Study On Production Of Fructosvltransferase Strain Screening And Fermentation Conditions

Fructooligosaccharides (FOS) is consist of sucrose and 1-3 fructose molecules combined by glucosidic bond, which is obtained in microbes and plants and formed by transferring fructose in sucrose by enzymes. Fructooligosaccharides can be widely used as feed additives, functional food and new functional sweeteners.The experimental research is mainly screening high fructosyltransferase activity of strain and increasing its enzymatic activity. By mutagenesis and fermentation optimization method, we can improve the Fructooligosaccharides yield.First, use sucrose to initial screening of strains producing fructooligosaccharides. Then detect Fructooligosaccharides existence and content in liquid fermentation by High Performance Liquid Chromatography (HPLC) to obtain strains producing fructooligosaccharides. Liquid chromatography detection by intracellular enzyme reaction of the crude enzyme solution to obtain the strain of high enzyme activity, enzyme activity reached 14.9U/mL screened strains. Colony morphology, bacteria, spores observations combined with identification of strains of Aspergillus niger strains. The strain was been named Aspergillus niger ZJ.Aspergillus niger strains after microwave radiation mutagenesis and ultraviolet radiation mutagenesis improve ZJ strain of Aspergillus niger fructosyltransferase activity. Screened strains of high enzyme activity by microwave mutagenesis, and then screened again ultraviolet radiation mutagenesis strains with high enzyme activity after the two joint mutagenic screened activity 21U/mL strains, The strain was been named Aspergillus niger ZJ04-5.Aspergillus niger ZJ04-5 as the originating strains, enzyme production optimization.Medium composition, fermentation conditions for single factor and orthogonal experimental analysis, screening out the concentration of sucrose, yeast extract concentration, fermentation temperature, the amount of inoculation as orthogonal analysis four factors, these four factorson a three-level design of experiments, orthogonal analysis. The optimal fermentation conditions can be obtained from Aspergillus niger ZJ04-5:20% sucrose, yeast extract 3% FeSO4·7H2O 0.05%, MgSO4·7H2O 0.05%, MnSO4 0.05%, pH6. The optimum culture conditions: culture temperature 26℃,3% of the inoculum size, liquid volume of 100 mL/300mL speed 150r/min, shake flasks time 3 days. Aspergillus niger ZJ04-5 strain cultured under the above conditions fructosyltransferase enzyme activity can be achieved 52U/mL. Optimization culture strains activity increases twice than before.