Characterization of nisin containing chitosan-alginate microparticles

Nisin-loaded chitosan/sodium alginate microspheres enhance the antimicrobial efficacy of nisin against Staphylococcus aureus

AIMS

To develop and evaluate nisin-loaded chitosan/sodium alginate (CS/SA) microspheres as an improved antimicrobial delivery system targeting Staphylococcus aureus strains.

METHODS AND RESULTS

The microspheres were prepared using a modified water-in-oil emulsion cross-linking method, resulting in spherical particles sized 1-8 µm with a surface charge of -7.92 ± 5.09 mV, confirmed by scanning electron microscopy (SEM) and Zetasizer analysis. Encapsulation efficiency (EE) and loading capacity (LC) of nisin were 87.60% ± 0.43% and 1.99% ± 0.01%, respectively. In vitro release studies over 48 h indicated a controlled release pattern of nisin, described by the Korsmeyer-Peppas model, with higher release rates at 37°C and alkaline pH. Antimicrobial assays showed an enhanced efficacy of nisin-loaded CS/SA microspheres compared to free nisin, with minimum inhibitory concentration values reduced by 50%. Confocal laser scanning microscopy (CLSM), SEM, and transmission electron microscopy showed significant bacterial membrane damage and cellular disruption induced by the microspheres.

CONCLUSIONS

This study highlights the potential of nisin-loaded CS/SA microspheres as an innovative antimicrobial delivery system with improved stability and antimicrobial efficacy against S. aureus, addressing limitations associated with nisin applied alone.

Synthesis and Characterization of a Novel Chitosan-Based Nanoparticle-Hydrogel Composite System Promising for Skin Wound Drug Delivery

As a natural preservative, nisin is widely used in the food industry, while its application in biomedicine is limited due to its susceptibility to interference from external conditions. In this study, a nanoparticle-hydrogel composite system was designed to encapsulate and release nisin. Nisin nanoparticles were identified with a smooth, spherical visual morphology, particle size of 122.72 ± 4.88 nm, polydispersity coefficient of 0.473 ± 0.063, and zeta potential of 23.89 ± 0.37 mV. Based on the sample state and critical properties, three temperature-sensitive hydrogels based on chitosan were ultimately chosen with a rapid gelation time of 112 s, outstanding reticular structure, and optimal swelling ratio of 239.05 ± 7.15%. The composite system exhibited the same antibacterial properties as nisin, demonstrated by the composite system's inhibition zone diameter of 17.06 ± 0.83 mm, compared to 20.20 ± 0.58 mm for nisin, which was attributed to the prolonged release effect of the hydrogel at the appropriate temperature. The composite system also demonstrated good biocompatibility and safety, making it suitable for application as short-term wound dressings in biomedicine due to its low hemolysis rate of less than 2%. In summary, our nanoparticle-based hydrogel composite system offers a novel application form of nisin while ensuring its stability, thereby deepening and broadening the employment of nisin.

Formulation and Evaluation of Polysaccharide Microparticles for the Controlled Release of Propranolol Hydrochloride

Propranolol hydrochloride, a non-cardio-selective beta blocker, is used to treat several conditions in children, including hypertension, arrhythmias, hyperthyroidism, hemangiomas, etc. Commercial liquid formulations are available in Europe and the US, but they have disadvantages, such as limited stability, bitter taste, and the need for multiple daily doses due to the drug's short half-life. Considering these limitations, controlled-release solid formulations, such as microparticles, may offer a better solution for pediatric administration. The main objective of this study was to formulate an encapsulation system for propranolol hydrochloride, based on sodium alginate and other polysaccharide polymers, to control and prolong its release. Microparticles were prepared using the ionotropic gelation method, which involves instilling a polymer solution into a solution of gelling ions via the extrusion technique. Physicochemical characterization was conducted by assessing the entrapment efficiency, drug loading, swelling index, microparticle size, rheological properties, and surface tension. In order to improve the characteristics of the tested microparticles, selected formulations were coated with chitosan. Further experimental work included differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) analysis, and SEM imaging. This in vitro release study showed that chitosan-coated microparticles demonstrate favorable properties, suggesting a novel approach to formulating pediatric dosage forms, although further optimization is necessary.

