Abstract:

Cordycepin, as a kind of nucleoside antibiotic, has various biological and pharmaceutical activities, such as anti-cancer and anti-tumor activities. Cordycepin is mainly obtained from liquid culture of Cordyceps militaris, whose low yield restricted its further application though. Considering the high concentration of cordycepin accumulation to produce strong feedback inhibition on its biosynthesis process, a strategy to remove some cordycepin and weaken the feedback inhibition to increase the production of cordycepin by fermentation separation coupling technique was proposed. Next, static adsorption test was taken and macroporous resin NKA-II was screened, followed by optimization of adsorption conditions such as resin usage (60 g·L^-1), temperature (37℃), and desorption solvent (100% ethanol), giving 644.50 mg·L^-1 cordycepin in fermentation under 30 g·L^-1 initial glucose with repeated adsorption processing (twice), 32.07% higher than the control. To further improve the cordycepin yield, fed-batch fermentation coupled with resin adsorption separation was performed, giving a final yield of 787.50 mg·L^-1, which was 35.78% higher than the control. It was found that the strategy of submerged liquid fermentation coupled with macroporous resin adsorption could efficiently weaken the feedback inhibition of cordycepin, and dramatically enhance the productivity of product, providing novel ideas for industrial cordycepin production.

Key words: fermentation, bioseparation, bioprocess, cordycepin, Cordyceps militaris

摘要：

虫草素是一种核苷类抗生素，具有抗癌、抗肿瘤等活性，主要由蛹虫草菌液体发酵生产，然而低产量限制了其应用。考虑到高浓度虫草素积累对其生物合成过程产生强烈反馈抑制，提出了应用发酵分离耦合技术移除部分虫草素、弱化反馈抑制作用以提高虫草素产量的策略。通过静态吸附实验，筛选出虫草素吸附和解吸性能良好的大孔树脂NKA-Ⅱ，并优化了大孔树脂使用量（60 g·L^-1）、吸附温度（37℃）和解吸剂种类（100%乙醇）。在30 g·L^-1葡萄糖的分批发酵体系中，经过两次树脂吸附，发酵21 d后虫草素产量达到644.50 mg·L^-1，较对照组提高32.07%；随后，将树脂吸附分离策略应用于补料分批发酵体系，虫草素产量达到787.50 mg·L^-1，较对照组提高35.78%。这些结果表明，将虫草素液体发酵与大孔树脂吸附分离耦合，有效弱化了虫草素反馈抑制，显著提高虫草素产量，为虫草素高效生产分离提供了新思路。

关键词: 发酵, 生物分离, 生物过程, 虫草素, 蛹虫草菌