Mitigating Milk-Associated Bacteria through Inducing Zinc Ions Antibiofilm Activity

Antifungal effect and mode of activity of zinc chloride against toxigenic fungus Aspergillus flavus

Fungal plant pathogens cause considerable losses in yield and quality of field crops worldwide. Under specific environmental conditions, many fungi, such as Aspergillus spp., produce mycotoxins while colonizing their host, which accumulate in human and animal tissues, posing a serious threat to consumer health. Extensive use of fungicides in crop protection has stimulated the emergence of acquired drug resistance in some plant and human fungal pathogens. The use of metal compounds as antimicrobial agents offers an alternative strategy for managing potentially resistant toxigenic fungi and reducing the required dosage of specific drugs. We investigated the effect of zinc chloride (ZnCl2) on Aspergillus flavus infection and aflatoxin biosynthesis in cereal grains (wheat and maize) and legume crops (groundnut and chickpea). Following ZnCl2 treatment, quantitative PCR analysis showed a significant decrease in fungal DNA content in cereal grain and legume samples contaminated with A. flavus. Chitin content was dramatically reduced in A. flavus as a result of ZnCl2 treatment, suggesting that the zinc compound acts by inhibiting the synthesis of chitin, a fungal cell-wall component. Moreover, 5 days of treatment with 10 mM ZnCl2 reduced aflatoxin production by A. flavus in the tested crops by up to 43 %, and 20 and 40 mM ZnCl2 showed 87.4 to 99.7 % inhibition of toxin synthesis. These findings were supported by quantitative real-time PCR analysis, showing downregulation of key genes involved in the aflatoxin-biosynthesis pathway under ZnCl2 treatment. Our results provide evidence for antifungal and antimycotoxigenic effects of ZnCl2 against the filamentous fungus A. flavus. Future application of these findings may enable sustainable use of the compound in agricultural settings, while reducing potential concerns over exposure to high doses of fungicides that are harmful to the environment.

Properties and antibacterial effectiveness of metal-ion doped borate-based bioactive glasses

Bioactive glasses (BGs) are physiologically reactive surface biomaterials widely used in biomedical applications and various treatments. Borate bioactive glasses (BBGs) are third-generation BGs, and they exhibit superior biodegradable, bioactive, osteoconductive, antibacterial, and biocompatible properties compared to other types of BGs. Certain concentrations of dopant ions can be incorporated into the chemical structure of BBGs to enhance their biological functionalities and antimicrobial properties. It was demonstrated that those ions play a crucial role in the biological responsiveness in vitro and in vivo once in contact with a physiological environment. The dissolution products of ion-doped BBGs were noted in their ability to stimulate gene expression related to cell differentiation and proliferation, promote angiogenesis, display anti-inflammatory effects, and inhibit bacterial growth within a few hours. Thus, metal-ion-doped BBGs address several limitations encountered by biomedical, tissue engineering, and infection control applications. Considering the research studies on BBGs to date, this review aims to analyze metal-ion-doped BBGs based on their primary antibacterial properties and effectiveness.

Recent progress in antibiofilm strategies in the dairy industry

Biofilm formation allows microorganisms including bacteria to persist on abiotic or biotic surfaces, to resist treatments with biocides (disinfectants and antibiotics) and to evade the immune response in animal hosts much more than they do in the planktonic form. Bacteria able to form biofilm can be troublesome in the dairy industry, both by causing clinical symptoms in livestock and by colonizing milking devices and milk processing equipment, resulting in dairy products of lower quality and sometimes raising serious food safety issues. In fact, most of the bacterial species isolated frequently in the dairy chain have the ability to form biofilm. Common examples include Staphylococcus aureus and other staphylococci that frequently infect mammary glands, but also Bacillus spp., Listeria monocytogenes and Pseudomonas spp. which cause spoilage of dairy products and sometimes foodborne illnesses. The economic losses due to biofilm formation in the dairy industry are considerable, and scientists are constantly solicited to develop new antibiofilm strategies, especially using biocides of natural origin. Although the number of studies in this subject area has exploded in recent years, the in vivo efficacy of most novel approaches remains to be explored. Used alone or to increase the efficacy of disinfectants or antibiotics, they could allow the implementation of strategies having less impact on the environment. Their use is expected to lead to less reliance on antibiotics to treat intramammary infections in dairy farms and to the use of lower concentrations of chemical disinfectants in dairy processing plants.

