Enzymatic Conversion Of Starch Production To Make Trehalose By Immobilized Cells

Trehalose is non-reducing saccharide, composed of two glucose molecules.Some species have tolerance in harsh environment such as high temperature, dry,dehydrated, frozen, high osmotic pressure and toxic substances, which is associatedwith their trehalose.The unique properties of trehalose make biological cells, nucleicacid, protein, fat, sugar and other material not damaged, so as to maintain cellactivities. Exogenous trehalose can also have good non-specific protection effects onorganism and biological macromolecules, therefore, trehalose is widely used in allwalks of life, such as food, medicine, agriculture, cosmetics and so on. But as a resultof the difficult preparation and purification of trehalose, its application islimited.Currently, the method of enzyme catalysis is commonly used.This researchadopted the enzymatic synthesis of trehalose.Contents included:Bacillus thermophilicwas selected to be the original strain,and then selected strains synthetizing trehalosesynthase with high yield, and made the preliminary identification of the strain,determination of toxicology, etc;And then made separation and purification oftrehalose synthase producing strains, and the determination of physiological andbiochemical characteristics; Choose the appropriate immobilized carrier and madereactive activation to determine the fixed condition of cells, the catalytic characteristicsof immobilized cells and vitality determination; Optimizing the immobilized cells forcontinuous use; Study separation and extraction of trehalose, to get trehalose productswith high purity.This study obtained recombinant Bacillus Subtilis with efficient expression ofTreS synthase, and successfully expressed trehalose synthase.We also made shake flaskculturing conditions and medium optimization of the restructure Bacillus Subtilis. Andinduction time is the middle and later periods of the logarithm.Inorganic nitrogensource was good for bacteria to grow, and had obvious effects on the proteinexpression.Organic nitrogen source of yeast powder and peptone not only affected thegrowth of bacteria,but also promoted protein expression, which layed the groundworkfor the fermentation tank culture and amplification.According to the sugar solution concentration and composition of feed afterconversion of trehalose synthase, the best separation result: the purity of trehalose was87.8%, its average mass concentration was57.1g/L; the purity of Maltose was96.8%,the average quality was70.2g/L.