肽聚糖水解酶基因缺失对解淀粉芽胞杆菌活菌数量及产碱性蛋白酶的影响

Effects of deleting peptidoglycan hydrolase genes on the viable cell counts of Bacillus amyloliquefaciens and the yield of alkaline protease

摘要:

为了探究肽聚糖水解酶对解淀粉芽胞杆菌(Bacillus amyloliquefaciens)活细胞数量以及碱性蛋白酶产量的影响,对解淀粉芽胞杆菌TCCC111018中的5个肽聚糖水解酶基因(lytC、lytD、lytE、lytF、lytG)分别进行敲除。通过分析对比基因缺失前后的生物量以及碱性蛋白酶酶活力发现,敲除菌株BA ΔlytC、BA ΔlytE在60 h的活菌数分别达到1.67×10⁶ CFU/mL、1.44×10⁶ CFU/mL,分别高出对照菌株BA Δupp32.5%、14.3%;其碱性蛋白酶酶活力分别为20 264 U/mL、17 265 U/mL,比对照菌株分别提高了43.1%、27.3%。该结果表明肽聚糖水解酶的缺失可以有效维持解淀粉芽胞杆菌活细胞数量和提高碱性蛋白酶的酶活力,为进一步构建工业酶生产宿主提供了新的思路和研究策略。

Abstract:

In order to explore the effect of peptidoglycan hydrolase on the viable cell counts of Bacillus amyloliquefaciens and the yield of alkaline protease,five peptidoglycan hydrolase genes (lytC,lytD,lytE,lytF and lytG) of B.amyloliquefaciens TCCC111018 were knocked out individually.The viable cell counts of the bacteria and their alkaline protease activities before and after gene deletion were determined.The viable cell counts of the knockout mutants BA ΔlytC and BA ΔlytE achieved 1.67×10⁶ CFU/mL and 1.44×10⁶ CFU/mL respectively after cultivation for 60 h,which were 32.5% and 14.3% higher than that of the control strain BA Δupp.Their alkaline protease activities reached 20 264 U/mL and 17 265 U/mL,respectively,which were 43.1% and 27.3% higher than that of the control strain.The results showed that deleting some of the peptidoglycan hydrolase genes effectively maintained the viable cell counts of bacteria and increased the activity of extracellular enzymes,which may provide a new idea for optimization of the microbial host for production of industrial enzymes.