筛选两株稻杆降解放线菌

Screening of two straw-cellulose degrading actinomycetes

摘要:

摘要:【目的】筛选能够同时降解纤维素、半纤维素、木质素的微生物菌株，并研究其对稻杆的降解效果。【方法】采用羧甲基纤维素钠、半纤维素平板水解圈法、苯胺蓝平板脱色法进行初筛;利用DNS 法测定胞外酶活性;在含有2%稻秆的液体发酵培养基中摇瓶培养10 天后，洗去菌体测定稻杆失重率、木质纤维素类物质降解率，同时测定稻杆断裂拉力进行复筛。【结果】筛选出两株能够同时高效降解木质纤维素的放线菌A3 和A6，其纤维素和半纤维素酶活较高，最高纤维素全酶活、β-葡萄糖苷酶活、外切酶活和内切酶活分别为:12.84和12.85、6.23和6.53、24.56和17.80、14.00和18.80U/mL;最高半纤维素酶活分别为: 83.05和52.98U/mL;木质素酶活较低，菌株A3和A6的木素过氧化物酶最大值为:12.72和14.67U/mL，锰过氧化物酶最大值分别为:22.48和24.67U/mL，漆酶最大值分别为:28.40和33.04U/mL。经形态学、培养特征和分子生物学分析，两株菌株鉴定为链霉菌，对稻杆均有较好的降解效果，在第10d后稻杆断裂拉力测定值分别比初始时降低62.67%和66.67%;稻杆失重率在31.50%和35.83%;菌株A3对纤维素、半纤维素、木质素降解率为38.73%、33.16%和20.68%，菌株A6为47.69%、28.64和22.59%。【结论】放线菌A3和A6对纤维素、半纤维素、木质素均具有降解作用，且酶活较高，具有较好的应用前景。

关键词:关键词:稻杆，降解菌，筛选，纤维素酶，半纤维素酶，木质素酶

Abstract:

Abstract:［Objective］The aim of this study was to screen microorganisms that could degrade rice straw.［Methods］We used selective medium to screen strains and determined straw fracture tension strength，weight loss，lignocellulose decomposition rate and extracellular enzyme activity as re-screening methods after 10 days shake flask culture.［Results］ We isolated two antinomycetes (A3 and A6)，the highest cellulose enzyme activity of holoenzyme，β-Glucosidase，endonuclease and exonclease for A3 were 12. 84，6. 23，24. 56and 14. 00 U/mL，and for A6 12. 85，6. 53，17. 80 and 18.80U/mL．The hemicelluloses enzyme activity was 83. 05 for A3 and 52. 98 U/mL for A6. Both strains belonged to Streptomyces． With 10 days' treatment，inoculated straws showed a decrease of straw fracture tension strength by 62.67% (A3) and 66. 67% (A6)，while weight loss of straw was 31. 50% (A3) and 35. 83% (A6)． A3's decomposition rate of cellulose，hemicellulose and lignin was 38. 73%，33. 16% and 20. 68%，and 47. 69%，28. 64% and 22. 59% for A6．［Conclusion］Antinomycetes A3 and A6 could degrad cellulose，hemicellulose and lignin.

Key words:Keywords: Straw degrading microorganism，screening cellulose enzyme，hemicellulose enzyme，lignin enzyme