低温纤维素降解细菌Duganella sp.的分离及降解能力解析

Isolation of a Duganella sp. of degrading cellulose bacterium at low temperatures and analysis of its degradation capacity

摘要:

【背景】低温是寒区秸秆还田后微生物降解的主要限制因素之一。【目的】获得低温纤维素降解细菌以提高寒区秸秆资源化利用率低的问题。【方法】取冬季土壤样品进行富集，以羧甲基纤维素钠(sodium carboxymethyl cellulose, CMC-Na)为唯一碳源，采用稀释涂布等方法分离纯培养菌株，通过单因素试验及正交试验对菌株产酶条件进行优化。【结果】获得一株15 ℃条件下降解纤维素的细菌，初步归类为杜擀氏菌属(Duganella)。其最佳产酶条件为：培养温度15 ℃，初始pH值7.0，装液量50/100 mL，接种量12.5%，此时的CMC酶活最高为398.2 U/mL，比优化前提高了40.45%。菌株在最佳培养条件下对滤纸、水稻秸秆和玉米秸秆的降解率分别为19.24%、9.48%和7.30%。【结论】本研究为寒区秸秆降解微生物资源提供了新的菌种资源，同时为后续低温纤维素降解菌株的研究提供了数据参考。

关键词:低温;纤维素降解;产酶条件优化

Abstract:

[Background] Low temperatures are one of the main factors limiting microbial degradation of straw returned to the field in cold regions. [Objective] To obtain the bacterial strains capable of degrading cellulose at low temperatures to improve the straw reutilization in cold regions. [Methods] The soil samples were collected in winter for strain enrichment with sodium carboxymethyl cellulose (CMC-Na) as the sole carbon source. The pure culture of the strain was obtained by the dilution-plate coating method, and the enzyme production conditions of the strain were optimized by single factor and orthogonal tests. [Results] A cellulose-degrading strain was obtained at 15 ℃ and identified as Duganella sp. The optimal enzyme production conditions of the strain were incubation with the liquid loading volume of 50/100 mL and inoculum volume of 12.5% at 15 ℃ and initial pH 7.0, under which the highest CMC enzyme activity was 398.2 U/mL, 40.45% higher than that before optimization. The degradation rates of filter paper, rice straw, and maize straw by the strain were 19.24%, 9.48%, and 7.30%, respectively, under optimal culture conditions. [Conclusion] This study provides new strain resources for straw degrading microbial resources in cold regions, as well as data reference for subsequent research on low temperature cellulose-degrading strains.

Key words:low temperature;cellulose degradation;optimization of enzyme production conditions