香菇UDP-葡萄糖焦磷酸化酶转录水平及酶活性对不同碳氮源的响应特征

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

以香菇新808为材料,利用苯酚-硫酸法和qPCR技术分析不同碳氮源下菌丝体多糖含量及尿苷二磷酸葡萄糖焦磷酸化酶基因相对表达量,并测定其酶活性.结果表明,与对照组相比,除硝酸铵处理外,其余处理均能提高香菇菌丝体生物量,以麦麸处理的生物量最大(0.63g).以小分子糖(蔗糖、麦芽糖和甘露糖)为碳源、有机复合物(麦麸和黄豆芽)为氮源时,UGP基因表达量明显上调,酶活性更高,菌丝胞内多糖含量也明显提高.其中蔗糖和麦麸处理下的UGP基因表达量、酶活性和菌丝胞内多糖含量最高.香菇菌丝UGP基因表达量、酶活性以及胞内多糖间存在明显的正相关关系.显示小分子碳源(蔗糖、麦芽糖和甘露糖)、有机氮源(麦麸和黄豆芽)有助于香菇菌丝多糖的合成,其中蔗糖和麦麸可作为香菇液体发酵优势碳源和氮源.

Different carbon and nitrogen sources were used to culture the Lentinula edodes Xin808 in this study. The contents of intracellular polysaccharide were determined by phenol-sulfuric acid. The expres- sion level of UDP-glucose pyrophosphorylase, UGP gene were analyzed by real-time quantitative PCR, and enzyme activity of UGP were also determined. The results showed that, comparing to the control, besides NH4NOa 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 relative expression level obviously were up-regulated, increased UGP activ- ity, promoted the biosynthesis of mycelium intracellular polysaccharide. With sucrose as carbon source and wheat bran as nitrogen source, the relative expression level of UGP gene, the activity of UGP and mycelium polysaccharide content were the highest. The expression level 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 ni- trogen sources （wheat bran and yellow bean sprouts） were helpful to the biosynthesis of mycelium poly- saccharide. Sugar and wheat bran could be used as advantage carbon source and nitrogen source under Letinous edodes liquid fermentation.