Enhance nisin yield via improving acid-tolerant capability of Lactococcus lactis F44.
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 tolerance genes during growth. Co-overexpression of hdeAB, murG, and ldh(Z) in strain F44 resulted in the nisin titer of 4913 IU/mL. The engineered strain (ABGL) could grow on plates with pH 4.2, comparing to the surviving pH 4.6 of strain F44. The fed-batch fermentation showed nisin titer of the co-expression L. lactis strain could reach 5563 IU/mL with lower pH condition and longer cultivation time. This work provides a novel strategy of constructing robust strains for use in industry process.
Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.|Key Laboratory of Systems Bioengineering, Ministry of Education Tianjin, 300072, China.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China.
Jian
J
Zhang
Key Laboratory of Systems Bioengineering, Ministry of Education Tianjin, 300072, China.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China.
Qinggele
Q
Caiyin
Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.|Key Laboratory of Systems Bioengineering, Ministry of Education Tianjin, 300072, China.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China.
Wenjing
W
Feng
Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.|Key Laboratory of Systems Bioengineering, Ministry of Education Tianjin, 300072, China.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China.
Xiuli
X
Zhao
Key Laboratory of Systems Bioengineering, Ministry of Education Tianjin, 300072, China.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China.
Bin
B
Qiao
Key Laboratory of Systems Bioengineering, Ministry of Education Tianjin, 300072, China.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China.
Guangrong
G
Zhao
Department of Pharmaceutical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China.|Key Laboratory of Systems Bioengineering, Ministry of Education Tianjin, 300072, China.|SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering, Tianjin 300072, China.
Jianjun
J
Qiao
D000143:Acids / Q000633:toxicity*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000633:toxicity*; D004361:Drug Tolerance; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D013294:Lactococcus lactis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods; D050296:Microbial Viability / Q000187:drug effects; D009561:Nisin / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D000143:Acids; D000900:Anti-Bacterial Agents; D011994:Recombinant Proteins; D009561:Nisin