Antimicrobial Active Packaging Containing Nisin for Preservation of Products of Animal Origin: An Overview

Holocellulose nanofibrils as effective nisin immobilization substrates for antimicrobial food packaging

Holocellulose nanofibrils (HCNF), a type of nanocellulose with abundant amorphous regions suitable for chemical modification, show promise for sustainable food packaging but remain underutilized. This study employed HCNF to immobilize nisin and then spray-coated on the surface of soy protein isolate (SPI) films to improve mechanical, barrier, and antimicrobial properties. HCNF was extracted from wood sheet through chemical delignification and low-energy defibrillation, and then oxidized to introduce aldehyde groups for efficient nisin conjugation. The abundant amorphous regions led to a high immobilization rate of 3.4 mg/g, and conjugated HCNF and nisin coatings on SPI films significantly enhanced tensile strength to 3.43 ± 0.09 MPa, reduced water vapor permeability to 2.48 ± 0.07 × 10-6 g m-1 h-1 Pa-1, and decreased oxygen permeability to 4.29 ± 0.46 × 10-4 cm3 m-1 day-1 atm-1. The conjugate sustained inhibition of S. aureus and L. monocytogenes, and the coating of 9 wt% conjugate on SPI films resulted in a 6-log reduction in bacterial count for both bacteria, while free nisin lost its antimicrobial efficacy during 24 h of pre-incubation. This work suggests feasibility of using HCNF as an effective substrate for nisin immobilization, providing a sustainable functional packaging solution with extended antimicrobial activity.

Review of Recent Advances in Intelligent and Antibacterial Packaging for Meat Quality and Safety

Intelligent and antimicrobial packaging technologies are transforming meat preservation by enhancing food safety, enabling real-time quality monitoring, and extending shelf life. This review critically examines advancements in intelligent systems, including radio frequency identification (RFID), gas sensors, time-temperature indicators (TTIs), and colorimetric indicators for continuous freshness assessment. A key focus is natural compound-based chromogenic indicators, which establish visual spoilage detection via distinct color transitions. Concurrently, antimicrobial systems integrating inorganic compounds, organic bioactive agents, and natural antimicrobials effectively inhibit microbial growth. Strategic incorporation of these agents into polymeric matrices enhances meat safety, supported by standardized evaluation protocols for regulatory compliance and quality assurance. Future research should prioritize optimizing sensitivity, cost-efficiency, and sustainability, alongside developing biodegradable materials to balance food safety with reduced environmental impact, advancing sustainable food supply chains.

High-level biosynthesis and purification of the antimicrobial peptide Kiadin based on non-chromatographic purification and acid cleavage methods

Antimicrobial peptides (AMPs) are renowned for their potent bacteriostatic activity and safety, rendering them invaluable in animal husbandry, food safety, and medicine. Despite their potential, the physiological toxicity of AMPs to host cells significantly hampers their biosynthetic production. This study presents a novel approach for the biosynthesis of the antimicrobial peptide Kiadin by engineering a DAMP4-DPS-Kiadin fusion protein to mitigate host cell toxicity and achieve high-level expression. Leveraging the unique properties of the DAMP4 protein, we developed a non-chromatographic purification method to isolate the DAMP4-DPS-Kiadin fusion protein with high purity. The instability of the D-P peptide bond under acidic conditions, combined with the thermal and saline stability of DAMP4, enabled efficient separation of Kiadin through acid cleavage and isoelectric precipitation, yielding Kiadin with 96% purity and a production yield of 29.3 mg/L. Our optimization of acid cleavage temperature, duration, and isoelectric precipitation conditions proved critical for maximizing the purification efficiency and expression levels of Kiadin. The biosynthesized Kiadin exhibited robust bacteriostatic activity against Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Bacillus cereus and Staphylococcus aureus. Notably, Kiadin demonstrated significant post-antibiotic effects by disrupting bacterial membrane integrity, inducing cytoplasmic leakage, and inhibiting biofilm formation in E. coli K88 and S. aureus Mu50, without cytotoxicity towards mouse macrophages. In vivo studies further confirmed Kiadin's exceptional therapeutic efficacy against abdominal infections caused by E. coli K88. The acid cleavage and non-chromatographic purification techniques developed in this study offer a cost-effective and efficient strategy for the high-purity production of AMPs.

