Transcriptome Analysis of Cordyceps militaris Reveals Genes Associated With Carotenoid Synthesis and Identification of the Function of the Cmtns Gene.

Cordyceps militaris, a valuable edible and medicinal fungus, has attracted increasing attention because of its various bioactive ingredients. However, the biosynthetic pathway of C. militaris carotenoids is still unknown due to lack of transcriptome information. To uncover genes related to the biosynthesis of C. militaris carotenoids, the transcriptomes of mycelia CM10_D cultured under dark conditions and mycelia CM10_L cultured under light exposure conditions were sequenced. Compared with mycelia CM10_D, 866 up-regulated genes and 856 down-regulated genes were found in mycelia CM10_L. Gene ontology (GO) analysis of differentially expressed genes (DEGs) indicated that DEGs were mainly classified into the "metabolic process," "membrane," and "catalytic activity" terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs suggested that DEGs were mainly enriched in "metabolic pathways," "MAPK signaling pathway-yeast," and "biosynthesis of secondary metabolites." In addition, the carotenoid content of the Cmtns gene deletion mutant (ΔCmtns) was significantly lower than that of the wild-type C. militaris CM10, while the carotenoid content of the complementary strain (ΔCmtns-c) of the Cmtns gene was not significantly different from that of C. militaris CM10, suggesting that the Cmtns gene significantly affected the biosynthesis of carotenoids in C. militaris. These results potentially pave the way for revealing the biosynthetic pathway of carotenoids and improving carotenoids production in C. militaris.

Optimization of Cultivation Conditions of Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes) for the Highest Antioxidant Activity and Antioxidant Content.

Ganoderma lucidum is a famous medicinal mushroom that is rich in antioxidants. The content of antioxidant components of grains can be effectively improved by G. lucidum as the fermenting strain. Optimization of the solid-state fermentation medium and optimization of the fermentation conditions were studied. The optimal fermentation substrate combination of G. lucidum TS (GL-TS) was 46.79% buckwheat, 53.21% rice; the optimal fermentation substrate combination of G. lucidum Am (GL-Am) was 4.17% soybean, 95.83% rice. The optimal fermentation conditions of GL-TS and GL-Am were as follows: inoculum amounts of 4.5% and 7.5%, temperatures of 30°C and 32°C, medium moisture content of 70% for both media, material granularities of 0.212-0.355 mm and 0.500-0.710 mm, and optimal fermentation time of 12.0 d and 10.5 d, respectively. Results of the analysis of antioxidant components in the fermentation substrates indicated that the antioxidant components were rich in antioxidant varieties and high in content. The contents of the antioxidant components (triterpenoids, total polyphenols, reducing sugars, anthocyanins, superoxide dismutase, glutathione, vitamin C, and vitamin E) in the full-fermentation substrates were greater than those in the nonfennentation substrates (except for flavonoids in the full-fermentation substrates, which were less than in the nonfennentation substrates). Glutathione was the major antioxidant component in the fermentation substrates, and the glutathione content was the highest. Therefore, the fermentation substrates of G. lucidum can be used to make antioxidant foods. This research contributes to the foundation for developing antioxidant foods based on G. lucidum.