木质素降解菌株的分离及其降解玉米秸秆过程中产酶特点

Isolation of lignin-degrading strain and its enzyme producing characteristics in corn stover degradation

【目的】筛选高效降解木质素的菌株,并研究其以玉米秸秆为底物时木素降解酶活性。【方法】本研究以愈创木酚培养基和苯胺蓝培养基从吉林省不同经纬度的自然朽木及腐朽玉米秸秆土壤样品中分离、筛选得到高效降解木质素的菌株,并对其形态学鉴定,通过ITS序列分析构建系统发育树,分析菌株的分类地位。通过秸秆固体发酵过程产生的胞外木质素酶的活性分析,选出高效秸秆降解菌。【结果】筛选出1株高效降解秸秆的真菌,对其进行形态学特征和ITS序列分析,命名为白囊耙齿菌W2(Irpex lacteus W2)。该菌株在4–8 d内产生的锰过氧化物酶(Manganese peroxidase)呈上升趋势,并且在8 d达到峰值86.31 U/mL,与黄孢原毛平革菌(Phanerochaete chrysosporium)的最高酶活力45.86 U/mL相比,高出了88.20%(P<0.01);该菌株的漆酶(Laccase)活力8 d时达到20.60 U/mL,比对照高40.76%(P<0.05)。【结论】本研究分离到一株具有较强降解秸秆能力的真菌,初步鉴定为Irpex lacteus W2,具有较强的降解秸秆能力,其降解秸秆过程中产生较高的锰过氧化物酶与漆酶活力。

[Objective] The objective of this study was to screen lignin-degrading fungi and study their lignin-degrading enzyme using corn stover as substrate. [Methods] Lignin-degrading fungi were isolated from decayed corn stover from different latitude and longitude of Jilin Province by using guaiacol and aniline blue culture medium. Strains were identified by morphological screening followed by the phylogenetic analysis of ITS sequences deciphering their taxonomic status. Through the analysis of the activity of extracellular ligninase produced during the solid-state fermentation of corn stover, the most efficient stover-degrading fungi were selected. [Results] A highly efficient corn stover degrading fungus was isolated and named as W2（Irpex lacteus W2）. Manganese peroxidase produced after 4 to 8 days showed an ascending trend, and reached the peak value of 86.31 U/mL at 8 d, which was 88.20% higher than that of Phanerochaete chrysosporium（P〈0.01）. Laccase activity of this fungus was higher than that of Phanerochaete chrysosporium（45.86 U/mL） and reached 20.60 U/mL at 8 d, which was 40.76% higher than the control（P〈0.05）. [Conclusion] An efficient corn stover degrading fungus was isolated and identified as Irpex lacteus W2, with high activity of peroxidase and laccase during the degradation process.