Antibacterial activities of bacteriocins: application in foods and pharmaceuticals

Comparative genomics of Vibrio toranzoniae strains

Vibrio toranzoniae is a marine bacterium belonging to the Splendidus clade that was originally isolated from healthy clams in Galicia (NW Spain). Its isolation from different hosts and seawater indicated two lifestyles and wide geographical distribution. The aim of the present study was to determine the differences at the genomic level among six strains (4 isolated from clam and 2 from seawater) and to determine their phylogeny. For this purpose, whole genomes of the six strains were sequenced by different technologies including Illumina and PacBio, and the resulting sequences were corrected. Genomes were annotated and compared using different online tools. Furthermore, the study of core- and pan-genomes were examined, and the phylogeny was inferred. The content of the core genome ranged from 2953 to 2766 genes and that of the pangenome ranged from 6278 to 6132, depending on the tool used. Although the strains shared certain homology, with DDH values ranging from 77.10 to 82.30 and values of OrthoANI values higher than 97%, some differences were found related to motility, capsule synthesis, iron acquisition systems or mobile genetic elements. Phylogenetic analysis of the core genome did not reveal a differentiation of the strains according to their lifestyle (commensal or free-living), but that of the pangenome indicated certain geographical isolation in the same growing area. This study led to the reclassification of some isolates formerly described as V. toranzoniae and demonstrated the importance of cured deposited sequences to proper phylogenetic assignment.

Natural Bioactive Compounds in the Management of Periodontal Diseases: A Comprehensive Review

Periodontal diseases, chronic inflammatory conditions affecting oral health, are primarily driven by microbial plaque biofilm and the body's inflammatory response, leading to tissue damage and potential tooth loss. These diseases have significant physical, psychological, social, and economic impacts, necessitating effective management strategies that include early diagnosis, comprehensive treatment, and innovative therapeutic approaches. Recent advancements in biomanufacturing have facilitated the development of natural bioactive compounds, such as polyphenols, terpenoids, alkaloids, saponins, and peptides, which exhibit antimicrobial, anti-inflammatory, and tissue regenerative properties. This review explores the biomanufacturing processes-microbial fermentation, plant cell cultures, and enzymatic synthesis-and their roles in producing these bioactive compounds for managing periodontal diseases. The integration of these natural compounds into periodontal therapy offers promising alternatives to traditional treatments, potentially overcoming issues like antibiotic resistance and the disruption of the natural microbiota, thereby improving patient outcomes.

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.

Time-resolved cell-to-cell heterogeneity of Listeria innocua after nisin exposure

The use of bacteriocins is a promising approach for addressing the immense threat of food-borne and drug-resistant pathogens. In recent years screening platforms for novel bacteriocins using whole-cell biosensors have been established. During screening cell-to-cell heterogeneity is currently neglected but might play a crucial role in signal development of the whole-cell biosensor after bacteriocin exposure. In this study, we explored the temporal dynamics of the signal heterogeneity of the biosensor Listeria innocua LMG2785/pNZpHin2 Lm after nisin exposure using microfluidic single-cell analysis. The results provided novel and detailed insights into the dynamics of cell-to-cell heterogeneity in L. innocua LMG2785/pNZpHin2 Lm at different nisin concentrations with a high spatio-temporal resolution. Furthermore, the formation of subpopulations during bacteriocin exposure was observed. In-depth single-cell tracking even revealed the regeneration of disrupted cells and recovery of pH homeostasis in rare instances. These findings are highly important for the future design and execution of bacteriocin assays and for the interpretation of fluorescence signal development at the population level after exposure to different concentrations of bacteriocins (here, nisin), as well as for obtaining deeper insights into single-cell persistence strategies to quantify the efficacy and efficiency of novel bacteriocins.

Comparative genomics of Vibrio toranzoniae strains

Vibrio toranzoniae is a marine bacterium belonging to the Splendidus clade, originally isolated from healthy clams in Galicia (NW Spain). Its isolation from different hosts and seawater indicated two lifestyles and wide geographical distribution. The aim of the present study was to determine the differences at genome level among strains, as well as to determine their phylogeny. For this purpose, whole genomes were sequenced by different technologies and the resulting sequences corrected. Genomes were annotated and compared with different online tools. Furthermore, the study of core and pan genome was examined, and the phylogeny was inferred. The content of the core genome ranged from 2,953 to 2,766 genes and that of the pangenome from 6,278 to 6,132, depending on the tool used. The comparison revealed that although the strains shared certain homology, with DDH values ranging from 77.10 to 82.30 and values of OrthoANI higher than 97%,notable differences were found related to motility, capsule synthesis, iron acquisition system or mobile genetic elements. The phylogenetic analysis of the core genome did not reveal a differentiation of the strains according to their lifestyle, but that of the pangenome pointed out certain geographical isolation in the same growing area. The study led to a reclassification of some isolates formerly described as V. toranzoniae and manifested the importance of cured deposited sequences to proper phylogenetic assignment.

In Vitro and In Silico Characterization of N-Formylated Two-Peptide Bacteriocin from Enterococcus faecalis CAUM157 with Anti-Listeria Activity

Enterococcus faecalis CAUM157 (KACC 81148BP), a Gram-positive bacteria isolated from raw cow's milk, was studied for its bacteriocin production. The antimicrobial activity of CAUM157 was attributed to a two-peptide class IIb bacteriocin with potent activity against food-borne pathogen Listeria monocytogenes and periodontal disease-causing pathogens (Prevotella intermedia KCTC 15693 T and Fusobacterium nucleatum KCTC 2488 T). M157 bacteriocins exhibit high temperature and pH stability and resist hydrolytic enzyme degradation and detergent denaturation, potentially due to their structural conformation. Based on amino acid sequence, M157A and M157B were predicted to be 5.176 kDa and 5.182 kDa in size, respectively. However, purified bacteriocins and chemically synthesized N-formylated M157 peptides both showed 5.204 kDa (M157A) and 5.209 kDa (M157B) molecular mass, confirming the formylation of the N-terminal methionine of both peptides produced by strain CAUM157. Furthermore, the strain demonstrated favorable growth and fermentation with minimal bacteriocin production when cultured in whey-based media, whereas a 1.0% tryptone or soytone supplementation resulted in higher bacteriocin production. Although Ent. faecalis CAUM157 innately harbors genes for virulence factors and antimicrobial resistance (e.g., tetracycline and erythromycin), its bacteriocin production is valuable in circumventing the need for live microorganisms, particularly in food applications for pathogen control.

Synergistic Inhibition of Synbiotic Cultures among Lactobacilli and Plant Extracts against Vaginal Discharge Causing Candida albicans

Vulvovaginal candidiasis (VVC) is the most common cause of vaginal discharge among women. The present study aimed to investigate the synergistic anticandidal effect of lactobacillus cultures supplemented with plant extracts. Among 600 isolates of lactic acid bacteria, 41 isolates exhibited inhibitory activity against Candida albicans ATCC10231. Six out of 41 cell-free supernatants demonstrated the most potent antibacterial and anticandidal activities. They also inhibited the clinical isolates of C. albicans, causing VVC and non-C. albicans. The synergistic effect between Lactobacillus crispatus 84/7 and Limosilactobacillus reuteri 89/4 was demonstrated by the lowest fractional inhibitory concentration index (FICI = 0.5). The synbiotic culture of bacterial combination, cultured with Jerusalem artichoke (H. tuberosus) extract, also exhibited the strongest inhibition against the tested C. albicans. Biofilm formation decreased after 12 h of incubation in the selected cell-free supernatants of this synbiotic culture. The anticandidal activity of crude extracts was lost after treatment with proteinase K and trypsin but not with heating conditions, suggesting that it may be a heat-stable substance. In conclusion, the combination of L. crispatus 84/7 and L. reuteri 89/4 with H. tuberosus may be a promising candidate for inhibiting Candida infection and biofilm formation, with the potential use as ingredients in vaginal biotherapeutic products.

Therapeutic bacteria and viruses to combat cancer: double-edged sword in cancer therapy: new insights for future

Cancer, ranked as the second leading cause of mortality worldwide, leads to the death of approximately seven million people annually, establishing itself as one of the most significant health challenges globally. The discovery and identification of new anti-cancer drugs that kill or inactivate cancer cells without harming normal and healthy cells and reduce adverse effects on the immune system is a potential challenge in medicine and a fundamental goal in Many studies. Therapeutic bacteria and viruses have become a dual-faceted instrument in cancer therapy. They provide a promising avenue for cancer treatment, but at the same time, they also create significant obstacles and complications that contribute to cancer growth and development. This review article explores the role of bacteria and viruses in cancer treatment, examining their potential benefits and drawbacks. By amalgamating established knowledge and perspectives, this review offers an in-depth examination of the present research landscape within this domain and identifies avenues for future investigation.

