P104: Overexpression of chitosanase gene in Bacillus subtilis for the production of glucosamine from chitosan

Glucosamine can be imported by cells and incorporated into newly synthesized UDP-N-acetylhexosamine, the precursors for glycosaminoglycan synthesis. It is commercially used by osteoarthritis patients for symptom relief. Glucosamine is produced by acid hydrolysis methods. A chitosanase gene was cloned from Bacillus subtilis NCHU-05 into expression vectors under the control of synthetic sigma A-type promoter and expressed in B. subtilis WB800. About 120 mg/l of recombinant chitosanase could be obtained after 16h incubation at 37°C. Expressed chitosanase could be recovered by adsorption-elution on chitin. About 89% of chitosanase in the culture broth could be absorbed on 8% chitin at pH5.6 and 40°C for 2h. Purified recombinant chitosanase exhibited specific activity of 3,780 U/mg. High performance liquid chromatography analysis revealed the major product from chitosan hydrolyzed by purified recombinant chitosanase was glucosamine (>99%). We found that glucosamine could also be produced from chitosan by using chitin-immobilized chitosanase.