嗜冷假单胞菌BYAU-6的分离及低温秸秆降解能力解析

Isolation of Pseudomonas psychrophila BYAU-6 capable of degrading straw at low temperatures

摘要:

目的 针对寒地黑土区水稻秸秆还田时秸秆腐解速度慢的问题，筛选低温木质素降解细菌以破除木质素的阻碍，提升寒区秸秆还田后秸秆的降解效率。方法 在冬季采集土壤样品，以木质素磺酸钠为唯一碳源，采用平板划线法分离纯培养菌株，并通过单因素试验及响应面试验对木质素降解条件进行优化。结果 获得了一株能在15 ℃条件下降解木质素的细菌，命名为嗜冷假单胞菌(Pseudomonas psychrophila) BYAU-6。该菌在5-15 ℃范围内均具有较强的木质素降解能力。筛选培养条件为：木质素磺酸钠添加量0.5 g/L、蛋白胨与酵母粉质量比5:1、初始pH 7.0、装液量80%。优化后的木质素降解条件为：木质素磺酸钠添加量0.3 g/L、蛋白胨与酵母粉质量比3.2:2.8、初始pH 5.3、装液量80%。在此条件下，木质素降解率由12.33%上升到15.78%，比优化前提高了21.9%。盆栽试验研究结果显示，添加菌剂对秸秆还田效率有显著影响。不接菌的对照组秸秆降解率为27.0%，而接种菌株P. psychrophila BYAU-6处理后秸秆降解率提升至37.5%，秸秆降解率提升了38.89% (P<0.05)。结论 本研究为寒区秸秆降解提供了新的微生物资源，并为后续低温木质素降解菌株的研究提供了数据参考。

Abstract:

Objective In view of the low decomposition rate of rice straw in black soil fields of cold regions, it is crucial to isolate lignin-degrading bacteria adaptive to low temperatures to enhance the straw degradation efficiency.Methods Soil samples were collected in winter, and the bacterial strains capable of degrading lignin were isolated by the streak-plate method with sodium lignosulfonate as a sole carbon source. The degradation conditions was carried out through optimized by single factor experiment sand response surface methodology.Results Pseudomonas psychrophila BYAU-6 was isolated, exhibiting strong lignin-degrading activity in low-temperature environments (5-15 ℃). The culture conditions for strain screening were as follows: sodium lignosulfonate addition amount of 0.5 g/L, a peptone-to-yeast powder mass ratio of 5:1, initial pH 7.0, and a liquid loading volume of 80%. The optimal culture conditions for lignin degradation were determined as follows: sodium lignosulfonate addition amount of 0.3 g/L, a peptone-to-yeast powder mass ratio of 3.2:2.8, initial pH 5.3, and a liquid loading volume of 80%. Under these conditions, the lignin degradation rate increased from 12.33% to 15.78%, representing an increase of 21.9%. The results of the pot experiment showed that the control group (without inoculation) achieved a straw degradation rate of 27.0%, while the inoculation with strain BYAU-6 achieved a straw degradation rate of 37.5%, an increase of 38.89% compared with the control (P<0.05).Conclusion This study provides novel microbial resources for straw degradation in cold regions and valuable data for future research on lignin-degrading strains under low-temperature conditions.