Cell-Free Protein Expression in Polymer Materials

While synthetic biology has advanced complex capabilities such as sensing and molecular synthesis in aqueous solutions, important applications may also be pursued for biological systems in solid materials. Harsh processing conditions used to produce many synthetic materials such as plastics make the incorporation of biological functionality challenging. One technology that shows promise in circumventing these issues is cell-free protein synthesis (CFPS), where core cellular functionality is reconstituted outside the cell. CFPS enables genetic functions to be implemented without the complications of membrane transport or concerns over the cellular viability or release of genetically modified organisms. Here, we demonstrate that dried CFPS reactions have remarkable tolerance to heat and organic solvent exposure during the casting processes for polymer materials. We demonstrate the utility of this observation by creating plastics that have spatially patterned genetic functionality, produce antimicrobials in situ, and perform sensing reactions. The resulting materials unlock the potential to deliver DNA-programmable biofunctionality in a ubiquitous class of synthetic materials.

Oral Biofilm Composition, Dissemination to Keratinocytes, and Inflammatory Attenuation Depend on Probiotic and Synbiotic Strain Specificity

Several inflammatory diseases are characterized by a disruption in the equilibrium between the host and its microbiome. Due to the increase in resistance, the use of antibiotics for the widespread, nonspecific killing of microorganisms is at risk. Pro-microbial approaches focused on stimulating or introducing beneficial species antagonistic toward pathobionts may be a viable alternative for restoring the host-microbiome equilibrium. Unfortunately, not all potential probiotic or synbiotic species and even subspecies (to strain level) are equally effective for the designated pathology, leading to conflicting accounts of their efficacy. To assess the extent of these species- and strain-specific effects, 13 probiotic candidates were evaluated for their probiotic and synbiotic potential with glycerol on in vitro oral biofilms, dissemination from biofilms to keratinocytes, and anti-inflammatory activity. Species- and strain-specific effects and efficacies were observed in how they functioned as probiotics or synbiotics by influencing oral pathobionts and commensals within biofilms and affected the dissemination of pathobionts to keratinocytes, ranging from ineffective strains to strains that reduced pathobionts by 3 + log. In addition, a minority of the candidates exhibited the ability to mitigate the inflammatory response of LPS-stimulated monocytes. For a comprehensive assessment of probiotic therapy for oral health, a judicious selection of fully characterized probiotic strains that are specifically tailored to the designated pathology is required. This approach aims to challenge the prevailing perception of probiotics, shifting the focus away from "form over function." Rather than using unproven, hypothetical probiotic strains from known genera or species, one should choose strains that are actually functional in resolving the desired pathology before labelling them probiotics.

Promiscuous, persistent and problematic: insights into current enterococcal genomics to guide therapeutic strategy

Vancomycin-resistant enterococci (VRE) are major opportunistic pathogens and the causative agents of serious diseases, such as urinary tract infections and endocarditis. VRE strains mainly include species of Enterococcus faecium and E. faecalis which can colonise the gastrointestinal tract (GIT) of patients and, following growth and persistence in the gut, can transfer to blood resulting in systemic dissemination in the body. Advancements in genomics have revealed that hospital-associated VRE strains are characterised by increased numbers of mobile genetic elements, higher numbers of antibiotic resistance genes and often lack active CRISPR-Cas systems. Additionally, comparative genomics have increased our understanding of dissemination routes among patients and healthcare workers. Since the efficiency of currently available antibiotics is rapidly declining, new measures to control infection and dissemination of these persistent pathogens are urgently needed. These approaches include combinatory administration of antibiotics, strengthening colonisation resistance of the gut microbiota to reduce VRE proliferation through commensals or probiotic bacteria, or switching to non-antibiotic bacterial killers, such as bacteriophages or bacteriocins. In this review, we discuss the current knowledge of the genomics of VRE isolates and state-of-the-art therapeutic advances against VRE infections.

Mechanism of Cell-Killing Activity of Plantaricin LD1 Against Escherichia coli ATCC 25922

Plantaricin LD1 was purified from a potential probiotic strain, Lactobacillus plantarum LD1 previously isolated from indigenous food, Dosa. In this study, we have performed a detailed mechanism of action of plantaricin LD1 against Escherichia coli ATCC 25922 considering Micrococcus luteus MTCC 106 as control. The plantaricin LD1 showed a minimum inhibitory concentration (MIC) of 34.57 µg/mL and a minimum bactericidal concentration (MBC) of 138.3 µg/mL against M. luteus MTCC 106, whereas MIC 69.15 µg/mL and MBC 276.6 µg/mL were found against E. coli ATCC 25922. The efflux of potassium ions, dissipation of membrane potential (∆ψ), and transmembrane pH gradient (∆pH) of plantaricin LD1-treated cells suggested the membrane-acting nature of plantaricin LD1. Plantaricin LD1 also caused degradation of the genomic DNA of the target strains tested. The cell killing was confirmed by staining with propidium iodide and visualized under light and electron microscopes. The bacteriocin-treated cells were found to be ruptured, swollen, and elongated. Thus, the findings indicate plantaricin LD1 kills E. coli ATCC 25922 by interacting with the cell membrane resulting in the efflux of intracellular contents and also causing degradation of nucleic acids leading to cell death.

Molecular Dynamic Study on the Structure and Thermal Stability of Mutant Pediocin PA-1 Peptides Engineered with Cysteine Substitutions

Pediocin and analogous bacteriocins, valued for thermal stability, serve as versatile antimicrobials in the food sector. Improving their resilience at high temperatures and deriving derivatives not only benefit food production but also offer broad-spectrum antimicrobial potential in pharmaceuticals, spanning treatments for peptic ulcers, women's health, and novel anticancer agents. The study aims to create mutant peptides capable of establishing a third disulfide bond or enhanced through cysteine substitutions. This involves introducing additional Cys residues into the inherent structure of pediocin PA-1 to facilitate disulfide bond formation. Five mutants (Mut 1-5) were systematically generated with double Cys substitutions and assessed for thermal stability through MD simulations across temperatures (298-394 K). The most robust mutants (Mut 1, Mut 4-5) underwent extended analysis via MD simulations, comparing their structural stability, secondary structure, and surface accessibility to the reference Pediocin PA-1 molecule. This comprehensive assessment aims to understand how Cys substitutions influence disulfide bonds and the overall thermal stability of the mutant peptides. In silico analysis indicated that Mut 1 and Mut 5, along with the reference structure, lose their helical structure and one natural disulfide bond at high temperatures, and may impacting antimicrobial activity. Conversely, Mut 4 retained its helical structure and exhibited thermal stability similar to Pediocin PA-1. Pending further experimental validation, this study implies Mut 4 may have high stability and exceptional resistance to high temperatures, potentially serving as an effective antimicrobial alternative.

Isolation, characterization of Weissella confusa and Lactococcus lactis from different milk sources and determination of probiotic features

This study aimed to investigate the probiotic properties of Lactic Acid Bacteria (LAB) isolates derived from various milk sources. These isolates identified based on their morphological characteristics and 16S rRNA gene sequencing. Four strains of Lactococcus lactis and two strains of Weissella confusa were identified with over 96% 16S rRNA gene similarity according to the NCBI-BLAST results. The survival of the isolates was determined in low pH, pepsin, bile salts, and pancreatin, and their adhesion ability was assessed by in vitro cell adhesion assay, hydrophobicity, auto- and co-aggregation, and safety criteria were determined by hemolytic, gelatinase activities, and DNAse production ability tests. The results showed that the LAB isolates had different levels of resistance to various stress factors. L. lactis subsp. cremoris MH31 showed the highest resistance to bile salt, while the highest pH resistance was observed in L. lactis MH31 at pH 3.0. All the isolates survived in pepsin exposure at pH 3.0 for 3 h. The auto-aggregation test results showed that all strains exhibited auto-aggregation ranging from 84.9 to 91.4%. Co-aggregation percentage ranged from 19 - 54% and 17 - 57% against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, respectively. The hydrophobicity capacity of the LAB isolated ranged from 35-61%. These isolates showed different adhesion abilities to Caco-2 cells (81.5% to 92.6%). None of the isolates exhibited DNase, gelatinase and hemolytic activity (γ-hemolysis). All results indicate that these LAB strains have the potential to be used as probiotics.