Biomimetic Apatite/Natural Polymer Composite Granules as Multifunctional Dental Tissue Regenerative Material

This study presents a comprehensive evaluation of novel composite biomaterials designed for dental applications, aiming to potentially address the prevalent challenge of dental and periodontal tissue loss. The composites consisted of biomimetic hydroxyapatite (mHA) enriched with Mg2+, CO32-, and Zn2+ ions, type I collagen, alginate, and, additionally, chitosan and sericin. The granules were loaded with ibuprofen sodium salt. The investigation encompassed a morphology characterization, a porosity analysis, a chemical structure assessment, and an examination of the swelling behavior, drug release kinetics (ibuprofen), and release profiles of zinc and magnesium ions. The granules exhibited irregular surfaces with an enhanced homogeneity in the chitosan-coated granules and well-developed mesoporous structures. The FT-IR spectra confirmed the presence of ibuprofen sodium, despite overlapping bands for the polymers. The granules demonstrated a high water-absorption capacity, with delayed swelling observed in the chitosan-coated granules. Ibuprofen displayed burst-release profiles, especially in the G1 and G3 samples. In the case of the chitosan-coated granules (G2 and G4), lower amounts of ibuprofen were released. In turn, there was a significant difference in the released amount of magnesium and zinc ions from the granules, which was most likely caused by their different location in the hydroxyapatite crystals. The cytotoxicity assays confirmed the non-cytotoxic behavior of the biomaterial. These findings suggest the potential applicability of these biomaterials in dental scenarios, emphasizing their multifunctional and biocompatible nature.

Zinc chloride is effective as an antibiotic in biofilm prevention following septoplasty

Biofilm-state bacterial infections associated with inserted medical devices constitute a massive health and financial problem worldwide. Although bacteria exhibit significantly lower susceptibility to antibiotics in the biofilm state, the most common treatment approach still relies on antibiotics, exacerbating the phenomenon of antibiotic-resistant bacteria. In this study, we aimed to assess whether ZnCl₂ coating of intranasal silicone splints (ISSs) can reduce the biofilm infections associated with the insertion of these devices and prevent the overuse of antibiotics while minimizing waste, pollution and costs. We tested the ability of ZnCl₂ to prevent biofilm formation on ISS both in vitro and in vivo by using the microtiter dish biofilm formation assay, crystal violet staining, and electron and confocal microscopy. We found a significant decrease in biofilm formation between the treatment group and the growth control when ZnCl₂-coated splints were placed in patients' nasal flora. According to these results, infections associated with ISS insertion may be prevented by using ZnCl₂ coating, thereby obviating the overuse and abuse of antibiotics.

Prevalence and Antibiotic Resistance of Bacillus sp. Isolated from Raw Milk

Milk, due to its diversity in terms of its nutritional content, is an important element of the human diet, as well as a good medium for the development of bacteria. The genus Bacillus contains ubiquitous aerobic, rod-shaped, endospore-producing gram-positive bacteria. Representatives of the Bacillus cereus group and the Bacillus subtilis group contribute to shortening the shelf life of milk and dairy products by degrading milk components and its additives. They also produce a number of heat-stable toxins and can cause a number of ailments, mainly in the digestive system. The aim of this research was to identify Bacillus sp. strains isolated from raw milk and to determine their antibiotic resistance. Strains isolated from raw milk samples (n = 45) were identified by MALDI-TOF MS. Ninety strains of Bacillus sp. were identified, for which the antibiotic resistance phenotype was determined. A total of 90 strains of Bacillus were classified in five groups (the Bacillus cereus group (n = 35), B. licheniformis (n = 7), the B. subtilis group (n = 29), B. pumilus (n = 16), and Bacillus sp. (n = 3). All isolates were susceptible to chloramphenicol and meropenem. The antibiotic resistance profiles of the tested groups of Bacillus spp. differed from each other, which is of particular concern in relation to multidrug-resistant representatives of the B. cereus group resistant to cefotaxime (94.29%), ampicillin (88.57%), rifampicin (80%), and norfloxacin (65.71%). Our study provides data on the prevalence and antibiotic sensitivity of Bacillus sp. In raw milk, suggesting a potential risk to health and the dairy industry.

