Optimization of protein extraction and two-dimensional gel electrophoresis profiles for the identification of Cordyceps sinensis and other similar species

Medium optimization for high mycelial soluble protein content of Ophiocordyceps sinensis using response surface methodology

Ophiocordyceps sinensis is widely utilized due to its pharmaceutical value. Mycelial protein forms a key active component of O. sinensis and determines the medicinal potential of fungus. Here, we describe the development of an optimized fermentation medium to obtain more mycelial soluble protein from O. sinensis using response surface methodology (RSM) and investigate the increased mycelial protein content using transcriptomics. The maximum mycelial protein content of 2.11% was obtained using a medium consisting of 20% beef broth, 0.10% peptone, 2% glucose, 0.15% yeast extract, 0.20% KH₂PO₄, and 0.02% MgSO₄. Transcriptome analysis identified 790 differentially expressed genes (DEGs), including 592 up-regulated genes and 198 down-regulated genes, optimisation resulted in more up-regulated genes. The main DEGs were enriched in metabolic pathways, ABC transporters, starch and sucrose metabolism, tyrosine metabolism, and glutathione metabolism. In addition, some DEGs associated with mycelial protein enhancement such as tyrosinase (TYR), glutathione S-transferase (GST), glutamine synthetase (glnA), and β-glucosidase may contribute to increased mycelial protein content. Real-time quantitative PCR (RT-qPCR) was used to confirm gene expression and the results support the accuracy of RNA-Seq and DEG analysis. This study provides an optimized fermentation method for enhancing the mycelial protein content of O. sinensis and a reference for the effective development of O. sinensis protein.

A rapid and simple signature peptides-based method for species authentication of three main commercial Pheretima

Pheretima with various activities is a commonly used animal-derived traditional medicine in Asia countries. However, almost half of them are non-pharmacopoeia species in the market due to the similar morphological characteristics between medicinal and non-medicinal species. This study aims to establish an effective method based on signature peptides for species authentication of three main commercial Pheretima, including two major Pheretima species (Amynthas aspergillum, Metaphire vulgaris) and one main adulteration (Metaphire magna). Firstly, the species of 52 batches of commercial Pheretima were authenticated based on DNA barcodes. Secondly, proteomic analysis was performed for protein characterization of three main commercial Pheretima. Furthermore, their signature peptides were screened and validated using ultra-high performance liquid chromatography coupled with mass spectrometry (UPLC-MS/MS) in multiple reaction monitoring (MRM) mode. Moreover, a simplified sample processing method was developed. Finally, large quantities of commercial Pheretima samples were analyzed for further verifying the feasibility of the signature peptides-based method. The result showed that the established method had a great application potential for authenticity identification of commercial Pheretima. SIGNIFICANCE: The authenticity assessment of medicinal materials is a main issue in the quality control process as deceptive practices could imply severe health risks. In this study, a rapid and simple method based on signature peptides was established for species authentication of three main commercial Pheretima, which can be an effective alternative to complex DNA barcoding and difficult morphological identification, and provided a reference for improvement of Pheretima quality standards.