Antimicrobial Substances Research Articles

Incorporating Single-Copper Sites and Host Defense Peptides into a Nanoreactor for Antibacterial Therapy by Bioinspired Design

A sustainable solution to the dramatic spread of antibiotic resistance threatening public health security is the development of antibiotic-free antimicrobial substances. Inspired by natural host defense mechanisms involving amino-terminal copper−nickel binding motif (ATCUN) antimicrobial peptides (AMPs), we have designed and prepared an artificial complex (Cu@G-AMPs) incorporating single-atom Cu catalysts for antibacterial therapy. The substrate of the complex, formed from guanine doped with abundant heteroatoms, anchored single Cu atoms with a coordination number of 2 and an average bond length of 1.91Å. Interestingly, Cu@G-AMPs, exhibiting Fenton-like catalytic activity, caused the inactivation of methicillin-resistant Staphylococcus aureus (MRSA) by generating and delivering reactive oxygen species (ROS) cargo. Mechanistically, the intrinsic stress response system of MRSA underwent an irreversible collapse when Cu@G-AMPs initiated its offensive program associated with non-specific targets. Furthermore, Cu@G-AMPs, which inherited the immunomodulatory properties of AMPs, sequentially carried out the functions of pulling edge closure, stabilizing granulation tissue, promoting collagen fiber proliferation, alleviating inflammation, and promoting neovascularization in wound areas infected by MRSA. Our results show that Cu@G-AMPs will provide a new perspective on untangling the complex regulatory networks that resistant bacteria have cultivated to deactivate commercial antibiotics.

Antimicrobial Properties of Fennel By-Product Extracts and Their Potential Applications in Meat Products.

Background: Beef burgers are perishable meat products, and to extend their shelf life, EU Regulation 1129/11 permits the use of certain additives. Objectives: However, given the concerns of health-conscious consumers and the potential toxicity of synthetic substances, this study aimed to explore the use of fennel waste extracts as natural preservatives. Methods: This study characterized the bioactive compounds (phenolic content), the antioxidant activity (ABTS+ and DPPH assay), and the antimicrobial properties (against Salmonella enterica serotype Enteritidis, Escherichia coli, Staphylococcus aureus, Bacillus cereusi, and Pseudomonas aeruginosa) of different fennel waste extracts (LF, liquid fraction; SF, solid fraction and PF, pellet fraction). Additionally, the potential use of the best fennel extract was evaluated for its impact on beef burger shelf life (up to 18 days at 4 ± 1 °C) in terms of microbiological profile, pH, and activity water (aw). Results: The PF extract, which was rich in flavones, hydroxybenzoic, and hydroxycinnamic acids, demonstrated the highest antioxidant and antimicrobial activities. Microbiological analyses on beef burgers with PF identified this extract as a potential antimicrobial substance. The aw and pH values did not appear to be affected. Conclusions: In conclusion, fennel extracts could be proposed as natural compounds exploitable in beef burgers to preserve their quality and extend their shelf-life.

MANFAAT BUAH ZAITUN DALAM SAINS DAN AL-QURAN

Many plants and fruits are mentioned in the Qur'an. Allah has grown all kinds of plants and all forms of plants that exist on this earth. There are many scientific miracles regarding agricultural fields in the Qur'an, one of which is the Olive fruit. Olives have the scientific name Olea europaea which are spread in the Mediterranean countries, Africa, the Arabian peninsula, India, and Asia. Olives have many benefits such as reducing high blood pressure, facilitating urination, lowering blood sugar levels, containing anti-microbial substances and effective in dealing with viruses, bacteria, and fungi. The content of compounds contained in olives such as phenols, tocopherols, sterols, pigans and squalene have an important role in health and can cure several diseases. Olives also contain omega 9 and omega 3 which can function as anti-inflammatory. Keywords: fruit, olives, science, plants, integrity, the Koran

Genetic identification of methicillin resistant Staphylococcus aureus (MRSA) isolated from diabetic foot ulcers and evaluating the inhibition activity of reuterin against this bacteria.

