苹果树腐烂病菌发酵液中根皮苷主要降解成分的分析

Component analysis of Valsa malivar.malifermentation liquid degrading phlorizin

【目的】明确苹果树腐烂病菌致病过程中对降解根皮苷发挥主要作用的物质,为揭示该病原菌的致病机理提供理论依据。【方法】以根皮苷为碳源发酵培养苹果树腐烂病菌10d后,测量菌丝干质量及病原菌对根皮苷的降解率;以淀粉为碳源获取病原菌30d的无菌发酵液,进一步分离发酵液中的有机酸和蛋白类物质。用HPLC法分别检测病原菌、淀粉无菌发酵液、有机酸类、蛋白类物质及发酵剩余液对根皮苷的降解作用。【结果】以根皮苷为碳源发酵培养病原菌10d后,每100mL发酵液中菌丝干质量为48mg,病原菌对根皮苷的降解率为92.46%,发酵液对根皮苷的降解率为99.88%。1mg/mL蛋白类物质与根皮苷作用5d的降解率为90.4%,有机酸类对根皮苷的降解率仅为1.6%,发酵剩余液对根皮苷的降解率为5.9%。根皮苷的降解率随蛋白液质量浓度的增加和作用时间的延长而升高。【结论】在根皮苷降解过程中起主要作用的物质为苹果树腐烂病菌代谢产生的蛋白,其可能为细胞壁降解酶类。

【Objective】 The study aimed at elucidating the Valsa mali var.mali metabolites produced during pathogenesis,which can degrade phlorizin,the main content in apple tree bark,and provide a theoretical basis for revealing the pathogenic mechanism.【Method】 Mycelium dry weight together with the degradation rate of phlorizin were measured 10 days after pathogen fermentation using phlorizin as carbon source.In the meantime,30 days＇ pathogen fermentation filtrate was obtained by using starch as carbon source.Then the organic acids and proteins were further isolated from the filtrate.The organic acids and proteins free filtrate were regarded as residual liquid.The degradation rate of phlorizin by the pathogen and the degradability of phlorizin by starch fermentation filtrate,organic acids,proteins and residual liquid were determined by HPLC.【Result】 Results showed that the mycelium dry weight was 48 mg per 100 mL in 10 day＇s fermentation liquid using phlorizin as carbon source.The degradation rate of phlorizin by the pathogen was 92.46% after 10 days＇ reaction,and the rate reached 99.88% by starch fermentation filtrate.Proteins of 1 mg/mL can degrade 90.4% of phlorizin after 5 days＇ treatment.Organic acids and residual liquid,on the other hand,could merely degrade 1.6% and 5.9% of phlorizin,respectively.And the phlorizin degradation rate increased as the proteins concentration and reaction time increased.【Conclusion】 Proteins,which possibly were cell wall degradation enzymes,produced by pathogen play an important role in phlorizin degradation.