Bacterial nanocellulose loaded with bromelain and nisin as a promising bioactive material for wound debridement

The bacterial nanocellulose (BnC) membranes were produced extracellularly by a novel aerobic acetic acid bacterium Komagataeibacter melomenusus. The BnC was modified in situ by adding carboxymethyl cellulose (CMC) into the culture media, obtaining a BnC-CMC product with denser fibril arrangement, improved rehydration ratio and elasticity in comparison to BnC. The proteolytic enzyme bromelain (Br) and antimicrobial peptide nisin (N) were immobilized to BnC matrix by ex situ covalent binding and/or adsorption. The optimal Br immobilization conditions towards the maximized specific proteolytic activity were investigated by response surface methodology as factor variables. At optimal conditions, i.e., 8.8 mg/mL CMC and 10 mg/mL Br, hyperactivation of the enzyme was achieved, leading to the specific proteolytic activity of 2.3 U/mg and immobilization efficiency of 39.1 %. The antimicrobial activity was observed against Gram-positive bacteria (S. epidermidis, S. aureus and E. faecalis) for membranes with immobilized N and was superior when in situ modified BnC membranes were used. N immobilized on the BnC or BnC-CMC membranes was cytocompatible and did not cause changes in normal human dermal fibroblast cell morphology. BnC membranes perform as an efficient carrier for Br or N immobilization, holding promise in wound debridement and providing antimicrobial action against Gram-positive bacteria, respectively.

Characterization and In-vitro Study of Micro-encapsulation Chitosan Alginate of Single-bulb Garlic Extract

BACKGROUND

Single-bulb garlic extract (SBGE) contains more active compounds than regular garlic, but it is unstable and easily degraded in the digestive tract. SBGE is expected to be protected by microencapsulation chitosan-alginate (MCA).

OBJECTIVE

The present study aimed to characterize and assess the antioxidant activity, hemocompatibility, and toxicity of MCA-SBGE in 3T3-L1 cells.

METHODS

The research procedures consist of extraction of single bulb garlic, preparation of MCASBGE, Particle Size Analyzer (PSA), FTIR analysis, DPPH assay, hemocompatibility test, and MTT assay.

RESULTS

The average size of MCA-SGBE was 423.7 ± 2.8 nm, the polydispersity index (PdI) was 0.446 ± 0.022, and the zeta potential was -24.5 ± 0.4 mV. MCA-SGBE was spherical with a diameter range of 0.65-0.9 μm. A shift in absorption and addition of functional groups was found in SBGE after encapsulation. MCA-SBGE, at a concentration of 24 x 103 ppm, has higher antioxidants than SBGE. The hemocompatibility test shows the hemolysis of MCA-SBGE lower than SBGE. MCA-SBGE was not toxic to 3T3-L1 cells with cell viability percentage above 100% at all concentrations.

CONCLUSION

MCA-SBGE characterization has microparticle criteria with homogeneous PdI values, low particle stability, and spherical morphology. The results showed that SBGE and MCA-SBGE are nonhemolytic, compatible with red blood cells, and non-toxic to 3T3-L1 cells.

Alginate Nanoencapsulated Synbiotic Composite of Pomegranate Peel Phytogenics and Multi-Probiotic Species as a Potential Feed Additive: Physicochemical, Antioxidant, and Antimicrobial Activities

