一株纤维素降解菌的分离、鉴定及对 玉米秸秆的降解特性

Isolation, identification and corn stalk degradation charac-teristics of cellulose-degrading bacterial strain NH11

摘要:

【目的】获得高产纤维素酶细菌菌株, 探讨以氨化预处理玉米秸秆为底物时的纤维素酶产酶特性及底物降解特性, 探讨纤维素酶作用机理, 提高玉米秸秆利用率。【方法】用LB培养基分离并纯化菌株, 羧甲基纤维素钠培养基培养、刚果红染色进行初步筛选。考察氨化预处理对底物降解率、产酶能力的影响。通过形态特征观察及16S rRNA、Biolog鉴定菌株。【结果】分离到一株高效纤维素降解菌NH11, 经鉴定为枯草芽孢杆菌(Bacillus subtilis)。30 °C、发酵5 d时, 预处理前后玉米秸秆降解率分别为14.24%和24.73%。30 °C、pH 7.2时, 处理组CMC酶活力峰值处为153.84 U/mL, FPA酶活力为197.24 U/mL, 比未处理组分别高出11.45%和10.59%。【结论】NH11具有较高的纤维素酶产酶能力, 氨化预处理能够提高菌株对玉米秸秆的降解率。该菌株在秸秆堆肥、制作食用菌培养基和制取反刍动物粗饲料方面具有很高的应用价值。

关键词:农业废弃物, 纤维素酶, 玉米秸秆, 分离筛选, 预处理, 降解

Abstract:

[Objective] This study is aimed to obtain effective cellulose-degrading bacterial strains and study the characteristics of cellulase production and degradation characteristics used NH3?H2O pretreated corn stalk as substrate, and explore mechanism of cellulose enzyme so as to improve the resource utilization rate of agricultural solid wastes. [Methods] LB medium was used to obtain eleven bacterial strains (NH1?11) from earthworm farm. CMC-Na was used in preliminary medium and congo red staining method to screening strains. Influence of pretreatment to cellulose production ability of NH11 and degradation rate of substrates was studied. Morphological characteristics of NH11 was observed by electron microscope and identified by 16S rRNA and Biolog method. [Results] Bacterial strain NH11 was isolated and identified as Bacillus subtilis. The maximum degradation rate of untreated and pretreated corn stalk was 14.24% and 24.73% when culture temperature was 30 °C after five days. CMC cel-lulose activity of NH11 reached to 153.84 U/mL and FPA cellulose activity to 197.24 U/mL in treatment group, 11.45% and 10.59% higher than untreated group. [Conclusion] NH11 has a high cellulase productivity, and NH3?H2O pretreatment could enhance the degradation rate of corn stalk. NH11 has a high value in straw compost, mushroom culture medium and ruminant feed production.

Key words:Agricultural wastes, Cellulase, Corn stalk, Isolation and identification, Pretreatment, Degradation