Study On Efficiently Microbial Transformation Of Polydatin By Endophyte In Polygonum Cuspidatum

Resveratrol is a natural active polyphenol compound. Resveratrol has many pharmacological functions such as cancer prevention, cardiovascular protection, anti-oxidation and anti-free radical. It was classified as one of the most promising anti-cancer drugs. Resveratrol in Polygonum cuspidatum is often in the form of Polydatin. Resveratrol content in the dry root and stem of Polygonum cuspidatum is only about0.2%, while polydatin content is up to2%. At present, directly extracting resveratrol from Polygonum cuspidatum was wasted too much time, labor and resources. The chemical synthesis methods also have several disadvantages, such as, low yield and environmental hazard. To solve these problems, the microbial transformation method was used to ferment Polygonum cuspidatum in the paper. Endophytic fungi strain J1was found have the efficient ability to transforming polydatin to resveratrol. Through mutation breeding, excellent mutant strain UJ1was obtained. Then optimization of fermentation medium and fermentation conditions of strain UJ1in shake flask was studied, and10L fermentor validation test was studied. The main results were as follows:1. Six endophytic fungi strains were screened from Polygonum cuspidatum s stem and root. It showed that, testing by HPLC, six endophytic fungi strains all have the ability to transforming polydatin. Strain J1had the highest conversion rate at25.6%. The resveratrol yield in fermentation broth was14.068μg/mL which was2.65times as that of culture medium before fermenting.2. Combined with morphological and molecular characteristics, strain J1was identified as Penicillium oxalicum and Genbank accession number was HQ732137.3. Endophytic fungi strain J1was mutanted by UV and60Co γ ray. The mutant strain UJ1with high genetic stability was obtained, whose conversion rate was8.4%higher than the original strain.4. According to the optimization of fermentation medium and fermentation conditions in flask, the optimal fermentation medium contained Polygonum powder1.5%, pure ethanol2%, CMC-Na2.5%, NH4NO30.2%, Na2HPO40.06%, CaCl20.1%. The optimal fermentation conditions were as follows:fermentation temperature of28℃, initial pH5.5, inoculum sizes of9%,250mL shake flask with30mL of medium, rotation speed of220r/min and fermentation time of60h. Under the optimal fermentation medium and fermentation conditions, the average conversion rate of polydatin could up to90.1%which was56.1%higher.5. Based on the optimal fermentation medium and fermentation conditions in flask,10L fermentor validation test was studied. The results showed that the highest conversion rate of polydatin J1strain in10L fermentation cylinder was82.5%at56hours.