中文摘要：

该文对不同龄期烘干前后蚕沙中菌群多样性进行分析与评价,以期明确其菌群组成及其丰富度差异,阐明烘干处理对中药材蚕沙中菌群的影响,为其功效科学内涵的揭示提供依据和参考。应用高通量测序技术测定蚕沙细菌的16S rDNA-V4变异区序列,应用Qiime,Mothur,PICRUSt等软件整理和统计样品序列数目和操作分类单元（OTUs）数量,分析蚕沙样品中菌群的组成、丰度、分布、Alpha多样性、Beta多样性,菌群差异性及对群落的代谢功能等进行预测。该研究获得用于分析的有效序列数为259 250;稀疏曲线表明测序深度充分,OTU的数量接近于饱和。蚕沙菌群主要由变形菌门（Proteobacteria,89.3%）、放线菌门（Actinobacteria,5.0%）、厚壁菌门（Firmicutes,4.4%）、拟杆菌门（Bacteroidetes,1.1%）、蓝细菌（Cyanobacteria,0.2%）组成,其优势菌门为变形菌门。烘干后蚕沙的菌群多样性及丰富度降低,五龄蚕沙尤为明显。PICRUSt分析蚕沙菌群对应的基因功能发现膜转运、碳水化合物代谢、氨基酸代谢、脂质代谢、核苷酸代谢,细胞过程与信号传导等基因功能丰度较高。烘干处理可显著降低蚕沙中致病菌的种类和数目,有利于药材药用品质,相比于低龄期蚕沙,五龄蚕沙更适宜入药。Illumina Mi Seq高通量测序技术为蚕沙菌群的研究提供了更加准确、科学的数据资源。

英文摘要：

This paper investigated the diversity of the silkworm excrement bacterial communities in different ages before and after drying,aiming to clarify the differences of bacterial communities in composition and bacterial abundance and the influences of drying treatment,and provide scientific basis for the efficacy of scientific connotation and utilization of silkworm excrement. High-throughput sequencing technique was used to measure the sequence of 16S rDNA-V4 variable region of bacteria in silkworm excrement. QIIME,Mothur and PICRUSt software programs were employed to sort and calculate the number of sequences and operational taxonomic units（ OTUs） for each sample. Thereafter,the abundance,distribution,alpha diversity index of species,beta diversity and bacterial communities diversity among different sample groups and predicted the bacterial gene functions were analyzed. In this study,the numbers of effective sequences for six samples were 259 250; the rarefaction curves showed a sufficient sequencing depth,and the number of OTUs was close to saturation. The bacteria in silkworm excrement belonged to the following five phylums： Proteobacteria（ 89. 3%）,Actinobacteria（ 5. 0%）,Firmicutes（ 4. 4%）,Bacteroidetes（ 1. 1%） and Cyanobacteria（ 0. 2%）. The dominant specie was Cyanobacteria of the total bacteria identified,respectively. The abundances and diversities of the silkworm excrement bacterial communities have been reduced after drying treatment,especially the silkworm excrement of the fifth instar. PICRUSt analysis was performed to show that abundance of the functional genes such as membrane transport,carbohydrate metabolism,amino acid metabolism,lipid metabolism,nucleotide metabolism,cellular processes and signaling were relatively high. The result showed that the drying treatment could decreased the species and numbers of pathogenic bacteria in silkworm excrement obviously and improve the quality of medicinal materials. Compared with the lower ages,silkworm excrement of fifth instar seems li