How probiotics, prebiotics, synbiotics, and postbiotics prevent dental caries: an oral microbiota perspective

Dental caries, a highly prevalent oral disease, impacts a significant portion of the global population. Conventional approaches that indiscriminately eradicate microbes disrupt the natural equilibrium of the oral microbiota. In contrast, biointervention strategies aim to restore this balance by introducing beneficial microorganisms or inhibiting cariogenic ones. Over the past three decades, microbial preparations have garnered considerable attention in dental research for the prevention and treatment of dental caries. However, unlike related pathologies in the gastrointestinal, vaginal, and respiratory tracts, dental caries occurs on hard tissues such as tooth enamel and is closely associated with localized acid overproduction facilitated by cariogenic biofilms. Therefore, it is insufficient to rely solely on previous mechanisms to delineate the role of microbial preparations in the oral cavity. A more comprehensive perspective should involve considering the concepts of cariogenic biofilms. This review elucidates the latest research progress, mechanisms of action, challenges, and future research directions regarding probiotics, prebiotics, synbiotics, and postbiotics for the prevention and treatment of dental caries, taking into account the unique pathogenic mechanisms of dental caries. With an enhanced understanding of oral microbiota, personalized microbial therapy will emerge as a critical future research trend.

Studies on a new antimicrobial peptide from Vibrio proteolyticus MT110

The marine environment is known for its vast diversity of the microbial population; however, less explored for bioactive compounds. In this study, an AMP produced by a new marine isolate, Vibrio proteolyticus MT110, showed broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria. The AMP was purified to homogeneity using ethyl acetate extraction followed by RP-HPLC, and LC-MS analysis showed its molecular weight as 980 Da. The MIC of AMP (peptide-MT110) was obtained in the 7.81-31.25 µg/mL range against different indicator strains. Peptide-MT110 showed stability of its antimicrobial activity at 15-121 °C and pH 4-10 and in the presence of various hydrolytic enzymes. The peaks at 1536 cm-1 and 1712 cm-1 wavenumbers in FTIR spectra confirmed the peptidic nature of AMP, and its amino acid analysis confirmed the presence of tyrosine and isoleucine. The antibacterial activity of peptide-MT110 is confirmed by PI assay and TEM. The optimization of peptide-MT110 production using statistical methods resulted in a 2.64-fold higher production. The physicochemical properties and stability in wide pH and temperature ranges showed the potential of peptide-MT110 for its development as a drug candidate. This is believed to be the first report on an AMP from Vibrio proteolyticus.

Microbial collaborations and conflicts: unraveling interactions in the gut ecosystem

The human gut microbiota constitutes a vast and complex community of microorganisms. The myriad of microorganisms present in the intestinal tract exhibits highly intricate interactions, which play a crucial role in maintaining the stability and balance of the gut microbial ecosystem. These interactions, in turn, influence the overall health of the host. The mammalian gut microbes have evolved a wide range of mechanisms to suppress or even eliminate their competitors for nutrients and space. Simultaneously, extensive cooperative interactions exist among different microbes to optimize resource utilization and enhance their own fitness. This review will focus on the competitive mechanisms among members of the gut microorganisms and discuss key modes of actions, including bacterial secretion systems, bacteriocins, membrane vesicles (MVs) etc. Additionally, we will summarize the current knowledge of the often-overlooked positive interactions within the gut microbiota, and showcase representative machineries. This information will serve as a reference for better understanding the complex interactions occurring within the mammalian gut environment. Understanding the interaction dynamics of competition and cooperation within the gut microbiota is crucial to unraveling the ecology of the mammalian gut microbial communities. Targeted interventions aimed at modulating these interactions may offer potential therapeutic strategies for disease conditions.

The Role of Probiotics in Improving Food Safety: Inactivation of Pathogens and Biological Toxins

Currently, many advances have been made in avoiding food contamination by numerous pathogenic and toxigenic microorganisms. Many studies have shown that different probiotics, in addition to having beneficial effects on the host's health, have a very good ability to eliminate and neutralize pathogens and their toxins in foods which leads to enhanced food safety. The present review purposes to comprehensively discuss the role of probiotics in improving food safety by inactivating pathogens (bacterial, fungal, viral, and parasite agents) and neutralizing their toxins in food products. Some recent examples in terms of the anti-microbial activities of probiotics in the body after consuming contaminated food have also been mentioned. This review shows that different probiotics have the potential to inactivate pathogens and neutralize and detoxify various biological agents in foods, as well as in the host body after consumption.

Bacteriocins: Curial guardians of gastrointestinal tract

The human gastrointestinal (GI) tract microbiome secretes various metabolites that play pivotal roles in maintaining host physiological balance and influencing disease progression. Among these metabolites, bacteriocins-small, heat-stable peptides synthesized by ribosomes-are notably prevalent in the GI region. Their multifaceted benefits have garnered significant interest in the scientific community. This review comprehensively explores the methods for mining bacteriocins (traditional separation and purification, bioinformatics, and artificial intelligence), their effects on the stomach and intestines, and their complex bioactive mechanisms. These mechanisms include flora regulation, biological barrier restoration, and intervention in epithelial cell pathways. By detailing each well-documented bacteriocin, we reveal the diverse ways in which bacteriocins interact with the GI environment. Moreover, the future research direction is prospected. By further studying the function and interaction of intestinal bacteriocins, we can discover new pharmacological targets and develop drugs targeting intestinal bacteriocins to regulate and improve human health. It provides innovative ideas and infinite possibilities for further exploration, development, and utilization of bacteriocins. The inevitable fact is that the continuously exploration of bacteriocins is sure to bring the promising future for demic GI health understanding and interference strategy.

Pathogen Eradication in Garlic in the Phytobiome Context: Should We Aim for Complete Cleaning?

Global food production is challenged by plant pathogens that cause significant crop losses. Fungi, bacteria, and viruses have long threatened sustainable and profitable agriculture. The danger is even higher in vegetatively propagated horticultural crops, such as garlic. Currently, quarantine, rouging infected plants, and control of natural vectors are used as the main means of disease and pest control in garlic crops. Agricultural biotechnology, meristem-tip culture, and cryotherapy offer solutions for virus eradication and for the multiplication of 'clean stocks', but at the same time, impact the symbiotic and beneficial components of the garlic microbiome. Our research involves the first metatranscriptomic analysis of the microbiome of garlic bulb tissue, PCR analyses, and a biological assay of endophytes and pathogens. We have demonstrated that in vitro sanitation methods, such as shoot tip culture or cryotherapy can alter the garlic microbiome. Shoot tip culture proved ineffective in virus elimination, but reduced bacterial load and eliminated fungal infections. Conversely, cryotherapy was efficient in virus eradication but demolished other components of the garlic microbiome. Garlic plants sanitized by cryotherapy exhibited a lower survival rate, and a longer in vitro regeneration period. The question arises whether total eradication of viruses, at the expense of other microflora, is necessary, or if a partial reduction in the pathogenic load would suffice for sanitized garlic production. We explore this question from both scientific and commercial perspectives.

Antimicrobial Peptides (Bacteriocins) Produced by Lactococcus lactis and Pediococcus pentosaceus Strains with Activity Against Clinical and Food-Borne Pathogens

Bacteriocins are ribosomal-synthesized peptides with antimicrobial activity, produced by different groups of bacteria, including lactic acid bacteria (LAB). Most of the produced by LAB bacteriocins can be described with rather broad spectra of inhibition and they offer suggested applications in food preservation and pharmaceutical sector. Different LAB were isolated from fermented food products and fruits, obtained from the region of Pohang, Korea, and identified based on physiological, biochemical, and molecular methods. The promising isolates, Pediococcus pentosaceus 732, Lactococcus lactis 808, and Lactococcus lactis subsp. lactis 431, were identified based on biochemical, physiological, and biomolecular approaches, including 16S rRNA partial sequencing, and were evaluated for production of bacteriocin, including stability in presence of enzymes, chemicals, pH, and temperatures. Adherence properties for the expressed bacteriocins by P. pentosaceus 732, Lc. lactis 808, and Lc. lactis subsp. lactis 431 were evaluated at presence of selected chemicals, pH, and temperatures. The presence of bacteriocin genes in the strains was investigated and analyzed. The bacterial effect of bacteriocin produced by studied strains on Listeria spp. and Staphylococcus spp. has been shown for actively growing and stationary cells. Similar growth and bacteriocin production were observed when studied strains were cultured in MRS at 30 °C or 37 °C. The presence of nisin operon with some point mutations on the genomic DNA was recorded based on the performed PCR reactions targeting different genes associated with nisin expression for both lactococcal strains. Pediocin PA-1 operon was evaluated in a similar manner for P. pentosaceus 732.

