Stability Of Nisin Research Articles

Preparation and antibacterial properties of high-methoxy pectin oligosaccharide -nisin nanoparticles

Nisin is a cationic polypeptide with high antibacterial activity. In different dosage forms, the immediate bacteriostatic effect of nisin was significantly reduced; and its antibacterial performance was easily affected by high temperature or non-acidic environment, which limited the widespread utilization of nisin. In order to improve the immediate bacteriostatic effect and the stability of nisin, nisin loaded high methoxy pectin oligosaccharide (HMPOS) nanoparticles were prepared by electrostatic self-assembly. Under the condition of mass ratio (HMPOS: nisin) 4:6 and pH 4.5, the particle size of nisin nanoparticles was 290–300 nm, and the encapsulation efficiency (EE%) was about 85 %. The analysis of particle size distribution, zeta potential, FT-IR, XRD and SEM suggested that nisin was successfully adsorbed on the surface of HMPOS. The isothermal adsorption results indicated that the combination of HMPOS and nisin was single-molecule layer adsorption. In addition, nisin nanoparticles had strong immediate bacteriostatic effect and good sustained release performance, and its release behavior belonged to Higuchi kinetic model.

Development of alkaline-stable nanoformulation of nisin: special insights through cytotoxic and antibacterial studies.

Nisin, a thermostable, approved food preservative, has limited therapeutic applications because of its high pH and proteolytic enzyme instability. The unavailability of a rapid, simple method of detection also restricts the research of nisin. The objective of this study was to adapt the simple, rapid protein estimation method of detection for nisin formulation and to formulate and evaluate site-specific nanoformulation for therapeutic applications, viz. colon cancer, and anti-bacterial action. Three nanoformulations of nisin with chitosan, gellan gum, and dextran (ECN, EGN, and EDN) were prepared and characterized in vitro. Among three, EGN was selected as a good formulation based on its size surface charge, morphology, drug loading, and release characteristics. FT-IR and DSC revealed the interaction pattern and stability nature. The stability of nisin in an alkaline environment was confirmed by CD. Its therapeutic applications were proved by efficiency against colon cancer cells evaluated by MTT assay and AO/EB staining using Caco-2 cell lines. The in situ sol-gel mechanism imparted by gellan gum was proved the sole reason for the stability and activity of nisin in EGN at lower GIT. This was confirmed (using rheometer) by shear-thickening characteristics of formulation EGN in simulated colon fluid. The antibacterial activity against Staphylococcus aureus by disk diffusion method was also performed to confirm the retention of antimicrobial activity of nisin in EGN. Hence, gellan gum-nisin colloidal nanoparticles are found good candidates for drug delivery at lower GIT and stabilizing alkaline food materials.

Nisin: Prerequisites and Prospects for Application in the Medical Field

Nisin is a typical representative of class I bacteriocins belonging to subtype A1 lantibiotics. This lantibiotic is produced by gram-positive bacteria of the genera Lactococcus, Streptococcus, Staphylococcus, and Blautia. Currently, at least twelve natural variants of nisin are known. They differ in some physicochemical properties and biological activity. Nisin is generally recognized as safe (GRAS) and has been used as a food additive for seven decades. The current review presents the data from scientific reports over the past decade supporting the value of this lantibiotic as a therapeutic agent. Most research works demonstrate a high inhibitory potential of nisin against antibiotic-resistant bacteria when using alone and in combination with antibiotics. A number of studies prove the ability of nisin to modulate the composition of oral and intestinal microbiomes, to inhibit the growth of both bacteria causing infectious processes and bacterial pathogens associated with cancer. Nisin has been shown to have its own antitumor potential and to be able to enhance the therapeutic effect of chemotherapeutic drugs. There is convincing evidence of its immunomodulatory and anti-inflammatory activity. The reasons limiting its widespread application in clinical practice can be successfully eliminated via modern bioengineering technologies that improve the functional characteristics and stability of nisin in various physiological conditions.

Production and stability of nisin in whey protein concentrate

The objective of this research was to manufacture nisin-containing whey protein concentrate (WPC) and study its stability during storage. Pasteurized reconstituted (6% w/v) sweet whey powder was used before or after ultrafiltration (UF) as a growth medium for nisin-producing strains of Lactococcus lactis subsp. lactis (ATCC 7962 or BS10). The fermented medium was freeze-dried, stored in polyethylene bags protected from light at 4 °C or 30 °C for 3 months. There was no difference in nisin yields by both strains between the regular and UF whey. Yeast extract supplementation resulted in an increase in nisin activity in UF whey fermented with BS10 and ATCC 7962 from 183 to 167 IU/ml to 1617 and 1667 IU/ml respectively. During storage at 4 °C for 1 month, the freeze dried WPC powder lost 55–60% of the nisin activity. At 30 °C for the same period, a 65–70% reduction in nisin activity was observed. Samples reconstituted at pH 2 and then boiled for 5 min increased nisin activity (P < 0.05). The present study presents WPC as an attractive, clean label ingredient with antimicrobial activities.

Assembly and stability of nisin-lipid II pores.

The peptide antibiotic nisin was the first reported example of an antibiotic that kills bacteria via targeted pore formation. The specific target of nisin is Lipid II, an essential intermediate in the bacterial cell-wall synthesis. High-affinity binding of the antibiotic to Lipid II is followed by rapid permeabilization of the membrane. Here, we investigated the assembly and stability of nisin-Lipid II pore complexes by means of pyrene fluorescence and circular dichroism. We demonstrated that nisin uses all available Lipid II molecules in the membrane to form pore complexes. The pore complexes have a uniform structure and consist of 8 nisin and 4 Lipid II molecules. Moreover, the pores displayed a remarkable stability, because they were able to resist the solubilization of the membrane environment by mild detergents. Similar experiments with [N20P/M21P]nisin showed that the hinge region is essential for the assembly into stable pore complexes. The new insights were used to propose a refined model for nisin pore formation.

Use of Nisin in Ice Cream and Effect on the Survival of Listeria monocytogenes

The survival characteristics of Listeria monocytogenes V7 were investigated in a full fat (10% fat) and reduced fat (3%) ice cream. The effect of nisin on the survival of Listeria monocytogenes in the ice creams was also evaluated. Ice cream mixes varying in composition were manufactured and inoculated with L. monocytogenes, passed through a “soft serve” freezer and then frozen at −18°C for up to 3 months. Samples were removed from storage throughout the three months, thawed, and then plated on Listeria-selective agar. In the samples that did not contain nisin, no reduction in the cell population was observed throughout manufacture and frozen storage. When nisin was present in the ice cream, a significant reduction in the cell population (P < .05) was observed. At the end of 3 months of frozen storage, no Listeria cells were detected in the 3% fat ice cream containing nisin. The effect of nisin on Listeria cells was decreased somewhat in the higher fat ice cream but this decrease was not significant over the 3 month storage. The stability of nisin in the ice cream remained constant throughout storage at −18°C.