Study on degradation of silkworm excrement chemical components in vitro / 中国中药杂志

The purpose of this article is to study the degradation of chemical compositions after the silkworm excrement being expelled from the silkworm, and to determine its main metabolic compositions and their changing relationships. This research is based on UPLC-Q-TOF-MS technology. Based on the systematic analysis of the main chemical compositions contained in silkworm excrement, the principal compositions analysis(PCA) and partial least squares discriminant analysis(OPLS-DA) on commercial silkworm excrement and fresh silkworm excrement were analyzed for differences. The S-plot chart of OPLS-DA was used to select and identify the chemical compositions that contributed significantly to the difference. At the same time, the relative peak areas of the different compositions were extracted by Masslynx to obtain the relative content of different compositions in fresh silkworm excrement. The results showed that there was a significant difference in the chemical compositions between fresh silkworm excrement and commercial silkworm excrement. The difference compositions were mainly flavonoid glycosides and Diels-Alder type composition, and two types of compounds are degradated during the storage of silkworm sand. In this study, the chemical compositions of fresh silkworm excrement were systematically identified and analyzed for the first time by mass spectrometry, and it was found that some chemical compositions of silkworm excrement were degradated with time during storage.

Silkworm excrement bacterial communities diversity in different instars based on 16S rDNA sequence analysis / 中国中药杂志

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 like to be more suitable for use in medicine. Illumina MiSeq high-throughput sequencing system provides a more accurate and scientific data resource for the study of bacteria in silkworm excrement.