Search Results (236)

Background/Objectives: Listeria monocytogenes is a foodborne pathogen of major public health concern due to its ability to invade host cells and cause severe illness. This study aimed to develop and validate a multi-tiered screening pipeline to identify Bacillus strains with probiotic potential against L. monocytogenes. Methods: A total of 26 Bacillus isolates were screened for antimicrobial activity, gastrointestinal resilience, and host cell adhesion. A fluorescence-based infection assay using mCherry-expressing HCT 116 cells was used to assess cytoprotection against L. monocytogenes NCTC 7973. Eight strains significantly improved host cell viability and were validated by quantification of intracellular CFU. Two top candidates were tested in a murine model of listeriosis. The genome of the lead strain was sequenced to evaluate safety and biosynthetic potential. Results: B. subtilis CECT 8266 completely inhibited intracellular replication of L. monocytogenes in HCT 116 cells, reducing bacterial recovery to undetectable levels. In vivo, it decreased splenic bacterial burden by approximately 6-fold. Genomic analysis revealed eight bacteriocin biosynthetic clusters and silent antibiotic resistance genes within predicted genomic islands, as determined by CARD and Alien Hunter analysis. The strain also demonstrated bile and acid tolerance, as well as strong adhesion to epithelial cells. Conclusions: The proposed pipeline enables efficient identification of probiotic Bacillus strains with intracellular protective activity. B. subtilis CECT 8266 is a promising candidate for translational applications in food safety or health due to its efficacy, resilience, and safety profile. Full article

The emergence of multidrug-resistant pathogens has driven the development of novel antimicrobial peptides (AMPs) as therapeutic alternatives. Lactolisterin LBU (LBU) is a bacteriocin with promising activity against Gram-positive bacteria, including Staphylococcus aureus. In this study, we designed and evaluated a panel of amino acid variants of LBU to investigate domain–activity relationships and improve activity. Peptides were commercially synthesized, and their effect was evaluated for minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), hemolytic activity, cytotoxicity, in vivo toxicity, and virulence modulation. AlphaFold3 structural prediction of LBU revealed a four-helix topology with amphipathic and hydrophobic segments. Helical wheel projections identified helices I and IV as amphipathic, suggesting their potential involvement in membrane interaction and activity. Glycine-to-alanine substitutions at helix I markedly increased antimicrobial activity but altered toxicity profiles. In contrast, changes at helix junctions and kinks reduced antimicrobial activity. We also showed differential regulation of virulence genes upon sub-MIC treatment. Overall, rational substitution enabled identification of residues critical for activity and toxicity, providing insights into therapeutic tuning of lactolisterin-based peptides. Full article

Microorganisms play a crucial role in food processes, safety, and quality through their dynamic interactions with other organisms. In recent years, biosensors have become essential tools for monitoring these processes in the dairy, meat, and fresh produce industries. This review highlights how microbial diversity, starter cultures, and interactions, such as competition and quorum sensing, shape food ecosystems. Diverse biosensor platforms, including electrochemical, optical, piezoelectric, thermal, field-effect transistor-based, and lateral flow assays, offer distinct advantages tailored to specific food matrices and microbial targets, enabling rapid and sensitive detection. Biosensors have been developed for detecting pathogens in real-time monitoring of fermentation and tracking spoilage. Control strategies, including bacteriocins, probiotics, and biofilm management, support food safety, while decontamination methods provide an additional layer of protection. The integration of new techniques, such as nanotechnology, CRISPR, and artificial intelligence, into Internet of Things systems is enhancing precision, particularly in addressing regional food safety challenges. However, their adoption is still hindered by complex food matrices, high costs, and the growing challenge of antimicrobial resistance. Looking ahead, intelligent systems and wearable sensors may help overcome these barriers. Although gaps in standardization and accessibility remain, biosensors are well-positioned to revolutionize food microbiology, linking ecological insights to practical solutions and paving the way for safer, high-quality food worldwide. Full article

