Study On Screening Of Hesperidinase-Producing Strain And Preparation Of Hesperetin Monoglucoside By Ferment-Extracted Coupling

Hesperetin monoglucoside (HMG) is formed by stripping rhamnose from hesperidin. Its physiological activity is similar to hesperidin, while its solubility and absorpting utilization are higher than hesperidin. The hesperidinase-producing strain screened, the fermentation conditions of the strain optimized and the yield of HMG improved were studied in this paper.A hesperidinase-producing strain from soil samples of the hesperidin-producing factory was screened and identified as Fusarium nivale by the micrograph morphology observation and18S rDNA sequence analysis. It was stored at the Institute of Microbiology, Chinese Academy of Sciences, accession number:6238. The main components of the enzymatic hydrolysate were HMG and hesperetin which indicated the enzyme contained a-L-rhamnosidase and B-D-glucosidase.Effects of carbon source, nitrogen source, inorganic salt, the addition of hesperidin, inoculation size, fermentation temperature, pH value and shaking speed on enzyme activity produced by Fusarium nivale6238were investigated. The fermentation conditions were optimized by response surface method (RSM). Results showed the optimum medium combinations were30g/L sucrose as carbon source,3g/L yeast extract as nitrogen source,1g/L K2HPO4as inorganic salt and3%hesperidin; and the optimum fermentation conditions were inoculum size6%(v/v), temperature30℃, pH6, speed158r/min. In this condition, a-L-rhamnosidase activity reached95.6U/ml.The resin HPD100with good adsorption and analytical capacity on HMG was chosen from the different polarity of resins. Effects of different adsorption and elution conditions were studied. Results showed in the elution condition of50%ethanol solution,2BV/h flow rate, HMG and hesperetin could be separated completely with the resin HPD100.Fermentor and macroporous resin column were connected to prepare HMG. Effects of different conditions on the yield of HMG were studied. Results showed the yield of HMG was increased from13.3%to48.3%on3BV/h reflux rate.A high yield hesperidinase-producing strain was screened in this study. The yield of HMG was significantly improved by the Fermentation-Enzymolysis-Extracted coupling. It provided a more feasible way to improve the added value of citrus flavonoids.