Fungi Sm0406 Species Separation And Identification Of Xylanase Purification Study

Xylan, the major component of hemicullulose, is the second abundant renewable energy source in the earth. It serves as the main carbon source for various kinds of microorganisms which could secret a series of xylanolytic enzymes. These xylanolytic enzymes act synergetically to hydrolyze the xylan to xylooligosaccharide and xylose. Xylanolytic enzymes have potential applications in a wide range of industrial fields, such as covering bioconversion, food, animal feed, paper and pulp, energy sources, medicine , weave et al.In the research, the strain named SM0406, which was preserved in our lab, could secret high amounts of endo-xylanase with relatively high activity towards xylan. The colony of SM0406 incubated in the potato medium presented dark green, round , bulgy, dry, lackluster. The hypha of the strain SM0406 was slightness, little fork, no diaphragm, smooth surface, and its diameter was 0.8-1.5 μm with Scanning Electron Microscope ; and conidiophore show broom shape, and spores put forth from the top of it. The shape of the spore assumed short stick, its diameter was 1 ² μm and it was 4⁶ μm in length. The strain SM0406 could hydrolyze the cellulose and starch, but it couldn't fluidify glutin. The 18S rDNA and partial ITS sequences was cloned, and the partial results of the 18S rDNA sequence of strain SM0406 aligned with the 18S rDNA sequences of a number of Myrothecium strains in the GenBank/EMBL, the strain had high similarity with the fungi Myrothecium sp., and therefore it was named Myrothecium sp. SM0406 (Msp. SM0406 for short) .At the same time, the liquid state fermentation media for xylanase production by M. sp. SM0406 was optimized. The optimized medium contained wheat bran 2 %; (NH₄)₂SO₄ 0.1 %; each 500 ml gular flask containing 100 ml of medium, inoculum size 3 % and a harvest time of 6 days. Under these optimized conditions, xylanase activity of 89.6 IU/ml was obtained.By centrifugation , ultrafiltration , gel filtration chromatography and anion-exchange, an endo-xylanase I was purified from the crude culture filtrate of M. sp. SM0406. The molecular weight of the purified xylanase was approximately 48 kDa.