To genetically diagnose the isolates of methicillin-resistant staphylococcus aureus taken from patients with severe diabetic foot infections, and to test the inhibitory effect of reuterin on the growth of these bacteria. The experimental study was conducted from June to November 2021 at the Diabetes Unit of Al-Faihaa General Hospital, Basrah, Iraq, and comprised 62 foot ulcer swabs from the necrotic lesions of patients with type 2 diabetes. The swabs were cultivated first in brain heart infusion broth media, and then streaked on Mannitol salt agar and staphylococcus chromogeneic agar media for phenotypic and genetic analysis. The genetic identification of bacteria was confirmed by deoxyribonucleic acid extraction, and methicillin-resistant staphylococcus aureus was confirmed by the presence of plasmid mecA gene. The inhibition activity of reuterin towards methicillin-resistant staphylococcus aureus was determined using the minimum inhibitory concentration test. All data was analyzed with SPSS version 23. A total of 62 swabs were taken from the necrotic lesions of type 2 diabetes mellitus (T2DM) patients with diabetic foot ulcers. Of the total isolates, 9(14.5%) gave mauve to purple colour on staphylococcus chromogeneic agar, which was then genetically confirmed as methicillin-resistant staphylococcus aureus. The minimum inhibitory concentration value of these bacteria was 10μl/ml at 16mm inhibition zone diameter. There was no cytotoxicity of reuterin to human red blood cells. Reuterin was found to be a natural antimicrobial substance suitable for use to disinfect diabetic foot wounds from bacterial contamination and infection, especially those caused by methicillin-resistant staphylococcus aureus.

Enhancement of microbial safety and shelf life of salmon fillets by Lactiplantibacillus plantarum 299 V fermented in pomelo (Citrus maxima) peel extract

This study demonstrated the selective support of pomelo (Citrus maxima) peel extract (PPE) on Lactiplantibacillus plantarum 299 V growth, of which the resultant enhanced microbial safety and shelf life of salmon fillets. Incorporating PPE fermented with L. plantarum 299 V for 48 h (FPPE-48h) into alginate coating inhibited both the spiked Listeria monocytogenes and the spoilage - causing bacteria (psychotrophic bacteria, Enterobacteriaceae, Pseudomonas spp.) on salmon fillets during the 4-day chilled storage, resulting in 1–1.5 log CFU/g lower bacterial counts (P < 0.05). FPPE-48h effectively suppressed biogenic amine-producing bacteria, and remarkably retarded the accumulation of putrescine, cadaverine, histamine, and tyramine (P < 0.05). Last, the key antimicrobial substances generated during the late stage of PPE fermentation were profiled using non-target ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) analysis. This study exemplifies a successful approach of fermenting probiotic utilizing food by-products/food waste to enhance the safety and shelf life of ready-to-eat foods.

Quercetin, the Potential Powerful Flavonoid for Human and Food: A Review

Flavonoids occur naturally in different types of fruits and vegetables, including tea, cabbage, cauliflower, elderberries, cranberries, red apples, lettuce, pears, spinach, green hot peppers, white and red onions, kale, blueberries, and nuts. Among these flavonoids is quercetin, a potent natural antioxidant and cytotoxic substance with a number of therapeutic functions. Nowadays, quercetin is a common ingredient in many nutraceutical and cosmeceutical products due to its antioxidant properties. Its antibacterial effects and possible action mechanisms have been explored in many studies. From these, it has been established that quercetin stops the activity of numerous Gram-negative and -positive bacteria, fungi, and viruses. This review clarifies the plant sources and extraction methods of quercetin, as well as its medicinal applications as an antibacterial, antifungal, antiviral, and antioxidant agent, with a particular emphasis on the underlying mechanisms of its biological activity. The mechanism of its antimicrobial effect involves damaging the cell membrane—e.g., by changing its permeability, preventing biofilm formation, reducing the mitochondrial expression of virulence factors, and inhibiting protein and nucleic-acid synthesis. Moreover, quercetin has been shown to impede the activity of a variety of drug-resistant bacterial strains, pointing to the possibility of using it as a strong antimicrobial substance against such strains. In addition, it has occasionally been demonstrated that specific structural alterations to quercetin can increase its antibacterial action in comparison to the parent molecule. Overall, this review synthesizes our understanding of the mode of action of quercetin and its prospects for use as a therapeutic material.