Influence of Nisin Grafting on the Antibacterial Efficacy of AMP Self-Assembled Monolayers (SAMs)

The use of antimicrobial peptides (AMPs) covalently grafted on surfaces has been recognized in recent years as a promising strategy to fight against biofilm formation. However, after grafting, the understanding of AMP-bacteria interactions is still debated in the literature. In this study, Nisin, a cyclic AMP, was grafted onto gold surfaces via an indirect grafting on acidic thiol self-assembled monolayers using succinimide linkers. The physical and chemical properties of these SAMs were then finely characterized by XPS and FT-IR to confirm the covalent grafting of Nisin. The antiadhesion and bactericidal effects were then studied for Escherichia coli ATCC25922, Staphylococcus aureus ATCC 25923, and Listeria ivanovii Li4(pVS2) by a posteriori analysis of the culture supernatants (i.e., indirect technique) and ex situ by optical microscopy following crystal violet staining (i.e., direct technique). Statistical analysis reveals that the Nisin coating has bactericidal and antiadhesive properties towards Gram-positive bacteria, while no significant results were obtained for Gram-negative bacteria.

Strategies for effective high pressure germination or inactivation of Bacillus spores involving nisin

The major challenge in employing high pressure (HP) at moderate temperature for sterilization is the remarkable resistance of bacterial spores. High isostatic pressure can initiate spore germination, enabling subsequent inactivation under mild conditions. However, not all spores could be triggered to germinate under pressure at temperatures ≤80°C so far. In this study, germination treatment combinations were evaluated for Bacillus spores involving moderate HP (150 MPa, 37°C, 5 min), very HP (vHP, 550 MPa, 60°C, 2.5 or 9 min), simple and complex nutrient germinants [L-valine, L-alanine, and tryptic soy broth (TSB)], nisin, and incubation at atmospheric pressure (37°C). The most effective combinations for Bacillus subtilis resulted in a reduction of culturable dormant spores by 8 log10 units. The combinations involved nisin, a nutrient germinant (L-valine or TSB), a first vHP treatment (550 MPa, 60°C, 2.5 min), incubation at atmospheric pressure (37°C, 6 h), and a second vHP treatment (550 MPa, 60°C, 2.5 min). Such treatment combination with L-valine reduced Bacillus amyloliquefaciens spores by only 2 log10 units. B. amyloliquefaciens, thus, proved to be substantially more HP-resistant compared to B. subtilis, validating previous studies. Despite combining different germination mechanisms, complete germination could not be achieved for either species. The natural bacteriocin nisin did seemingly not promote HP germination initiation under chosen HP conditions, contrary to previous literature. Nevertheless, nisin might be beneficial to inhibit the growth of HP-germinated or remaining ungerminated spores. Future germination experiments might consider that nisin could not be completely removed from spores by washing, thereby affecting plate count enumeration.

IMPORTANCE

Extremely resistant spore-forming bacteria are widely distributed in nature. They infiltrate the food chain and processing environments, posing risks of spoilage and food safety. Traditional heat-intensive inactivation methods often negatively affect the product quality. HP germination-inactivation offers a potential solution for better preserving sensitive ingredients while inactivating spores. However, the presence of ungerminated (superdormant) spores hampers the strategy's success and safety. Knowledge of strategies to overcome resistance to HP germination is vital to progress mild spore control technologies. Our study contributes to the evaluation and development of mild preservation processes by evaluating strategies to enhance the HP germination-inactivation efficacy. Mild preservation processes can fulfill the consumers' demand for safe and minimally processed food.

