeate medium, was studied using ammonium sulfate precipitation and electrodialysis (ED) as a promising eco-friendly process for nisin purification. Results showed an increase in nisin precipitation using a 40% ammonium sulfate saturation (ASS) level with a purification fold of 73.8 compared with 34.5 and no purification fold for a 60% and 20% ASS level, respectively. The results regarding nisin purification using ED showed an increase in nisin purification and concentration fold, respectively, of 21.8 and 156 when comparing the final product to the initial CFS. Nisin-specific activity increased from 75.9 ± 4.4 to 1652.7 ± 236.8 AU/mg of protein. These results demonstrated the effectiveness of ED coupled with salting out for nisin purification compared with common techniques. Furthermore, the process was noteworthy for its relevance in a circular economy scheme, as it does not require any solvents and avoids generating polluting effluents. It can be employed for the purification of nisin and the recovery of salts from salting out, facilitating their reuse in a circular economy.

Bioactive Ingredients from Dairy-Based Lactic Acid Bacterial Fermentations for Functional Food Production and Their Health Effects

Lactic acid bacteria are traditionally applied in a variety of fermented food products, and they have the ability to produce a wide range of bioactive ingredients during fermentation, including vitamins, bacteriocins, bioactive peptides, and bioactive compounds. The bioactivity and health benefits associated with these ingredients have garnered interest in applications in the functional dairy market and have relevance both as components produced in situ and as functional additives. This review provides a brief description of the regulations regarding the functional food market in the European Union, as well as an overview of some of the functional dairy products currently available in the Irish and European markets. A better understanding of the production of these ingredients excreted by lactic acid bacteria can further drive the development and innovation of the continuously growing functional food market.

Control of the Growth of Listeria monocytogenes in Cooked Ham through Combinations of Natural Ingredients

In the ready-to-eat food industry, Listeria control is mandatory to ensure the food safety of the products since its presence could cause a disease called listeriosis. The objective of the present study was to carry out a challenge test to verify the efficiency of different combinations of natural antimicrobial ingredients against Listeria monocytogenes to be used in ready-to-eat foods. Six different formulations of cooked ham were prepared: a control formulation and five different formulations. An initial inoculation of 2 log cycles was used in the different products, and the growth of Listeria was monitored at different temperatures and times (4 °C for 17 w and 7 °C for 12 w). Control samples showed a progressive growth, reaching 5-6 log after 3 or 4 weeks. The rest of the samples showed constant counts of Listeria during the entire study. Only samples containing 100 ppm nitrite + 250 PPM ascorbic acid + 0.7% PRS-DV-5 did not control the growth of Listeria at 7 °C after 7 w of storage. The results obtained allowed us to classify the cooked ham prepared using natural ingredient combinations as a "Ready-to-eat food unable to support the growth of L. monocytogenes other than those intended for infants and for special medical purposes".

Phenotypic and genomic analyses of bacteriocin-producing probiotic Enterococcus faecium EFEL8600 isolated from Korean soy-meju

Enterococcus faecium is a prevalent species found in fermented soybean products, known for its contributions to flavor development and inhibition of pathogenic microorganisms during fermentation. This study aims to provide comprehensive phenotypic and genomic evidence supporting the probiotic characteristics of E. faecium EFEL8600, a bacteriocin-producing strain isolated from Korean soy-meju. Phenotypic analysis revealed that EFEL8600 produced a peptide with inhibitory activity against Listeria monocytogenes, estimated to be 4.6 kDa, corresponding to the size of enterocins P or Q. Furthermore, EFEL8600 exhibited probiotic traits, such as resilience in gastrointestinal conditions, antioxidant and anti-inflammatory activities, and protection of the intestinal barrier. Safety assessments demonstrated no hemolytic and bile salt deconjugation activities. Genomic analysis revealed the presence of several genes associated with probiotic characteristics and bacteriocin production, while few deleterious genes with a low likelihood of expression or transferring were detected. Overall, this study highlights E. faecium EFEL8600 as a potent anti-listeria probiotic strain suitable for use as a starter culture in soymilk fermentation, providing potential health benefits to consumers.

Complete Genome Sequencing and Bacteriocin Functional Characterization of Pediococcus ethanolidurans CP201 from Daqu

This study aims to sequence the whole genome of Pediococcus ethanolidurans CP201 isolated from Daqu and determine the anti-corrosion ability of bacteriocins on chicken breast. The whole genome sequence information of P. ethanolidurans CP201 was analyzed, and its gene structure and function were explored. It was found that gene1164 had annotations in the NR, Pfam, and Swiss-Prot databases, and was related to bacteriocins. The exogenous expression of the bacteriocin gene Pediocin PE-201 was analyzed based on the pET-21b vector and the host BL21, and the corresponding bacteriocin was successfully expressed under the induction of IPTG. After purification by NI-NTA column, enterokinase treatment, membrane dialysis concentration treatment, and SDS-PAGE electrophoresis, the molecular weight was about 6.5 kDa and the purity was above 90%. By applying different concentrations of bacteriocin to chicken breast with different levels of contamination, the control of pathogenic bacteria, the ordinary contamination level (OC) group, and the high contamination level (MC) group could be completely achieved with 25 mg/L bacteriocin. In conclusion, the bacteriocin produced by the newly isolated CP201 can be applied to the preservation of meat products to prevent the risk of food-borne diseases.

