Bacteriocin-Based Synergetic Consortia: a Promising Strategy to Enhance Antimicrobial Activity and Broaden the Spectrum of Inhibition

High-throughput ecological interaction mapping of dairy microorganisms

To engineer efficient microbial management strategies in the food industry, a comprehensive understanding of microbial interactions is crucial. Microorganisms live in communities where they influence each other in several ways. Although much attention has been paid to the production of antagonistic metabolites in lactic acid bacteria (LAB), research that accounts for the complexity of their ecological interactions and their dynamics remains limited. This study explores binary interactions within a mock community of 94 strains, including 23 LAB from culture collections and 71 isolated from dairy products. Using a colony-picking robot and image analysis, bidirectional interactions were measured at high throughput on solid media, where one test strain was challenged against other mock community members as the target strains. Assays of 15 test strains (14 LAB and one yeast) yielded 1,142 bidirectionally mapped interactions, classified by ecological type over seven days. The results showed variation in the strength, directionality, and type of interactions depending on the origin of the target strains. Cooperation rates increased for strains isolated from raw milk to pasteurized milk and cheese, while exploitation was more common in raw milk strains. Cooperating strains also exhibited more similar ecological behaviors than competing strains, suggesting the presence of microbial cliques. Interestingly, Lactococcus cremoris ATCC 19257 developed pink-red pigmentation when co-cultured with Pseudomonas aeruginosa. Overall, these findings present an unprecedented exploratory data set that significantly improves our understanding of microbial interactions at the system level, with potential applications in strain selection for food processes such as fermentation, bioprotection, and probiotics.

Isolation, Genomics-Based and Biochemical Characterization of Bacteriocinogenic Bacteria and Their Bacteriocins, Sourced from the Gastrointestinal Tract of Meat-Producing Pigs

Antimicrobial resistance (AMR) poses a significant challenge to animal production due to the widespread use of antibiotics. Therefore, there is an urgent need for alternative antimicrobial strategies to effectively manage bacterial infections, protect animal health, and reduce reliance on antibiotics. This study evaluated the use of emerging approaches and procedures for the isolation, identification, and characterization of bacteriocin-producing bacteria and their bacteriocins, sourced from the gastrointestinal tract (GIT) of meat-producing pigs. Out of 2056 isolates screened against Gram-positive and Gram-negative indicator strains, 20 of the most active antimicrobial isolates were subjected to whole genome sequencing (WGS) for the prediction of coding DNA sequences (CDS) and the identification of bacteriocin gene clusters (BGC) and their functions. The use of an in vitro cell-free protein synthesis (IV-CFPS) protocol and the design of an IV-CFPS coupled to a split-intein mediated ligation (IV-CFPS/SIML) procedure made possible the evaluation of the production and antimicrobial activity of described and putatively novel bacteriocins. A colony MALDI-TOF MS procedure assisted in the identification of class I, II, and III lanthipeptides. MALDI-TOF MS and a targeted proteomics, combined with a massive peptide analysis (LC-MS/MS) approach, has proven valuable for the identification and biochemical characterization of previously described and novel bacteriocins encoded by the isolated bacteriocin-producing strains.

Developing Robust Probiotic Consortia: A Methodological Optimization Approach

Developing effective probiotic consortia requires a comprehensive understanding of strain interactions. While traditional methods focus on direct interactions of the participating microbes, the role of microbial metabolites remains largely unexplored. Present study introduces a novel approach of evaluating the impact of strains as well as their secondary metabolites on compatibility during co-culture by assessing the antagonistic and synergistic attributes for multi-strain probiotic formulation. Assessment of antagonistic activity by spot method indicated suppressive nature of PIG1FD and PIG1IR on other strain's growth, hence not appropriate for consortia formulation. Findings of synergistic attribute demonstrated growth promoting role of cell supernatants from isolates PIG6IR and PIG5CI significantly, as it accelerated the entry of all other isolates into the log phase by 5-6 h and 0-2 h, respectively. By employing this methodology, we identified PIG5CI and PIG6IR (isolates identified as Bacillus spizizenii BAB 7915 and Bacillus subtilis BAB 7918 by 16S RNA sequencing method) as promising candidates for consortium formation due to their ability to enhance the growth of other strains through metabolite production. By attempting to elucidate the microbial interactions and metabolite-mediated effects, this research contributes to a more comprehensive understanding of probiotic consortia dynamics and offers valuable insights for future translational studies.

