PRODUCTION OF CHITOSAN BY FUNGI

Chitosan is a novel biopolymer with numerous industrial, food, and bio medical applications. Our studies examined the production of chitosan from mycelia of Absidia coerulea, Mucor rouxii, Gongronella butleri, P hycomyces blakesleeanus and Absidia blakesleeana. In batch culture, st rains were screened to determine the fastest growing and greatest chit osan-yielding fungi. Optimum chitosan yields were observed for most cu ltures at 21-degrees and 26-degrees-C in 1% yeast extract, 0.4% glucos e, and 0.3% peptone. A. coerulea ATCC 14076 and NRRL 1315 were the bes t producers of chitosan of the strains examined. Chitosan yields of A. coerulea, M. rouxii, G. butleri, P. blakesleeanus and A. blakesleeana were 47-50, 29-32, 21-25, 6 and 7 mg/100 mL of medium, respectively. The degree of acetylation of chitosan ranged from 6 to 15%; the lowest was from strains of A. coerulea. Viscosity average molecular weights of fungal chitosans were equivalent, approximately 4.5 x 10(5) daltons . A. coerulea 14076 yielded the most chitosan, 51 mg/100 mL of medium at pH 5.5 in 48 h. Supplementation with 0.5 mg of cobalt/100 mL medium showed an increase of approximately 20% in the chitosan yield form A. coerulea 14076. Batch fermentations were carried out in flask, airlif t and stirred tank fermentors. Fermentation by continuous culture in t he stirred tank reactor produced the highest amount of chitosan from A . coerulea 14076 resulting in an approximate three-fold increase in ch itosan production as compared to batch culture.