Contribution of Ammonium-Induced Nitrifier Denitrification to N2O in Paddy Fields

Paddy fields are one of the most important sources of nitrous oxide (N₂O), but biogeochemical N₂O production mechanisms in the soil profile remain unclear. Our study used incubation, dual-isotope (¹⁵N-¹⁸O) labeling methods, and molecular techniques to elucidate N₂O production characteristics and mechanisms in the soil profile (0-60 cm) during summer fallow, rice cropping, and winter fallow periods. The results pointed out that biotic processes dominated N₂O production (72.2-100%) and N₂O from the tillage layer accounted for 91.0-98.5% of total N₂O in the soil profile. Heterotrophic denitrification (HD) was the main process generating N₂O, contributing between 53.4 and 96.6%, the remainder being due to ammonia oxidation pathways, which was further confirmed by metagenomics and quantitative polymerase chain reaction (qPCR) assays. Nitrifier denitrification (ND) was an important N₂O production source, contributing 0-46.6% of total N₂O production, which showed similar trends with N₂O emissions. Among physicochemical and biological factors, ammonium content and the ratio of total organic matter to nitrate were the main driving factors affecting the contribution ratios of the ammonia oxidation pathways and HD pathway, respectively. Moisture content and pH affect norC-carrying Spirochetes and thus the N₂O production rate. These findings confirm the importance of ND to N₂O production and help to elucidate the impact of anthropogenic activities, including tillage, fertilization, and irrigation, on N₂O production.

Anti-biofilm activity of biochanin A against Staphylococcus aureus

Biofilm-forming Staphylococcus aureus can easily accumulate on various food contact surfaces which induce cross-contamination and are difficult to eliminate in the food industry. This study aimed to evaluate the anti-biofilm effects of natural product biochanin A against S. aureus. Results showed that biochanin A effectively eradicated established S. aureus biofilms on different food-contact materials. Fluorescence microscopic analyses suggested that biochanin A disintegrated the established biofilms by dissociate extracellular polymeric substance (EPS) in matrix. In addition, biochanin A at the sub-MIC concentration also effectively inhibited the biofilm formation by regulating the expression of biofilm-related genes (icaA, srtA, eno) and suppressing the release of EPS in biofilm matrix. Molecular docking also demonstrated that biochanin A conducted strong interactions with biofilm-related proteins (Ica A, Sortase A, and Enolase). These findings demonstrated that biochanin A has the potential to be developed as a potent agent against S. aureus biofilm in food industries. KEY POINTS: • Anti-biofilm effect of biochanin A against S. aureus was revealed for the first time. • Biofilm of S. aureus on various food-contact surfaces were efficiently eradicated. • Biochanin A prevented S. aureus biofilm formation via reducing EPS production.

Application of Plant-Derived Nanoparticles (PDNP) in Food-Producing Animals as a Bio-Control Agent against Antimicrobial-Resistant Pathogens

Antibiotics are regularly used in animal husbandry to treat diseases. This practice is beneficial to animals' health and helps ensure food security. However, the misuse of antibiotics, especially in food-producing animals, has resulted in the advent of antimicrobial resistance (AMR) and its dissemination among foodborne pathogens. The occurrence of AMR in bacteria pathogens that cause infections in animals and those associated with food spoilage is now considered a global health concern affecting humans, animals and the environment. The search for alternative antimicrobial agents has kindled the interest of many researchers. Among the alternatives, using plant-derived nanoparticles (PDNPs) for treating microbial dysfunctions in food-producing animals has gained significant attention. In traditional medicine, plant extracts are considered as safe, efficient and natural antibacterial agents for various animal diseases. Given the complexity of the AMR and concerns about issues at the interface of human health, animal health and the environment, it is important to emphasize the role of a One Health approach in addressing this problem. This review examines the potential of PDNPs as bio-control agents in food-producing animals, intending to provide consumers with microbiologically safe food while ensuring food safety and security, better health for animals and humans and a safe environment.

Antibiofilm Activity of Biocide Metal Ions Containing Bioactive Glasses (BGs): A Mini Review

One of the major clinical issues during the implantation procedure is the bacterial infections linked to biofilms. Due to their tissue localization and the type of bacteria involved, bacterial infections at implant sites are usually difficult to treat, which increases patient morbidity and even mortality. The difficulty of treating biofilm-associated infections and the emergence of multidrug-resistant bacteria are further challenges for the scientific community to develop novel biomaterials with excellent biocompatibility and antibacterial properties. Given their ability to stimulate bone formation and have antibacterial properties, metal ion-doped bioactive glasses (BGs) have received considerable research. This mini review aims to be successful in presenting the developments made about the role of biocide metal ions incorporated into BGs against the development of bacterial biofilms and the spread of nosocomial diseases.

