Strategy on rapid discrimination of different varieties based on the combination of HS-GC-IMS and DNA Mini-barcode, spore powder of Ganoderma as a case study

Abstract

The demand for the consumption of Ganoderma (LingZhi) is increasing significantly nowadays. While the wild resources of Ganoderma lucidum and Ganoderma sinense have been reduced severely, and artificially cultivated products are gradually occupying the market. However, it is usually difficult to distinguish the different species of Ganoderma spore powder (GSP). In this research, a rapid and accurate identification method which combined headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) with the DNA mini-barcode was successfully developed to discriminate different GSP. The feasibility of the method was evaluated by both GSP and its Chinese patent medicines. HS-GC-IMS was used to characterize GSP volatile organic compounds (VOCs) and a total of seventy-one VOCs were identified. Principal component analysis could be utilized to show the significantly difference between Korean LingZhi (KL) and American LingZhi (AL) or Taishan LingZhi (TL). Then, we clarified the species information of all samples based on the internal transcribed spacer (ITS) regions. The identification results showed that TL and KL were Ganoderma lucidum, and the AL was Ganoderma resinaceum. Furthermore, according to the mutation sites of the above ITS sequences, the specialized DNA mini-barcode was successfully developed and applied. The artificial mixtures of the three types of GSP and Chinese patent medicines containing GSP were used to authenticate the barcode capability. The mixing experiment found that there was a linear relationship between the sequence numbers and the mixed biomass, indicating that the qualitative and quantitative ability of DNA mini-barcode performed well. The investigation of the ingredients of commercially available GSP products found that the commercial products maybe contain Ganoderma resinaceum, Ganoderma applanatum and Daedaleopsis confragosa, except for Ganoderma lucidum. Therefore, the results suggested that the available GSP products might be adulterated according to Chinese Pharmacopoeia. In this paper, we established a novel approach to distinguish the different GSP samples based on HS-GC-IMS and DNA mini-barcode, and the results indicated that our strategy could not only discriminate different GSP samples, but also identify the origins in their related products.