Enhance the antibacterial activity of Nisin

Nisin is a small peptide synthesized and secreted by Lactococcus lactis during metabolism, composed of 34 amino acids with strong bactericidal effects, effectively inhibiting the growth of Gram-positive bacteria. The following focuses on genetic engineering modification of Nisin and enhancement of its antibacterial activity:

I. Genetic Engineering Modification Methods

1. Increasing Copy Number of Key Genes

Nisin synthesis is completed by a 14kb gene cluster (nisABTCIPRKFEG) on the Lactococcus lactis genome. Studies show that increasing the copy number of key genes involved in Nisin synthesis in producing strains enhances Nisin biosynthesis. For example, Stein et al. introduced a recombinant vector containing nisi into wild-type Lactococcus lactis, increasing Nisin yield by 20%.

2. Gene Tandem Technology

This technology directionally links target genes for expressing small peptides under the control of a recombinant vector promoter. Research has used this to tandem nisa (the precursor gene controlling Nisin synthesis), constructing high-yield recombinant expression vectors and strains, thereby improving Nisin protein expression. Compared with conventional single-gene recombinant Lactococcus lactis strains, this method increases Nisin gene transcription. The extracted/purified Nisin protein is simple—high-purity Nisin can be obtained via one-step AKTA Pure method. Additionally, tandem nisa enhances Nisin tolerance in producing strains, reducing growth inhibition by Nisin during fermentation.

3. Constructing High-Efficiency Secretory Engineered Strains

An invention introduced nisa, nisi, and nisRK into Lactococcus lactis CICC6242 via single transformation, obtaining new genetically engineered strains. These strains increase Nisin yield to the ten-thousand-level production scale, making industrial production and capacity expansion promising. This technology successfully introduces related genes into Lactococcus lactis via single transformation, requiring minimal transformation workload and easy recombinant strain cultivation—applying to industrial scale-up will significantly reduce production costs.

II. Effects of Enhanced Antibacterial Activity

Genetic engineering modification significantly enhances Nisin’s antibacterial activity. For example, the high-yield Lactococcus lactis recombinant strain constructed by gene tandem technology expresses Nisin in a tandem form, with experimental results showing that the tandem form has stronger bacteriostatic effects than the monomer. The genetically engineered strain for high-efficiency Nisin secretion constructed by single transformation exhibits strong bacteriostatic activity against Staphylococcus aureus and Micrococcus luteus.

These modified Nisins have broader application prospects in food preservation, medicine, and other industries: they more effectively inhibit harmful bacteria, ensure food safety and quality, and assist in treating related bacterial infections in the medical field.