Study On The Production Of Hexosamine By Microbial Fermentation

In nature,the hexosamine including glucosamine, galactosamine,mannosamine et al,is an ageneraldesignation of the compounds which individual hydroxyl is substituted byamino,Which is widespread as an amino-monosaccharide. Currently, D-galactosaminewhich can cause animals to obtain hepatitis is used for biochemical studies, Its inducedmechanism of liver injury specifically and as drug target have been researched broadlyand deeply. D-glucosamine was confirmed as the first amino-monosaccharide byLedderhose in1878,which exists in the form of N-acetyl derivative among thepolysaccharides of many animal and microbial sources,not only is a natural componentof the food,but also is an important nutrient for the formation of cartilage cells.Besides,D-glucosamine has a lot of important applications,such as anti-inflammatoryfunction and protecting the liver, stimulating the proliferation of Bifidobacteria in theinfant gut, the treatment of rheumatoid arthritis and stomach ulcers,and inhibiting thegrowth of cancer cells.which cause the global market demand increase sharply. In thispaper, a strain producting galactosamine has been found from the soil samples throughscreening and rescreening,is identified and optimized for fermentation characteristics.What’s more,another strain generating chitosanase has been discovered from the naturalsoil samples and the fermentation conditions have been optimized.(1) A bacteria named YR06is isolated and screened from a rich crab septic mudin Dongying Yellow River mouth wetlands, which can produce galactosamine and isidentified as Aeromonas hydrophila according to the morphological, physiological andbiochemical characteristics and16S rDNA sequence analysis.(2) By the fermentation of the strain with single factor experiment and orthogonaltest, the optimization of medium composition and culture conditions are researched:Fructose10g/L, urea15g/L,Na2HPO415g/L，CaCl222.2g/L，MgSO40.18g/L，KH2PO45g/L,Initial pH for fermentation broth6.5,liquid volume in flask60mL/250mL,temperature33℃and incubation time14h.Under these conditions,theoutput of galactosamine reached128mg/L.(3) A strain with high chitosanase activity was obtained from soil samples usingscreening medium for chitosan as sole carbon source.The chitosanase activity reached2.13U/mL.The strain was identified as Bacillus sp.The fermentation conditions of theenzyme production for the strain was optimized and the best carbon source and nitrogen source were determined that are0.8%colloidal chitosan+0.5%glucose,and0.8％(NH4)2SO4. In the conditions of initial pH6.0, liquid volume in flask50mL (250mL flask),inoculum volume2%,35°C,150r/min fermentation72h,Chitosanase activity reached6.76U/mL in fermentation broth that increased by217.4%than the initial enzymeactivity.