Transcriptional expression profiles and enzyme activity of UGPase from Letinous edodes under different carbon and nitrogen sources

Abstract:

[Objectives] UDP-glucose pyrophosphorylase (UGPase) is a key enzyme involved in carbohydrate metabolism, which plays an important role in the biosynthesis of secondary metabolites. It will be helpful to elucidate the molecular mechanism of glucose metabolism to study the UGPase. [Methods] Different carbon and nitrogen sources were used to culture the Lentinula edodes Xin808 in this study. The biomasses were measured by drying the mycelium. The contents of intracellular polysaccharide were determined by phenol-sulfuric acid. The transcriptional expression profiles of ugp were analyzed by real-time quantitative PCR, and enzyme activity of UGPase were also determined. [Results] The results showed that, comparing to the control, besides NH4NO3 treatment group, the rest of carbon and nitrogen sources could increase the biomass of Letinous edodes, among which wheat bran exhibited as the best (0.63g). The small molecule (sucrose, maltose and mannose) as carbon sources and organic compounds(wheat bran and yellow bean sprouts) as nitrogen sources, ugp gene expression quantity obviously were up-regulated, increased UGPase activity, promoted the biosynthesis of mycelium intracellular polysaccharide. With sucrose as carbon source and wheat bran as nitrogen source, the transcriptional expression level of ugp gene, the activity of UGPase (4043.80U/mg and 3873U/mg) and mycelium polysaccharide content (3.60% and 3.86%) were the highest, ugp gene expression quantity respectively were 8.19 and 6.52 times to the control group. [Conclusions] The transcriptional expression levels of ugp gene, the activity of UGPase and mycelium intracellular polysaccharide of Letinous edodes showed high positive correlation between the three. The small molecule carbon sources(sucrose, maltose and mannose) and organic nitrogen sources (wheat bran and yellow bean sprouts) were helpful to the biosynthesis of mycelium polysaccharide. Sugar and wheat bran could be used as advantage carbon source and nitrogen source under Letinous edodes liquid fermentation.