A synbiotic composed of alginate nanoencapsulated prebiotic (pomegranate peel phytogenics) and multi-species probiotics (Lactococcus lactis, Lactobacillus plantarum, Lactobacillus paracasei, and Saccharomyces cerevisiae) has been developed as a potential eco-friendly alternative to antibiotics. The physicochemical properties of the encapsulated synbiotic were evaluated, and its gastric and storage tolerance, as well as its antioxidant and antimicrobial activity, were tested and compared to that of the non-encapsulated synbiotic (free synbiotic). The results showed that the prebiotic pomegranate peel ethanolic extract contained seven phenolic compounds, with cinnamic being the most abundant (13.26 µL/mL). Sodium alginate-CaCl2 nanocapsules were effective in encapsulating 84.06 ± 1.5% of the prebiotic's phenolic compounds and 98.85 ± 0.57% of the probiotics. The particle size of the alginate-CaCl2 nanoencapsulated synbiotic was 544.5 nm, and the polydispersity index and zeta potential values were 0.593 and -12.3 mV, respectively. Thermogravimetric analysis showed that the alginate-CaCl2 nanoencapsulated synbiotic had high thermal stability at high temperatures, with only 2.31% of its weight being lost within the temperature range of 70-100 °C. The count of viable probiotics in the nanoencapsulated synbiotic was significantly higher than that in the free synbiotic after exposure to gastric acidity and storage for six months at room temperature. The percent inhibition values of the nanoencapsulated synbiotic and ascorbic acid (as a standard antioxidant) were comparable and significantly greater than those of the free synbiotic. The half-maximal inhibitory concentrations (IC50) of the nanoencapsulated synbiotic and ascorbic acid were significantly lower than those of the free synbiotic (3.96 ± 0.42 µg/mL and 4.08 ± 0.79 µg/mL for nanoencapsulated synbiotic and ascorbic acid, respectively, vs. 65.75 ± 2.14 µg/mL for free synbiotic). The nanoencapsulated synbiotic showed the highest significant antimicrobial activity against Escherichia coli (ATCC 8739). Both the nanoencapsulated and free synbiotics showed antimicrobial activity against Staphylococcus aureus (ATCC 6538), similar to that of gentamicin, although the nanoencapsulated synbiotic showed significantly higher inhibition activity compared to the free synbiotic. The nanoencapsulated synbiotic showed antimicrobial activity comparable to gentamicin against Pseudomonas aeruginosa (ATCC 90274), whereas the free synbiotic showed the least antimicrobial activity (p < 0.05). Both synbiotics showed significantly higher antimicrobial activity against Salmonella typhi (ATCC 6539) than gentamicin. Both synbiotics showed antifungal activity against Aspergillus niger and Aspergillus flavus, with a stronger effect observed for the nanoencapsulated synbiotic. However, the activity of both synbiotics was significantly lower than that of fluconazole (an antifungal drug).

Protein Transduction System Based on Tryptophan-zipper against Intracellular Infections via Inhibiting Ferroptosis of Macrophages

Cells penetrating molecules in living systems hold promise of capturing and eliminating threats and damage that can plan intracellular fate promptly. However, it remains challenging to construct cell penetration systems that are physiologically stable with predictable self-assembly behavior and well-defined mechanisms. In this study, we develop a core-shell nanoparticle using a hyaluronic acid (HA)-coated protein transduction domain (PTD) derived from the human immunodeficiency virus (HIV). This nanoparticle can encapsulate pathogens, transporting the PTD into macrophages via lipid rafts. PTD forms hydrogen bonds with the components of the membrane through TAT, which has a high density of positive charges and reduces the degree of membrane order through Tryptophan (Trp)-zipper binding to the acyl tails of phospholipid molecules. HA-encapsulated PTD increases the resistance to trypsin and proteinase K, thereby penetrating macrophages and eliminating intracellular infections. Interestingly, the nonagglutination mechanism of PTD against pathogens ensures the safe operation of the cellular system. Importantly, PTD can activate the critical pathway of antiferroptosis in macrophages against pathogen infection. The nanoparticles developed in this study demonstrate safety and efficacy against Gram-negative and Gram-positive pathogens in three animal models. Overall, this work highlights the effectiveness of the PTD nanoparticle in encapsulating pathogens and provides a paradigm for transduction systems-anti-intracellular infection therapy.

Preparation and Characteristics of Alginate Microparticles for Food, Pharmaceutical and Cosmetic Applications

Alginates are the most widely used natural polymers in the pharmaceutical, food and cosmetic industries. Usually, they are applied as a thickening, gel-forming and stabilizing agent. Moreover, the alginate-based formulations such as matrices, membranes, nanospheres or microcapsules are often used as delivery systems. Alginate microparticles (AMP) are biocompatible, biodegradable and nontoxic carriers, applied to encapsulate hydrophilic active substances, including probiotics. Here, we report the methods most frequently used for AMP production and encapsulation of different actives. The technological parameters important in the process of AMP preparation, such as alginate concentration, the type and concentration of other reagents (cross-linking agents, oils, emulsifiers and pH regulators), agitation speed or cross-linking time, are reviewed. Furthermore, the advantages and disadvantages of alginate microparticles as delivery systems are discussed, and an overview of the active ingredients enclosed in the alginate carriers are presented.

Nisin and nisin-loaded nanoparticles: a cytotoxicity investigation

OBJECTIVE

Nisin is an antibacterial peptide with anticancer properties, but the main drawback is its rapid enzymatic degradation and limited permeation across the cell membrane. This research aims to to overcome these drawbacks by developing nisin-loaded nanoparticles with improved cytotoxic effects.

SIGNIFICANCE

PLGA nanoparticles are one of the most effective biodegradable and biocompatible drug delivery carriers. In the present study, nisin-loaded nanoparticles showed enhanced anticancer effects.

METHODS

NPN was prepared by a double emulsion solvent evaporation method and characterized for different parameters. The cytotoxic investigation of NPN was carried out on various cell lines, including A549, SW-620, HT-29, PC-3, MDA-MB-231, MCF-7, MiaPaca-2, and fR2 by sulforhodamine B (SRB) assay. Mechanistic investigation of cellular cytotoxicity was performed by using bright-field microscopy, DAPI staining, intracellular reactive oxygen species (ROS), changes in mitochondrial membrane potential (ΔΨm), and western blotting. A comparative cytotoxicity study of nisin and NPN was performed on normal breast epithelial cells (fR-2).

RESULTS

NPN showed spherical shape, 289.09 ± 3.63 nm particle size, and 63.37 ± 3.12% entrapment efficiency. NPN was more cytotoxic to the MDA-MB-231 cell line, showing higher nuclear fragmentation, ROS generation, and depletion of ΔΨm like apoptosis signs compared to nisin and with no cytotoxicity on normal cells.

CONCLUSIONS

The findings suggest that nisin delivery via PLGA nanoparticles can be used to treat cancer without significant effects on healthy cells.

Preparation and Characterization of Methyl Jasmonate Microcapsules and Their Preserving Effects on Postharvest Potato Tuber

Potato tubers tend to sprout during long-term storage, resulting in quality deterioration and shortened shelf life. Restrictions on the use of chlorpropham, the major potato sprout suppressant, have led to a need to seek alternative methods. In this study, the effects of methyl jasmonate (MeJA) solutions and MeJA microcapsules on sprouting and other key quality attributes of the potato tuber were investigated. The results showed that the MeJA solution was most effective at 300 μmol L⁻¹ according to TOPSIS analysis. To prepare MeJA microcapsules, the optimal formulation is with 0.04% emulsifier, 2.5% sodium alginate, 0.5% chitosan and 3% CaCl₂. Compared to 300 μmol L⁻¹ MeJA solution, MeJA microcapsules consumed a lower dose of MeJA but demonstrated a better retaining effect on the overall quality attributes of potato tubers. MeJA microcapsules are promising agents for the preservation of postharvest potato tubers.

Protein-based natural antibacterial materials and their applications in food preservation

Plastics materials used for food packaging are recalcitrant, leading to a growing global environmental problem, which arouses the attention of environmental protection departments in many countries. Therefore, to meet the increasing demand for sustainable and environment-friendly consumer products, it is necessary for the food industry to develop natural antibacterial materials for food preservation. This review summarizes the common biodegradable natural antimicrobial agents and their applications in food preservation; as well as an overview of five commonly used biodegradable protein-based polymers, such as zein, soy protein isolate, gelatin and whey protein, with special emphasis on the advantages of protein-based biopolymers and their applications in food packaging industry.