The growth of aquaculture production in recent years has revealed multiple challenges, including the rise of antimicrobial resistance (AMR) in aquatic animal production, which is currently attracting significant attention from multiple one-health stakeholders. While antibiotics have played a major role in the treatment of bacterial infections for almost a century, a major consequence of their use is the increase in AMR, including the emergence of AMR in aquaculture. The AMR phenomenon creates a situation where antibiotic use in one system (e.g., aquaculture) may impact another system (e.g., terrestrial–human). Non-prudent use of antibiotics in aquaculture and animal farming increases the risk of AMR emergence, since bacteria harboring antibiotic resistance genes can cross between compartments such as wastewater or other effluents to aquatic environments, including intensive aquaculture. Transferable antimicrobial resistance gene (AMG) elements (plasmids, transposons, integrons, etc.) have already been detected in varying degrees from pathogenic bacteria that are often causing infections in farmed fish (Aeromonas, Vibrio, Streptococcus, Pseudomonas, Edwardsiella, etc.). This review of current veterinary approaches for the prevention and control of AMR emergence in aquaculture focuses on the feasibility of alternatives to antimicrobials and supplemental treatment applications during on-farm bacterial disease control and prevention. The use of vaccines, bacteriophages, biosurfactants, probiotics, bacteriocins, and antimicrobial peptides is discussed. Full article

Staphylococcus pseudintermedius, an opportunistic pathogen of veterinary and zoonotic concern, harbors diverse biosynthetic gene clusters (BGCs) that may contribute to its ecological fitness and virulence. In this study, we performed a comparative genomic analysis of 6815 S. pseudintermedius isolates. Using Roary, we identified core and accessory genomes, revealing the subtilosin A gene (sboA) as part of the accessory genome, present in a subset of S. pseudintermedius isolates from clinical (n = 657), environmental (n = 1031), and unclassified sources (n = 487). AntiSMASH v8.0.0 analysis confirmed the presence of subtilosin A BGCs annotated as a sactipeptide with low similarity confidence to Bacillus subtilis subsp. spizizenii ATCC 6633 subtilosin A cluster. Further characterization using BAGEL4 identified multiple genes homologous to the Bacillus subtilis subtilosin A biosynthetic machinery (sbo-albABCDEFG), although albB, albG, and sboX were not annotated, raising questions about cluster completeness and functionality. BLAST v2.12.0 analysis of the full BGC identified by BAGEL4, revealing high conservation (99.6–100% pairwise identity) of gene content and order in 395 clinical, 593 environmental, and 417 unclassified S. pseudintermedius isolates. Incomplete clusters were identified in 763 clinical, 942 environmental, and 201 unclassified S. pseudintermedius isolates. The discrepancy between the number of isolates containing sboA and those harboring the full cluster may reflect evolutionary divergence or could be attributed to limitations in assembly quality. The functional implications of the identified cluster in S. pseudintermedius remain to be elucidated; however, its potential role in conferring competitive fitness by inhibiting closely related species is supported by previous findings in other staphylococci. Full article

The whole-genome sequencing of lactic acid bacteria provides a valuable resource for identifying the genetic determinants underlying molecular mechanisms related to their probiotic properties. Analysis of draft genome sequences relies on bioinformatics tools for genetic data processing and in silico analytical methods to pinpoint the genetic determinants encoding biologically active compounds. The aim of this study was to perform the phenotypic determination of the antibiotic sensitivity and bioinformatics analyses on whole-genome assemblies from LAB from the human oral microbiome, and determine the presence of acquired antibiotic resistance genes, peptidases, adhesion proteins, and bacteriocins. Bioinformatics processing was performed in order to establish the molecular mechanisms responsible for the previously observed probiotic properties. The tested LAB strains exhibited a broad spectrum of antibiotic multiresistance, but did not possess acquired antibiotic resistance genes. The detected genes for peptidase activity were from the Pep family of hydrolase enzymes. Genetic determinants for adhesion proteins contained LPxTG, YSIRK, KxYKxGKxW, and SEC 10/PgrA domains, as well as MucBP domains. Lectins were found for five of the strains with the presence of WxL domains from the CscC protein family and L-type lectin domains. The in silico analyses show that some of the tested strains possessed mechanisms for bacteriocin production. Full article