Activity and safety evaluation of natural preservatives

Synthetic preservatives are widely used in the food industry to control spoilage and growth of pathogenic microorganisms, inhibit lipid oxidation processes and extend the shelf life of food. However, synthetic preservatives have some side effects that can lead to poisoning, cancer and other degenerative diseases. With the improvement of living standards, people are developing safer natural preservatives to replace synthetic preservatives, including plant derived preservatives (polyphenols, essential oils, flavonoids), animal derived preservatives (lysozyme, antimicrobial peptide, chitosan) and microorganism derived preservatives (nisin, natamycin, ε-polylysine, phage). These natural preservatives exert antibacterial effects by disrupting microbial cell wall/membrane structures, interfering with DNA/RNA replication and transcription, and affecting protein synthesis and metabolism. This review summarizes the natural bioactive compounds (polyphenols, flavonoids and terpenoids, etc.) in these preservatives, their antioxidant and antibacterial activities, and safety evaluation in various products.

The Effect of Nanoscale Modification of Nisin by Different Milk-Derived Proteins on Its Physicochemical Properties and Antibacterial Activity

Nisin is used as a natural food preservative because of its broad-spectrum antimicrobial activity against Gram-positive bacteria. However, free nisin is susceptible to various factors that reduce its antimicrobial activity. Milk protein, a protein derived from milk, has self-assembly properties and is a good carrier of bioactive substances. In this study, lactoferrin-nisin nanoparticles (L-N), bovine serum albumin-nisin nanoparticles (B-N), and casein-nisin nanoparticles (C-N) were successfully prepared by a self-assembly technique, and then their properties were investigated. The studies revealed that lactoferrin (LF) and nisin formed L-N mainly through hydrophobic interactions and hydrogen bonding, and L-N had the best performance. The small particle size (29.83 ± 2.42 nm), dense reticular structure, and good thermal stability, storage stability, and emulsification of L-N laid a certain foundation for its application in food. Further bacteriostatic studies showed that L-N enhanced the bacteriostatic activity of nisin, with prominent inhibitory properties against Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus, which mainly disrupted the cell membrane of the bacteria. The above results broaden our understanding of milk protein-nisin nanoparticles, while the excellent antibacterial activity of L-N makes it promising for application as a novel food preservative, which will help to improve the bioavailability of nisin in food systems.

Preparation and characterization of nisin-loaded chitosan nanoparticles functionalized with DNase I for the removal of Listeria monocytogenes biofilms

Listeria monocytogenes biofilms represent a continuous source of contamination, leading to serious food safety concerns and economic losses. This study aims to develop novel nisin-loaded chitosan nanoparticles (CSNPs) functionalized with DNase I and evaluate its antibiofilm activity against L. monocytogenes on food contact surfaces. Nisin-loaded CSNPs (CS-N) were first prepared by ionic cross-linking, and DNase I was covalently grafted on the surface (DNase-CS-N). The NPs were subsequently characterized by Zetasizer Nano, transmission electron microscopy, Fourier transform infrared (FT-IR), and X-ray diffraction (XRD). The antibiofilm activity of NPs was evaluated against L. monocytogenes on polyurethane (PU). The DNase-CS-N was fabricated and characterized with quality attributes (particle size-427.0 ± 15.1 nm, polydispersity [PDI]-0.114 ± 0.034, zeta potential-+52.5 ± 0.2 mV, encapsulation efficiency-46.5% ± 3.6%, DNase conjugate rate-70.4% ± 0.2). FT-IR and XRD verified the loading of nisin and binding of DNase I with chitosan. The DNase-CS-N caused a 3 log colony-forming unit (CFU)/cm2 reduction of L. monocytogenes biofilm cells, significantly higher than those in CSNPs (1.4 log), CS-N (1.8 log), and CS-N in combination with DNase I (2.2 log) treatment groups. In conclusion, nisin-loaded CSNPs functionalized with DNase I were successfully prepared and characterized with smooth surface and nearly spherical shape, high surface positive charge, and good stability, which is effective to eradicate L. monocytogenes biofilm cells on food contact surfaces, exhibiting great potential as antibiofilm agents in food industry. PRACTICAL APPLICATION: Listeria monocytogenes biofilms are a common safety hazard in food processing. In this study, novel nanoparticles were successfully constructed and are expected to be a promising antibiofilm agent in the food industry.

