Characterization of the structural gene encoding nisin F, a new lantibiotic produced by a Lactococcus lactis subsp. lactis isolate from freshwater catfish (Clarias gariepinus)

Abstract

Lactococcus lactis F10, isolated from freshwater catfish, produces a bacteriocin (BacF) active against Staphylococcus aureus, Staphylococcus carnosus, Lactobacillus curvatus, Lactobacillus plantarum, and Lactobacillus reuteri. The operon encoding BacF is located on a plasmid. Sequencing of the structural gene revealed no homology to other nisin genes. Nisin F is described.

FIG. 1.

Separation of partially purified nisin F by SDS-polyacrylamide gel electrophoresis. Lane 1, rainbow low-range protein size marker RPN755 (Amersham International, United Kingdom); lane 2, protein band representing nisin F (arrow); lane 3, inhibition of S. aureus K (arrow), embedded in BHI soft agar (1%).

FIG. 2.

Amino acid sequences of nisin F, deduced from the DNA sequence (GenBank accession number EU057979) and compared to the amino acid sequences of nisin A, nisin Z, and nisin Q. The leader peptide of each nisin variant consists of 13 amino acids (from position −13 to −1), followed by amino acids encoding the mature protein (amino acid positions 1 to 34). Differences in amino acids are indicated by letters with a black background.