Reuterin Enhances the Efficacy of Peracetic Acid Against Multi-species Dairy Biofilm

Biofilms may contain pathogenic and spoilage bacteria and can become a recurring problem in the dairy sector, with a negative impact on product quality and consumer health. Peracetic acid (PAA) is one of the disinfectants most frequently used to control biofilm formation and persistence. Though effective, it cannot be used at high concentrations due to its corrosive effect on certain materials and because of toxicity concerns. The aim of this study was to test the possibility of PAA remaining bactericidal at lower concentrations by using it in conjunction with reuterin (3-hydroxypropionaldehyde). We evaluated the efficacy of PAA in pure form or as BioDestroy®, a PAA-based commercial disinfectant, on three-species biofilms formed by dairy-derived bacteria, namely Pseudomonas azotoformans PFlA1, Serratia liquefaciens Sl-LJJ01, and Bacillus licheniformis Bl-LJJ01. Minimum inhibitory concentrations of the three agents were determined for each bacterial species and the fractional inhibitory concentrations were then calculated using the checkerboard assay. The minimal biofilm eradication concentration (MBEC) of each antibacterial combination was then calculated against mixed-species biofilm. PAA, BioDestroy®, and reuterin showed antibiofilm activity against all bacteria within the mixed biofilm at respectively 760 ppm, 450 ppm, and 95.6 mM. The MBEC was lowered significantly to 456 ppm, 337.5 ppm, and 71.7 mM, when exposed to reuterin for 16 h followed by contact with disinfectant. Combining reuterin with chemical disinfection shows promise in controlling biofilm on food contact surfaces, especially for harsh or extended treatments. Furthermore, systems with reuterin encapsulation and nanotechnologies could be developed for sustainable antimicrobial efficacy without manufacturing disruptions.

Bacteriocins sourced from traditional fermented foods for ensuring food safety: the microbial guards

Concerns about food safety have consistently driven the exploration of potent antimicrobials with probiotic origins. Identification of probiotic-derived bacteriocins as robust alternatives to antibiotics has gained traction following the COVID-19 pandemic. Additionally, the global market is witnessing an increasing preference for minimally processed food products free from chemical additives. Another contributing factor to the search for potent antimicrobials is the escalating number of infections caused by antibiotic-resistant bacteria and the need to mitigate the significant damage inflicted on the commensal human microbiota by broad-spectrum antibiotics. As an alternative bio-preservation strategy, there is substantial enthusiasm for the use of bacteriocins or starter cultures producing bacteriocins in preserving a variety of food items. This review specifically focuses on bacteriocins originating from lactic acid bacteria associated with fermented foods and explores their technological applications as nanobiotics. The food-grade antibiotic alternatives, whether utilized independently or in combination with other antimicrobials and administered directly or encapsulated, are anticipated to possess qualities of safety, stability and non-toxicity suitable for application in the food sector. © 2024 Society of Chemical Industry.

Classification and Multi-Functional Use of Bacteriocins in Health, Biotechnology, and Food Industry

Bacteriocins is the name given to products of the secondary metabolism of many bacterial genera that must display antimicrobial activity. Although there are several bacteriocins described today, it has not been possible to reach a consensus on the method of classification for these biomolecules. In addition, many of them are not yet authorized for therapeutic use against multi-drug-resistant microorganisms due to possible toxic effects. However, recent research has achieved considerable progress in the understanding, classification, and elucidation of their mechanisms of action against microorganisms, which are of medical and biotechnological interest. Therefore, in more current times, protocols are already being conducted for their optimal use, in the hopes of solving multiple health and food conservation problems. This review aims to synthetize the information available nowadays regarding bacteriocins, and their classification, while also providing an insight into the future possibilities of their usage for both the pharmaceutical, food, and biotechnological industry.

