CHITOSAN FROM ABSIDIA-COERULEA

The chitosan-glucan complex system in Absidia coerulea grown in YM medium aerobically for 72 h at 25 degrees C is more sensitive to alkali than the complex from other Mucoraceae previously studied. As a consequence, the chitosan can be isolated by boiling the biomass in 25% NaOH for 3 h, washing to neutrality and freeze-drying. Typically, the chitosan is highly filmogenic and has degree of acetylation 0.052, free amine 0.86 and average molecular weight 5 x 10(5); it is poorly susceptible to the hydrolytic action of lysozyme, papain and lipase. The reacetylated chitosan (degree of acetylation 0.23), besides being soluble in the usual pH range for chitosans, is exceptionally soluble at pH values over pH 9 and is promptly depolymerized by lysozyme, papain and lipase.