Bromelain and Nisin: The Natural Antimicrobials with High Potential in Biomedicine

Infectious diseases along with various cancer types are among the most significant public health problems and the leading cause of death worldwide. The situation has become even more complex with the rapid development of multidrug-resistant microorganisms. New drugs are urgently needed to curb the increasing spread of diseases in humans and livestock. Promising candidates are natural antimicrobial peptides produced by bacteria, and therapeutic enzymes, extracted from medicinal plants. This review highlights the structure and properties of plant origin bromelain and antimicrobial peptide nisin, along with their mechanism of action, the immobilization strategies, and recent applications in the field of biomedicine. Future perspectives towards the commercialization of new biomedical products, including these important bioactive compounds, have been highlighted.

Composites Based on Gellan Gum, Alginate and Nisin-Enriched Lipid Nanoparticles for the Treatment of Infected Wounds

Due to growing antimicrobial resistance to antibiotics, novel methods of treatment of infected wounds are being searched for. The aim of this research was to develop a composite wound dressing based on natural polysaccharides, i.e., gellan gum (GG) and a mixture of GG and alginate (GG/Alg), containing lipid nanoparticles loaded with antibacterial peptide-nisin (NSN). NSN-loaded stearic acid-based nanoparticles (NP_NSN) were spherical with an average particle size of around 300 nm and were cytocompatible with L929 fibroblasts for up to 500 µg/mL. GG and GG/Alg sponges containing either free NSN (GG + NSN and GG/Alg + NSN) or NP_NSN (GG + NP_NSN and GG/Alg + NP_NSN) were highly porous with a high swelling capacity (swelling ratio above 2000%). Encapsulation of NSN within lipid nanoparticles significantly slowed down NSN release from GG-based samples for up to 24 h (as compared to GG + NSN). The most effective antimicrobial activity against Gram-positive Streptococcus pyogenes was observed for GG + NP_NSN, while in GG/Alg it was decreased by interactions between NSN and Alg, leading to NSN retention within the hydrogel matrix. All materials, except GG/Alg + NP_NSN, were cytocompatible with L929 fibroblasts and did not cause an observable delay in wound healing. We believe that the developed materials are promising for wound healing application and the treatment of bacterial infections in wounds.

The Layered Encapsulation of Vitamin B2 and β-Carotene in Multilayer Alginate/Chitosan Gel Microspheres: Improving the Bioaccessibility of Vitamin B2 and β-Carotene

This research underlines the potential of alginate multilayered gel microspheres for the layered encapsulation and the simultaneous delivery of vitamin B₂ (VB) and β-carotene (BC). Chitosan was used to improve the stability and controlled release ability of alginate-based gel microspheres. It was shown that a clear multilayered structure possessed the characteristics of pH response, and excellent thermal stability. The sodium alginate concentration and the number of layers had notable effects on mechanical properties and particle size of gel microspheres. Fourier-transform infrared spectroscopy and X-ray diffraction analyses further proved that VB and BC were encapsulated within the gel microspheres. Compared with the three-layer VB-loaded gel microspheres, the total release of VB from the three-layer VB and BC-loaded gel decreased from 93.23% to 85.58%. The total release of BC from the three-layer VB and BC-loaded gel increased from 66.11% to 69.24% compared with three-layer BC-loaded gel. The simultaneous encapsulation of VB and BC in multilayered gel microspheres can markedly improve their bioaccessibility and bioavailability. These results showed the multilayer gel microspheres synthesized herein have potential for applications in the layered encapsulation and simultaneous delivery of various bioactive substances to the intestinal tract.

