发酵木糖高产乙醇树干毕赤酵母菌株的Co60诱变选育

【目的】选育能够利用木糖高产乙醇的酵母菌株。【方法】采用Co60诱变树干毕赤酵母(Pichia stipitis),筛选乙醇产量高的突变菌株,并对原始菌株、突变菌株的生长发酵特性和两个菌株对高浓度木糖、乙醇的耐受性进行比较。【结果】在YPX培养基上筛选获得1株能够高效发酵木糖的突变菌株1K-9。该菌株在50mL 15%FM发酵84h,发酵液乙醇含量最高达(51.034±0.112)g/L,比原始菌株提高10.05%;在500mL 15%FM发酵96h,乙醇含量最高达(51.390±0.119)g/L;在500mL 20%FM发酵156h,乙醇含量最高达(52.496±0.513)g/L。菌株1K-9在HSM培养基或含4%~5%乙醇的YPX培养基中生长良好,在含6%~7%乙醇的YPX培养基中生长缓慢。【结论】Co60诱变对于树干毕赤酵母(Pichia stipitis)菌株是有效的,能选育出木糖高产乙醇酵母菌株1K-9。

Breeding of High-yield Pichia stipitis Strains by Co60 Mutagenesis for Ethanol Fermentation from Xylose

[Objective] To breed high-yield ethanol strains, which can use xylose in fermentation, [Method] xylose-fermenting yeast Pichia stipitis was mutated by Co⁶⁰ rays. The growth and fermentation characteristics of original and mutant strains were analyzed, and their tolerances against relatively high concentrations of xylose and ethanol were compared.[Result] The mutant 1K-9, which shows superior xylose utilizing, growing and ethanol producing efficiency was screened on YPX.After fermenting in 15%FM for 84h, the concentration of ethanol reached(51.034±0.112)g/L, increased by 10.05% comparing to the original strain.When amplifying fermentation with strain 1K-9 was conducted in 500mL medium, 15%FM and 20%FM could produce the concentration of ethanol reaching (51.390±0.119)g/L and (52.496±0.513)g/L after fermenting for 96h and 156h, respectively.The mutant strain 1K-9 could grow easily and quickly in HSM or in YPX containing 4%~5% ethanol, but hard in YPX containing 6%~7% ethanol. [Conclusion] Mutagenesis of Pichia stipitis can be effectively conducted by Co⁶⁰ rays, through which the mutant strain 1K-9 was breed out and it can yield high production of ethanol from fermenting xylose.