Comparative genomics reveals key molecular targets for mutant Pediococcus pentosaceus C23221 producing pediocin

Listeria monocytogenes is a common microorganism that causes food spoilage. Pediocins are some biologically active peptides or proteins encoded by ribosomes, which have a strong antimicrobial activity against L. monocytogenes. In this study, the antimicrobial activity of previously isolated P. pentosaceus C-2-1 was enhanced by ultraviolet (UV) mutagenesis. A positive mutant strain P. pentosaceus C23221 was obtained after 8 rounds of UV irradiation with increased antimicrobial activity of 1448 IU/mL, which was 8.47 folds higher than that of wild-type C-2-1. The genome of strain C23221 and wild-type C-2-1 was compared with identify the key genes for higher activity. The genome of the mutant strain C23221 consists of a chromosome of 1,742,268 bp, with 2052 protein-coding genes, 4 rRNA operons, and 47 tRNA genes, which is 79,769 bp less than the original strain. Compared with strain C-2-1, a total of 19 deduced proteins involved in 47 genes are unique to C23221 analyzed by GO database; the specific ped gene related to bacteriocin biosynthesis were detected using antiSMASH in mutant C23221, indicating mutant C23221 produced a new bacteriocin under mutagenesis conditions. This study provides genetic basis for further constituting a rational strategy to genetically engineer wild-type C-2-1 into an overproducer.

Assessing the efficacy of probiotics in augmenting bovine reproductive health: an integrated in vitro, in silico, and in vivo study

The aim of this study was to isolate and characterize bovine-vaginal probiotics genotypically and phenotypically using in silico and evaluate their in vivo performance in buffaloes with endometritis. For the in vitro isolation and characterization, vaginal swabs were collected from 34 cows and 17 buffaloes, and 709 primary bacterial isolates with probiotic activity were obtained using MRS agar media. Two isolates Lactiplantibacillus plantarum KUGBRC (LPKUGBRC) and Pediococcus pentosaceus GBRCKU (PPGBRCKU) demonstrated optimum in vitro probiotic activities as compared to Lacticaseibacillus rhamnosus GG including, acid production, secretion of fatty acids and exopolysaccharide, cell surface hydrophobicity, self-aggregating and co-aggregating capacity with pathogens, anti-microbial activity and bacteriocin-like compounds against pathogens Escherichia coli and Staphylococcus aureus in cell-free supernatant and absence of hemolytic activity. Their phenotypic capacity was confirmed by analyzing the whole genome sequencing data and identifying genes and pathways associated with probiotic properties. These probiotic isolates have shown no virulence genes were discovered in their genomic study. In vivo study of 92 buffaloes suffering from clinical endometritis with purulent cervico-vaginal mucus (CVM) were randomly allocated 40 × 10⁸ CFU/ml LPKUGBRC and PPGBRCKU and 40 ml Normal saline. The LPKUGBRC reduced the duration between administration of probiotic to induction of healthy estrus significantly. However, no effect was observed on pregnancy rate. These results suggest that LPKUGBRC and PPGBRCKU probiotic bacteria demonstrate probiotic efficiency and adaptability. Further sourced from the same niche as the targeted infection, they offer a distinct advantage in targeting the specific microbial population associated with endometritis. The findings of this study highlight the potential of LPKUGBRC and PPGBRCKU probiotics in treating endometritis and suggest further exploration of their clinical applications.

Effectiveness of raw bacteriocin produced from lactic acid bacteria on biofilm of methicillin-resistant Staphylococcus aureus

Background and Aim

Probiotics are proven beneficial to health since they enhance immunity against dangerous pathogens and increase resistance to illness. Bacteriocin produced by lactic acid bacteria (LAB), demonstrates a broad inhibitory spectrum and therapeutic potential. This study aimed to isolate LAB-producing bacteriocin and investigate the effect of crude bacteriocin on biofilm from methicillin-resistant Staphylococcus aureus (MRSA).

Materials and Methods

This study used randomly collected 80 white soft local cheeses (40 each from cows and sheep) from different supermarkets in Basrah Province. The obtained samples were cultured and the bacterial suspension of S. aureus was prepared at 1.5 × 10⁸ cells/mL. The crude bacteriocin extracted from LAB was obtained, and the tube was dried and inverted to detect the biofilm loss at the bottom.

