虫草素是蛹虫草菌发酵的重要生物活性物质之一，具有多种医学功效，然而，低产率限制了其大规模生产和应用。为了提高虫草素产率，本研究通过超声波和硫酸二乙酯复合诱变、定向筛选得到一株黄嘌呤和鸟嘌呤双重营养缺陷型突变株xan－gua－-c，其虫草素产量较原始菌株提高约40%，达到1.76 g/L（发酵20 d）。本研究进一步考察了外源添加虫草素结构类似物对突变株合成虫草素的影响，发现添加1.0 g/L腺苷和1.0 g/L腺嘌呤后，第20 d虫草素产量分别提高了33.5%和103.5%，达到2.35 g/L和3.59 g/L。代谢途径分析表明，蛹虫草菌中可能同时存在由腺嘌呤或腺苷合成虫草素的代谢途径，甚至这两条合成途径本就是重合的，且阻断黄嘌呤和鸟嘌呤的合成代谢是促进蛹虫草菌积累虫草素的有效策略。

Cordycepin, with a variety of medical and health benefits, is one of the key bioactive compounds in Cordyceps militaris. However, the low fermentation yield restricts its industrial production and applications. To enhance the yield of cordycepin, a xanthine-guanine double auxotrophic mutant, xan-gua--c, was obtained by ultrasound mutagenesis combined with diethyl sulfate treatments, followed by directional screening, and its yield of cordycepin was improved to 1.76 g/L on the 20th day of batch fermentation, about 40% higher than that of the control. The effects of structural analogs of cordycepin on the cordycepin production capacity of the mutant were then investigated. The results showed that the addition of 1.0 g/L adenosine and 1.0 g/L adenine could improve the production of cordycepin (on the 20th day) by 33.5% (to 2.35 g/L) and 103.5% (to 3.59 g/L), respectively, compared with that of the control. Metabolic pathway analysis indicated that there might be two metabolic pathways used to synthesize cordycepin from adenine or adenosine. The two metabolic processes might overlap, and blocking the anabolism of xanthine and guanine might be an effective strategy to promote Cordyceps militaris to accumulate cordycepin.

辽宁省教育厅科学研究一般项目（715020）；大连工业大学青年基金项目（67007907）