Gas Chromatography-Mass Spectrometry Profiling of Volatile Metabolites Produced by Some Bacillus spp. and Evaluation of Their Antibacterial and Antibiotic Activities

Bacillus species produce different classes of antimicrobial and antioxidant substances: peptides or proteins with different structural compositions and molecular masses and a broad range of volatile organic compounds (VOCs), some of which may serve as biomarkers for microorganism identification. The aim of this study is the identification of biologically active compounds synthesized by five Bacillus species using gas chromatography coupled to mass spectrometry (GC-MS). The current study profoundly enhances the knowledge of antibacterial and antioxidant metabolites ensuring the unambiguous identification of VOCs produced by some Bacillus species, which were isolated from vegetable samples of potato, carrot, and tomato. Phylogenetic and biochemical studies were used to identify the bacterial isolates after culturing. Phylogenetic analysis proved that five bacterial isolates BSS12, BSS13, BSS16, BSS21, and BSS25 showed 99% nucleotide sequence similarities with Bacillus safensis AS-08, Bacillus cereus WAB2133, Bacillus acidiproducens NiuFun, Bacillus toyonesis FORT 102, and Bacillus thuringiensis F3, respectively. The crude extract was prepared from bacterial isolates to assess the antibiotic resistance potency and the antimicrobial potential against various targeted multidrug-resistant strains, including yeast strains such as Candida albicans, Candida krusei, and bacterial strains of Enterococcus hirae, Escherichia coli, Klebsiella aerogenes, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus group B, Streptococcus mutans, Shigella sonnei, Salmonella enteritidis, Serratia marcescens, Pseudomonas aeruginosa, and Proteus vulgaris. GC-MS analysis of bacterial strains found that VOCs from Bacillus species come in a variety of chemical forms, such as ketones, alcohols, terpenoids, alkenes, etc. Overall, 69 volatile organic compounds were identified from five Bacillus species, and all five were found to share different chemical classes of volatile organic components, which have a variety of pharmacological applications. However, eight antibacterial compounds with different concentrations were commonly found in all five species: acetoin, acetic acid, butanoic acid, 2-methyl-, oxime-, methoxy-phenyl, phenol, 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester, nonanoic acid, and hexadecanoic acid, methyl. The present study has demonstrated that bacterial isolates BSS25, BSS21, and BSS16 display potent inhibitory effects against Candida albicans, while BSS25, BSS21, and BSS13 exhibit the ability to restrain the growth and activity of Candida krusei. Notably, BSS25 and BSS21 are the only isolates that demonstrate substantial inhibitory activity against Klebsiella aerogenes. This disparity in inhibitory effects could be attributed to the higher concentrations of acetoin in BSS25 and BSS21, whereas BSS16 and BSS13 have relatively elevated levels of butanoic acid, 2-methyl-. Certainly, the presence of acetoin and butanoic acid, 2-methyl-, contributes to the enhanced antibacterial potential of these bacterial strains, in conjunction with other organic volatile compounds and peptides, among other factors. The biology and physiology of Bacillus can be better understood using these results, which can also be used to create novel biotechnological procedures and applications. Moreover, because of its exceptional ability to synthesize and produce a variety of different antibacterial compounds, Bacillus species can serve as natural and universal carriers for antibiotic compounds in the form of probiotic cultures and strains to fight different pathogens, including mycobacteria.

Use of Postbiotic as Growth Promoter in Poultry Industry: A Review of Current Knowledge and Future Prospects

Health-promoting preparations of inanimate microorganisms or their components are postbiotics. Since probiotics are sensitive to heat and oxygen, postbiotics are stable during industrial processing and storage. Postbiotics boost poultry growth, feed efficiency, intestinal pathogen reduction, and health, making them acceptable drivers of sustainable poultry production. It contains many important biological properties, such as immunomodulatory, antioxidant, and anti-inflammatory responses. Postbiotics revealed promising antioxidant effects due to higher concentrations of uronic acid and due to some enzyme's production of antioxidants, e.g., superoxide dismutase, glutathione peroxidase, and nicotinamide adenine dinucleotide oxidases and peroxidases. Postbiotics improve intestinal villi, increase lactic acid production, and reduce Enterobacteriaceae and fecal pH, all of which lead to a better immune reaction and health of the gut, as well as better growth performance. P13K/AKT as a potential target pathway for postbiotics-improved intestinal barrier functions. Similarly, postbiotics reduce yolk and plasma cholesterol levels in layers and improve egg quality. It was revealed that favorable outcomes were obtained with various inclusion levels at 1 kg and 0.5 kg. According to several studies, postbiotic compounds significantly increased poultry performance. This review article presents the most recent research investigating the beneficial results of postbiotics in poultry.

Natural diversity of lactococci in γ-aminobutyric acid (GABA) production and genetic and phenotypic determinants

BACKGROUND

γ-aminobutyric acid (GABA) is a bioactive compound produced by lactic acid bacteria (LAB). The diversity of GABA production in the Lactococcus genus is poorly understood. Genotypic and phenotypic approaches were therefore combined in this study to shed light on this diversity. A comparative genomic study was performed on the GAD-system genes (gadR, gadC and gadB) involved in GABA production in 36 lactococci including L. lactis and L. cremoris species. In addition, 132 Lactococcus strains were screened for GABA production in culture medium supplemented with 34 mM L-glutamic acid with or without NaCl (0.3 M).

RESULTS

Comparative analysis of the nucleotide sequence alignments revealed the same genetic organization of the GAD system in all strains except one, which has an insertion sequence element (IS981) into the PgadCB promoter. This analysis also highlighted several deletions including a 3-bp deletion specific to the cremoris species located in the PgadR promoter, and a second 39-bp deletion specific to L. cremoris strains with a cremoris phenotype. Phenotypic analysis revealed that GABA production varied widely, but it was higher in L. lactis species than in L. cremoris, with an exceptional GABA production of up to 14 and 24 mM in two L. lactis strains. Moreover, adding chloride increased GABA production in some L. cremoris and L. lactis strains by a factor of up to 16 and GAD activity correlated well with GABA production.

CONCLUSIONS

This genomic analysis unambiguously characterized the cremoris phenotype of L. cremoris species and modified GadB and GadR proteins explain why the corresponding strains do not produce GABA. Finally, we found that glutamate decarboxylase activity revealing GadB protein amount, varied widely between the strains and correlated well with GABA production both with and without chloride. As this protein level is associated to gene expression, the regulation of GAD gene expression was identified as a major contributor to this diversity.

Identification of novel bacteriocin against Staphylococcus and Bacillus species

Objectives

Due to the continues emergence of antimicrobial resistance, discovery of novel compounds are urgently required. Thus, this study is focused to identify a novel antimicrobial peptide (bacteriocin) targeting multidrug-resistant pathogenic bacteria.

Methods

About 80 environmental isolates were recovered and screened for anti-bacterial activity using simultaneous antagonism assays. Produced peptide (AB3) was purified using Strata-XL-C and Sep-Pack columns. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis and MIC were conducted on the AB3 peptide to determine its molecular weight and spectrum of activity. Extraction and amplification for the 16S rRNA gene of the producing strain was accomplished using QIAamp DNA Mini Kit and GeneAmp PCR system thermocycler, respectively. Novelty of the compound was assessed based on all obtained genomic and proteomic data using Basic Local Alignment Search Tool search and Unni-Prot and Bactibase, respectively.

Results

About 5% of screened isolates showed antagonistic activity toward tested indicators. Obtained compound showed narrow spectrum of activity toward certain Gram-positive species including, methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA) and Bacillus species. MALDI-TOF analysis revealed the flowing molecular masses: 1288.207 Da, 1304.536 Da, 1326.529 Da, 1403.591 Da, and 1472.792 Da. The extensive genomic and proteomic analysis have indicated the discovery of novel bacteriocin produced by Bacillus malacitensis.

