木质素降解菌BYL-7的筛选及降解条件优化

【背景】微生物降解木质素因其具有降解效率高和环保等特点而备受关注。【目的】筛选高效木质素降解真菌，并对其降解条件进行优化。【方法】通过愈创木酚-马铃薯葡萄糖琼脂(potato dextrose agar，PDA)和苯胺蓝平板法筛选高效木质素降解菌株，利用单因素筛选及响应面试验对培养条件进行优化。【结果】筛选到一株高效木质素降解菌BYL-7，经形态和多序列分析初步确定为Trametes versicolor。单因素试验证明初始pH、温度和接种量为降解木质素显著影响因子，响应面试验确定降解木质素最优条件为：初始pH 6.7，温度25 °C，接种量8%。在此条件下，碱性木质素降解率为36.5%，比未优化前提高54.0%；水稻秸秆木质素、半纤维素和纤维素降解率分别为32.8%、21.5%、13.2%，其中木质素降解率比未优化前提高36.1%；漆酶活性在第6天达到峰值120.0 U/L，比未优化前提高25.0%；木质素过氧化物酶活性在第6天达到峰值1 343.8 U/L，比未优化前提高36.0%；锰过氧化物酶活性在第5天达到峰值463.8 U/L，比未优化前提高31.7%。【结论】研究结果为木质素的降解提供了良好的菌种资源，同时也为后续木质素的研究积累了相关数据。

Screening of lignin degrading strain BYL-7 and optimization of degradation conditions

Background] Microbial degradation lignin has attracted more attention due to its characteristics of high degradation efficiency and environmental protection. Objective] Screening highly efficient lignin degradation fungi and optimizing their degradation conditions. Methods] High efficiency lignin degradation strains were screened by guaiacol-PDA and aniline blue plate methods, and the culture conditions were optimized by single-factor screening and response surface experiment. Results] An efficient lignin degradation bacteria BYL-7 was screened and initially identified as Trametes versicolor by morphological and multi-sequence analysis. The single factor test proved that the initial pH, temperature and inoculum amount were the significant influencing factors for lignin degradation, and the response surface test determined that the optimal conditions for degradation lignin were initial pH 6.7, temperature 25 °C, and inoculum amount 8%. Under these conditions, the alkaline lignin degradation rate was 36.5%, which was 54.0% higher than before; the degradation rates of rice straw lignin, hemicellulose, and cellulose were 32.8%, 21.5%, and 13.2%, respectively. Among them, the lignin degradation rate was enhanced by 36.1% compared with before. Laccase activity peaked at 120.0 U/L in the 6th day, which was 25.0% higher than before; the lignin peroxidase activity reached a peak of 1 343.8 U/L in the 6th day, which was 36.0% higher than before; the manganese peroxidase activity peaked at 463.8 U/L in the 5th day, which was 31.7% higher than before. Conclusion] The experimental results provided a useful bacteria resource for lignin degradation, but also accumulated relevant data for subsequent research on lignin.