Fabrication of Biomolecule-Covalent-Organic-Framework Composites as Responsive Platforms for Smart Regulation of Fermentation Application

Exploration of novel material platforms to protect biological preservatives and realize intelligent regulation during fermentation is of great significance in industry. Herein, we established an intelligent responsive platform by introducing antimicrobial biomolecules (nisin) into rationally designed covalent organic frameworks (COFs), resulting in a new type of "smart formulation", which could responsively inhibit microbial contamination and ensure the orderly progression of the fermentation process. The encapsulated biomolecules retained their activity while exhibiting enhanced stability and pH-responsive releasing process (100% bacteriostatic efficiency at a pH of 3), which can ingeniously adapt to the environmental variation during the fermentation process and smartly fulfill the regulation needs. Moreover, the nisin@COF composites would not affect the fermentation strains. This study will pave a new avenue for the preparation of highly efficient and intelligent antimicrobial agents for the regulation of the fermentation process and play valuable roles in the drive toward green and sustainable biomanufacturing.

Inhibition of Listeria monocytogenes growth in turkey fillets by alginate edible coating with Trachyspermum ammi essential oil nano-emulsion

The objective of this study was to determine the chemical composition and antibacterial activity of Trachyspermum ammi essential oil (TAEO). Moreover, the present study comparatively investigated TAEO in the forms of emulsion and Nano-emulsion in alginate-based edible coatings against inoculated Listeria monocytogenes in turkey fillets during 12 days in cold storage (at a temperature of 4 ± 1 °C). Alginate solutions with two levels of TAEO (in emulsion and Nano-emulsion forms) were prepared in this study. The bacterial count was performed on days 0, 1, 2, 4, 8, and 12. Based on the obtained results of the current study, a comparison of different treatments with the blank samples (without any coating) showed that the highest considerable result was observed in the samples with Nano-emulsion coating (P < 0.05). Nano-emulsion loaded alginate coating prevented the growth of listeria in turkey fillets even after 12 days of cold storage. According to the findings of this study, the application of alginate edible coatings containing TAEO, especially in Nano-form, can be very effective in controlling the growth of L. monocytogenes, as a foodborne pathogen, during storage; therefore, it is a good choice to be applied in the meat industry.

Elaboration and characterization of curcumin-loaded soy soluble polysaccharide (SSPS)-based nanocarriers mediated by antimicrobial peptide nisin

Curcumin was recently attracted great interest owing to its multiple bioactivities; however, the use of curcumin was hindered by its poor solubility and stability. In this study, curcumin-nisin-soy soluble polysaccharide nanoparticles (Cur-Nisin-SSPS-NPs, size = 118.76 nm) have been successfully elaborated to improve the application of curcumin. The formation of Cur-Nisin-SSPS-NPs was mediated by amphiphilic and positively charged nisin: SSPS encapsulated nisin, which was mainly driven by electrostatic attraction. And nisin-SSPS complex encapsulated curcumin mainly through hydrophobic interactions between nisin and curcumin. The encapsulation efficiency of curcumin (91.66%) in this novel nanocarriers was significantly higher than that in nanoparticles prepared by a single SSPS (31.82%) or nisin (41.69%), most likely because more hydrophobic regions of nisin were exposed after interacting with SSPS through electrostatic interaction. Consequently, this facile and green nanocarriers improved the solubility/dispersibility and stability of curcumin and nisin, as well as endowed SSPS-based nanoparticles with antioxidant and antimicrobial activities.

Ultrasound-Combined Sterilization Technology: An Effective Sterilization Technique Ensuring the Microbial Safety of Grape Juice and Significantly Improving Its Quality

: The effects of ultrasound (US), thermosonication (TS), ultrasound combined with nisin (USN), TS combined with nisin (TSN), and conventional thermal sterilization (CTS) treatments on the inactivation of microorganisms in grape juice were evaluated. TS, TSN, and CTS treatments provided the desirable bactericidal and enzyme inactivation, and nisin had a synergistic lethal effect on aerobic bacteria in grape juice while not having any obvious effect on the mold and yeast. Compared with CTS, the sensory characteristics of grape juice treated with TS and TSN are closer to that of fresh juice, its microbial safety is ensured, and the physicochemical properties are basically unchanged. More importantly, the total phenolic content and antioxidant capacity of juice treated with TS and TSN were significantly increased, and the total anthocyanin and flavonoid contents were largely retained. Taken together, these findings suggest that TS and TSN has great potential application value and that it can ensure microbial safety and improve the quality of grape juice.