Results

There were 67 (83.75%) LAB isolates. Among 40 milk samples collected directly and indirectly, there were 36 (83.33%). Staphylococcus aureus isolates based on conventional bacteriological analysis and biochemical tests. Molecular testing was conducted to identify LAB and MRSA. Depending on genotypic results, the effect of white soft local cheese (cows and sheep) and the amplification results of the 16S rRNA gene were detected in 46 LAB isolates from white soft local cheese from cows and sheep. Based on the molecular identification of the mecA, results on Staphylococcus determined that only 2 of 36 isolates of S. aureus carried the mecA. Moreover, there were 26 (86.66%) isolates (MRSA) from samples of raw milk from local markets and subclinical mastitis in cows. The ability of LAB isolates was tested. The effects of bacteriocin production on preventing biofilm growth and formation were investigated. Results demonstrated that bacteriocin has high activity. Microtiter plates applied to investigate the ability of S. aureus to produce biofilms revealed that all isolates were either weak or moderate biofilm producers, with neither non-biofilm nor strong biofilm producers found among the tested isolates.

Conclusion

Lactic acid bacteria demonstrate a high ability to produce bacteriocin. Crude bacteriocin from LAB has a restrictive effect on biofilms produced by MRSA; thus, it can be used to reduce the pathogenicity of this bacterium.

Limosilactobacillus fermentum 3872 That Produces Class III Bacteriocin Forms Co-Aggregates with the Antibiotic-Resistant Staphylococcus aureus Strains and Induces Their Lethal Damage

LF3872 was isolated from the milk of a healthy lactating and breastfeeding woman. Earlier, the genome of LF3872 was sequenced, and a gene encoding unique bacteriocin was discovered. We have shown here that the LF3872 strain produces a novel thermolabile class III bacteriolysin (BLF3872), exhibiting antimicrobial activity against antibiotic-resistant Staphylococcus aureus strains. Sequence analysis revealed the two-domain structural (lysozyme-like domain and peptidase M23 domain) organization of BLF3872. At least 25% residues of this protein are expected to be intrinsically disordered. Furthermore, BLF3872 is predicted to have a very high liquid-liquid phase separation. According to the electron microscopy data, the bacterial cells of LF3872 strain form co-aggregates with the S. aureus 8325-4 bacterial cells. LF3872 produced bacteriolysin BLF3872 that lyses the cells of the S. aureus 8325-4 mastitis-inducing strain. The sensitivity of the antibiotic-resistant S. aureus collection strains and freshly isolated antibiotic-resistant strains was tested using samples from women with lactation mastitis; the human nasopharynx and oral cavity; the oropharynx of pigs; and the cows with a diagnosis of clinical mastitis sensitive to the lytic action of the LF3872 strain producing BLF3872. The co-cultivation of LF3872 strain with various antibiotic-resistant S. aureus strains for 24 h reduced the level of living cells of these pathogens by six log. The LF3872 strain was found to be able to co-aggregate with all studied S. aureus strains. The cell-free culture supernatant of LF3872 (CSLF3872) induced S. aureus cell damage and ATP leakage. The effectiveness of the bacteriolytic action of LF3872 strain did not depend on the origin of the S. aureus strains. The results reported here are important for the creation of new effective drugs against antibiotic-resistant strains of S. aureus circulating in humans and animals.

Biopreservative efficacy of Enterococcus faecium-immobilised film and its enterocin against Salmonella enterica

The growing awareness about the adverse health effects of artificial synthetic preservatives has led to a rapid increase in the demand for safe food preservation techniques and bio preservatives. Thus, in this study, the biopreservatives efficacy of enterocin-producing Enterococcus faecium Smr18 and its enterocin, ESmr18 was evaluated against Salmonella enterica contamination in chicken samples. E. faecium Smr18 is susceptible to the antibiotics penicillin-G, ampicillin, vancomycin, and erythromycin, thereby indicating that it is a nonpathogenic strain. Further, the enterocin ESmr18 was purified and characterised as a 3.8 kDa peptide. It possessed broad spectrum antibacterial activity against both Gram-positive and Gram-negative pathogens including S. enterica serotypes Typhi and Typhimurium. Purified ESmr18 disrupted the cell membrane permeability of the target cell thereby causing rapid efflux of potassium ions from L. monocytogenes and S. enterica. Chicken samples inoculated with S. enterica and packaged in alginate films containing immobilised viable E. faecium resulted in 3 log₁₀ colony forming units (CFU) reduction in the counts of S. enterica after 34 days of storage at 7-8 °C. The crude preparation of ESmr18 also significantly (p < 0.05) reduced the CFU counts of salmonella-inoculated chicken meat model. Purified ESmr18 at the concentration upto 4.98 µg/ml had no cytolytic effect against human red blood cells. Crude preparation of ESmr18 when orally administered in fish did not cause any significant (p < 0.05) change in the biochemical parameters of sera samples. Nonsignificant changes in the parameters of comet and micronucleus assays were observed between the treated and untreated groups of fishes that further indicated the safety profile of the enterocin ESmr18.