Conclusion

A novel bacteriocin (AB3) was identified from B. malacitensis, which has showed promising in vitro bactericidal activity toward MSSA, MRSA, and Bacillus subtilis. This compound holds great potential to replace or used in combination with currently used antibiotics to treat serious untreatable bacterial infections. However, further investigations to determine its suitability for therapeutic use in human health are needed.

Minimal Processing Technologies for Production and Preservation of Tailor-Made Foods§

Tailor-made foods, also known as foods with programmable properties, are specialised systems with unique composition prepared by different methods, using the known mechanisms of action of their bioactive ingredients. The development of tailor-made foods involves the evaluation of individual components, including bioactive substances derived from waste products of other productions, such as essential oils. These components are evaluated both individually and in combination within food compositions to achieve specific functionalities. This review focuses on the application of minimal processing technologies for the production and preservation of tailor-made foods. It examines a range of approaches, including traditional and emerging technologies, as well as novel ingredients such as biomolecules from various sources and microorganisms. These approaches are combined according to the principles of hurdle technology to achieve effective synergistic effects that enhance food safety and extend the shelf life of tailor-made foods, while maintaining their functional properties.

Gene expression and cell culture assays reveal cheese isolate Lactococcus lactis MC5 may influence the virulence of Staphylococcus aureus

Staphylococcus aureus (SA) can thrive in a wide variety of hosts and environments, causing clinical infections and foodborne intoxications. In Brazil, SA is commonly isolated from traditional soft cheeses, especially those prepared from unpasteurized milk. In this research, the isolate S. aureus SABRC1 was evaluated for virulence traits under different conditions, including co-inoculation with Lactococcus lactis MC5 (isolated from "Fresh Minas Cheese"), which produces antibacterial peptides. Results from experiments with Caco-2 culture indicated S. aureus SABRC1 was able to adhere (42.83 ± 1.79%) and to invade (48.57 ± 0.41%) the intestinal cells. On the other hand, L. lactis MC5 presented anti-staphylococcal activity as indicated by agar assays, and it was also able to antagonize intestinal cell invasion by S. aureus. Moreover, Reverse Transcriptase-PCR experiments showed virulence genes of S. aureus SABRC1 (hla, icaA and sea) were differentially expressed under diverse culture conditions, which included Brain Heart Infusion modified or not by the addition of glucose, sodium chloride, milk or cheese. This suggests the virulence of S. aureus SABRC1 is influenced by compounds commonly found in daily diets, and not only by its genetic repertoire, adding a novel level of complexity for controlling infection by this pathogen.

Biofilm-a Syntrophic Consortia of Microbial Cells: Boon or Bane?

Biofilm is the conglomeration of microbial cells which is associated with a surface. In the recent times, the study of biofilm has gained popularity and vivid research is being done to know about the effects of biofilm and that it consists of many organisms which are symbiotic in nature, some of which are human pathogens. Here, in this study, we have discussed about biofilms, its formation, relevance of its presence in the biosphere, and the possible remediations to cope up with its negative effects. Since removal of biofilm is difficult, emphasis has been made to suggest ways to prevent biofilm formation and also to devise ways to utilize biofilm in an economically and environment-friendly method.

Discovery and Characterization of a Novel Bacteriocin HA2-5 that Strongly Inhibits Propionibacterium acnes

Increased drug resistance has significantly reduced the effectiveness of antibiotics used in the treatment of Propionibacterium acnes. Therefore, there has been a trend toward the development of new antimicrobial agents to circumvent drug resistance. In this study, we isolated and purified a novel bacteriocin, HA2-5, from Bacillus haynesii HA2, which effectively killed P. acnes through membrane disruption at a minimum inhibitory concentration (MIC) of 8 μg/mL. HA2-5 with 2× MIC was able to kill 99.9% of P. acnes within 24 h. HA2-5 shows excellent stability and tolerance to temperature, pH, proteases, chemical reagents, UV radiation, and metal ions, with almost no loss of inhibitory activity after treatment. In addition, the very low hemolytic activity and cytotoxicity suggest that HA2-5 is biosafe. Notably, HA2-5 exhibits preferred antibacterial activity against gram-positive pathogens with an MIC of 16-32 μg/mL. In conclusion, this study shows that bacteriocin HA2-5 has the potential to be used as an alternative to antibiotics for acne treatment.

Role of Antimicrobial Peptides in Immunity of Parasitic Leeches

The review summarizes the current state of knowledge about leech immunity, with emphasis on the special role of antimicrobial peptides (AMPs), and highlights the wide variety of primary AMP structures, which seem to correlate with a variety of life strategies and the ecology of ectoparasites. Antimicrobial proteins and AMPs are a diverse class of natural molecules that are produced in all living organisms in response to an attack by a pathogen and are essential components of the immune system. AMPs can have a wide range of antibiotic activities against foreign and opportunistic bacteria, fungi, and viruses. AMPs play an important role in selection of colonizing bacterial symbionts, thus helping multicellular organisms to cope with certain environmental problems. AMPs are especially important for invertebrates, which lack an adaptive immune system. Although many AMPs are similar in physicochemical properties (a total length from 10 to 100 amino acids, a positive total charge, or a high cysteine content), their immunomodulatory activities are specific for each AMP type.

Antimicrobial Peptides in Infectious Diseases and Beyond-A Narrative Review

Despite recent medical research and clinical practice developments, the development of antimicrobial resistance (AMR) significantly limits therapeutics for infectious diseases. Thus, novel treatments for infectious diseases, especially in this era of increasing AMR, are urgently needed. There is ongoing research on non-classical therapies for infectious diseases utilizing alternative antimicrobial mechanisms to fight pathogens, such as bacteriophages or antimicrobial peptides (AMPs). AMPs are evolutionarily conserved molecules naturally produced by several organisms, such as plants, insects, marine organisms, and mammals, aiming to protect the host by fighting pathogenic microorganisms. There is ongoing research regarding developing AMPs for clinical use in infectious diseases. Moreover, AMPs have several other non-medical applications in the food industry, such as preservatives, animal husbandry, plant protection, and aquaculture. This review focuses on AMPs, their origins, biology, structure, mechanisms of action, non-medical applications, and clinical applications in infectious diseases.

Comprehensive Analysis of Bacteriocins Produced by the Hypermucoviscous Klebsiella pneumoniae Species Complex

Klebsiella pneumoniae produces several kinds of bacteriocins that have antimicrobial effects against closely related species, but few studies have comprehensively reported bacteriocin distribution among the Klebsiella population. In this study, we identified bacteriocin genes in 180 K. pneumoniae species complex genomes, including 170 hypermucoviscous isolates, and investigated the antibacterial activity against 50 strains, including antimicrobial-resistant organisms, belonging to multiple species, namely, Klebsiella spp., Escherichia coli, Pseudomonas spp., Acinetobacter spp., Enterobacter cloacae, Stenotrophomonas maltophilia, Chryseobacterium indologenes, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus mutans. Our study determined that 32.8% (59/180) of isolates carried at least one bacteriocin type. Different types of bacteriocin were usually present in different specific sequence types (STs); meanwhile, bacteriocins were not detected in certain STs. Microcin E492 was the most prevalent bacteriocin (14.4%), mostly in ST23 isolates, and displayed a wide spectrum of activity, including against Klebsiella spp., E. coli, Pseudomonas spp., and Acinetobacter spp. Cloacin-like bacteriocin was detected in 7.2% of strains, all of which were non-ST23 isolates, and exhibited inhibitory activity against closely related species, mainly Klebsiella spp. Klebicin B-like bacteriocin was detected at a rate of 9.4%, although 82.4% of these strains carried a disrupted bacteriocin gene, and an inhibitory effect could not be observed from the intact-gene-carrying isolates. Other bacteriocins, such as microcin S-like, microcin B17, and klebicin C-like, were detected at lower rates and had limited inhibitory activity. Our findings suggested that Klebsiella strains that carry different bacteriocin types may affect the composition of the surrounding bacterial community. IMPORTANCE Klebsiella pneumoniae is a Gram-negative commensal bacterium that asymptomatically colonizes human mucosal membranes, such as the intestinal tract, but it is also a leading cause of health care- and community-associated infections. Additionally, multidrug-resistant K. pneumoniae has been continuously evolving, which significantly challenges the available chemotherapeutic treatment for its infections. K. pneumoniae produces several kinds of antimicrobial peptides known as bacteriocins, which have antibacterial activity against closely related species. This work was the first comprehensive report of bacteriocin distribution among the hypermucoviscous K. pneumoniae species complex population and the inhibitory activity of each bacteriocin type against various species, including multidrug-resistant strains. Our findings provide a foundation for future studies on the K. pneumoniae species complex, including studies on the competition within the microflora and the potential applications of bacteriocins in treating multidrug-resistant bacteria.

