Stimulation of Nisin Production from Whey by a Mixed Culture of Lactococcus lactis and Saccharomyces cerevisiae

Abstract

L.lactis, a Gram-positive bacterium, grows on lactose or milk sugar and produces lactic acid as a byproduct. L.lactis also generates a non-toxic and antibacterial chemical called nisin which is often used as a natural food preservative. Therefore, a continuous growth of L.lactis is often desirable to increase the production of nisin. However, lactic acid accumulation lowers the pH of fermentation broth thus creates a non-sustainable environment for the growth of L.lactis. This research project aims to create a stress-free growth environment for L.lactis via in-situ removal of lactic acid. Saccharomyces cerevisiae or generally known as Baker’s yeast is used to consume lactic acid as a carbon source for metabolism activity.