Global concerns about environmental pollution, poor waste management, and the rise in antimicrobial resistance due to uncontrolled antibiotic use have driven researchers to seek alternative, multifaceted solutions. Plants, animals, microorganisms, and their processing wastes serve as valuable sources of natural biopolymers and bioactive compounds. Through nanotechnology, these can be assembled into formulations with enhanced antimicrobial properties, high safety, and low toxicity. This review explores polysaccharides, including chitosan, alginate, starch, pectin, cellulose, hemicellulose, gums, carrageenan, dextran, pullulan, and hyaluronic acid, used in nanotechnology, highlighting their advantages and limitations as nanocarriers. Addressing the global urgency for alternative antimicrobials, we examined natural compounds derived from plants, microorganisms, and animals, such as phytochemicals, bacteriocins, animal antimicrobial peptides, and proteins. Focusing on their protection and retained activity, this review discusses polysaccharide-based nanoformulations with natural antimicrobials, including nanoparticles, nanoemulsions, nanocapsules, nanoplexes, and nanogels. Special emphasis is placed on strategies and formulations for the encapsulation, entrapment, and conjugation of natural compounds using polysaccharides as protective carriers and delivery systems, including a brief discussion on their future applications, prospects, and challenges in scaling up. Full article

Background: The genus Enterococcus includes a diverse group of bacteria that are commonly found in the gastrointestinal tracts of humans and animals, as well as in various environmental habitats. Methods: In this study, Enterococcus lactis RB10, isolated from goat feces, was subjected to comprehensive genomic and functional analysis to assess its safety and potential as a probiotic strain. Results: The genome of E. lactis RB10, with a size of 2,713,772 bp and a GC content of 38.3%, was assembled using Oxford Nanopore Technologies (ONT). Genome annotation revealed 3375 coding sequences (CDSs) and highlighted key metabolic pathways involved in carbohydrate, protein, and amino acid metabolism. The strain was susceptible to important antibiotics, including ampicillin, chloramphenicol, tetracycline, and vancomycin, but exhibited resistance to aminoglycosides, a common trait in Enterococcus species with non-hemolytic activity. Genomic analysis further identified two intrinsic antimicrobial resistance genes (ARGs). The strain also demonstrated antimicrobial activity against Bacillus cereus DMST 11098 and Salmonella Typhi DMST 22842, indicating pathogen-specific effects. Key genes for adhesion, biofilm formation, and stress tolerance were also identified, suggesting that RB10 could potentially colonize the gut and compete with pathogens. Moreover, the presence of bacteriocin and secondary metabolite biosynthetic gene clusters suggests its potential for further evaluation as a biocontrol agent and gut health promoter. Conclusions: However, it is important to note that E. lactis RB10 was isolated from goat feces, a source that may harbor both commensal and opportunistic bacteria, and therefore additional safety assessments are necessary. While further validation is needed, E. lactis RB10 exhibits promising probiotic properties with low pathogenic risk, supporting its potential use in food and health applications. Full article

Listeriosis is a disease associated with the consumption of food contaminated with Listeria monocytogenes. Probiotic lactic acid bacteria (LAB) or their postbiotics have been of interest for their anti-listerial effect. This study focused on isolating LAB from artisanal cheeses and characterizing their potential as probiotics. Twelve LAB isolates exhibiting typical LAB traits were evaluated for their ability to survive in simulated gastric juice, hydrolyze bile salts, auto-aggregate, hydrophobicity, and antagonistic activity against L. monocytogenes. The four most promising LAB strains demonstrated anti-listerial probiotic potential and were identified as Latilactobacillus (Lat.) curvatus SC076 and Lactiplantibacillus (Lact.) paraplantarum SC291, SC093, and SC425. The antimicrobial activity of these strains was mainly attributed to bacteriocin-like substances and organic acids. While three Lact. paraplantarum strains were resistant to ampicillin, Lat. curvatus was sensitive to all tested antibiotics. All selected strains exhibited no hemolytic, gelatinase, and lecithinase activity. Exposure to LAB supernatants resulted in a significant reduction in the adhesion and intracellular count of L. monocytogenes in Caco-2 cells, with Lat. curvatus SC076 showing the most significant effect. Based on its probiotic characteristics, Lat. curvatus SC076 is a promising candidate for functional foods, pending further in vivo studies to assess its potential in the food industry. Full article

