象白蚁肠道中一个纤维素降解菌群的分离和特性研究

利用滤纸培养基从象白蚁(Nasutitermes sp.)肠道中分离出一个具有纤维素降解能力,能够降解滤纸的混合菌群。在起始pH 6.5,37℃培养条件下培养6d可得到最高的纤维素酶(CMCase和FPase)活性。在优化条件下,混合菌群的滤纸降解率在第15d达到最大值66.3%,显示出较高的滤纸降解效率。酶谱活性染色分析显示,混合菌群在以滤纸为唯一碳源的生长过程中至少表达了8种内切葡聚糖酶和4种木聚糖酶。扫描电镜观察到该混合菌群包含短杆状和球形两种形态的细菌。基于16SrRNA基因的系统发育分析表明,该混合菌群中至少存在两种细菌,分别属于沙雷氏菌属(Serratia)和类芽胞杆菌属(Paenibacillus)。这两种细菌协同降解纤维素的机制值得进一步深入研究。

Isolation and characterization of a cellulose-degrading bacterial consortium from the gut of Nasutitermes sp.

In this study,a bacterial consortium with the ability of cellulose degradation was isolated from the gut of Nasutitermes sp.using filter paper culture medium.The bacterial consortium was able to degrade the filter paper steadily within 6 days in continuous culture.It showed the maximum cellulase activity (CMCase and FPase) on the 6th day of fermentation at 37 ℃ with initial pH 6.5.Under the optimum conditions,the degradation rate of filter paper reached 66.3 ％ on the 15th day,indicated a high efficiency of cellulose degradation.Zymogram analysis showed that at least eight endoglucanases and four xylanases were expressed by the bacterial consortium during fermentation.Scanning electron microscopy (SEM) revealed that the bacterial consortium contained bacteria of two morphologies:short rods and spheres.Phylogenetic analysis based on 16S rRNA genes showed that there were at least two species of bacteria in the bacterial consortium,which belonged to genera Paenibacillus and Serratia.Further studies will be made to investigate the synergistic mechanisms of these two bacteria in the degradation of cellulose.