Screening Of Fucoidanase Producing Bacteria And Study On Its Enzyme Characters And The Application Of Oligosaccharides

Fucoidans is a unique class of sulfated polysaccharide with many special activities. And oligosaccharides from fucoidans are more valuable than the whole fucoidans due to their low conglutination and high solubility. In this paper, samples are collected from different coastal areas in Qingdao in order to obtain bacteria producing fucoidanase. After enriching, separating, first-screening and second-screening, induced mutation and screening after induced mutation, five strains capable of producing high fucoidanase activities are separated and selected. Among them, the strain A has the highest activity and the fucoidanase activity is as high as 3.68U. After the thalli and colony features are analyzed, the strain A is identified to be Erysipelothrix Rosenbach according to Bergey's Manual of Determinative Bacteriology. Besides, the optimal culture media, the optimal fermentation condition and some factors effects on fucoidanase activity are investigated through the single factor test.By studying characteristics of fucoidanase, a conclusion has been made that the fucoidanase has a high thermal stability and pH stability. And fucoidanase can retain its activity under 50 centigrade and within pH 4-7. At the same time, the study shows that Mg2+ can promote the fucoidanase activity greatly when its concentration is up to 1 10-2mol/LIn addition, the formation of cerium(IV)-oligosaccharide complexes and catalytic hydrolysis of collagen by the complexes are also discussed in this research. After fucoidans degrading, oligosaccharides with different molecular weight, Fl, F2 and F3, are gained. The molecular weight range of Fl, F2 and F3 are more than 5000, from 1000 to 5000 and less than 1000 respectively. The result shows that F3 is obviously easy to form the complex with cerium compared with F2 and F3. And the cerium(IV)-F3 complex has much greater catalytic activity of hydrolysis collagen than cerium(IV)-Fl and cerium(IV)-F2 complexes. Moreover, the optimum ratio and the optimum hydrolysis conditions are also obtained in this article.