Progress in the Study of Natural Antimicrobial Active Substances in Pseudomonas aeruginosa.

The prevalence of antimicrobial resistance reduces the effectiveness of antimicrobial drugs in the prevention and treatment of infectious diseases caused by pathogens such as bacteria, fungi, and viruses. Microbial secondary metabolites have been recognized as important sources for new drug discovery and development, yielding a wide range of structurally novel and functionally diverse antimicrobial drugs for the treatment of a variety of diseases that are considered good producers of novel antimicrobial drugs. Bacteria produce a wide variety of antimicrobial compounds, and thus, antibiotics derived from natural products still dominate over purely synthetic antibiotics among the antimicrobial drugs developed and introduced over the last four decades. Among them, Pseudomonas aeruginosa secondary metabolites constitute a richly diverse source of antimicrobial substances with good antimicrobial activity. Therefore, they are regarded as an outstanding resource for finding novel bioactive compounds. The exploration of antimicrobial compounds among Pseudomonas aeruginosa metabolites plays an important role in drug development and biomedical research. Reports on the secondary metabolites of Pseudomonas aeruginosa, many of which are of pharmacological importance, hold great promise for the development of effective antimicrobial drugs against microbial infections by drug-resistant pathogens. In this review, we attempt to summarize published articles from the last twenty-five years (2000-2024) on antimicrobial secondary metabolites from Pseudomonas aeruginosa.

Production and characterization of bacteriocin from lactic acid bacteria isolated from fermented food products

Bacteriocin is a natal antimicrobial which can be exploited to evade the inevitability of adding chemical preservatives to food products. This study is aimed at the production and characterization of bacteriocin from Lactic acid bacteria (LAB) isolated from fermented food products. Sixteen (16) samples of various fermented food products (abacha, fufu, ogi and yoghurt) were screened for the presence of bacteriocin producing LAB using agar well diffusion method. The strain designated C6 was selected for further studies due to its broad inhibitory effect on the growth of all tested organisms (Enterococcus faecalis ATCC 33090, Pseudomonas aeruginosa MN 515053, Listeria innocua ATCC 2127, Staphylococcus aureus, Escherichia coli, Candida spp and Aspergillus terrus MN907795). Molecular characterization spotted C6 isolated from yoghurt as Lactobacillus fermentum (accession no. MN907811). Purification of the antimicrobial substance was achieved using High performance liquid chromatography (HPLC) with nisin as Standard which revealed it to be bacteriocin a proteinaceous antimicrobial that is stable to heat and organic solvents. Effect of substrate level on the growth of Lactobacillus fermentum and optimization of physicochemical parameters on bacteriocin production revealed optimum condition of 1.0 % glucose, 0.5 % sodium nitrate, pH of 6.0, incubation temperature of 35°C for 72h. This makes Lactobacillus fermentum and its bacteriocin a good antagonistic agent for exploitation in pharmaceutical and food processing industries as well as in the field of biotechnology.

Effectiveness of Essential Oil Component Cocrystals Against Food Spoilage Bacteria

AbstractImproving food preservation technologies is a key aspect in the struggle to reduce global food waste, and natural antimicrobial substances, such as essential oil (EO) components represent very promising food preserving agent. However, their intrinsic chemico‐physical properties, such as the low melting point, low water solubility and high volatility, pose some practical difficulties in exploiting them for practical applications. Cocrystallization is used to stabilize liquid or volatile EO components providing them whit a crystalline environment, thus improving their potential application as antibacterial agents. Five EO active ingredients (THY = thymol, CAR = carvacrol, EUG = eugenol, CAD = trans‐cinnamaldehyde, and VAN = o‐vanillin) and two coformers (INA = Isonicotinamide, and HBA = 4‐hydroxybenzoic acid) have been combined and the corresponding cocrystals have been studied for their potential inhibiting effect against four food spoilage bacteria (Bacillus thuringiensis, Enterobacter cloacae, Pseudomonas fluorescens, and Serratia marcescens). The structures of the five cocrystals have been used to derive structure‐activity relationships in terms of release energy of the active ingredients form the crystalline environment, and a correlation has been derived with the Intermolecular Interaction Energies of the EO molecules.