Bacteriocins: potentials and prospects in health and agrifood systems

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

The pearl jubilee of microcin J25: thirty years of research on an exceptional lasso peptide

Covering: 1992 up to 2023Since their discovery, lasso peptides went from peculiarities to be recognized as a major family of ribosomally synthesized and post-translationally modified peptide (RiPP) natural products that were shown to be spread throughout the bacterial kingdom. Microcin J25 was first described in 1992, making it one of the earliest known lasso peptides. No other lasso peptide has since then been studied to such an extent as microcin J25, yet, previous review articles merely skimmed over all the research done on this exceptional lasso peptide. Therefore, to commemorate the 30th anniversary of its first report, we give a comprehensive overview of all literature related to microcin J25. This review article spans the early work towards the discovery of microcin J25, its biosynthetic gene cluster, and the elucidation of its three-dimensional, threaded lasso structure. Furthermore, the current knowledge about the biosynthesis of microcin J25 and lasso peptides in general is summarized and a detailed overview is given on the biological activities associated with microcin J25, including means of self-immunity, uptake into target bacteria, inhibition of the Gram-negative RNA polymerase, and the effects of microcin J25 on mitochondria. The in vitro and in vivo models used to study the potential utility of microcin J25 in a (veterinary) medicine context are discussed and the efforts that went into employing the microcin J25 scaffold in bioengineering contexts are summed up.

Ligilactobacillus salivarius 7247 Strain: Probiotic Properties and Anti-Salmonella Effect with Prebiotics

The Ligilactobacillus salivarius 7247 (LS7247) strain, originally isolated from a healthy woman's intestines and reproductive system, has been studied for its probiotic potential, particularly against Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) as well as its potential use in synbiotics. LS7247 showed high tolerance to gastric and intestinal stress and effectively adhered to human and animal enterocyte monolayers, essential for realizing its probiotic properties. LS7247 showed high anti-Salmonella activity. Additionally, the cell-free culture supernatant (CFS) of LS7247 exhibited anti-Salmonella activity, with a partial reduction upon neutralization with NaOH (p < 0.05), suggesting the presence of anti-Salmonella factors such as lactic acid (LA) and bacteriocins. LS7247 produced a high concentration of LA, reaching 124.0 ± 2.5 mM after 48 h of cultivation. Unique gene clusters in the genome of LS7247 contribute to the production of Enterolysin A and metalloendopeptidase. Notably, LS7247 carries a plasmid with a gene cluster identical to human intestinal strain L. salivarius UCC118, responsible for class IIb bacteriocin synthesis, and a gene cluster identical to porcine strain L. salivarius P1ACE3, responsible for nisin S synthesis. Co-cultivation of LS7247 with SE and ST pathogens reduced their viability by 1.0-1.5 log, attributed to cell wall damage and ATP leakage caused by the CFS. For the first time, the CFS of LS7247 has been shown to inhibit adhesion of SE and ST to human and animal enterocytes (p < 0.01). The combination of Actigen prebiotic and the CFS of LS7247 demonstrated a significant combined effect in inhibiting the adhesion of SE and ST to human and animal enterocytes (p < 0.001). These findings highlight the potential of using the LS7247 as a preventive strategy and employing probiotics and synbiotics to combat the prevalence of salmonellosis in animals and humans caused by multidrug resistant (MDR) strains of SE and ST pathogens.

Use of Probiotics to Control Biofilm Formation in Food Industries

Microorganisms tend to adhere to food contact surfaces and form biofilms, which serve as reservoirs for bacteria that can contaminate food. As part of a biofilm, bacteria are protected from the stressful conditions found during food processing and become tolerant to antimicrobials, including traditional chemical sanitisers and disinfectants. Several studies in the food industry have shown that probiotics can prevent attachment and the consequent biofilm formation by spoilage and pathogenic microorganisms. This review discusses the most recent and relevant studies on the effects of probiotics and their metabolites on pre-established biofilms in the food industry. It shows that the use of probiotics is a promising approach to disrupt biofilms formed by a large spectrum of foodborne microorganisms, with Lactiplantibacillus and Lacticaseibacillus being the most tested genera, both in the form of probiotic cells and as sources of cell-free supernatant. The standardisation of anti-biofilm assays for evaluating the potential of probiotics in biofilm control is of extreme importance, enabling more reliable, comparable, and predictable results, thus promoting significant advances in this field.

