Studies On Oxyresveratrol Using Microbial Transformation Method

ObjectiveTo study on oxyresveratrol by using the method of microbial transformation in order to provide a new approach to increase the yield of the production of oxyresveratrol.Methods(1) This study adopted liquid fermentation method for transformation which based on mulberry branch and Asperigillus niger;(2) HPLC method was found to investigate the fluctuation of contents of stibenes;(3) Orthogonal experiment was used twice to optimize the culture medium and condition of fermentation;(4) In addition, the stability of oxyresveratrol was observated and studied.Results(1) Established the method of HPLC which is simply, accurate and available for determination simultaneously the contents of mulberroside A and oxyresveratrol. The mulberry branch was selected as a kind of appropriate substrate martial under measurement different parts of mulberry. Moreover, mulberroside A which occupies the highest percentage of the mulberry branch was defined as the transformation substrate.(2) The optimum fermentation culture medium were investigated by the first orthogonal test. They are soluble starch4%, peptone1%, mulberry branch2%, KH2PO40.4%,(NH4)2SO40.4%, MgSO40.08%.(3) The optimum fermentation concisions were investigated by the second orthogonal test. They are initial pH at3.5, rotating speed of150rpm, culture temperature of45℃, inoculums size of3%.(4) Oxyresveratrol performs superiority at thermostability, but shows inferior light stability.Conclusion(1) There are abundant resources for mulberry in our country. The experiment determination results that the oxyresveratrol was mainly existence in the form of mulberroside A of picked mulberry at end of May which leads to the content of mulberroside A was far more over than the content of oxyresveratrol. In that case, the mulberroside A may can be one of the main source of oxyresveratrol.(2) In this paper, it had been discovered that the mulberroside A could be efficiently transformed to the oxyresveratrol by Aspergillus Niger. The largest transformation rate was achieved in99.8%by terms of orthogonal experiment.(3) The microbial transformation has owned the advantages of short period, environment friendly and cost efficiency. This method is proved potential for industrial application due to its gentle reaction, simply procedure, lower cost as well as high yield of oxyresveratrol.