Study On Extraction And Microbial Transformation Of Total Saponins From Dioscorea Zingiberensis

Dioscorea zingiberensis is a unique plant resource of China.Diosgenin is an important medicinal raw materials produced from D.zingiberensis.At present,the traditional method to produce diosgenin is acid hydrolysis method.Pollution caused by acid hydrolysis process is extremely serious for environment and the pollution problem has become the bottleneck restricting the development of diosgenin production industry.So it is extremely important to find a clean process to produce diosgenin.In this study,a new process for the efficient extraction and clean conversion of diosgenin was established.The main results are as follows:（1）The process of ultrasonic assisted extraction of total saponins from Dioscorea zingiberensis was established:First,the method of determining the total saponin content by perchloric acid coloring method was established.The method could quickly and accurately determine the total saponin content.At the same time,the optimum process of ultrasonic extraction of total saponins was determined as follows:ethanol volume fraction70%,material ratio 1:15,ultrasonic power 200w,ultrasonic extraction 30 min,under the extraction conditions,a total of 23±0.3 mg of total saponins can be extracted from the dry powder of Dioscorea zingiberensis.（2）The fermentation conditions for the production of saponins from total saponins from Aspergillus tubingensis were established and optimized.The optimum conditions for inactivation were as follows:inoculation amount 10%,substrate concentration 2g/L,initial pH 6.0,conversion temperature 37℃.The yield of diosgenin was19.1±0.3 mg/g,and the total saponin conversion rate was 80%.（3）Through the study of the catalytic properties of extracellular glucosidase,the conversion of total saponins was improved.By studying the catalytic properties of the glucosidase,it was found that the optimum temperature of the enzyme was 50℃,the optimum pH was 6.0,and the addition of Mg²⁺could increase the activity of 30%.According to the above catalytic properties of the enzyme,In the late stage of transformation of the total saponins of Aspergillus tubingensis,the temperature was raised to 50°C,and the yield of diosgenin was 21.2±0.6 mg/g DZW,which was 10.5%higher than that before.In summary,this paper established the technology of the extraction of total saponins from Dioscorea zingiberensis and the production of diosgenin from Aspergillus tubingensis,which provided the experimental basis for the industrial application of clean production of saponin by microbial transformation.