发酵条件优化及基因簇加倍对厦门霉素生物合成的影响

Medium optimization and biosynthetic gene cluster doubling enhance xiamenmycin yield

摘要:

【目的】优化发酵培养条件及加倍xim基因簇，提高厦门霉素的产量。【方法】采用单因素添加：C源(鼠李糖、葡萄糖酸)、无机N源(KNO3)、稀有金属元素(ScCl3)及A-Factor (γ-丁内酯)，优化适宜厦门链霉菌318菌株产生厦门霉素的培养条件；通过位点特异性整合将厦门霉素生物合成基因簇进行加倍，构建高产的基因工程菌株厦门链霉菌318Pls1，并对其培养基进行了正交实验优化。【结果】与初产量(15 mg/L)相比，在GYM培养基中进行单因素添加可使318菌株的厦门霉素产量达到20 mg/L；而基因簇加倍菌株318Pls1在GYM培养基上的厦门霉素产量可达35 mg/L，在正交实验优化后的9#培养基中厦门霉素产量可达76.15 mg/L。【结论】对厦门霉素的发酵培养条件进行了优化，并通过基因簇过表达获得了生物合成能力提高的菌株，为进一步提高其产量奠定了基础。

Abstract:

[Objective] To improve xiamenmycin yield from Streptomyces xiamenensis 318 we optimized fermentation medium and doubled biosynthetic gene cluster. [Methods] Glucose-yeast extract-maltose medium (GYM) was optimized by a series of single-factor experiments with variation of carbon source (rhamnose and gluconic acid), nitrogen source (KNO3), trace element (ScCl3) and A-Factor analogous (γ-butyrolactone). Subsequently, the biosynthetic gene cluster xim was doubled by site-specific integration to obtain a genetic engineering strain S. xiamenensis 318Pls1 and orthogonal experiment was applied to optimize the medium. [Results] The single-factor experiments improved xiamenmycin yield in wild-type strain 318 from 15 mg/L to 20 mg/L. The yield in biosynthetic gene doubling strain 318Pls1 attained to 35 mg/L in GYM and was increased to 76.15 mg/L in the optimized medium 9# by orthogonal experiment. [Conclusion] This study shows that the medium optimization combined with biosynthetic gene cluster doubling enhanced xiamenmycin yield and provides an opportunity for further improvement of high productivity strain.