1株纤维素降解细菌的筛选及其对甘蔗叶的降解效果

Screening of a cellulose-degrading bacterium and its degradation effect on sugarcane leaf

  • 摘要: 【目的】筛选对甘蔗叶有降解效果的细菌菌株,为其在蔗叶还田中的应用及甘蔗叶田间高效生物腐解剂和纤维素酶制剂产品的研发提供参考。【方法】用以甘蔗叶粉为唯一碳源的培养基对田间腐解甘蔗叶样品中的降解菌进行富集,通过刚果红培养基初筛和羧甲基纤维素酶(CMCase)活性测定复筛纤维素降解菌,结合形态特征和16S rDNA序列分析,明确筛选菌株的系统分类地位;分析经菌株发酵处理后甘蔗叶的失重率,利用透射电镜和扫描电镜观察甘蔗叶超微组织结构变化,明确菌株对甘蔗叶的降解效果。【结果】经过初筛和复筛,获得1株高效产CMCase菌株XW005,其纤维素酶活力为80.51 U/mL,经16S rDNA序列及系统发育分析,将XW005菌株鉴定为Brucella intermedia细菌(NCBI登录号: MW538324.1)。电镜观察甘蔗叶显微结构,发现经菌株发酵处理的甘蔗叶表皮层开裂,维管束和质膜解体,受损的叶片呈疏松状态,平坦表面受到破坏,致密结构变得松散。甘蔗叶降解试验结果表明,发酵处理20 d后,菌株处理的甘蔗叶失重率达45.09%。【结论】菌株XW005是1株具有降解纤维素能力的细菌,在常温条件下可对甘蔗叶进行有效降解,具有潜在的开发价值和良好的应用前景。

     

    Abstract: 【Objective】 To screen bacteria with degradation effects on sugarcane leaves,and to provide reference for application of bacteria in sugarcane leaf returning and development of efficient biological decomposition agents and cellulase preparation products for sugarcane leaf in field.【Method】Medium with sugarcane leaf powder as the only carbon source was used to enrich cellulose-degrading bacteria of sugarcane leaf decomposition in field. Cellulose-degrading bacteria were preliminarily screened using Congo red medium and rescreened via determination of carboxymethyl cellulose (CMCase)activity,and according to analysis of morphological characteristics and 16S rDNA sequences,systematic taxonomic classification position of the screened bacteria were made clear. Weight loss rate of sugarcane leaves after fermentation treatment was analyzed and transmission electron microscope and scanning electron microscope were used to observe the change of sugarcane leaf ultrastructure, so as to make clear effects of the strain on sugarcane leaf degradation.【Result】 Through preliminary screening and rescreening,a strain of CMCase-producing strain XW005 with cellulase activity of 80.51 U/mL was obtained. According to analysis of 16S rDNA gene sequence and phylogenetic analysis,XW005 strain was identified as bacterium Brucella intermedia(NCBI accession number:MW538324.1). Electron microscopic observation of sugarcane leaf microstructure showed that epidermis of sugarcane leaves under fermentation treatment of the strain cracked,while vascular bundles and plasma membrane disintegrated,the damaged leaves were loosened,the flat surface was destroyed,and the dense structure became loose. The results of sugarcane leaf degradation test showed that after 20 d of fermentation treatment,the weight loss rate of sugarcane leaves under the strain treatment reached 45.09%.【Conclusion】 XW005 is a bacterium capable of degrading cellulose and it can effectively degrade sugarcane leaves at room temperature, which has potential of development and prospect for application.

     

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