一种评价稻秆降解菌分解能力的方法

Study on evaluation of the degradation ability of rice straw-degrading bacteria

[目的]探究一种评价稻秆降解菌分解能力的新方法。[方法]以10株秸秆降解细菌为材料,研究其在羧甲基纤维素钠平板上的水解圈以及其在纯稻秆粉为碳源的液体发酵培养基中的纤维素和半纤维素酶活力与稻秆相对降解率(RDR)的关系。[结果]菌株在羧甲基纤维素钠平板上的水解圈直径(D)、水解圈-菌落直径比(D/d)、纤维素和半纤维素最大酶活力与RDR均未达到显著关系(P>0.05);液体发酵培养1周内每天的纤维素和半纤维素酶活力与RDR没有显著线性关系。而菌株在液体发酵培养1周内的累积纤维素酶活力、累积半纤维素酶活力与RDR成显著正相关(P<0.05);培养1周内累积纤维素半纤维素酶活力与RDR达到极显著水平(P<0.01)。[结论]说明采用单个累积酶活力和总累积酶活力(纤维素酶和半纤维酶)能够更好地评价菌株对稻秆的实际降解能力,可作为秸秆降解菌降解能力的评价指标。

[ Objectives ] A better method for evaluation of the degradation ability of rice straw-degrading bacteria was explored. [ Methods] Ten strains of straw-degrading bacteria were used to study the relationship between the hydrolysis ring（ on CMC-Na plate）, carboxymethyl cellulase（CMCase）and xylanase activity in rice straw powder as carbon source for liquid fermentation medium and the relative degradation rate of rice straw. [ Results ] The hydrolysis zone diameter on CMC-Na plate （ D）, the ratio of hydrolysis zone to colony diameter（D/d）,the largest CMCase and xylanase activities of each day of strains were not significantly correlated with their relative degradation rate（RDR） on rice straw（P〉0.05）. Positive correlations were observed between the CMCase or xylanase activities accumulated for one week and RDR（P〈0.05）, while the total cumulative enzyme （CMCase plus xylanase）activity in one week was significantly correlated with RDR（P〈0.01 ）. [ Conclusions] The cumulative enzyme activity of strain is better to evaluate the actual degradation effects, and this new evaluation method provides a more accurate identification of reference for the degradation ability of the straw-degrading bacteria.