Clinical Trial Findings and Drug Development Challenges for Curcumin in Infectious Disease Prevention and Treatment.

Since ancient times, turmeric, scientifically known as Curcuma longa, has been renowned for its therapeutic properties. Recently, extensive documentation has highlighted the prevalence of microbial diseases without effective treatments, the increased expense of certain antimicrobial medications, and the growing occurrence of antimicrobial drug resistance. Experts predict that drug resistance will emerge as a significant global cause of death by the middle of this century, thereby necessitating intervention. Curcumin, a major curcuminoid molecule, has shown extensive antimicrobial action. Improving and altering the use of natural antimicrobial agents is the most effective approach to addressing issues of targeted specificity and drug resistance in chemically synthesized medicines. Further research is required to explore the efficacy of curcumin and other natural antimicrobial substances in combating microbial infections. The solubility and bioavailability of curcumin impede its antimicrobial capability. To enhance curcumin's antimicrobial effectiveness, researchers have recently employed several methods, including the development of curcumin-based nanoformulations. This review seeks to compile the latest available literature to assess the advantages of curcumin as a natural antimicrobial agent (particularly antiviral and antibacterial) and strategies to enhance its medical efficacy. The future application of curcumin will help to alleviate microbial infections, thereby promoting the sustainability of the world's population.

Silkworm Gut Microflora as a Source: Biotechnological Applications

The term "microflora" has gained popularity as researchers explore the symbiotic relationships between microorganisms and their hosts, from our skin to our gut. Insects, including the silkworm, have mutualistic ties with their gut microflora, making them a valuable resource for studying essential molecules. The silkworm, with its rapid generation time, abundant genetic resources, well-defined genetic background, and numerous homologous genes, is an ideal model organism for various life science studies. Silkworm rearing is simple, inexpensive, and does not require ethical clearance, allowing the gut microflora of Bombyx mori to be harnessed for biotechnological applications. Silkworm gut microbes can synthesize and produce extracellular enzymes, such as cellulases, proteases, and lipases, which are crucial for industries ranging from biofuel production to waste management and textile processing. Additionally, these microbes can produce vitamins, such as vitamin B12, and metabolites like short-chain fatty acids (SCFAs), which have potential applications in the food and pharmaceutical industries. Antimicrobial substances produced by the gut microflora, including bacteriocins and lactic acid, are of particular therapeutic importance, offering natural alternatives to traditional antibiotics and contributing to the development of novel antimicrobial therapies. Moreover, the antioxidants generated by these symbionts, such as glutathione and superoxide dismutase (SOD), have significant implications for health supplements and cosmetics, owing to their ability to combat oxidative stress and support immune function. Beyond their metabolic capacities, silkworm symbionts can be used to enhance health, target and manage agricultural pests, and control vectors of human diseases in an environmentally friendly manner. Recent research has also highlighted the potential of mutualistic symbiotic bacteria for plastic disposal, with enzymes like PETases showing promise in degrading synthetic polymers. Despite extensive knowledge on the biology and physiology of the silkworm Bombyx mori, few studies have focused on its gut microflora. Modern genetic techniques, such as the genetic transformation of silkworms with genes of interest, may help overcome these research gaps. Increasing research efforts on silkworm gut microflora will not only reveal new symbiotic relationships but also identify new sources of biotechnologically important molecules and enzymes for therapeutic and industrial applications.

Antifungal metabolites of biocontrol stain LB-1 and their inhibition mechanism against Botrytis cinerea.

