Laboratory scale production of 13C labeled chitosan by fungi Absidia coerulea and Gongronella butleri grown in solid substrate and submerged fermentation

Nowadays, chitin and chitosan are applied in many medical and pharmaceutical products. However little is known about the metabolism of chitin and chitosan in vivo. In the human body, lysozyme will degrade chitin and chitosan into chito-oligosaccharides. 13C labeled chitosan is an essential prerequisite for the further study of the fate of chito-oligosaccharides in vivo. To fulfill this requirement, chitosans were extracted from mycelia of fungi, Absidia coerulea ATCC 14076 and Gongronella butleri USDB 0201 and ATCC 42618 grown in solid substrate fermentation (SSF) and submerged fermentation (SMF) to select the best fungus and fermentation method for the production of 13C labeled chitosan. Based on the production yield of chitosan, the SSF method is the best method for the production of fungal chitosan when compared with SMF methods (i.e., fed-batch fermentation and batch fermentation). However synthesis of 13C labeled chitosan in cell wall of G. butleri grown in SSF medium coated with 1-13C-glucose was not observed. Alternatively, fungus A. coerulea was grown in SMF medium containing 2-13C-glucose. The successful synthesis of 13C labeled glucosamine from 2-13C-glucose was observed in mycelia of A. coerulea grown in SMF medium containing 2-13C-glucose in a yield of about 13 g/100 g mycelia.