CHITOSAN FROM ABSIDIA-COERULEA

The chitosan-glucan complex system in Absidia coerulea grown in YM med ium aerobically for 72 h at 25 degrees C is more sensitive to alkali t han the complex from other Mucoraceae previously studied. As a consequ ence, the chitosan can be isolated by boiling the biomass in 25% NaOH for 3 h, washing to neutrality and freeze-drying. Typically, the chito san is highly filmogenic and has degree of acetylation 0.052, free ami ne 0.86 and average molecular weight 5 x 10(5); it is poorly susceptib le to the hydrolytic action of lysozyme, papain and lipase. The reacet ylated chitosan (degree of acetylation 0.23), besides being soluble in the usual pH range for chitosans, is exceptionally soluble at pH valu es over pH 9 and is promptly depolymerized by lysozyme, papain and lip ase.