Synthetic and natural antimicrobials as a control against food borne pathogens: A review

Food borne pathogens are one of the most common yet concerning cause of illnesses around the globe. These microbes invade the body via food items, through numerous mediums of contamination and it is impossible to completely eradicate these organisms from food. Extensive research has been made regarding their treatment. Unfortunately, the only available treatment currently is by antibiotics. Recent exponential increase in antibiotic resistance and the side effect of synthetic compounds have established a need for alternate therapies that could be utilized either on their own or along with antibiotics to provide protection against food-borne diseases. The aim of this review is to provide information regarding some common food borne diseases, their current and possible natural treatment. It will include details regarding some common foodborne pathogens, the disease they cause, prevalence, manifestations and treatment of the respective disease. Some natural modes of potential treatment will be summarized, which including phytochemicals, derived from plants either as crude extracts or as purified form and Bacteriocins as microbial based treatment, obtained from various types of bacteria. The paper will describe their mechanism of action, classification, susceptible organisms, some antimicrobial compounds and producing organisms, application in food systems and as potential treatment. Along with that, synthetic treatment i.e., antibiotics will be discussed including the first-line treatment of some common food borne infections, prevalence and mechanism of resistance against antibiotics in the pathogens.

Metagenome-mining indicates an association between bacteriocin presence and strain diversity in the infant gut

BACKGROUND

Our knowledge about the ecological role of bacterial antimicrobial peptides (bacteriocins) in the human gut is limited, particularly in relation to their role in the diversification of the gut microbiota during early life. The aim of this paper was therefore to address associations between bacteriocins and bacterial diversity in the human gut microbiota. To investigate this, we did an extensive screening of 2564 healthy human gut metagenomes for the presence of predicted bacteriocin-encoding genes, comparing bacteriocin gene presence to strain diversity and age.

RESULTS

We found that the abundance of bacteriocin genes was significantly higher in infant-like metagenomes (< 2 years) compared to adult-like metagenomes (2-107 years). By comparing infant-like metagenomes with and without a given bacteriocin, we found that bacteriocin presence was associated with increased strain diversities.

CONCLUSIONS

Our findings indicate that bacteriocins may play a role in the strain diversification during the infant gut microbiota establishment.

Nanomedicine for drug resistant pathogens and COVID-19 using mushroom nanocomposite inspired with bacteriocin – A Review

Multidrug resistant (MDR) pathogens have become a major global health challenge and have severely threatened the health of society. Current conditions have gotten worse as a result of the COVID-19 pandemic, and infection rates in the future will rise. It is necessary to design, respond effectively, and take action to address these challenges by investigating new avenues. In this regard, the fabrication of metal NPs utilized by various methods, including green synthesis using mushroom, is highly versatile, cost-effective, eco-compatible, and superior. In contrast, biofabrication of metal NPs can be employed as a powerful weapon against MDR pathogens and have immense biomedical applications. In addition, the advancement in nanotechnology has made possible to modify the nanomaterials and enhance their activities. Metal NPs with biomolecules composite to prevents their microbial adhesion and kills the microbial pathogens through biofilm formation. Bacteriocin is an excellent antimicrobial peptide that works well as an augmentation substance to boost the antimicrobial effects. As a result, we concentrate on the creation of new, eco-compatible mycosynthesized metal NPs with bacteriocin nanocomposite via electrostatic, covalent, or non-covalent bindings. The synergistic benefits of metal NPs with bacteriocin to combat MDR pathogens and COVID-19, as well as other biomedical applications, are discussed in this review. Moreover, the importance of the adverse outcome pathway (AOP) in risk analysis of manufactured metal nanocomposite nanomaterial and their future possibilities also discussed.

BacSp222 bacteriocin as a novel ligand for TLR2/TLR6 heterodimer

OBJECTIVE AND DESIGN

BacSp222 bacteriocin is a bactericidal and proinflammatory peptide stimulating immune cells to produce selected cytokines and NO in NF-ĸB dependent manner. This study aims to identify the receptor which mediates this activity.

METHODS

We applied fluorescently labeled BacSp222 and a confocal microscopy imaging to analyze the direct interaction of the bacteriocin with the cells. Reporter HEK-Blue cells overexpressing human toll-like receptors (TLR2, TLR4, TLR5 or TLR2/TLR1 and TLR2/TLR6 heterodimers) were stimulated with BacSp222, and then the activity of NF-ĸB-dependent secreted embryonic alkaline phosphatase (SEAP) was measured. In turn, formylated peptide receptor (FPR) or TLR2 antagonists were used to verify bacteriocin-stimulated TNF production by murine monocyte-macrophage cell lines.

RESULTS

BacSp222 undergoes internalization into cells without disturbing the cell membrane. FPR antagonists do not affect TNF produced by BacSp222-stimulated murine macrophage-like cells. In contrast, BacSp222 stimulates NF-ĸB activation in HEK-Blue overexpressing TLR2 or TLR2/TLR6 heterodimer, but not TLR2/TLR1, TLR4 or TLR5 receptors. Moreover, TLR2-specific antagonists inhibit NF-ĸB signaling in BacSp222-stimulated HEK-Blue TLR2/TLR6 cells and reduce TNF release by BacSp222-treated RAW 264.7 and P388.D1.

CONCLUSIONS

BacSp222 is a novel ligand for TLR2/TLR6 heterodimer. By binding TLR complex the bacteriocin undergoes internalization, inducing proinflammatory signaling that employs MyD88 and NF-ĸB pathways.

Development of novel broad-spectrum antimicrobial lipopeptides derived from plantaricin NC8 β

Bacterial resistance towards antibiotics is a major global health issue. Very few novel antimicrobial agents and therapies have been made available for clinical use during the past decades, despite an increasing need. Antimicrobial peptides have been intensely studied, many of which have shown great promise in vitro. We have previously demonstrated that the bacteriocin Plantaricin NC8 αβ (PLNC8 αβ) from Lactobacillus plantarum effectively inhibits Staphylococcus spp., and shows little to no cytotoxicity towards human keratinocytes. However, due to its limitations in inhibiting gram-negative species, the aim of the present study was to identify novel antimicrobial peptidomimetic compounds with an enhanced spectrum of activity, derived from the β peptide of PLNC8 αβ. We have rationally designed and synthesized a small library of lipopeptides with significantly improved antimicrobial activity towards both gram-positive and gram-negative bacteria, including the ESKAPE pathogens. The lipopeptides consist of 16 amino acids with a terminal fatty acid chain and assemble into micelles that effectively inhibit and kill bacteria by permeabilizing their cell membranes. They demonstrate low hemolytic activity and liposome model systems further confirm selectivity for bacterial lipid membranes. The combination of lipopeptides with different antibiotics enhanced the effects in a synergistic or additive manner. Our data suggest that the novel lipopeptides are promising as future antimicrobial agents, however additional experiments using relevant animal models are necessary to further validate their in vivo efficacy.

BADASS: BActeriocin-Diversity ASsessment Software

BACKGROUND

Bacteriocins are defined as thermolabile peptides produced by bacteria with biological activity against taxonomically related species. These antimicrobial peptides have a wide application including disease treatment, food conservation, and probiotics. However, even with a large industrial and biotechnological application potential, these peptides are still poorly studied and explored. BADASS is software with a user-friendly graphical interface applied to the search and analysis of bacteriocin diversity in whole-metagenome shotgun sequencing data.

RESULTS

The search for bacteriocin sequences is performed with tools such as BLAST or DIAMOND using the BAGEL4 database as a reference. The putative bacteriocin sequences identified are used to determine the abundance and richness of the three classes of bacteriocins. Abundance is calculated by comparing the reads identified as bacteriocins to the reads identified as 16S rRNA gene using SILVA database as a reference. BADASS has a complete pipeline that starts with the quality assessment of the raw data. At the end of the analysis, BADASS generates several plots of richness and abundance automatically as well as tabular files containing information about the main bacteriocins detected. The user is able to change the main parameters of the analysis in the graphical interface. To demonstrate how the software works, we used four datasets from WMS studies using default parameters. Lantibiotics were the most abundant bacteriocins in the four datasets. This class of bacteriocin is commonly produced by Streptomyces sp.

