Studay On Sreening Of Gucuronic Acid-producing Srains And The Clture Cnditions

Currently the preparation of glucuronic acid mainly uses chemical technology,but there are still many problems in the actual production process to be solved.Considering these existing problems,this paper presents a method of using microbiological technology to produce GA,namely to produce GA by producing capsular polysaccharide which is enriched with GA through bacterial fermentation.This technology provides a new idea for the industrial production of GA and has prolong significance in energy saving and environmental protection.A GA-producing strain is isolated and purified from 13 composite bacteria powder,named JZYB@-1 and Laboratory strains of the preservation JZYB@-2,which produces capsular polysaccharide containing rich GA.Through the physiological and biochemical identification,JZYB@-1 is a silicate bacterium,belonging to the category of bacillus mucilaginosus.Initially optimize the liquid culture conditions through the single-factor experiments,orthogonal experiment and the response surface optimization test method to increase the polysaccharide yield,which lays foundation for further expansion of the production scale of fermentation and the production of GA.This part consists of the optimization of both medium and fermentation conditions.The result of medium optimization;glucose source 2.5%,MgSO4·7H2O 0.8 g/L,K2HPO4 1.8 g/L,without nitrogen source,the yield of polysaccharide is 3.39 g/L on this medium.The result of fermentation conditions optimization:temperature34?,inoculum size 6%,rotary shaker 220 r/min,pH7.0,medium capacity 50 mL/250 mL,inoculum age 48 h,fermentation time 6 d,the yield of polysaccharide is 5.31 g/L in thisfermentation condition.Extract the crude polysaccharide from fermentation liquid,after being extracted by DEAE-Cellulose ion-exchange column chromatography,the polysaccharide will be graded and collected,named EPS-I,accounting for 79.0%of the total polysaccharide.Then the polysaccharide products will be further purified through SephadexG-100 gel chromatography.The purity rate is 98.6%.Determine the GA content of the pure EPS-1 by sulfuric-carbazole and HPLC,respectively,as follows:39.2%and32.7%.