College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China.
Biomed Res Int. 2018 Oct 14;2018:1934309. doi: 10.1155/2018/1934309. eCollection 2018.
Polymyxin E or colistin, produced by , is an important antibiotic against Gram-negative pathogens. The objective of this study is to evaluate the effect of starch in fermentation medium on colistin biosynthesis in . The results indicated that replacement of glucose by starch stimulated colistin production and biosynthesis rate. Overall, the stimulation extent was starch concentration-dependent. As expected, addition of starch induced the expression of encoding amylase and increased amylase activity in fermentation solution. Additionally, replacement of glucose by starch resulted in residue reducing sugar and pH of fermentation mixture low relative to glucose as the sole sugar source. At the molecular level, it was found that replacement of glucose by starch has enhanced the relative expression level of encoding catabolite control protein A. Therefore, the repression of starch utilization by glucose could be probably relieved. In addition, use of starch stimulated the expression of regulatory gene but repressed the expression of another regulatory gene . As a result, the expression of genes directly involved in colistin biosynthesis and secretion increased, indicating that at the transcriptional level and played opposite roles in regulating colistin biosynthesis in . Taken together, our data demonstrated that starch instead of glucose can promote colistin production probably by affecting the expression of colistin biosynthesis-related genes, as well as reducing the repression of glucose to a secondary metabolic product.
多粘菌素 E 或粘菌素由产生，是一种对抗革兰氏阴性病原体的重要抗生素。本研究旨在评估发酵培养基中淀粉对粘菌素生物合成的影响。结果表明，用淀粉替代葡萄糖可刺激粘菌素的产生和生物合成速率。总的来说，这种刺激程度与淀粉浓度有关。正如预期的那样，添加淀粉诱导编码淀粉酶的基因的表达，并增加发酵液中的淀粉酶活性。此外，用淀粉替代葡萄糖会导致发酵混合物中的残留还原糖和 pH 值低于葡萄糖作为唯一糖源。在分子水平上，发现用淀粉替代葡萄糖增强了编码分解代谢物控制蛋白 A 的基因的相对表达水平。因此，可能缓解了葡萄糖对淀粉利用的抑制作用。此外，淀粉的利用刺激了调节基因的表达，但抑制了另一个调节基因的表达。结果，直接参与粘菌素生物合成和分泌的基因的表达增加，表明在转录水平上和在调节中的作用相反。综上所述，我们的数据表明，淀粉替代葡萄糖可以促进粘菌素的产生，可能是通过影响粘菌素生物合成相关基因的表达，以及减少葡萄糖对次级代谢产物的抑制作用。