CONCLUSIONS

With a user-friendly graphical interface and a complete pipeline, BADASS proved to be a powerful tool for prospecting bacteriocin sequences in Whole-Metagenome Shotgun Sequencing (WMS) data. This tool is publicly available at https://sourceforge.net/projects/badass/ .

Molecular identification, characterization, and antagonistic activity profiling of Bacillus cereus LOCK 1002 along with the in-silico analysis of its presumptive bacteriocins

Objectives

This research aimed to isolate, identify, and characterize a new strain of Bacillus cereus through different molecular biology approaches so that it could be further studied for therapeutic purposes against selective enteric pathogens.

Materials and Methods

Pure isolates of B. cereus were prepared from buffalo yogurt samples in REMBA medium. Initially, the morphological, physiological, and biochemical properties were studied accordingly. Following the tests, the molecular identification for the strain identification was conducted through plasmid DNA extraction, PCR, agarose gel electrophoresis, and 16S rRNA sequencing up to 1.37 kb. Afterward, the antibiotic sensitivity [Epsilometer test (E-Test)] and antifungal activity were tested considering different concentrations. Being classified from the aforementioned tests, a comprehensive antimicrobial activity test was conducted using the cell-free-supernatant (CFS) of the test strain against selective enteric pathogens in humans in vitro. Besides, the different clusters of genes were identified and characterized for understanding the presumptive bacteriocins present in the CFS of the strain in silico, where molecular string properties were calculated. Finally, the evolutionary relationship among diversified bacteriocins synthesized by different Bacillus strains was studied to predict the CFS-containing bacteriocins of the new strain.

Results

Purified isolates of B. cereus were Gram-positive rods and showed significant tolerance (p < 0.0001) to different concentrations of pH, phenol, bile salt, and NaCl. 16S rRNA revealed the strain as LOCK 1002, which was strongly sensitive to all the antibiotics used and resistant to selective antifungal agents. The CFS of B. cereus LOCK 1002 was found to be a very promising antagonist to all the enteric pathogens used in the culture condition. Two gene clusters were predicted to be interconnected and responsible for different presumptive bacteriocins.

Conclusion

The newly identified LOCK 1002 can be a very potent strain of B. cereus in use as an antimicrobial agent for having different bacteriocin coding gene clusters.

A Review of the Antimicrobial Potential of Musca domestica as a Natural Approach with Promising Prospects to Countermeasure Antibiotic Resistance

Drug-resistant pathogens have become a serious public health concern worldwide considering the rapid emergence and distribution of new strains, which outpace the development of antimicrobial drugs. It is a complex and serious clinical problem that can cause an epidemic of a disease; consequently, numerous research studies are conducted to determine the solution to these problems, including the development of new antibiotics derived from natural sources such as insects. The housefly (Musca domestica L.), an insect known as a cosmopolitan pest, possesses several qualities that can ameliorate diseases; consequently, they can be used as a bioactive component in the development of medicines. These qualities include its potential as a source of antibacterial agents. The external surface components, wings, internal organs, and whole body extract of M. domestica can all contribute antimicrobial potential due to bioactive compounds they produce. This article discusses several antimicrobial properties of M. domestica that could be utilized for healthcare benefits.

Resistance Mechanism and Physiological Effects of Microcin Y in Salmonella enterica subsp. enterica Serovar Typhimurium

Salmonella bacteria pose a significant threat to animal husbandry and human health due to their virulence and multidrug resistance. The lasso peptide MccY is a recently discovered antimicrobial peptide that acts against various serotypes of Salmonella. In this study, we further explore the resistance mechanism and activity of MccY. Mutants of Ton system genes, including tonB, exbB, and exbD, in Salmonella enterica subsp. enterica serovar Typhimurium were constructed, and the MICs to MccY exhibited significant increases in these deletion mutants compared to the MIC of the parent strain. Subsequently, MccY resistance was quantitatively analyzed, and these mutants also showed greatly reduced rates of killing, even with a high concentration of MccY. In addition, a minimal medium with low iron environment enhanced the sensitivity of these mutants to MccY. Measurements of a series of physiological indicators, including iron utilization, biofilm formation, and motility, demonstrated that MccY may decrease the virulence of S. Typhimurium. Transcriptomic analysis showed that iron utilization, biofilm formation, flagellar assembly, and virulence-related genes were downregulated to varying degrees when S. Typhimurium was treated with MccY. In conclusion, deletion of Ton system genes resulted in resistance to MccY and the susceptibility of these mutants to MccY was increased and differed under a low-iron condition. This lasso peptide can alter multiple physiological properties of S. Typhimurium. Our study will contribute to improve the knowledge and understanding of the mechanism of MccY resistance in Salmonella strains. IMPORTANCE The resistance of Salmonella to traditional antibiotics remains a serious challenge. Novel anti-Salmonella drugs are urgently needed to address the looming crisis. The newly identified antimicrobial peptide MccY shows broad prospects for development and application because of its obvious antagonistic effect on various serotypes of Salmonella. However, our previous study showed that the peptide could confer resistance to Salmonella by disrupting the receptor gene fhuA. In this study, we further explored the potential resistance mechanism of MccY and demonstrated the importance of the Salmonella Ton complex for MccY transport. Disruption in Ton system genes resulted in S. Typhimurium resistance to this peptide, and MccY could alter multiple bacterial physiological properties. In summary, this study further explored the resistance mechanism and antibacterial effect of MccY in S. Typhimurium and provided a scientific basis for its development and application.

Bread packaging techniques and trends

Bread staling and microbial growth is a complex physiochemical change that occurs during bread storage mainly reducing the quality and consumer acceptance. It is significant to understand the causes of physical, chemical, and microbial spoilage of bakery products in the food industry, to prevent quality decay and economic loss for manufacturers and consumers. Traditional packaging has limitations in protecting and preserving the final products' safety, hygiene, and quality. Effective novel strategies must be included in food packaging, especially to minimize the organoleptic losses of baked foods during their shelf life. Furthermore, owing to the spread of foodborne diseases, which directly affect the safety of the products, customer demand is increasing significantly to reduce the use of synthetic preservatives instead of natural ones. Innovative packaging is altering the way food items are packed in several ways to extend and monitor product shelf life. Traditional packaging includes packaging food in synthetic polymer film; however, modern technology allows them to interact with active/functional substances. This paper discusses innovative bread packaging strategies such as modified atmosphere packaging (MAP), active packaging (AP), intelligent packaging (IP), biosensor, and nano packaging. Furthermore, MAP and AP have received greater attention in this study due to their considerable effect in prolonging the shelf life of bread and naturally preventing fungal activity, and have gained a lot of interest among producers and consumers in recent years.

Compositional Changes in the Gut Microbiota of Responders and Non-responders to Probiotic Treatment Among Patients With Diarrhea-predominant Irritable Bowel Syndrome: A Post Hoc Analysis of a Randomized Clinical Trial

Background/Aims

We aim to evaluate the differences in the microbiome of responders and non-responders, as well as predict the response to probiotic therapy, based on fecal microbiome data in patients with diarrhea-predominant irritable bowel syndrome (IBS-D).

Methods

A multi-strain probiotics that contains Lactobacillus acidophilus (KCTC 11906BP), Lactobacillus plantarum (KCTC11867BP), Lactobacillus rhamnosus (KCTC 11868BP), Bifidobacterium breve (KCTC 11858BP), Bifidobacterium lactis (KCTC 11903BP), Bifidobacterium longum (KCTC 11860BP), and Streptococcus thermophilus (KCTC 11870BP) were used. Patients were categorized into probiotic and placebo groups, and fecal samples were collected from all patients before and at the end of 8 weeks of treatment. The probiotic group was further divided into responders and non-responders. Responders were defined as patients who experienced adequate relief of overall irritable bowel syndrome symptoms after probiotic therapy. Fecal microbiota were investigated using Illumina MiSeq and analyzed using the EzBioCloud 16S database and microbiome pipeline (https://www.EZbiocloud.net).