Evidence for Widespread Class II Microcins in Enterobacterales Genomes

Microcins are a class of antimicrobial peptides produced by certain Gram-negative bacterial species to kill or inhibit the growth of competing bacteria. Only 10 unique, experimentally validated class II microcins have been identified, and the majority of these come from Escherichia coli. Although the current representation of microcins is sparse, they exhibit a diverse array of molecular functionalities, uptake mechanisms, and target specificities. This broad diversity from such a small representation suggests that microcins may have untapped potential for bioprospecting peptide antibiotics from genomic data sets. We used a systematic bioinformatics approach to search for verified and novel class II microcins in E. coli and other species within its family, Enterobacteriaceae. Nearly one-quarter of the E. coli genome assemblies contained one or more microcins, where the prevalence of hits to specific microcins varied by isolate phylogroup. E. coli isolates from human extraintestinal and poultry meat sources were enriched for microcins, while those from freshwater were depleted. Putative microcins were found in various abundances across all five distinct phylogenetic lineages of Enterobacteriaceae, with a particularly high prevalence in the "Klebsiella" clade. Representative genome assemblies from species across the Enterobacterales order, as well as a few outgroup species, also contained putative microcin sequences. This study suggests that microcins have a complicated evolutionary history, spanning far beyond our limited knowledge of the currently validated microcins. Efforts to functionally characterize these newly identified microcins have great potential to open a new field of peptide antibiotics and microbiome modulators and elucidate the ways in which bacteria compete with each other. IMPORTANCE Class II microcins are small bacteriocins produced by strains of Gram-negative bacteria in the Enterobacteriaceae. They are generally understood to play a role in interbacterial competition, although direct evidence of this is limited, and they could prove informative in developing new peptide antibiotics. However, few examples of verified class II microcins exist, and novel microcins are difficult to identify due to their sequence diversity, making it complicated to study them as a group. Here, we overcome this limitation by developing a bioinformatics pipeline to detect microcins in silico. Using this pipeline, we demonstrate that both verified and novel class II microcins are widespread within and outside the Enterobacteriaceae, which has not been systematically shown previously. The observed prevalence of class II microcins suggests that they are ecologically important, and the elucidation of novel microcins provides a resource that can be used to expand our knowledge of the structure and function of microcins as antibacterials.

Bacteriocin: A natural approach for food safety and food security

The call to cater for the hungry is a worldwide problem in the 21st century. Food security is the utmost prime factor for the increasing demand for food. Awareness of human health when using chemical preservatives in food has increased, resulting in the use of alternative strategies for preserving food and enhancing its shelf-life. New preservatives along with novel preservation methods have been instigated, due to the intensified demand for extended shelf-life, along with prevention of food spoilage of dairy products. Bacteriocins are the group of ribosomally synthesized antimicrobial peptides; they possess a wide range of biological activities, having predominant antibacterial activity. The bacteriocins produced by the lactic acid bacteria (LAB) are considered to be of utmost importance, due to their association with the fermentation of food. In recent times among various groups of bacteriocins, leaderless and circular bacteriocins are gaining importance, due to their extensive application in industries. These groups of bacteriocins have been least studied as they possess peculiar structural and biosynthetic mechanisms. They chemically possess N-to-C terminal covalent bonds having a predominant peptide background. The stability of the bacteriocins is exhibited by the circular structure. Up till now, very few studies have been performed on the molecular mechanisms. The structural genes associated with the bacteriocins can be combined with the activity of various proteins which are association with secretion and maturation. Thus the stability of the bacteriocins can be used effectively in the preservation of food for a longer period of time. Bacteriocins are thermostable, pH-tolerant, and proteolytically active in nature, which make their usage convenient to the food industry. Several research studies are underway in the domain of biopreservation which can be implemented in food safety and food security.

Lactic Acid Bacteria and Bacteriocins: Novel Biotechnological Approach for Biopreservation of Meat and Meat Products

Meat and meat products are perishable in nature, and easily susceptible to microbial contamination and chemical deterioration. This not only results in an increased risk to health of consumers, but also causes economic loss to the meat industry. Some microorganisms of the lactic acid bacteria (LAB) group and their ribosomal-synthesized antimicrobial peptides-especially bacteriocins-can be used as a natural preservative, and an alternative to chemical preservatives in meat industry. Purified or partially purified bacteriocins can be used as a food additive or incorporated in active packaging, while bacteriocin-producing cells could be added as starter or protective cultures for fermented meats. Large-scale applications of bacteriocins are limited, however, mainly due to the narrow antimicrobial spectrum and varying stability in different food matrixes. To overcome these limitations, bioengineering and biotechnological techniques are being employed to combine two or more classes of bacteriocins and develop novel bacteriocins with high efficacy. These approaches, in combination with hurdle concepts (active packaging), provide adequate safety by reducing the pathogenicity of spoilage microorganisms, improving sensory characteristics (e.g., desirable flavor, texture, aroma) and enhancing the shelf life of meat-based products. In this review, the biosynthesis of different classes of LAB bacteriocins, their mechanism of action and their role in the preservation of meats and meat products are reviewed.