Electrochemical Control of Biofilm Formation and Approaches to Biofilm Removal

This review deals with microbial adhesion to metal-based surfaces and the subsequent biofilm formation, showing that both processes are a serious problem in the food industry, where pathogenic microorganisms released from the biofilm structure may pollute food and related material during their production. Biofilm exhibits an increased resistance toward sanitizers and disinfectants, which complicates the removal or inactivation of microorganisms in these products. In the existing traditional techniques and modern approaches for clean-in-place, electrochemical biofilm control offers promising technology, where surface properties or the reactions taking place on the surface are controlled to delay or prevent cell attachment or to remove microbial cells from the surface. In this overview, biofilm characterization, the classification of bacteria-forming biofilms, the influence of environmental conditions for bacterial attachment to material surfaces, and the evaluation of the role of biofilm morphology are described in detail. Health aspects, biofilm control methods in the food industry, and conventional approaches to biofilm removal are included as well, in order to consider the possibilities and limitations of various electrochemical approaches to biofilm control with respect to potential applications in the food industry.

Chickpea-Derived Prebiotic Substances Trigger Biofilm Formation by Bacillus subtilis

Chickpea-based foods are known for their low allergenicity and rich nutritional package. As an essential dietary legume, chickpea is often processed into milk or hummus or as an industrial source of protein and starch. The current study explores the feasibility of using the chickpea-derived prebiotic substances as a scaffold for growing Bacillus subtilis (a prospective probiotic bacterium) to develop synbiotic chickpea-based functional food. We report that the chickpea-derived fibers enhance the formation of the B. subtilis biofilms and the production of the antimicrobial pigment pulcherrimin. Furthermore, electron micrograph imaging confirms the bacterial embedding onto the chickpea fibers, which may provide a survival tactic to shield and protect the bacterial population from environmental insults. Overall, it is believed that chickpea-derived prebiotic substances provide a staple basis for developing functional probiotics and synbiotic food.

Antimicrobial Effect of Zn2+ Ions Governs the Microbial Quality of Donor Human Milk

Donor human milk (HM) obtained at HM banks is exceptionally crucial for the feeding and treatment of preterm infants. Bacterial contaminations of HM in various stages of its handling are very common and can lead to disqualification of donations or severe infections in worse cases. Hence, HM donations are subject to strict bacteriological evaluations pre- and post-pasteurization. The main contaminating species vary between countries, banks and donors and even exhibit inter-individual variation. We initiated an assessment of the bacteriological composition of HM donated by women hospitalized in a neonatal intensive care unit in Israel. The most common bacterium identified was Staphylococcus epidermidis, found in all but one of the HM samples; the presence of several species of coagulase-negative Staphylococci was also noted. Next, we sought to develop a platform towards antibacterial treatment using Zn2+ ions that have recently been found to be potent against contaminants isolated from bovine milk. Zn2+ efficiently inhibited the growth of viable aerobic population and S. epidermidis in HM. Growth was also inhibited in other Gram-positive bacteria such as Bacillus cereus, a well-known food-borne pathogen. S. epidermidis and B. cereus cells grown in the presence of zinc were taken for microscopic evaluation, aiming to demonstrate zinc's antimicrobial mode of action morphologically. Images obtained using scanning electron microscopy indicated leakage of cellular content and cell lysis in S. epidermidis. Besides, B. cereus cells showed abnormalities in their cell surface and complete loss of flagella upon treatment with zinc. Along with the above findings, it should be noted that this was a pilot study that tested how high doses of Zn2+ affect breast milk as a product. Further research is likely needed on the safety of consumption of Zn2+-treated HM in infants and older children.

Microbial biofilm: A matter of grave concern for human health and food industry

Pathogenic microorganisms have adapted different strategies during the course of time to invade host defense mechanisms and overcome the effect of potent antibiotics. The formation of biofilm on both biotic and abiotic surfaces by microorganisms is one such strategy to resist and survive even in presence of antibiotics and other adverse environmental conditions. Biofilm is a safe home of microorganisms embedded within self-produced extracellular polymeric substances comprising of polysaccharides, extracellular proteins, nucleic acid, and water. It is because of this adaptation strategy that pathogenic microorganisms are taking a heavy toll on the health and life of organisms. In this review, we discuss the colonization of pathogenic microorganisms on tissues and medically implanted devices in human beings. We also focus on food spoilage, disease outbreaks, biofilm-associated deaths, burden on economy, and other major concerns of biofilm-forming pathogenic microorganisms in food industries like dairy, poultry, ready-to-eat food, meat, and aquaculture.