Results

There was no significant difference in the alpha and beta diversity between the responder and non-responder groups. The abundances of the phylum Proteobacteria and genus Bacteroides significantly decreased after probiotic treatment. Bifidobacterium bifidum, Pediococcus acidilactici, and Enterococcus faecium showed a significantly higher abundance in the probiotic group after treatment compared to the placebo group. Enterococcus faecalis and Lactococcus lactis were identified as biomarkers of non-response to probiotics. The abundance of Fusicatenibacter saccharivorans significantly increased in the responders after treatment.

Conclusions

Probiotic treatment changes some composition of fecal bacteria in patients with IBS-D. E. faecalis and L. lactis may be prediction biomarkers for non-response to probiotics. Increased abundance of F. sccharivorans is correlated to symptom improvement by probiotics in patients with IBS-D.

Antimicrobial cryogel dressings towards effective wound healing

Cryogels are macroporous hydrogels that have been widely utilized in a variety of biomedical applications including wound dressings. Cryogels reveal superior mechanical and swelling properties as well as large and interconnected porosity. As traditional hydrogel wound dressings generally show undesirable mechanical and swelling characteristics, cryogels, due to their toughness and superfast swelling, offer an outstanding platform to address the growing number of various types of wounds. Moreover, recently, cryogel wound dressings loaded with an antimicrobial agent emerged as a feasible option to reduce infection, and thus improve the wound healing process. However, a comprehensive review of antimicrobial cryogels as a wound dressing is still lacking in the literature. In this review, we summarize the progress of cryogels in the area of wound dressings and provide an overview of the various polymers, namely, natural and synthetic which have been employed in cryogel wound dressing preparation. Furthermore, the most prominent antimicrobial agents incorporated in cryogel wound dressings are provided. Finally, the future directions of cryogel wound dressings for wound healing are also discussed.

The effect of Escherichia coli ŽP strain with a conjugation-based colicin E7 delivery on growth performance, hematological, biochemical, and histological parameters, gut microbiota, and nonspecific immunity of broilers

The Escherichia coli ŽP strain (ŽP) was constructed based on the known probiotic E. coli strain Nissle 1917. It was genetically modified to carry the colicin E7 synthesis gene encoding DNase on a conjugative plasmid and the colicin E7 immunity gene in the chromosome. The aim of this study was to evaluate the effects of the daily ŽP per oral administration (5 × 10⁸ or 5 × 10¹⁰ CFU per bird) on the growth performance, hematological, biochemical, histological parameters, gut microbiota, and nonspecific immunity of the 4-24 days old broilers. The ŽP administration increased the abundance of genera Bacillus, Butyrivibrio, and Clostridium and did not influence the weight gain of 4-16 days old broilers. The biochemical parameters were within normal ranges for poultry in experimental and control groups. The ŽP administration had no effect on the erythrocyte numbers, hemoglobin and immunoglobulin Y concentrations, but significantly increased the serum lysozyme concentration, leukocyte numbers, and reactive oxygen species production by phagocytes compared with the control group. It did not cause inflammatory changes in intestinal mucosa, Peyer's patches, and spleen. Thus, the ŽP had no detrimental effects on broiler health and could be an efficient probiotic for the broiler colibacillosis prophylaxis.

Colicins and Microcins Produced by Enterobacteriaceae: Characterization, Mode of Action, and Putative Applications

Enterobacteriaceae are widely present in many environments related to humans, including the human body and the food that they consume, from both plant or animal origin. Hence, they are considered relevant members of the gastrointestinal tract microbiota. On the other hand, these bacteria are also recognized as putative pathogens, able to impair human health and, in food, they are considered indicators for the microbiological quality and hygiene status of a production process. Nevertheless, beneficial properties have also been associated with Enterobacteriaceae, such as the ability to synthesize peptides and proteins, which can have a role in the structure of microbial communities. Among these antimicrobial molecules, those with higher molecular mass are called colicins, while those with lower molecular mass are named microcins. In recent years, some studies show an emphasis on molecules that can help control the development of pathogens. However, not enough data are available on this subject, especially related to microcins. Hence, this review gathers and summarizes current knowledge on colicins and microcins, potential usage in the treatment of pathogen-associated diseases and cancer, as well as putative applications in food biotechnology.

Structure of Lacticaseicin 30 and Its Engineered Variants Revealed an Interplay between the N-Terminal and C-Terminal Regions in the Activity against Gram-Negative Bacteria

Lacticaseicin 30 is one of the five bacteriocins produced by the Gram-positive Lacticaseibacillus paracasei CNCM I-5369. This 111 amino acid bacteriocin is noteworthy for being active against Gram-negative bacilli including Escherichia coli strains resistant to colistin. Prediction of the lacticaseicin 30 structure using the Alphafold2 pipeline revealed a largely helical structure including five helix segments, which was confirmed by circular dichroism. To identify the structural requirements of the lacticaseicin 30 activity directed against Gram-negative bacilli, a series of variants, either shortened or containing point mutations, was heterologously produced in Escherichia coli and assayed for their antibacterial activity against a panel of target strains including Gram-negative bacteria and the Gram-positive Listeria innocua. Lacticaseicin 30 variants comprising either the N-terminal region (amino acids 1 to 39) or the central and C-terminal regions (amino acids 40 to 111) were prepared. Furthermore, mutations were introduced by site-directed mutagenesis to obtain ten bacteriocin variants E6G, T7P, E32G, T33P, T52P, D57G, A74P, Y78S, Y93S and A97P. Compared to lacticaseicin 30, the anti-Gram-negative activity of the N-terminal peptide and variants E32G, T33P and D57G remained almost unchanged, while that of the C-terminal peptide and variants E6G, T7P, T52P, A74P, Y78S, Y93S and A97P was significantly altered. Finally, the N-terminal region was further shortened to keep only the first 20 amino acid part that was predicted to include the first helix. The anti-Gram-negative activity of this truncated peptide was completely abolished. Overall, this study shows that activity of lacticaseicin 30, one of the rare Gram-positive bacteriocins inhibiting Gram-negative bacteria, requires at least two helices in the N-terminal region and that the C-terminal region carries amino acids playing a role in modulation of the activity. Taken together, these data will help to design forthcoming variants of lacticaseicin 30 as promising therapeutic agents to treat infections caused by Gram-negative bacilli.

Eco-Friendly Edible Packaging Systems Based on Live-Lactobacillus kefiri MM5 for the Control of Listeria monocytogenes in Fresh Vegetables

To meet consumer requirements for high quality food free of chemical additives, according to the principles of sustainability and respect for the environment, new “green” packaging solutions have been explored. The antibacterial activity of edible bioactive films and coatings, based on biomolecules from processing by-products and biomasses, added with the bacteriocin producer Lactobacillus kefiri MM5, has been determined in vegetables against L. monocytogenes NCTC 10888 (i) “in vitro” by a modified agar diffusion assay and (ii) “on food” during storage of artificially contaminated raw vegetable samples, after application of active films and coatings. Both polysaccharides-based and proteins-based films and coatings showed excellent antilisterial activity, especially at 10 and 20 days. Protein-based films displayed a strong activity against L. monocytogenes in carrots and zucchini samples (p < 0.0001). After 10 days, both polysaccharide-based and protein-based films demonstrated more enhanced activity than coatings towards the pathogen. These edible active packagings containing live probiotics can be used both to preserve the safety of fresh vegetables and to deliver a beneficial probiotic bacterial strain. The edible ingredients used for the formulation of both films and coatings are easily available, at low cost and environmental impact.

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.

Influence of Gut–Liver Axis on Portal Hypertension in Advanced Chronic Liver Disease: The Gut Microbiome as a New Protagonist in Therapeutic Management

Clinically significant portal hypertension is associated with most complications of advanced chronic liver disease (ACLD), including variceal bleeding, ascites, spontaneous bacterial peritonitis, hepatorenal syndrome, and hepatic encephalopathy. Gut dysbiosis is a hallmark of ACLD with portal hypertension and consists of the overgrowth of potentially pathogenic bacteria and a decrease in autochthonous bacteria; additionally, congestion makes the intestinal barrier more permeable to bacteria and their products, which contributes to the development of complications through inflammatory mechanisms. This review summarizes current knowledge on the role of the gut–liver axis in the pathogenesis of portal hypertension, with a focus on therapies targeting portal hypertension and the gut microbiota. The modulation of the gut microbiota on several levels represents a major challenge in the upcoming years; in-depth characterization of the molecular and microbiological mechanisms linking the gut–liver axis to portal hypertension in a bidirectional relationship could pave the way to the identification of new therapeutic targets for innovative therapies in the management of ACLD.