Chaetomium subaffine LB-1 is a novel biocontrol strain that produces non-volatile metabolites that inhibit the growth of Botrytis cinerea. However, the specific metabolites and antimicrobial mechanism of the strain LB-1 remains unclear. In this study, the antifungal substances produced by strain LB-1, as well as the underlying mechanism of its inhibitory effect against B. cinerea, were explored using metabolomic and transcriptomic analysis. The results found that 45 metabolites might be the key antifungal substances, such as ouabain, ferulic acid, chlorogenic acid, spermidine, stachydrine, and stearic acid. The transcriptomic analysis indicated that the inhibition effect of LB-1 on B. cinerea resulted in the upregulation of genes related to adenosine triphosphate (ATP)-binding cassette (ABC) transporters, peroxisome, ER stress, and multiple metabolic pathways, and in downregulation of many genes associated with the synthesis of cell walls/membranes, carbohydrate metabolism, cell cycle, meiosis, and DNA replication. These results suggested that the inhibitory effect of strain LB-1 against B. cinerea might be due to the destroyed cell wall and membrane integrity exerted by antimicrobial substances, which affect cell metabolism and inhibit cell proliferation.

The Complex and Changing Genus Bacillus: A Diverse Bacterial Powerhouse for Many Applications

For years, the Bacillus genus has encompassed a heterogeneous group of individuals whose main common trait was their ability to sporulate in the presence of oxygen. This criterion has been revised, resulting in the reclassification of several species into new genera and to a redefinition of the characteristics of the members of this taxon. Currently, the species of the genus are grouped into the Subtilis clade and the Cereus clade. The former, called Bacillus sensu stricto, initially composed of B. subtilis, B. licheniformis, B. pumilus, and B. amyloliquefaciens, has subsequently incorporated new species related to these. The Cereus clade, Bacillus cereus sensu lato, consists of pathogenic species (B. anthracis, B. cereus, and B. thuringiensis) as well as others of significance in agriculture and industry. Furthermore, identifying these individuals remains complex, requiring alternatives to 16S rRNA sequencing. The ability to form spores resistant to stressful conditions provides a significant advantage over other genera, with observable differences in sporulation rates and spore structure among different species. Additionally, Bacillus spp. are known for their capacity to produce antimicrobial substances, lytic enzymes, and volatile organic compounds, each with diverse applications. Some species are even used as probiotics. This review delves into aspects related to the taxonomy and identification of microorganisms belonging to the genus Bacillus, which often present challenges. The aim is to provide a comprehensive overview of the topic. In addition, it highlights the characteristics and applications of the genus, emphasizing its importance in biotechnology and microbiology.

Interventions based on alternative and sustainable strategies for postharvest control of anthracnose and maintain quality in tropical fruits.

Colletotrichum spp. is a phytopathogen causing anthracnose in a variety of tropical fruits. Strategies used to control postharvest diseases in tropical fruits typically rely on the use of synthetic fungicides, which have stimulated the emergence of resistant pathogens. Safer alternative strategies to control anthracnose in tropical fruits have been described in the literature. This review presents and discusses the main innovative interventions concerning the application of sustainable alternative strategies in the postharvest control of pathogenic Colletotrichum species in tropical fruits, with a particular emphasis on the studies published in the last 5 years. The available studies have shown the use of various methods, including physical barriers, natural antimicrobials, and biological control with antagonistic microorganisms, to reduce anthracnose lesion severity and incidence in tropical fruits. The available literature showed high inhibitory activity in vitro, reduced anthracnose incidence and lesion diameter, and total disease inhibition in tropical fruits. Most studies focused on the inhibition of Colletotrichum gloeosporioides on avocado, papaya, and mango, as well as of Colletotrichum musae on banana; however, the inhibition of other Colletotrichum species was also demonstrated. The application of emerging sustainable alternative methods, including natural antimicrobial substances, also stimulated the induction of defense systems in tropical fruits, including enzymatic activity, such as polyphenol oxidase, peroxidase, and phenylalanine ammonia-lyase. The retrieved data helped to understand the current state of the research field and reveal new perspectives on developing efficient and sustainable intervention strategies to control pathogenic Colletotrichum species and anthracnose development in tropical fruits.

