Development of a novel controller for antimicrobial nisin production, using interaction of microorganisms

点击翻译按钮获取中文摘要

In order to control pH in an antimicrobial peptide (nisin) production process by a lactic acid bacterium (LAB), Lactococcus lactis subsp. lactis (ATCC11454), a novel method was developed, in which neither addition of alkali nor a separation system such as ceramic membrane filter and electrodialyzer was adopted. A mixed culture of L. lactis with Kluyveromyces marxianus, which was isolated from kefir grains, was utilized in the developed system. Interaction between lactate production by L. lactis and its assimilation by K. marxianus was used to control the pH. In order to utilize microbial interaction to maintain high production of nisin, the kinetics of growth and production of lactate, acetate and nisin by L. lactis were investigated. Kinetics of growth and lactic acid consumption of K. marxianus were also investigated. Because pH level in the medium could be controlled by the lactate consumption of K. marxianus and the specific lactate consumption rate of K. marxianus could be controlled by changing the dissolved oxygen (DO) concentration, a cascade pH controller coupled with DO control was newly developed. As a result, pH and lactate were kept at low levels and nisin accumulated in the medium to a high level, compare with other pH control strategies such as processes without pH control and with pH control by addition of alkali.