诱变选育棉籽粕高效脱毒菌株

Breeding of highly efficient detoxification strains of cottonseed meal

以橄榄假丝酵母(Candida oleophila)、克雷克酵母(Kloeckera lindneri)、红酵母(Rhodotheceglutinis)为出发菌株,采用物理诱变剂紫外线和化学诱变剂硫酸二乙酯(DES)对其进行单一诱变及复合诱变处理,选育出棉酚降解率较高的菌株,并确定单一诱变和复合诱变的最佳诱变条件.结果表明:出发菌株经紫外线和硫酸二乙酯诱变处理后再进行有利突变株的筛选,通过初筛、复筛,获得6株棉酚降解率较高的突变株(GJ-Z-25、GJ-D-25、GJ-Z-25-D-25、GJ-Z-20-D-20、HJ-D-20、HJ-Z-20-D-20),棉酚降解率分别高达90.69%、91.40%、93.78%、89.64%、90.78%和89.56%,比诱变前分别提高了50.00%、51.20%、55.14%、48.29%、26.33%和24.63%;橄榄假丝酵母的复合诱变效果好于单一诱变,最佳诱变条件是紫外线照射25 s,DES处理25 min;红酵母的DES诱变效果好于复合诱变,最佳诱变条件是DES处理20 min.通过本实验获得了高浓度棉酚耐受菌株,棉酚的降解率极显著提高,从而使棉粕营养价值显著提高.

The aim was to improve and screen the strains with high free gossypol（FG） degradation rate.With Candida oleophila,Kloeckera lindneri,Rhodothece glutinis as the starting strains,the mutants with high free gossypol（FG） degradation rate were bred after the starting strains were treated by ultraviolet（UV）,diethyl sulfate（DES） and UV＋DES mutation.And the optimal conditions for mutation were confirmed.The results showed that six available mutant strains were screened through primary screening and secondary screening（GJ-Z-25,GJ-D-25,GJ-Z-25-D-25,GJ-Z-20-D-20,HJ-D-20,HJ-Z-20-D-20）.The FG degradation rate of mutant strains were 90.69%,91.40%,93.78%,89.64%,90.78% and 89.56% respectively,increased by 50.00%,51.20%,55.14%,48.29%,26.33% and 24.63%,compared with the starting strains.The composite mutation（UV irradiation mutagenesis of 25 s,DES treatment of 25 min） of C.oleophila was more effective than alone mutation;but alone DES mutagenesis of R.glutinis was more effective than the compound mutation,and the best condition for DES mutagenesis treatment was for 20 min.The experiment obtained high concentrations gossypol tolerated strains,enhanced the degradation rate of gossypol significantly and increased nutritional value of cottonseed meal.