Preparation and characterization of gellan gum-guar gum blend films incorporated with nisin

Demand for antimicrobial packaging films is growing due to public attention to food safety. The structures and properties of gellan gum-guar gum blend films incorporated with nisin were investigated in this paper. Fourier transform infrared spectroscopy, rheological analyses showed intermolecular interactions among gellan gum, guar gum, and nisin. Furthermore, scanning electron microscopy and thermogravimetric analysis also indicated higher compatibility of the blend film components and better thermal stability than the gellan gum film. Tensile strength (TS), elongation at break (EAB) and water vapor permeability (WVP) of the blend films were enhanced with the addition of guar gum. The TS of the blend film reached 2.89 × 10³  MPa, the EAB increased to 67.99%, and the WVP increased to 1.80 × 10^-5  g/mm·s·Pa. Additionally, the film with nisin had antibacterial activity for Bacillus subtilis. The results demonstrated that a homogenous and smooth antimicrobial film with gellan gum, guar gum, and nisin could be a good option of antimicrobial packaging film for food preservation. PRACTICAL APPLICATION: This work investigated blend package films of gellan gum and guar gum incorporated with nisin. The results showed compatibility and thermal stability of the film were improved with adding a certain amount of guar gum, and also antibacterial activity for Bacillus subtilis of the blend film with nisin. Therefore, it can be used to the development of antimicrobial packaging films.

Designing soluble soybean polysaccharides-based nanoparticles to improve sustained antimicrobial activity of nisin

Nisin is a natural antimicrobial agent and food-grade material, while the poor stability and short duration of antimicrobial activity limit its widespread use in the food industry. In the present work, soluble soybean polysaccharide (SSPS)-based nanoparticles have been developed to improve the stability and sustained antimicrobial activity of nisin. The encapsulation efficiency (EE) of nisin-loaded SSPS nanoparticles (Nisin-SSPS-NPs) prepared under the optimized conditions can be up to 99.8%, and the particle size is about 112 nm. The formation of Nisin-SSPS-NPs was mainly mediated by the electrostatic interactions and hydrogen bonding, which was evidenced by the results of zeta potential and Fourier Transform infrared spectroscopy (FTIR). Agar diffusion assay exhibited that Nisin-SSPS-NPs had confirmed antimicrobial activity against Gram-positive bacteria, such as Listeria monocytogenes, Bacillus subtilis, and Staphylococcus aureus. The sustained release of nisin in Nisin-SSPS-NPs endows nisin with a long-lasting antimicrobial activity, which increases the shelf-life of the fresh tomato juice.

Using drug-loaded pH-responsive poly(4-vinylpyridine) microspheres as a new strategy for intelligent controlling of Lactobacillus plantarum contamination in bioethanol fermentation

Bioethanol fermentation is usually contaminated by bacteria, especially lactic acid bacteria (LAB), thereby leading to decrease of bioethanol yield and serious economic losses. Nisin is safer for controlling of bacterial contamination than antibiotics that are widely applied in industry. Moreover, in LAB contaminative bioethanol fermentation system, consistently decreased pH value provides opportunity to realize pH value responsive material-based release of anti-bacteria substances for intelligent and persistent controlling of bacterial contamination. In this study, nisin was embedded into pH-sensitive poly(4-vinylpyridine) (P4VP) microspheres synthesized by suspension polymerization to realize intelligent controlling of Lactobacillus plantarum contamination in bioethanol fermentation. Chloramphenicol with the highest antimicrobial activity and excellent stability was chosen as the model drug to be embedded into P4VP microspheres to test the drug release behavior. The drug release curve of chloramphenicol-loaded P4VP microspheres showed sustained and pH-responsive release properties. The diameters of the microspheres ranged from 40 to 100 µm. The encapsulation efficiency of nisin into P4VP microspheres was 47.67% and the drug-loading capacity of nisin was 2.5%. Nisin-loaded P4VP microspheres were added into the simulated contaminative fermentation system, and successfully reversed the decline of bioethanol yield secondary to L. plantarum contamination. The results in this study indicated that L. plantarum contamination in bioethanol fermentation could be effectively controlled by nisin-loaded P4VP microspheres.

