海洋真菌Xylaria sp.(No.2508)生产xyloketal B的发酵优化

Fermentation optimization of xyloketal B produced by marine fungus Xylaria sp.(No.2508)

对海洋真菌Xylaria sp.(No.2508)生产xyloketal B的摇瓶发酵过程进行了初步优化。结果表明,Xylaria sp.(No.2508)在培养120h时xyloketal B产量最高,当培养168 h后菌体进入衰亡期且xyloketal B迅速降解,因此Xylaria sp.(No.2508)生产xyloketal B的最适发酵周期为120h;Xylaria sp.(No.2508)合成xyloketal B的过程及用乙酸乙酯萃取xyloketal B的过程对pH非常敏感,其中最适xyloketal B生产的发酵液初始pH为5.7,利用乙酸乙酯萃取xyloketal B时的发酵液最适pH为3.0;最适接种量为10%(υ/υ);接种前发酵液中加入10g/L的大孔树脂XAD-16可以降低某些代谢产物对xyloketal B合成的抑制作用,从而使产量提高2倍左右,而菌体进入稳定期以后加入大孔树脂XAD-16对产物产量没有影响。

The fermentation optimization of xyloketal B produced by marine fungus Xylaria sp. （No. 2508 ） was preliminarily investigated in shake flask. The results showed that the production of xyloketal B was the highest at 120 h after inoculation. Xylaria sp. （No. 2508） reached decline phase at 168 h and at that time the xyloketal B was degraded rapidly. Therefore the optimal fermentation cycle for producing xyloketal B by Xylaria sp. （ No. 2508） was 120 h. It was found that both the biosynthesis and extraction by ethyl acetate for xyloketal B was sensitive to pH. The best initial pH of production culture was 5.7 while the optimal pH of the culture before extraction was 3. 0. The optimal inoculum concentration was 10% （v/v）. Meanwhile it was found that the addition of 10 g/L XAD-16 macroporous resin before inoculation could reduce the inhibition of producing xyloketal B by the metabolic products of Xylaria sp. （ No. 2508 ） and increase the production of xyloketal B by 2 times. However the addition of XAD-16 macroporous resin in the stationary phase had no effect on the production of xyloketal B.