Processing interventions for enhanced microbiological safety of beef carcasses and beef products: A review

Chilled beef is inevitably contaminated with microorganisms, starting from the very beginning of the slaughter line. A lot of studies have aimed to improve meat safety and extend the shelf life of chilled beef, of which some have focused on improving the decontamination effects using traditional decontamination interventions, and others have investigated newer technologies and methods, that offer greater energy efficiency, lower environmental impacts, and better assurances for the decontamination of beef carcasses and cuts. To inform industry, there is an urgent need to review these interventions, analyze the merits and demerits of each technology, and provide insight into 'best practice' to preserve microbial safety and beef quality. In this review, the strategies and procedures used to inhibit the growth of microorganisms on beef, from slaughter to storage, have been critiqued. Critical aspects, where there is a lack of data, have been highlighted to help guide future research. It is also acknowledge that different intervention programs for microbiological safety have different applications, dependent on the initial microbial load, the type of infrastructures, and different stages of beef processing.

Applications of Bacteriocins of Lactic Acid Bacteria in Biotechnology and Food Preservation: A Bibliometric Review

Introduction:

Due to the growing prevalence of antibiotic resistance in microorganisms and the demand for safe food, there is increasing interest in using natural bioproducts such as the antimicrobial peptides bacteriocins to extend the shelf-life of foods. This is because of their spectrum of activity, ease of synthesis and applicability. This study reports on the global trends in lactic acid bacteria (LAB) bacteriocins based research publications in the Web of Science core collections within the last 20 years (2000-2019), with specific focus to their applications in biotechnology and food science.

Methods:

Data analysis was undertaken using VOSviewer and HistCite software to evaluate relationships between articles and visualise research linkages amongst authors, institutions and countries.

Results:

In the 20 years under review, a total of 1741 bacteriocin related articles were published, with the most cited publication examining the anti-infective activity of Lactobacillus salivarius. The highest research output was recorded by the United States, followed by Spain and China. However, Europe as a continent had the highest research output with a higher inter-institution collaboration network and stronger food safety legislations.

Discussion:

The bibliometric analysis gave insights into the research areas, cooperation network of authors, co-citation maps and co-occurrence of keywords utilized in the research field and indicates that bacteriocin-based research is highly multidisciplinary with a global reach.

Conclusion:

Key focus is on the control of foodborne disease pathogens, search for new producer organisms and approaches to improve bacteriocin yield and application. This class of antimicrobial peptides has the potential to replace chemical food preservatives in the future.

Application of Lactic Acid Bacteria (LAB) in Sustainable Agriculture: Advantages and Limitations

Lactic acid bacteria (LAB) are significant groups of probiotic organisms in fermented food and are generally considered safe. LAB regulate soil organic matter and the biochemical cycle, detoxify hazardous chemicals, and enhance plant health. They are found in decomposing plants, traditional fermented milk products, and normal human gastrointestinal and vaginal flora. Exploring LAB identified in unknown niches may lead to isolating unique species. However, their classification is quite complex, and they are adapted to high sugar concentrations and acidic environments. LAB strains are considered promising candidates for sustainable agriculture, and they promote soil health and fertility. Therefore, they have received much attention regarding sustainable agriculture. LAB metabolites promote plant growth and stimulate shoot and root growth. As fertilizers, LAB can promote biodegradation, accelerate the soil organic content, and produce organic acid and bacteriocin metabolites. However, LAB show an antagonistic effect against phytopathogens, inhibiting fungal and bacterial populations in the rhizosphere and phyllosphere. Several studies have proposed the LAB bioremediation efficiency and detoxification of heavy metals and mycotoxins. However, LAB genetic manipulation and metabolic engineered tools provide efficient cell factories tailor-made to produce beneficial industrial and agro-products. This review discusses lactic acid bacteria advantages and limitations in sustainable agricultural development.

Multi-Omics Approach in Amelioration of Food Products

Determination of the quality of food products is an essential key factor needed for safe-guarding the quality of food for the interest of the consumers, along with the nutritional and sensory improvements that are necessary for delivering better quality products. Bacteriocins are a group of ribosomally synthesized antimicrobial peptides that help in maintaining the quality of food. The implementation of multi-omics approach has been important for the overall enhancement of the quality of the food. This review uses various recent technologies like proteomics, transcriptomics, and metabolomics for the overall enhancement of the quality of food products. The matrix associated with the food products requires the use of sophisticated technologies that help in the extraction of a large amount of information necessary for the amelioration of the food products. This review would provide a wholesome view of how various recent technologies can be used for improving the quality food products and for enhancing their shelf-life.

