Effects of temperature and trehalose on foam separation of nisin from the culture broth produced by Lactococcus lactis subspecies lactis W28.

Nisin is an antimicrobial peptide, an important biopreservative, and it is produced by certain strains of Lactococcus lactis ssp. lactis. In this paper, a foam separation technique was used for the separation of nisin from its culture broth, and the effects of temperature and trehalose on the performance of foam separation of nisin were studied to increase the enrichment ratio and recovery percentage of nisin and decrease the inactivity percentage of nisin. The results showed that temperature and trehalose significantly affected the performance of foam separation of nisin. Under the optimum conditions of 50°C temperature, 150-mL/min air flow rate, 400-mL initial loading liquid volume, and 1-g/L trehalose concentration, the maximum enrichment ratio, recovery percentage, and the minimum inactivity percentage of nisin reached 23.7, 84.1%, and 5.9%, respectively, which were, respectively, 5.04, 0.93, and 1.03 times more than those under the conditions of 20°C temperature, 150-mL/min air flow rate, 400-mL initial loading liquid volume, and no trehalose addition. These results indicated that the change of temperature and the addition of trehalose could improve the performance of foam separation of nisin.