Cera-Glow, ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201, improves skin barrier function in clinical study

BACKGROUND

Ceramides are essential lipids in stratum corneum for skin permeability barrier function in that they retain the skin moisture and protect from the invasion of foreign pathogens. Previously, we demonstrated that ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201 enhanced ceramide production in human epidermal keratinocytes. Furthermore, for comprehensive knowledge of this effect, in vitro experiments and multi-omics analysis were conducted to explore the underlying mechanisms.

AIMS

This study was designed to identify whether a cosmetic sample (i.e., Cera-Glow) containing the lysates improves the skin barrier function in clinical trials.

PATIENTS/METHODS

Twenty-four female participants (45.46 ± 9.78 years) had been enrolled in the transepidermal water loss (TEWL) measurement for 5 days and 21 female participants (50.33 ± 5.74 years) had undergone a skin hydration evaluation for 4 weeks. TEWL and skin hydration were evaluated using a Tewameter and the Epsilon Permittivity Imaging System, respectively. After applying the Cera-Glow sample, all participants recorded a satisfaction survey questionnaire (e.g., satisfaction, efficacy, and adverse reactions).

RESULTS

Application of Cera-Glow significantly improved transepidermal water loss induced by 1% (w/v) sodium lauryl sulfate (p < 0.05-0.01) and increased skin hydration (p < 0.01). Metabolic analysis suggested that Cera-Glow should contain beneficial gradients for skin barrier function. According to the questionnaire, most of participants were satisfied with the skin hydration improvement and efficacy of Cera-Glow.

CONCLUSIONS

Cera-Glow, ferment lysates of Lacticaseibacillus rhamnosus IDCC 3201, can significantly improve skin barrier function.

Antimicrobial Compounds in Food Packaging

This review presents current knowledge on antimicrobial agents that are already used in the food packaging industry. At the beginning, innovative ways of food packaging were discussed, including how smart packaging differs from active packaging, and what functions they perform. Next, the focus was on one of the groups of bioactive components that are used in these packaging, namely antimicrobial agents. Among the antimicrobial agents, we selected those that have already been used in packaging and that promise to be used elsewhere, e.g., in the production of antimicrobial biomaterials. Main groups of antimicrobial agents (i.e., metals and metal oxides, organic acids, antimicrobial peptides and bacteriocins, antimicrobial agents of plant origin, enzymes, lactoferrin, chitosan, allyl isothiocyanate, the reuterin system and bacteriophages) that are incorporated or combined with various types of packaging materials to extend the shelf life of food are described. The further development of perspectives and setting of new research directions were also presented.

Microbial derived antimicrobial peptides as potential therapeutics in atopic dermatitis

Atopic dermatitis (AD) is a common chronic inflammatory skin disease that significantly affects the patient's quality of life. A disrupted skin barrier, type 2 cytokine-dominated inflammation, and microbial dysbiosis with increased Staphylococcus aureus colonization are critical components of AD pathogenesis. Patients with AD exhibit decreased expression of antimicrobial peptides (AMPs) which is linked to increased colonization by Staphylococcus aureus. The skin microbiome itself is a source of several AMPs. These host- and microbiome-derived AMPs define the microbial landscape of the skin based on their differential antimicrobial activity against a range of skin microbes or their quorum sensing inhibitory properties. These are particularly important in preventing and limiting dysbiotic colonization with Staphylococcus aureus. In addition, AMPs are critical for immune homeostasis. In this article, we share our perspectives about the implications of microbial derived AMPs in AD patients and their potential effects on overlapping factors involved in AD. We argue and discuss the potential of bacterial AMPs as therapeutics in AD.