Hurdle Concept and The Role of Lactic Acid Bacteria

The hurdle idea is a food preservation technique that includes building up a number of barriers to prevent microbes from growing and prolong the shelf life of perishable goods. The idea of using lactic acid bacteria (LAB), which are essential for food preservation, is one that is significant. Through a variety of processes, including fermentation, competitive exclusion, metabolite generation, biofilm formation, nutritional competition, and metabolic activity, LAB support the hurdle concept. Lactic acid bacteria (LAB) ferment glucose to produce lactic acid, which results in an acidic environment that prevents infections and spoiling germs from growing. Additionally, LAB generates antimicrobial substances such as hydrogen peroxide, organic acids, and bacteriocins, which work by competitively excluding harmful germs from growing. Furthermore, metabolites of lactic acid bacteria (LAB) such acetic acid, diacetyl, and carbon dioxide enhance the flavor of fermented foods and serve as organic preservatives. Moreover, LAB have the ability to create biofilms that shield them from antimicrobial agents and environmental stressors, increasing their survival and persistence in food matrices. By means of nutritional competition, LAB outcompetes pathogenic or spoilage bacteria in the consumption of available resources, hence restricting their growth. In addition, LAB produces enzymes and antibacterial substances, among other metabolic activities that further impede the growth of infections.

Multifunctional applications of seaweed extract-infused hydroxyethyl cellulose-polyvinylpyrrolidone aerogels: Antibacterial, and antibiofilm proficiency for water decontamination

Establishing a reliable and secure water supply is still a significant challenge in many areas that need more infrastructure. Eliminating harmful bacteria from water systems is a critical obstacle to managing the spread of waterborne illnesses and protecting public health. Thus, this work focuses on enhancing the efficiency of using marine waste extract, namely seaweed, by its integrating its extract into aerogels based on Hydroxyethyl cellulose (HEC) and polyvinylpolypyrrolidone (PVP). Four formulations were created with increasing concentrations of Padina extract (PE): PE-0, PE-1, PE-2, and PE-3 loaded HEC-PVP aerogels. PE-3 loaded HEC-PVP aerogel showed remarkable efficacy in completely deactivating several types of bacteria, including Escherichia coli, Salmonella enterica, Enterococcus faecalis, and Bacillus subtilis. This antibacterial impact was seen within a short time frame of 75 min after treatment, making it the most significant outcome. Significantly, it had the greatest level of inhibition against E. coli (IZD: 24 mm) and showed potent inhibitory effects against S. enterica, E. faecalis, and B. subtilis, with IZD values of 18, 15, and 14 mm, respectively. These results indicate that the aerogel's ability to prohibite the harmfull microorganisms may be due to its surface qualities, which help release antimicrobial substances from the PE contained in the aerogel.

Regulatory mechanisms of the microbial starter fortification on the community and flavor characteristics in Doubanjiang

Doubanjiang is a special Chinese seasoning paste produced by mixing broad bean paste with chili paste. Besides the antimicrobial substances, such as capsaicin contained in chili, the microbiota and metabolism are directly developed by the stress effect of abiotic factors that periodically change during the fermentation process. The microbial starter is a promising way to improve the quality of Doubanjiang production. In the present study, the regulatory mechanisms of the microbial starters (Tetragenococcus halophilus, Zygosaccharomyces rouxii, and Candida versatilis) were explored by comparing the microbial community, flavor characteristics and their correlation networks between the fortified and control groups. In comparison to the control group, the volatile compound content increased by 30.77%, with notable increases in phenylethyl alcohol, beta-ionone, etc. Conversely, there was a reduction in non-volatile compounds, including reducing sugar, acidity, amino acid nitrogen, and organic acids. The microbial structure underwent a shift, with an increase in the relative abundance of C. versatilis, while Z. rouxii demonstrated no variance and T. halophilus was not detected. The correlations of the specific microbes and certain flavor compounds were modified by the starter (p < 0.05). Notably, the correlation between Enterobacter/Malassezia and 3-furaldehyde was shifted from a negative to a positive conversion. The observed increase in beta-ionone, ethyl phenylacetate, etc., resulted from the synergistic effects, correlated transformations, and reduction of antagonistic interactions. These findings indicate that the starter powerfully regulates the interactions between microbial communities and metabolic networks, thereby provide valuable insights for the improvement of Doubanjiang quality.