Nanocomposites and their application in antimicrobial packaging

The advances in nanocomposites incorporating bioactive substances have the potential to transform the food packaging sector. Different nanofillers have been incorporated into polymeric matrixes to develop nanocomposite materials with improved mechanical, thermal, optical and barrier properties. Nanoclays, nanosilica, carbon nanotubes, nanocellulose, and chitosan/chitin nanoparticles have been successfully included into polymeric films, resulting in packaging materials with advanced characteristics. Nanostructured antimicrobial films have promising applications as active packaging in the food industry. Nanocomposite films containing antimicrobial substances such as essential oils, bacteriocins, antimicrobial enzymes, or metallic nanoparticles have been developed. These active nanocomposites are useful packaging materials to enhance food safety. Nanocomposites are promising materials for use in food packaging applications as practical and safe substitutes to the traditional packaging plastics.

Characterization of Antimicrobial Peptide Produced by Bacillus Subtilis Subsp. Subtilis.. [DOI: 10.21203/rs.3.rs-2856256/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Purpose: Antimicrobial peptides are amongst the most promising class of peptides to contract the rise of global antimicrobial resistant. This article investigates a new antimicrobial peptide from bacteria.Methods: Bacterial identification was based on phenotypical and biochemical properties as well as 16S rRNA gene sequence homology. Bacterial growth and production of the inhibitory substance was standardized and optimized. The newly antimicrobial peptide was purified to homogeneity, subsequently analyzed by PAGE and MALDI-TOF-MS.Results: The bacterium identified as Bacillus subtilis subsp. subtilis and designated as strain MZ-32. Landy medium was best for the production when compared with different media after fixing the least influential variables in standardized fermentation conditions. Carbohydrate and nitrogen supplements investigated to improve production in Landy medium. The antimicrobial peptide of 2.158-Da was active against a broad range of skin-born pathogenic bacteria that were resistant to standard antibiotics, and possessed the physico-chemical properties of an ideal antimicrobial agent in terms of water solubility, thermal resistance, and stability towards acid/alkali (pH 4.0 to 9.0) treatments.Conclusion: The new strain and its associated peptide are potentially new candidates for medical and biotechnological applications.

Development of a Halochromic, Antimicrobial, and Antioxidant Starch-Based Film Containing Phenolic Extract from Jaboticaba Peel

In this study, the antioxidant, antimicrobial, mechanical, optical, and barrier attributes of Solanum lycocarpum starch bio-based edible films incorporated with a phenolic extract from jaboticaba peel were investigated. Aiming to determine the effect of the polymers and the phenolic extract on the properties of the films, a three-factor simplex-lattice design was employed, and the formulation optimization was based on the produced films' antioxidant potential. The optimized formulation of the starch-PEJP film showed a reddish-pink color with no cracks or bubbles and 91% antioxidant activity against DPPH radical. The optimized starch-PEJP film showed good transparency properties and a potent UV-blocking action, presenting color variation as a function of the pH values. The optimized film was also considerably resistant and highly flexible, showing a water vapor permeability of 3.28 × 10-6 g m-1 h-1 Pa-1. The microbial permeation test and antimicrobial evaluation demonstrated that the optimized starch-PEJP film avoided microbial contamination and was potent in reducing the growth of Escherichia coli, Staphylococcus aureus, and Salmonella spp. In summary, the active starch-PEJP film showed great potential as an environmentally friendly and halochromic material, presenting antioxidant and antimicrobial properties and high UV-protecting activity.