Biotechnological Innovations and Therapeutic Application of Pediococcus and Lactic Acid Bacteria: The Next-Generation Microorganism

Lactic acid bacteria represent a worthwhile organism within the microbial consortium for the food sector, health, and biotechnological applications. They tend to offer high stability to environmental conditions, with an indicated increase in product yield, alongside their moderate antimicrobial activity. Lack of endotoxins and inclusion bodies, extracellular secretion, and surface display with other unique properties, are all winning attributes of these Gram-positive lactic acid bacteria, of which, Pediococcus is progressively becoming an attractive and promising host, as the next-generation probiotic comparable with other well-known model systems. Here, we presented the biotechnological developments in Pediococcal bacteriocin expression system, contemporary variegated models of Pediococcus and lactic acid bacteria strains as microbial cell factory, most recent applications as possible live delivery vector for use as therapeutics, as well as upsurging challenges and future perspective. With the radical introduction of artificial intelligence and neural network in Synthetic Biology, the microbial usage of lactic acid bacteria as an alternative eco-friendly strain, with safe use properties compared with the already known conventional strains is expected to see an increase in various food and biotechnological applications in years to come as it offers better hope of safety, accuracy, and higher efficiency.

Bacteriocin-Producing Lactic Acid Bacteria Strains with Antimicrobial Activity Screened from Bamei Pig Feces

Lactic acid bacteria (LAB), which are characterized by producing various functional metabolites, including antioxidants, organic acids, and antimicrobial compounds, are widely used in the food industry to improve gut health and prevent the growth of spoilage microorganisms. With the continual incidence of foodborne disease and advocacy of consumers for gut health, LAB have been designated as vital biopreservative agents in recent years. Therefore, LAB with excellent antimicrobial properties and environmental tolerance should be explored further. In this study, we focus on screening the LAB strains from a specialty pig (Bamei pig) feces of the Tibetan plateau region and determine their antimicrobial properties and environmental tolerance to evaluate their potential probiotic values. A total of 116 LAB strains were isolated, from which the LAB strain Qinghai (QP)28-1 was identified as Lactiplantibacillus (L.) plantarum subsp. plantarum using 16S rDNA sequencing and recA amplification, showing the best growth capacity, acid production capacities, environmental tolerance, hydrophobicity, antibiotic susceptibility, and bacteriocin production capacity. Furthermore, this strain inhibited the growth of multiple pathogens by producing organic acids and bacteriocin. These bacteriocin-encoding genes were identified using PCR amplification, including plnS, plnN, and plnW. In conclusion, bacteriocin-producing L. plantarum subsp. plantarum QP28-1 stands out among these 116 LAB strains, and was considered to be a promising strain used for LAB-related food fermentation. Moreover, this study provides a convenient, comprehensive, and shareable profile for screening of superior functional and bacteriocin-producing LAB strains, which can be used in the food industry.

Strategies for Biocontrol of Listeria monocytogenes Using Lactic Acid Bacteria and Their Metabolites in Ready-to-Eat Meat- and Dairy-Ripened Products

Listeria monocytogenes is one of the most important foodborne pathogens. This microorganism is a serious concern in the ready-to-eat (RTE) meat and dairy-ripened products industries. The use of lactic acid bacteria (LAB)-producing anti-L. monocytogenes peptides (bacteriocins) and/or lactic acid and/or other antimicrobial system could be a promising tool to control this pathogen in RTE meat and dairy products. This review provides an up to date about the strategies of use of LAB and their metabolites in RTE meat products and dairy foods by selecting the most appropriate strains, by analysing the mechanism by which they inhibit L. monocytogenes and methods of effective application of LAB, and their metabolites in these kinds of products to control this pathogen throughout the processing and storage. The selection of LAB with anti-L. monocytogenes activity allows to dispose of effective strains in meat and dairy-ripened products, achieving reductions form 2–5 logarithmic cycles of this pathogen throughout the ripening process. The combination of selected LAB strains with antimicrobial compounds, such as acid/sodium lactate and other strategies, as the active packaging could be the next future innovation for eliminating risk of L. monocytogenes in meat and dairy-ripened products.

Targeted Genome Mining Reveals the Psychrophilic Clostridium estertheticum Complex as a Potential Source for Novel Bacteriocins, Including Cesin A and Estercticin A

