Cascade pH Control in Antimicrobial Peptide, Nisin, Production Process, Utilizing a Mixed Culture System

摘要

In order to control pH in an antimicrobial peptide (nisin) production process by a lactic acid bacterium (LAB), Lactococcus lactis sbsp. lactis (ATCC11454), a novel method without alkaline addition and mechanistic separation system was developed,using interaction of L. lactis and another microorganism. A lactic acid assimilating yeast, Kulyveromyces marxianus was isolated from a fermentation food, kefir grains, and a mixed culture system with L. lactis and K. marxianus was developed. The kinetics of growth and production by both microorganisms were investigated in detail. The specific lactic acid consumption rate of K. marxianus was controlled by changing in the dissolved oxygen concentration (DO) and a cascade controller of pH and DO wasdeveloped. Lactic acid concentration was kept at low level and nisin was highly produced, comparing with the production processes without pH control and with pH control by alkaline addition.