The aim of the study was to examine the possibility to use acid whey derived from fresh curd cheese as a substrate for the cultivation of lactic acid bacteria of Lactococcus (Lc.) lactis species producing bacteriocin nisin. By measuring the optical density at 630 nm we determined the growth of lactococci in BHI broth, autoclaved and microfiltered whey without supplements or supplemented with minerals and / or yeast extract (5 %), after 20 and 40 hours of incubation. In the culture supernatants we determined the antimicrobial activity against the indicator strain of Lactobacillus (L.) sakei subsp. sakei ATCC 15521. Selected lactococci strains were able to grow in acid whey depleted of proteins, and their growth and bacteriocin production was improved especially with the addition of yeast extract (5 %). We also monitored the stability of bacteriocins in the lyophilized culture supernatants, adjusted to pH 3 or 6, during 1-month storage at different temperatures (room temperature, 4 º C or – 20 º C). The antimicrobial activity of freeze-dried nisin was better preserved in acidic environment (pH = 3), while the storage temperature had no visible effect. The nisin from the culture supernatants was partially purified by precipitation with ammonium sulfate, concentrated by ultrafiltration and detected by SDS-PAGE electrophoresis, RP-HPLC and agar diffusion test, using an L. sakei subsp. sakei ATCC 15521 indicator strain.
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