Enhance nisin yield via improving acid-tolerant capability of Lactococcus lactis F44.

ABSTRACT: Traditionally, nisin was produced industrially by using Lactococcus lactis in the neutral fermentation process. However, nisin showed higher activity in the acidic environment. How to balance the pH value for bacterial normal growth and nisin activity might be the key problem. In this study, 17 acid-tolerant genes and 6 lactic acid synthetic genes were introduced in L. lactis F44, respectively. Comparing to the 2810 IU/mL nisin yield of the original strain F44, the nisin titer of the engineered strains over-expressing hdeAB, ldh and murG, increased to 3850, 3979 and 4377 IU/mL, respectively. These engineered strains showed more stable intracellular pH value during the fermentation process. Improvement of lactate production could partly provide the extra energy for the expression of acid to

SUBMITTER: Zhang J 

PROVIDER: S-EPMC4910042 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature