Nisin is a small-molecule polypeptide, synthesized and secreted by Lactococcus lactis subsp. lactis during metabolism. It possesses antimicrobial activity against a wide range of Gram-positive bacteria, including Clostridium botulinum, Staphylococcus aureus, Streptococcus haemolyticus, Listeria monocytogenes, Bacillus stearothermophilus, Bacillus subtilis and some others. In 1969, nisin was approved as a safe food additive by the Joint Food and Agriculture Organization/World Health Organization (FAO/WHO). Currently, it is licensed in over 50 countries, and has significantly impacted the food industry as a natural biopreservative for different types of foods, particularly in dairy products, canned foods, plant protein foods, juice, beer & related product, cured meat and processing of fermentation products. At normal levels of use, it does not affect the colour, odour or flavour of the finished product.
Figure 1. Nisin biosynthesis, regulation, and immunity. Field, Des, et al. After a century of nisin research-where are we now? FEMS microbiology reviews 47.3 (2023): fuad023.
Nisin (Cat# MFTP-114) is a natural antimicrobial peptide (bacteriocin) and widely used in food preservation due to its safety, efficacy, and clean-label appeal.
| Parameter | Details | Food Type | Function of Nisin | Maximum Usage (g/kg) |
|---|---|---|---|---|
| CAS No. | 1414-45-5 | Dairy (e.g., cheese, milk) | Prevents Clostridium, Listeria, spoilage bacteria | 0.5 |
| Molecular Weight | ~3.35 kDa | Canned foods | Prevents heat-resistant spore formers | 0.2 |
| Molecular Formula | C₁₄₃H₂₂₈N₄₂O₃₇S₇ | Meat and poultry | Controls Listeria monocytogenes | 0.5 |
| Structure | 34-amino acid lantibiotic with lanthionine rings | Beverages (low pH) | Controls lactic acid bacteria and spore formers | 0.2 |
| Appearance | Off-white to light yellow powder | Bakery (moist cakes) | Extends shelf life by inhibiting bacteria | 0.3 |
| Solubility | Soluble in water and dilute acids | Plant-based foods (Pickled vegetables) | Preserves freshness in vegan sauces and ready meals | 0.5 |
| Stability | Stable at low pH (2–5); heat-stable | Soy sauce & Compound condiments | High antimicrobial activity at nanomolar concentrations | 0.2 |
Activation of the strains
The primary bacteria cultivation
The secondary bacteria cultivation
Fermentation and cultivation
Filtration
Ultrafiltration concentration
Spray drying
Packaging
Storage
Food-grade nisin production process, focusing on microbial fermentation, downstream processing, and formulation, widely used in both industrial and research-scale production:
| Fermentation Process | Downstream Purification | ||
|---|---|---|---|
| Step | Details | Step | Method |
| Media Composition | Glucose/lactose, peptone/yeast extract, salts (e.g., NaCl, MgSO₄), vitamins | Cell Separation | Centrifugation or depth filtration |
| pH Control | Optimal at pH 6.5 initially, adjusted to pH 5–5.5 during nisin production | pH Adjustment | Adjust to ~2–3 to stabilize nisin and precipitate proteins |
| Temperature | 28–32 °C (optimal growth and production temperature) | Extraction | Acid precipitation, solvent extraction (e.g., isopropanol or ammonium sulfate) |
| Aeration | Microaerobic to anaerobic conditions | Concentration | Ultrafiltration or rotary evaporation |
| Fermentation Duration | ~16–24 hours | Purification | Ion exchange or reversed-phase chromatography (for high purity) |
| Induction | Some systems use self-induction or external signals for nisin synthesis | Drying | Spray drying or lyophilization to obtain powder form |
| Formulation | Quality Control | ||
|---|---|---|---|
| Product Form | Details | Parameter | Test |
| Powder (2.5–5% active) | Most common commercial form; standardized with NaCl or other carriers | Nisin activity (IU/mg) | Agar diffusion assay using Lactobacillus plantarum or Micrococcus luteus |
| Liquid solution | Sometimes offered for ready-to-use spray or beverage applications | Purity | HPLC or spectrophotometric analysis |
| Stabilizers | Sodium chloride, citric acid, phosphate buffer (optional for stability) | Moisture content | Karl Fischer or loss-on-drying |
| Regulatory Compliance | Microbial limits | Total count, yeast & mold, coliforms | |
| USA: GRAS-listed | EU: E234 (Max levels vary by product type) | Residual solvents | GC/MS (if solvents are used in purification) |
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