[Conditions for nisin adsorption by Streptococcus lactis cells].

Some conditions for absorption of nisin, a polypeptide antibiotic by the cells of Str. lactis were studied. The amounts of nisin adsorbed by the cells depended on the culture age: at the late stationary phase the adsorption level was 2 times higher than that at the logarithmic phase. The cells grown on a "poor" medium adsorbed 85-90 per cent of nisin added to the solution, while the cells grown on the "rich" medium adsorbed 50 per cent of the antibiotic. The adsorption level of nisin by the cells subjected to a thermal shock was higher than that by the live cells. Desorption of nisin from the cells with acid ethanol and bivalent cation solutions was insignificant. Nisin is adsorbed by the cells of other microorganisms, the adsorption levels by the cells of Bac. brevis being the same as those by the streptococcal cells, while the levels adsorbed by Bac. polymyxa being 4 times lower.