Antimicrobial resistance in pathogenic bacteria is considered a major public health issue necessitating the discovery of alternative antimicrobial compounds. In this regard, targeted genome mining in bacteria occupying under-explored ecological niches has the potential to reveal such compounds, including bacteriocins. In this study, we determined the bacteriocin biosynthetic potential of the psychrophilic Clostridium estertheticum complex (CEC) through a combination of genome mining and phenotypic screening assays. The genome mining was performed in 40 CEC genomes using antiSMASH. The production of bacteriocin-like compounds was phenotypically validated through agar well (primary screening) and disk diffusion (secondary screening) assays using cell free supernatants (CFS) and partially purified extracts, respectively. Stability of four selected CFS against proteolytic enzymes, temperature and pH was determined while one CFS was analyzed by HRMS and MS/MS to identify potential bacteriocins. Twenty novel bacteriocin biosynthetic gene clusters (BBGC), which were classified into eight (six lantibiotics and two sactipeptides) distinct groups, were discovered in 18 genomes belonging to C. estertheticum (n = 12), C. tagluense (n = 3) and genomospecies2 (n = 3). Primary screening linked six BBGC with narrow antimicrobial activity against closely related clostridia species. All four preselected CFS retained activity after exposure to different proteolytic, temperature and pH conditions. Secondary screening linked BBGC1 and BBGC7 encoding a lantibiotic and sactipeptide, respectively, with activity against Bacillus cereus while lantibiotic-encoding BBGC2 and BBGC3 were linked with activity against B. cereus, Staphylococcus aureus (methicillin-resistant), Escherichia coli and Pseudomonas aeruginosa. MS/MS analysis revealed that C. estertheticum CF004 produces cesin A, a short natural variant of nisin, and HRMS indicated the production of a novel sactipeptide named estercticin A. Therefore, we have shown the CEC, in particular C. estertheticum, is a source of novel and stable bacteriocins that have activities against clinically relevant pathogens.

Anti-Salmonella activity of lactobacilli from different habitats

Lactic acid bacteria (LAB) may contribute to the food safety. In the present study, the antagonistic activity of 45 Bulgarian Lactobacillus homo- and heterofermentative strains of human and dairy origin, and 4 multibacterial formulas against Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) was assessed. In vitro tests were performed in different model systems - milk, soymilk, De Man Rogose Sharp (MRS) medium, to simulate real conditions in the food chain. The highest antagonistic activity was observed with cell-free supernatants of exponential MRS broth cultures of the strains isolated from breast milk, followed by lactobacilli from white brined and green cheese. The detected antimicrobial activity against the pathogen was strain-specific and depended on the culture conditions. Lactobacillus (reclassified as Lactoplantibacillus) plantarum strains, cultivated in skimmed milk and whey protein medium, were able to inhibit S. Typhimurium growth, while a limited inhibitory activity was detected for fermented soymilks. A bacteriocinogenic Ligilactobacillus (the previous Lactobacillus) salivarius strain reduced the number of living pathogenic cells during co-cultivation in whole milk. The inhibition was significant only when L. salivarius was inoculated in predominance. In case of underrepresented LAB number, S. Typhimurium over-growth was observed. Eight lactobacilli in combination as a multibacterial co-culture expressed synergic antagonistic effect against Salmonella and were pre-selected as promising. Further characterisation of their active metabolites, however, is needed before their classification as bio-protective agents.

Lactic Acid Bacteria as Antimicrobial Agents: Food Safety and Microbial Food Spoilage Prevention

In the wake of continual foodborne disease outbreaks in recent years, it is critical to focus on strategies that protect public health and reduce the incidence of foodborne pathogens and spoilage microorganisms. Currently, there are limitations associated with conventional microbial control methods, such as the use of chemical preservatives and heat treatments. For example, such conventional treatments adversely impact the sensorial properties of food, resulting in undesirable organoleptic characteristics. Moreover, the growing consumer advocacy for safe and healthy food products, and the resultant paradigm shift toward clean labels, have caused an increased interest in natural and effective antimicrobial alternatives. For instance, natural antimicrobial elements synthesized by lactic acid bacteria (LAB) are generally inhibitory to pathogens and significantly impede the action of food spoilage organisms. Bacteriocins and other LAB metabolites have been commercially exploited for their antimicrobial properties and used in many applications in the dairy industry to prevent the growth of undesirable microorganisms. In this review, we summarized the natural antimicrobial compounds produced by LAB, with a specific focus on the mechanisms of action and applications for microbial food spoilage prevention and disease control. In addition, we provide support in the review for our recommendation for the application of LAB as a potential alternative antimicrobial strategy for addressing the challenges posed by antibiotic resistance among pathogens.

Development of Active Packaging Based on Agar-Agar Incorporated with Bacteriocin of Lactobacillus sakei

In the search for new biodegradable materials and greater microbiological safety and stability of perishable food products, this study aimed to develop a bioplastic antibacterial film incorporating bacteriocin for application in commercial curd cheese and monitoring of microbiological stability. Films with good handling characteristics as well as physical, barrier, and mechanical properties were obtained. Regarding the antibacterial activity, the microbial reduction was demonstrated in a food matrix, obtaining a reduction of 3 logarithmic cycles for the group of coagulase positive staphylococci and from 1100 to <3.00 MPN/g in the analysis of thermotolerant coliforms. Therefore, the film presented food barrier characteristics with the external environment and adequate migration of the antibacterial compound to the product, contributing to the reduction of contamination of a food with high initial microbial load.