Listeriosis, the disease caused by the bacterium L. monocytogenes, can take invasive forms, with severe complications such as septicemia or meningitis, mainly affecting vulnerable people, such as pregnant women, the elderly, and immunocompromised people. The main transmission is through the consumption of contaminated food, and unpasteurized dairy products are common sources of infection. Due to the high mortality and the difficulty in eliminating the bacterium from the production environment, rigorous hygiene and control measures are essential to prevent the spread of Listeria in the food chain, and research on biofilm formation and bacterial resistance is vital to improve food safety. Dairy products, raw milk, and soft cheeses are among the most vulnerable to contamination with L. monocytogenes, especially due to pH values and low-temperature storage conditions. This paper presents a synthesis of the specialized literature on methods to reduce the incidence of L. monocytogenes in milk and dairy products. Conventional strategies, such as pasteurization and the use of chemical disinfectants, are effective but can affect food quality. Specialists have turned their attention to innovative and safer approaches, such as biocontrol and the use of nonthermal methods, such as pulsed electric fields, irradiation, and nanotechnology. Barrier technology, which combines several methods, has demonstrated superior efficiency in combating the bacterium without compromising product quality. Additionally, lactic acid bacteria (LAB) and bacteriocins are examples of biopreservation techniques that provide a future option while preserving food safety. Natural preservatives, especially those derived from plants and fruits, are promising alternatives to synthetic compounds. Future solutions should focus on developing commercial formulations that optimize these properties and meet consumer demands for healthy, environmentally friendly, and clean-label products. Full article

Background/Objectives: Listeria monocytogenes is a major foodborne pathogen responsible for listeriosis, a serious illness with high morbidity and mortality, particularly in vulnerable populations. Its persistence in food processing environments and resistance to conventional preservation methods pose significant food safety challenges. Lactic acid bacteria (LAB) offer a promising natural alternative due to their antimicrobial properties, especially through the production of bacteriocins. This study investigates the competitive interactions between Lactococcus lactis and L. monocytogenes under co-culture conditions, with a focus on changes in their secretomes to better understand how LAB-derived bacteriocins can help mitigate the Listeria burden. Methods: Proteomic approaches, including Tricine-SDS-PAGE, two-dimensional electrophoresis, and shotgun proteomics, were employed to analyze the molecular adaptations of both species in response to bacterial competition. Results: Our results reveal a significant increase in the secretion of enolase by L. monocytogenes when in competition with L. lactis, suggesting its role as a stress-responsive moonlighting protein involved in adhesion, immune evasion, and biofilm formation. Concurrently, L. lactis exhibited a shift in the production of its bacteriocin, nisin, favoring the expression of Nisin Z—a variant with improved solubility and diffusion properties. This differential regulation indicates that bacteriocin production is modulated by bacterial competition, likely as a defensive response to the presence of pathogens. Conclusions: These findings highlight the dynamic interplay between LAB and L. monocytogenes, underscoring the potential of LAB-derived bacteriocins as natural biopreservatives. Understanding the molecular mechanisms underlying microbial competition could enhance food safety strategies, particularly in dairy products, by reducing reliance on chemical preservatives and mitigating the risk of L. monocytogenes contamination. Full article

The study of bacteriocins has significantly enhanced our understanding of microbial interactions, notably within the genus Streptococcus. Among the most functionally diverse and clinically relevant bacteriocins are those belonging to the lantibiotic class, which exhibit potent antimicrobial properties and are central to the competitive dynamics of streptococcal species. This review focuses on the discovery and characterization of bacteriocins produced by Streptococcus pyogenes and Streptococcus salivarius, emphasizing their biological significance within their exclusive human host. A cornerstone of these studies has been the development and application of the pioneer agar culture-based bacteriocin detection methodology, known as streptococcal bacteriocin fingerprinting. This approach has proven invaluable for the initial detection and differentiation of a wide array of bacteriocin-like inhibitory substances (BLIS) in streptococcal populations. A central theme of this review is the diverse biological roles of lantibiotics in S. pyogenes and S. salivarius, particularly in relation to microbial competition, colonization dynamics, and host interactions. The expression of lantibiotic determinants provides distinct advantages to the producing strain, including enhanced niche establishment and the ability to suppress competing microbes. Furthermore, the presence of specific lantibiotic immunity mechanisms safeguards the producer from self-inhibition and potential antagonism from closely related competitors. In S. pyogenes, lantibiotic production has been implicated in virulence modulation, raising important questions about its role in pathogenicity and host immune evasion. Conversely, S. salivarius, a prominent commensal and probiotic candidate species, utilizes its lantibiotic arsenal to confer colonization benefits and mediate beneficial interactions, especially within the oral and upper respiratory tract microbiomes. The implications of in situ lantibiotic expression extend beyond microbial ecology, presenting opportunities for innovative probiotic and therapeutic applications. The potential for harnessing bacteriocin-producing streptococci in antimicrobial interventions, particularly in combating antibiotic-resistant pathogens, underscores the translational relevance of these findings. This review integrates historical and contemporary perspectives on streptococcal bacteriocin research, providing insights into future avenues for leveraging these bioactive peptides in clinical and biotechnological contexts. Full article

