高效木质纤维素分解菌Aspergillus fumigatus Z5原位分解小麦秸秆的研究

Insight into the degradation of wheat straw by an efficient lignocellulosic-decomposing fungus Aspergillus fumigatus Z5

[目的]本研究旨在评价高效木质纤维素分解菌Aspergillus fumigatus Z5分解木质纤维素的能力,并以小麦秸秆为材料解析其分解过程。[方法]以小麦秸秆为唯一碳源,研究接种菌株Z5后小麦秸秆物理、化学特性及胞外水解酶活力,并结合扫描电镜、原子力显微镜、傅里叶红外光谱和二维核磁共振等方法,原位分析菌株Z5对小麦秸秆的分解过程。[结果]与对照相比,接种28 d后小麦秸秆的总碳相对含量减少了22.05%,总氮相对含量却增加了76.77%,而纤维素和半纤维素含量分别下降了36.97%和39.77%。电子扫描电镜和原子力显微镜观察结果表明,小麦秸秆表面在生物降解过程中发生了明显变化,28 d后表面出现孔洞,而且表面粗糙度由0.97%上升到43.83%。X-ray分析结果表明:随着降解时间的增加,小麦秸秆的结晶度由43.8%减小到28.3%,小麦秸秆中大部分的纤维素和半纤维素被菌株Z5分解。二维核磁共振分析结果表明:小麦秸秆中的多糖类、脂肪族类和芳香族类化合物都发生了分解,其中多糖类化合物最容易被降解,特别是β-D-木二糖和α-L-阿拉伯糖类化合物。[结论]菌株A.fumigatus Z5通过分泌多种胞外水解酶,从小麦秸秆的表面逐渐将纤维素、半纤维素等多糖类化合物分解,在农业废弃物处理及木质纤维类物质的资源化利用方面将具有较好的应用前景。

[Objectives]This paper was aimed to evaluate the lignocelluloses degrading capacity of an efficient lignocellulosic-decomposing fungus Aspergillus fumigatus Z5 and analyze the biodegradation process of wheat straw. [Methods]The physicochemical characteristics changes of the wheat straw during the biodegradation were evaluated with various advanced analysis methods,such as scanning electronic microscope（ SEM）,atomic force microscope（ AFM）,Fourier transform infrared spectroscopy（ FTIR）,X-ray and heteronuclear singular quantum correlation（ HSQC）. [Results]The relative total carbon content decreased for 22.05% by comparing with the original wheat straw,while the relative total nitrogen content increased to 76.77% higher than that of the original sample. The contents of cellulose and hemicellulose also decreased to 36.97% and 39.77%,respectively. Images of SEM and AFM indicated that clear hole appeared on the surface of the wheat straw,and the roughness increased from 0.97% to 43.83%. The X-ray analysis results indicated that the crystallinity of the wheat straw decreased from 43.8% to 28.3% as the cultivation time,and most of the cellulose and hemicellulose were degraded by A. fumigatus Z5. The HSQC analysis results showed that the polysaccharide anomeric group,aliphatic group and aromatic group were the major components contained in the wheat straw,while the polysaccharide anomeric group was easer to degrade by A. fumigatus Z5,especially β-D-Xylp and α-L-Araf. [Conclusions]The strain of A. fumigatus Z5 owns an efficient capacity in lignocelluloses degradation by secreting various extracellular hydrolytic enzymes,and it would have a great potential to be applied in the agricultural solid wastes treatment and the bioenergy industry.