The expected rise in human population by 2050 demands an additional 60% increase in food production. The objective seems tough to achieve considering a significant global upsurge in food spoilage due to physicochemical and microbial factors posing major threats to food security and safety. Innovative nanotechnology solutions addressing field-deployable antimicrobials, functional food packaging, storage container materials, and preservatives along with efficient supply chain management hold promise for reducing food wastage. For instance, the use of halloysite nanotubes (HNTs) in packaging films not only improves the mechanical strength, and barrier properties but also enables encapsulation and controlled release of bioactive agents. Further, the unique and desirable properties of HNTs for biomedical, agri-food, industrial, and environmental applications along with their natural origins in abundance make it a promising platform for developing sustainable nanotechnology applications. As the third chapter of Section III, we will focus our discussion on the multifunctional roles of HNTs in active/intelligent food-packaging systems as nanofillers, nano-carriers, food-quality indicators, coatings, fibers, and capsules. Moreover, HNTs in therapeutic development and delivery for application in animal and plant agriculture will be addressed. Current limitations and future perspectives concerning health risk assessment, material transformation, migration, and regulatory issues will be systematically discussed.
Abstract Background Staphylococcus aureus is one of the prevalent etiological agents of contagious bovine mastitis, causing a significant economic burden on the global dairy industry. Given the emergence of antibiotic resistance (ABR) and possible zoonotic spillovers, S aureus from mastitic cattle pose threat to both veterinary and public health. Therefore, assessment of their ABR status and pathogenic translation in human infection models is crucial. Results In this study, 43 S. aureus isolates associated with bovine mastitis obtained from four different Canadian provinces (Alberta, Ontario, Quebec, and Atlantic provinces) were tested for ABR and virulence through phenotypic and genotypic profiling. All 43 isolates exhibited crucial virulence characteristics such as hemolysis, and biofilm formation, and six isolates from ST151, ST352, and ST8 categories showed ABR. Genes associated with ABR ( tetK, tetM, aac6’, norA, norB, lmrS , blaR, blaZ , etc.), toxin production ( hla, hlab , lukD , etc.), adherence ( fmbA, fnbB, clfA, clfB , icaABCD , etc.), and host immune invasion ( spa, sbi, cap, adsA , etc.) were identified by analyzing whole-genome sequences. Although none of the isolates possessed human adaptation genes, both groups of ABR and antibiotic-susceptible isolates demonstrated intracellular invasion, colonization, infection, and death of human intestinal epithelial cells (Caco-2), and Caenorhabditis elegans . Notably, the susceptibilities of S. aureus towards antibiotics such as streptomycin, kanamycin, and ampicillin were altered when the bacteria were internalized in Caco-2 cells and C. elegans . Meanwhile, tetracycline, chloramphenicol, and ceftiofur were comparatively more effective with ≤ 2.5 log 10 reductions of intracellular S. aureus . Conclusions This study demonstrated the potential of S. aureus isolated from mastitis cows to possess virulence characteristics enabling invasion of intestinal cells thus calling for developing therapeutics capable of targeting drug-resistant intracellular pathogens for effective disease management.
Poor mechanical and water barrier properties restrict the applicability of protein-based packaging in high-moisture food commodities. In this study, a nanocomposite (Nc) of tannic acid-loaded halloysite nanotubes grafted with silver nanoparticles was developed as a reinforcement agent to enhance the functional properties of soy protein isolate (SPI)-based films. The 5%- and 10%-Nc incorporation in SPI films significantly (p<0.05) improved the tensile strength (by 1.94-3.14 fold) and thermal stability (by 5-7%) and reduced water vapor permeability (by 1.28-1.30 fold), oxygen permeability (by 2.72-3.84 fold), and water solubility (by 6.3-9.5 fold). The 5%- and 10% Nc/SPI films showed antioxidant properties (by scavenging 18%-28% of DPPH) and exhibited a 3-5 log10 reduction in multi-drug resistant S. aureus and S. Typhimurium contamination in chicken breast fillets. Although 10% Nc/SPI exhibited silver migration to chicken fillets beyond the acceptable limit contributing to color change, 5% Nc/SPI films enhanced the shelf-life of fillets for 4 days by facilitating a controlled pH, lipid oxidation, and microbial growth with acceptable levels of silver migration. In conclusion, the multifunctionality of Nc in SPI films enables its potential to be an alternative to non-biodegradable and non-eco-friendly polymers.
The emergence of multidrug-resistant (MDR) bacterial pathogens in farm animals and their zoonotic spread is a concern to both animal agriculture and public health. Apart from antimicrobial resistance (AMR), bacterial pathogens from the genera of Salmonella and Staphylococcus take refuge inside host cells, thereby demanding intervention strategies that can eliminate intracellular MDR pathogens. In this study, seven clinical isolates of Salmonella and Staphylococcus from swine farms were characterized for antibiotic (n = 24) resistance, resistance mechanisms, and virulence characteristics. All isolates showed resistance to one or more antibiotics and S. enterica ser. Typhimurium isolate had the highest resistance to the panel of antibiotics tested. Major resistance mechanisms identified were efflux pump and beta-lactamase enzyme activities. Staphylococcus isolates showed complete hemolysis and strong biofilm formation, while Salmonella isolates caused partial hemolysis, but showed no or weak biofilm formation. MDR isolates of S. aureus M12 and S. enterica ser. Typhimurium bacteria were subsequently tested against combinations of antibiotics and potentiating adjuvants for improved antibacterial efficacy using a checkerboard assay, and their fractional inhibitory concentration index (FICI) was calculated. A combination of chitosan and silica nanoparticles containing tetracycline (TET) and efflux pump inhibitor chlorpromazine (CPZ), respectively, was characterized for physicochemical properties and effectiveness against MDR Salmonella enterica ser. Typhimurium isolate. This combination of nano-encapsulated drugs improved the antibacterial efficacy by inhibiting AMR mechanisms (efflux activity, beta-lactamase enzyme activity, and hydrogen sulfide (H2S) production) and reducing intracellular pathogen load by 83.02 ± 14.35%. In conclusion, this study sheds light on the promising applicability of nanoparticle-enabled combination therapy to combat multidrug-resistant pathogens encountered in animal agriculture.
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