Targeting Enterococci with Antimicrobial Activity against Clostridium perfringens from Poultry

Necrotic enteritis (NE), caused by Clostridium perfringens, is an emerging issue in poultry farming. New approaches, other than antibiotics, are necessary to prevent NE development and the emergence of multidrug-resistant bacteria. Enterococci are commensal microorganisms that can produce enterocins, antimicrobial peptides with activities against pathogens, and could be excellent candidates for protective cultures. This study aimed to screen and characterize Enterococcus strains of poultry origin for their inhibitory activity against C. perfringens. In total, 251 Enterococcus strains of poultry origin plus five bacteriocin-producing (BP+) E. durans strains of other origins were screened for antimicrobial activity against the indicator C. perfringens X2967 strain using the "spot on the lawn" method. We detected thirty-two BP+ strains (eleven Enterococcus faecium, nine E. gallinarum, eight E. faecalis, three E. durans, and one E. casseliflavus). We further studied the antimicrobial activity of the supernatants of these 32 BP+ strains using agar well diffusion and microtitration against a collection of 20 C. perfringens strains. Twelve BP+ enterococci that were found to exhibit antimicrobial activity against C. perfringens were characterized using whole genome sequencing. Among these, E. faecium X2893 and X2906 were the most promising candidates for further studies as protective cultures for poultry farming. Both strains belong to the sequence type ST722, harbor the genes encoding for enterocin A and enterocin B, do not possess acquired resistance genes, do not carry plasmids, and present the acm gene, which is implicated in host colonization. Further research is needed to determine the utility of these strains as protective cultures.

Strategies for the Development of Bioprotective Cultures in Food Preservation

Consumers worldwide are increasingly demanding food with fewer ingredients, preferably without chemical additives. The trend called "Clean Label" has stimulated the development and commercialization of new types of bioprotective bacterial cultures. These bacteria are not considered new, and several cultures have been available on the market. Additionally, new bioprotective bacteria are being identified to service the clean label trend, extend the shelf life, and, mainly, improve the food safety of food. In this context, the lactic acid bacteria (LAB) have been extensively prospected as a bioprotective culture, as they have a long history in food production and their antimicrobial activity against spoilage and pathogenic microorganisms is well established. However, to make LAB cultures available in the market is not that easy, the strains should be characterized phenotypically and genotypically, and studies of safety and technological application are necessary to validate their bioprotection performance. Thus, this review presents information on the bioprotection mechanisms developed by LAB in foods and describes the main strategies used to identify and characterize bioprotective LAB with potential application in the food industry.

Characterization of Lactic Acid-Producing Bacteria Isolated from Rumen: Growth, Acid and Bile Salt Tolerance, and Antimicrobial Function

Lactic acid bacteria are some of the dominant bacteria in the rumen, and they have a high ability for lactic acid production. The present study aimed to screen and evaluate the performance of culturable rumen bacteria from Chinese Holstein dairy cows as a potential probiotic or inoculant for silage production, in order to isolate ruminal lactic acid bacteria and evaluate their potential as probiotics. Three strains of Enterococcus avium (E. avium, EA1-3); three strains of Streptococcus lutetiensis (S. lutetiensis, SL1-3); and six strains of Streptococcus equinus (S. equinus, SE1-6) were successfully identified from the rumen fluid using modified De Man Rogosa sharp medium supplemented with 0.325% lactic acid. E. avium, S. lutetiensis and S. equinus are clustered in the phylogenetic tree. All the 12 Gram-positive strains reached the plateau growth phase in 6–10 h, with an OD600 at about 1.8. Both gas and acid accumulation reached plateaus at about 10–12 h in all strains, and S. equinus showed the strongest capacity. The highest lactic acid accumulation was detected in S. equinus broth (up to 219.77 μmol/L). The growth of all isolates was inhibited at pH 4.0, and EA2, SL1, SL2, SL3 and SE2 were tolerant to 0.1%, 0.2% and 0.3% bile salt. In addition, the supernatants of the strains had inhibitory effects on Escherichia coli and Staphylococcus aureus. Specifically, the S. equinus strains exhibited the strongest inhibition of the pathogens. In conclusion, these 12 strains had good potential as silage inoculants or probiotics for edible animals, especially S. equinus.