Description and Assessment of an Antimicrobial Substance from Marine Actinobacteria

Streptomyces is thought to be the primary source of bacteria for the synthesis of bioactive substances, such as naturally occurring antibiotics. Finding and identifying the actinomycetes exhibiting antagonistic activity was the primary goal of the current investigation. A strain of actinomycetes that was isolated from marine sand samples that were collected off the Indian coast of Vedharanyam exhibited antimicrobial activity against a number of microbial pathogens. The nutritional requirements and cultural conditions for maximal growth and yield of bioactive compounds have been optimized under shake flask condition. Analyze the compound characterization of the sample such as UV, FT-IR, GC-MS and sequencing 16S rRNA for species identification. The actinomycetes isolates which are isolated from sediment sample can be further used as antimicrobial activity agents against bacterial and fungal pathogens and their compound characterization.

Microbial Contamination of Food: Probiotics and Postbiotics as Potential Biopreservatives.

Microbial contamination of food and alimentary toxoinfection/intoxication in humans are commonly caused by bacteria such as Salmonella spp., Escherichia coli, Yersinia spp., Campylobacter spp., Listeria monocytogenes, and fungi (Aspergillus, Fusarium). The addition of probiotic cultures (bacterial strains Lactobacillus and Bifidobacterium and the yeast Saccharomyces cerevisiae var. boulardii) to food contributes primarily to food enrichment and obtaining a functional product, but also to food preservation. Reducing the number of viable pathogenic microorganisms and eliminating or neutralizing their toxins in food is achieved by probiotic-produced antimicrobial substances such as organic acids (lactic acid, acetic acid, propionic acid, phenylacetic acid, and phenyllactic acid), fatty acids (linoleic acid, butyric acid, caproic acid, and caprylic acid), aromatic compounds (diacetyl, acetaldehyde, reuterin), hydrogen peroxide, cyclic dipeptides, bacteriocins, and salivabactin. This review summarizes the basic facts on microbial contamination and preservation of food and the potential of different probiotic strains and their metabolites (postbiotics), including the mechanisms of their antimicrobial action against various foodborne pathogens. Literature data on this topic over the last three decades was searched in the PubMed, Scopus, and Google Scholar databases, systematically presented, and critically discussed, with particular attention to the advantages and disadvantages of using probiotics and postbiotics as food biopreservatives.

High toxinogenic potential of Staphylococcus aureus from wild ungulates in Brandenburg, Germany with a low level of antibiotic resistance.

Data regarding the occurrence and virulence of Staphylococcus (S.) aureus in wild living animals is rare. However, S. aureus may carry a multitude of virulence factors and express resistance to several antimicrobial substances. Handling game meat may thus lead to serious infections or food poisoning. The aim of this study was to provide insights into the occurrence and characteristics of S. aureus in wild ungulates from Brandenburg, Germany. Nasal swabs of externally healthy-looking wild boars, roe, fallow and red deer were collected in hunts during season 2021/2022 and analyzed for S. aureus by selective enrichment. Species were determined using matrix assisted laser desorption ionization mass spectrometry and tested for phenotypic antimicrobial resistance. Whole-genome sequencing was conducted for genotyping, determination of virulence associated genes and analysis of phylogenetic relationships. S. aureus were recovered from approximately 8% of nasal swabs. However, the strains were only obtained from the sampled wild ruminants. S. aureus isolates were associated with sequence types (ST) 1, ST30, ST133, ST425, ST582 and ST6238. Isolates of ST1 clustered closely together in the phylogenetic analysis. Genes encoding staphylococcal enterotoxin (SE) or SE-like (SEl) were found in 14/17 isolates. In particular, a seh gene was present in 12/17 isolates. Moreover, two isolates harbored a multiplicity of genes encoding SE or SEl. In addition, the toxic shock syndrome toxin encoding tst gene was detected in one isolate. This isolate was resistant to penicillin and cefoxitin and accordingly harbored the blaZ gene. Wild ungulates intended for human consumption may carry potentially virulent S. aureus. In one case, the close phylogenetic relationship of S. aureus isolates indicates a possible intraspecific spread within a common territory. However, for others, the origin or the spread pattern can only be inferred. Handling of animals or their carcasses might contribute to staphylococcal infections in humans. Moreover, food poisoning due to SE producing strains may occur, if recommended hygiene practices are not applied during processing of game meat.