Sea Squirt Shell Protein and Polylactic Acid Laminated Films Containing Cinnamon Bark Essential Oil

Sea squirt (Halocynthia roretzi) shell protein (SSP) was used as a biodegradable film material and laminated with polylactic acid (PLA) to improve its physical and water barrier properties. Cinnamon bark oil (CBO) was incorporated into the SSP film as a bioactive material. After laminating with PLA, the tensile strength and elongation at break of the SSP film increased from 4.07 to 9.09 MPa and from 8.68 to 138.84%, respectively. In addition, water vapor permeability and water solubility decreased from 5.62 to 0.91 × 10^-9 g m/m² s Pa and from 42.17% to 23.93%, respectively. DSC results of the SSP films indicate that melting point temperature increased 140.05 to 163.52 °C by laminating PLA. The addition of 0.5%, 0.7%, and 1.0% CBO conferred the antimicrobial activity against four pathogenic bacteria to the SSP/PLA-laminated films. The SSP/PLA-laminated films containing CBO also had antioxidant activities. Therefore, the SSP/PLA-laminated films containing CBO are applicable as biodegradable packaging films.

PRACTICAL APPLICATION

Sea squirt shell has been discarded after the consumption of sea squirt, and sea squirt shell protein can be a base material for biodegradable films. In this study, sea squirt shell protein and polylactic acid laminated films containing cinnamon bark essential oil were developed. The developed films are promising environmentally-friendly alternatives for active packaging material.

Polyelectrolyte Multicomponent Colloidosomes Loaded with Nisin Z for Enhanced Antimicrobial Activity against Foodborne Resistant Pathogens

Food grade micro- or nano-carrier systems (NCS) are being developed to improve the controlled release of antimicrobial agents. To augment the stability of liposomal NCS and to overcome the limitations associated with the use of free bacteriocin (nisin) in the food system, multi-component colloidosomes (MCCS) were developed by electrostatic interactions between anionic alginate and cationic chitosan (multilayer) around phospholipids based liposomes (core). Zeta-sizer results revealed the average diameter of 145 ± 2 nm, 596 ± 3 nm, and 643 ± 5 nm for nano-liposome (NL), chitosomes (chitosan coated NL) and MCCS, respectively. Zeta potential values of NCS varied from −4.37 ± 0.16 mV to 33.3 ± 6 mV, thus both chitosomes (CS) and MCCS were positively charged. Microstructure analysis by scanning electron microscope (SEM) revealed relatively higher size of MCCS with smooth and round morphology. TGA and DSC based experiments revealed that MCCS were thermally more stable than uncoated liposomes. Encapsulation efficiency of nisin in MCCS was observed to be 82.9 ± 4.1%, which was significantly higher than NL (56.5 ± 2.5%). FTIR analyses confirmed the cross-linking between sodium alginate and chitosan layer. Both qualitative (growth kinetics) and quantitative (colony forming unit) antimicrobial assays revealed that nisin loaded MCCS have superior potential to control resistant foodborne pathogens including Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis, (5.8, 5.4, and 6.1 Log CFUmL⁻¹ reduction, respectively) as compared to free nisin, loaded NL or CS. Controlled release kinetics data fitted with Korsmeyer–Peppas model suggested that nisin release from MCCS followed Fickian diffusion. Cytotoxic studies on human blood cells and HepG2 cell lines revealed hemocompatibility and non-toxicity of MCCS. Thus, due to enhanced controlled release, stability and biocompatibility; these multi-component colloidosomes can be useful for incorporating antimicrobial agents into functional foods, beverages and pharmaceutical products to combat pathogenic and spoilage bacteria.