Application of UHPLC-MS/MS-Based on Metabonomic Techniques to Analyze the Cordyceps cicadae Metabolic Profile Changes on Urea Response Mechanism in the Process of Ergosterol Synthesis

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Abstract

Nitrogen source is a necessary nutrient factor in the process of mycelial growth and metabolite synthesis. In the previous study, we have explored the differentially expressed genes resulted from urea by transcriptome analysis. In the present study, urea was used to examine its effects on cell membrane permeability and metabolic flow in the process of Cordyceps cicadae fermentation and ergosterol synthesis. Metabonomic results showed that urea supplementation caused significant changes in five aspects: (1) urea anotably increased biomass growth and extracellular ergosterol, and decreased intracellular ergosterol concentration; (2) urea boosted inositol 1,4-bisphosphate level, which implied the acceleration of cell membrane decomposition, the weakening of integrity, and the increase of permeability; (3) urea increased the levels of amino acids, vitamins, hormones, and nucleotides, which exhibited an elevated biomass growth; (4) urea promoted the synthesis of intracellular flavonoids, alkaloids, and terpenes, which facilitated extracellular ergosterol syn-thesis by increasing membrane permeability; (5) In the fermentation anaphase, urea caused that the 6-phosphogluconate dehydrogenase and α-ketoglutarate dehydrogenase activities were inhibited, and decreased NADPH, NADH and ATP synthesis, and finally inhibited the biomass growth and ergosterol synthesis. Collectively, metabonomics was a valuable strategy to study the regulatory effects of medium composition and incubation conditions on the ergosterol synthesis by C. cicadae.