Zhu Duolong, Zhao Kai, Xu Haijin, Bai Yanling, Zhang Xiuming, Qiao Mingqiang
Wei Sheng Wu Xue Bao. 2015 Apr 4;55(4):440-7.
To accelerate the formation of nisin through overexpressing 6-phosphofructokinase gene pfk in nisin-producer Lactococcus lactis N8.
The genes of pfk and pkaC encoding the catalytic subunit of cAMP-dependent protein kinase were cloned into the vector pMG36e andtransformed into L. lactis N8, resulting in the recombinant strain L. lactis N8-pMG36e-pfk-pkaC. Several biochemical and physological factors, including growth profiles, activity of 6-phosphofructokinase, expression of nisA , antibacterial activity of supernatants and nisin titer, were monitored to investigate the differences between the recombinant strain and the parental strain.
No significant difference was observed with respect to the growth patterns of the recombinant strain and the wild type. As expected, the biological activity of PFK in recombinant strain was increased for all examined samples. Correspondingly, the yield of nisin was increased by 20% in the recombinant strain after fermentation for 10 hours, which could be attributed to the accelerated biosynthesis of nisin. As a result, the fermentation cycle was reduced about 2 hours. Meanwhile, different concentration of glucose did not affect the formation of nisin.
The overexpression of pfk and pkaC genes in the nisin-producer strain can effectively accelerate nisin biosynthesis.
通过在乳酸乳球菌N8中过表达6-磷酸果糖激酶基因pfk来加速乳酸链球菌素的形成。
将pfk基因和编码cAMP依赖性蛋白激酶催化亚基的pkaC基因克隆到载体pMG36e中，并转化到乳酸乳球菌N8中，得到重组菌株乳酸乳球菌N8-pMG36e-pfk-pkaC。监测了包括生长曲线、6-磷酸果糖激酶活性、nisA表达、上清液抗菌活性和乳酸链球菌素效价在内的几个生化和生理因素，以研究重组菌株与亲本菌株之间的差异。
重组菌株和野生型的生长模式没有显著差异。正如预期的那样，重组菌株中PFK的生物活性在所有检测样品中均有所提高。相应地，重组菌株发酵10小时后乳酸链球菌素的产量提高了20%，这可能归因于乳酸链球菌素生物合成的加速。结果，发酵周期缩短了约2小时。同时，不同浓度的葡萄糖不影响乳酸链球菌素的形成。
在乳酸链球菌素生产菌株中过表达pfk和pkaC基因可有效加速乳酸链球菌素的生物合成。
