# Valorisation of acid whey permeate for high-purity nisin Z production using artisanal Lactococcus lactis isolates

## TL;DR

This study explores using acid whey permeate to produce high-purity nisin Z with artisanal Lactococcus lactis isolates.

## Contribution

A cost-effective, circular method for high-purity nisin Z production from dairy byproducts using artisanal isolates.

## Key findings

- Strain IM 145 produced up to 51,200 BA/mL of nisin in PUFAW with yeast extract.
- Purified nisin Z achieved 79.2% chromatographic purity via ammonium sulphate and RP-HPLC.
- Tricine-SDS-PAGE and mass spectrometry confirmed the identity of the purified nisin Z.

## Abstract

The growing demand for sustainable bioprocessing has positioned whey, a side stream of the dairy industry, as a valuable substrate for producing high-value compounds. This study investigated the production and purification of nisin, a potent lantibiotic, using permeate (10 kDa cut-off) of ultrafiltered acid whey (PUFAW) devoid of lactoferrin as growth medium. Three strains of Lactococcus lactis subsp. lactis, including two artisanal isolates (IM 143 and IM 145) and a reference strain (IM 407), were evaluated for nisin production in PUFAW supplemented with yeast extract (YE) and mineral salts. Strain IM 145 showed superior growth and antimicrobial activity in PUFAW with YE (30 g/L) and produced up to 51,200 BA/mL of nisin. The bacteriocin was purified by ammonium sulphate precipitation followed by preparative RP-HPLC, yielding a product with 79.2% chromatographic purity. Tricine-SDS-PAGE and mass spectrometry confirmed the identity of the purified compound as nisin Z. This study presents a cost-effective, circular economy approach for the production of high-purity nisin from dairy side streams, with potential applications in food preservation and biomedicine.

The online version contains supplementary material available at 10.1186/s12866-025-04543-x.