油菜秸秆木质素高效降解菌的筛选、鉴定及降解效果研究

Screening and identification of efficient lignin-degrading strain in rape straw and their degradation applications

试验旨在研究油菜秸秆木质素高效降解菌的筛选、鉴定及降解效果。从油菜秸秆的还田土壤中筛选得到一株木质素高效降解菌株MS25,鉴定其为青霉属真菌(Penicillium)。基于单因素试验及响应面试验方法,对MS25菌株进行产酶特性探究及条件优化,并检验木质素降解能力。结果表明:菌株最佳产漆酶(Lac)时间为5 d,产过氧化物酶(Lip)和锰过氧化物酶(MnP)时间为7 d,最佳温度为50℃,摇床转速为140 r/min,碳氮比为15,产MnP的最适pH值为5,产Lip和Lac最适pH值为6。优化后最佳产酶条件为温度50.22℃、碳氮比12.29、pH值6.21、该条件下Lip、MnP、Lac的活性分别为1984.89、774.87、291.74 U/L,较优化前分别提高33.97%、33.28%、40.35%。最优条件下,秸秆、菌糠中木质素降解率分别为44.67%、43.29%。研究表明,菌株MS25可有效降解木质素,可作为油菜秸秆发酵的优质微生物,并可应用于饲料生产领域。

The experiment aimed to study the screening,identification,and degradation efficiency of efficient lignindegrading strain in rape straw.A highly efficient lignin degrading strain MS25 was screened from the returned soil of rapeseed straw and identified as a Penicillium fungus.Based on single factor experiments and response surface methodology,the enzyme production characteristics was invstigated and the conditions of MS25 strain was optimized,and the lignin degradation ability was tested.The results showed that the optimal time for the strain to produce laccase(Lac)was 5 days,and the time to produce peroxidase(Lip)and manganese peroxidase(MnP)was 7 days.The best temperature was 50℃,the shaking table speed was 140 r/min,the carbon to nitrogen ratio was 15,and the most suitable pH value for producing MnP was 5,while the most suitable pH values for producing Lip and Lac were 6.The optimal enzyme production conditions after optimization were temperature of 50.22℃,carbon to nitrogen ratio of 12.29,and pH value of 6.21.Under these conditions,the activities of Lip,MnP,and Lac enzymes were 1984.89,774.87,and 291.74 U/L,respectively,which were 33.97%,33.28%,and 40.35%higher than before optimization.Under optimal conditions,the lignin degradation rates of straw and fungal bran of the strains were 44.67%and 43.29%,respectively.The study indicates that strain MS25 can effectively degrade lignin and can be used as a high-quality microorganism for rape straw fermentation,and can be specifically applied in the field of feed production.