Transcriptomic Responses of Cordyceps militaris to Salt Treatment During Cordycepins Production

Abstract

Cordycepin is a major bioactive compound found in Cordyceps militaris (C. militaris) that exhibits a broad spectrum of biological activities. Hence, it is potentially a bioactive ingredient of pharmaceutical and cosmetic products. However, overexploitation and low productivity of natural C. militaris is a barrier to commercialization, which leads to insufficient supply to meet its existing market demands. In this study, a preliminary study of distinct concentrations of salt treatments toward C. militaris was conducted. Although the growth of C. militaris was inhibited by different salt treatments, the cordycepin production increased significantly accompanied by the increment of salt concentration. Among them, the content of cordycepin in the 7% salt-treated group was five-fold higher than that of the control group. Further transcriptome analysis of samples with four salt concentrations, coupled with Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, several differentially expressed genes (DEGs) were found. Finally, dynamic changes of the expression patterns of four genes involved in the cordycepin biosynthesis pathway were observed by the quantitative real-time PCR. Taken together, our study provides a global transcriptome characterization of the salt treatment adaptation process in C. militaris and facilitates the construction of industrial strains with a high cordycepin production and salt tolerance.

Transcriptome and metabolome profiling unveils the mechanisms of naphthalene acetic acid in promoting cordycepin synthesis in Cordyceps militaris

“…An increase in NAA concentration increases the accumulation of toxic substances caused by serious damage to the cell membrane, reducing the ability to grow. During stress, the body undergoes major changes in morphology, and primary and secondary metabolites to adapt to the environment for survival, which is consistent with the corresponding physiological characteristics of Saccharomyces cerevisiae , Streptomyces caeruleus , and C. militaris (high salt stress) under stress conditions ( 37 – 39 ). The fruiting body undergoes different morphological, physiological, and molecular changes to adapt to the environment.…”

“…The C. militaris strain significantly enriches the biosynthesis pathway and glyceride metabolism pathway of unsaturated fatty acids under high salt conditions. Therefore, the reaction of C. militaris under NAA treatment is similar to that of S. cerevisiae and C. militaris under a high salt environment ( 39 ). As an important component of the cell membrane, lipids are highly sensitive to environmental changes.…”

“…The significant enrichment of this pathway showed that cell growth is affected by adverse stress, which is consistent with the significant decline noted in the dry weight of C. militaris with an increase in NAA concentration ( 42 ). Under high salt conditions, glyceride metabolism and high osmotic glycerol (HOG) signal pathways in S. cerevisiae enable microorganisms to respond to different extracellular stimuli and adjust their cellular mechanisms to alter their environment ( 39 , 43 ). The C. militaris strain significantly enriches the biosynthesis pathway and glyceride metabolism pathway of unsaturated fatty acids under high salt conditions.…”

Molecular Mechanisms Underlying Phenotypic Degeneration inCordyceps militaris: Insights from Transcriptome Reanalysis and Osmotic Stress Studies

“…In support of this notion, our experiments under hyperosmotic conditions revealed that all three neutralized C. militaris strains underwent phenotypic degeneration, characterized by suppressed fruiting body and hyphal development, but increased conidia density and glycerol accumulation. Moreover, the radical growth of C. militaris and the expression of the Fus3 and Hog1 genes were repressed in a concentration-dependent manner under hyperosmotic conditions (42). Taken together, these findings suggest that the continuous activation of the HOG cascade under artificial culture conditions may lead to the dysregulation of MAPK pathway genes and phenotypic switching.…”

Research Progress in Understanding the Molecular Biology of Cordyceps militaris

“…In our previous study, C. militaris growth was inhibited by salt treatments, but COR production increased significantly with an increase in salt concentration. Transcriptome analysis of the salt-treated and control C. militaris groups revealed 3885 DEGs, among which DEGs associated with amino sugar and nucleotide sugar pathways were significantly enriched in the salt-treated group [51]. Salt treatment might increase energy molecule production and further promote COR accumulation.…”