Processing of byproducts to improve nisin production by <i>Lactococcus lactis</i>

Abstract

In the last years, disposal from dairy industries have received a special attention due its polluting power in the environment. For this reason, studies have obtained a positive support to develop different alternatives to recycle milk whey components. One of them is its utilization as culture media, aiming to produce biomolecules with noble applications. Nisin is an extracellular peptide, produced by Lactococcus lactis, this peptide has been applied as a natural additive once it presents broad antibacterial activity. Applications of this bacteriocin include dental care products, pharmaceutical products such as stomach ulcers and colon infection treatment and potential birth control. In batch cultures, L. lactis was performed in two different groups of assays. The first group milk whey was prepared in distilled water in four different concentrations: 100 g/l (S100); 50 g/l (S50); 30 g/l (S30); 10 g/l (S10). In the second group of assays, two supplements were added in milk whey with concentration 100 g/l (S100): (1) 5 g/l yeast extract (A1); (2) 5 g/l yeast extract and 10 ml (v/v) tomato extract. Nisin activity was assayed through agar diffusion utilizing Lactobacillus sakei. The results show that the utilization of powder milk whey with concentration of 100 g/l can be used as a culture medium with supplementation. This media is favorable to develop L. lactis cells and nisin production, reaching an activity of about 4 logAU. Biological processing of milk byproduct can be considered as one of the profitable utilization alternatives, generating high-value bioproducts and stimulates researches for its use.

Key words: Nisin, byproducts, Lactococcus lactis, batch culture, powder milk whey.