Antibiotic-resistant bacteria are major contributors to food spoilage, animal diseases, and the emergence of multidrug-resistant (MDR) bacteria in healthcare, highlighting the urgent need for effective treatments. Bacteriocins produced by lactic acid bacteria (LAB) have gained attention for their non-toxic nature and strong antimicrobial properties. LAB-derived bacteriocins have been successfully applied in food preservation and are classified by the U.S. Food and Drug Administration (FDA) as ‘food-grade’ or ‘generally recognized as safe’ (GRAS). This review summarizes recent progress in the production, purification, and emerging applications of LAB bacteriocins. It emphasizes their versatility in food preservation, agriculture, and medicine, providing insights into their role in antimicrobial development and functional food innovation. Full article

Background: Bacterial vaginosis (BV) is considered the most common cause of vaginal discharge, which is related to several public health issues, such as an increased risk for sexually transmitted infections, pelvic inflammatory disease, pregnancy-related problems such as abortion, stillbirth or premature birth, and tubal factor infertility. BV is not considered an infection but an imbalance in the vaginal microbiota, characterized by a substitution of the normal Lactobacilli flora by anaerobe. Reducing resistance against infections by several mechanisms, including bacterial homeostasis, stabilization of acid pH, inhibition of pathogens adhesion by polyamine degradation, production of anti-inflammatory molecules, surfactants, and antimicrobial substances like hydrogen peroxide, acids, and bacteriocins. Approximately half of women with BV can experience symptoms, which mainly include vaginal malodor, fishy discharge, stinging sensation, and increased vaginal pH. The treatment of BV is based primarily on promoting Lactobacilli restoration and eliminating dangerous microbiota with antibiotic therapy. However, there is a high rate of recurrence and relapse. Objective: Based on the current literature, this review aims to propose a list of ten BV hallmarks: dysbiosis, inflammation, apoptosis, pH basification, mucosal barrier integrity, pathway activation, epithelial damage, genomic instability, oxidative stress (OS), and metabolic reconfiguration. Conclusions: Understanding the causes of BV and the pathogenicity mechanisms is critical for preventing and improving the current therapeutic management of patients. Full article

Lactiplantibacillus plantarum GUANKE (L. plantarum GUANKE) is a Gram-positive bacterium isolated from the feces of healthy volunteers. Whole-genome sequencing analysis (WGS) revealed that the genome of L. plantarum GUANKE consists of one chromosome and two plasmids, with the chromosome harbors 2955 CDS, 66 tRNAs, and 5 rRNAs. The genome is devoid of virulence factors and Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems. It contains three intact prophage regions and bacteriocin biosynthesis genes (plantaricins K, F, and E), as well as seventeen genomic islands lacking antibiotic resistance or pathogenicity determinants. Functional prediction outcomes identified that the genome of L. plantarum GUANKE is closely related to transcription, carbohydrate transport and metabolism, and amino acid transport and metabolism. Carbohydrate-active enzymes (CAZymes) analysis and GutSMASH analysis revealed that the genome of L. plantarum GUANKE contained 100 carbohydrate-active enzyme genes and two specialized metabolic gene clusters. Safety assessments confirmed that L. plantarum GUANKE neither exhibited β-hemolytic activity nor harbored detectable transferable drug resistance genes. The strain exhibited remarkable acid tolerance and bile salt resistance. Cellular adhesion assays demonstrated moderate binding capacity to Caco-2 intestinal epithelium (4.3 ± 0.007)%. In vitro analyses using lipopolysaccharide (LPS)-stimulated macrophage models demonstrated that L. plantarum GUANKE significantly suppressed the secretion of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β), exhibiting dose-dependent anti-inflammatory activity. In vivo experiments showed that L. plantarum GUANKE was involved in the regulation of the apical junction pathway and interferon pathway in colon tissue of normal mice. Full article