[Rapid identification of geographical origins and determination of polysaccharides contents in Ganoderma lucidum based on near infrared spectroscopy and chemometrics]

Near infrared spectroscopy combined with chemometrics methods was used to distinguish Ganoderma lucidum samples collected from different origins, and a prediction model was established for rapid determine polysaccharides contents in these samples. The classification accuracy for training dataset was 96.87%, while for independent dataset was 93.33%; as for the prediction model, 5-fold cross-validation was used to optimize the parameters, and different signal processing methods were also optimized to improve the prediction ability of the model. The best square of correlation coefficients for training dataset was 0.965 4, and 0.851 6 for validation dataset; while the root-mean-square deviation values for training dataset and validation dataset were 0.018 5 and 0.023 6, respectively. These results showed that combining near infrared spectroscopy with suitable chemometrics approaches could accuracy distinguish different origins of G. lucidum samples; the established prediction model could precious predict polysaccharides contents, the proposed method can help determine the activity compounds and quality evaluation of G. lucidum.

[Cloning and prokaryotic expression analysis of DNA methyltransferas 1(MET1) in Ganoderma lucidum]

DNA methyltransferase is the key enzyme in the process of DNA methylation, playing an important role in regulation of gene expression in vivo. According to the Ganoderma lucidum transcriptome data, a full-length cDNA sequence of MET1 from G. lucidum was cloned for the first time, the GenBank registration number is KU239998, and we conducted a comprehensive bioinformatics analysis of the genetic characteristics and spatial structure. The prokaryotic expression analysis showed that E.coli[pET28a(+)-GlMET1] in BL21(DE3) could induce objective protein, shaking the culture at 16 ℃ until the host bacterium(A₆₀₀) was approximately 0.8, and added IPTG to finally concentration of 0.2 mmol•L⁻¹, and then the optimal expression of GlMET1 recombinant protein was accumulated for the induction time of 20 h. The real-time PCR results showed that the expression levels of GlMET1 had obvious differences among varieties of G. lucidum. During the maturity stage, the expression levels of GlMET1 were lower than that in juvenile stage, the results showed that with the growth of G. lucidum, the expression levels of GlMET1 were on the decline. The research provided an important basis for studying the mechanism of DNA methyltransferase thoroughly.