Kombucha Tea-A Double Power of Bioactive Compounds from Tea and Symbiotic Culture of Bacteria and Yeasts (SCOBY)

Kombucha is a low alcoholic beverage with high content of bioactive compounds derived from plant material (tea, juices, herb extracts) and metabolic activity of microorganisms (acetic acid bacteria, lactic acid bacteria and yeasts). Currently, it attracts an increasing number of consumers due to its health-promoting properties. This review focuses on aspects significantly affecting the bioactive compound content and biological activities of Kombucha tea. The literature review shows that the drink is characterized by a high content of bioactive compounds, strong antioxidant, and antimicrobial properties. Factors that substantially affect these activities are the tea type and its brewing parameters, the composition of the SCOBY, as well as the fermentation parameters. On the other hand, Kombucha fermentation is characterized by many unknowns, which result, inter alia, from different methods of tea extraction, diverse, often undefined compositions of microorganisms used in the fermentation, as well as the lack of clearly defined effects of microorganisms on bioactive compounds contained in tea, and therefore the health-promoting properties of the final product. The article indicates the shortcomings in the current research in the field of Kombucha, as well as future perspectives on improving the health-promoting activities of this fermented drink.

Antibacterial Activity of Pediocin and Pediocin-Producing Bacteria Against Listeria monocytogenes in Meat Products

One of the most important challenges in the food industry is to produce healthy and safe food products, and this could be achieved through various processes as well as the use of different additives, especially chemical preservatives. However, consumer awareness and concern about chemical preservatives have led researchers to focus on the use of natural antimicrobial compounds such as bacteriocins. Pediocins, which belong to subclass IIa of bacteriocin characterized as small unmodified peptides with a low molecular weight (2.7-17 kDa), are produced by some of the Pediococcus bacteria. Pediocin and pediocin-like bacteriocins exert a broad spectrum of antimicrobial activity against Gram-positive bacteria, especially against pathogenic bacteria, such as Listeria monocytogenes through formation of pores in the cytoplasmic membrane and cell membrane dysfunction. Pediocins are sensitive to most protease enzymes such as papain, pepsin, and trypsin; however, they keep their antimicrobial activity during heat treatment, at low temperatures even at -80°C, and after treatment with lipase, lysozyme, phospholipase C, DNase, or RNase. Due to the anti-listeria activity of pediocin on the one hand and the potential health hazards associated with consumption of meat products on the other hand, this review aimed to investigate the possible application of pediocin in preservation of meat and meat products against L. monocytogenes.

Purification, characterization, and mode of action of Paracin 54, a novel bacteriocin against Staphylococci

Staphylococci belong to conditionally pathogenic bacteria, and the pathogenicity of Staphylococcus aureus is the strongest among them. Enterotoxin produced by it can contaminate food and cause food poisoning. Bacteriocin is a kind of polypeptide with antibacterial activity synthesized by some bacteria during metabolism. In this study, we report on purification, characterization, and mode of action of the bacteriocin named Paracin 54, produced by Lactobacillus paracasei ZFM54. Paracin 54 was purified by precipitation with 80% ammonium sulfate, strong cation-exchange chromatography, G-25 gel column, and reversed-phase high-performance liquid chromatography (HPLC). The molecular weight of Paracin 54 (5718.1843 Da) was determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Paracin 54 showed broad-spectrum inhibitory activity. It had a strong inhibitory effect on Staphylococci with minimum inhibitory concentration values of 3.00-4.50 μg/mL. Paracin 54 was heat-stable and active only in acidic pH range (2-6). After treatment with proteases, the activity was lost. The results of mode of action showed Paracin 54 damaged the cell membrane and cell wall of Staphylococcus aureus, and then the cytoplasm leaked out, leading to death of the bacteria. These properties make Paracin 54 a promising candidate to prevent the growth of spoilage bacteria and control food poisoning caused by Staphylococci. KEY POINTS: • Paracin 54 was purified from Lactobacillus paracasei ZFM54 with good biochemical characteristics. • Paracin 54 had a strong effect against Staphylococci, making it a promising preservative to prevent the growth of Staphylococci in food. • The mode of action of Paracin 54 on Staphylococcus aureus was revealed.

Characterization of a Potent New-Generation Antimicrobial Peptide of Bacillus

An antimicrobial peptide [Bacillus antimicrobial peptide (BAMP)] produced by Bacillus paralicheniformis was isolated from the Indian traditional fermented food and characterized. The antimicrobial peptide BAMP showed many unique features such as thermostability (4.0-125°C), pH tolerance (pH 2.0-9.0), and resistance to physiological enzymes (trypsin, chymotrypsin, pepsin, proteinase K, protease, and catalase), and food-grade metal salts do not inhibit the activity. The broad spectrum of BAMP (antimicrobial activity) makes it a suitable candidate for food preservation as well as antimicrobial therapy. BAMP was found to exhibit a bacteriostatic effect on Salmonella typhi and controls the viability of Listeria monocytogenes in chicken meat efficiently. BAMP was found to establish eubiosis, as it is not antagonistic to Lactobacillus. Its non-hemolytic nature makes it suitable for therapy. Various genome prediction tools were adopted and applied to understand their localization, gene arrangement, and type of antimicrobials. Founded on its superior functional attributes, BAMP is a potent new-generation antimicrobial peptide.