Concurrent production of chitin from shrimp shells and fungi

Crustacean shells constitute the traditional and current commercial source of chitin. Conversely, the control of fungal fermentation processes to prod uce quality chitin makes fungal mycelia an attractive alternative source. T herefore, the exploitation of both of these sources to produce chitin in a concurrent process should be advantageous and is reported here. Three prote olytic Aspergillus niger (strains 0576, 0307 and 0474) were selected from a screening for protease activity from among 34 zygomycete and deuteromycete strains. When fungi and shrimp shell powder were combined in a single reac tor, the release of protease by the fungi facilitated the deproteinization of shrimp-shell powder and the release of hydrolyzed proteins. The hydrolyz ed proteins in turn were utilized as a nitrogen source for fungal growth, l eading to a lowering of the pH of the fermentation medium, thereby further enhancing the demineralization of the shrimp-shell powder. The shrimp-shell powders and fungal mycelia were separated after fermentation and extracted for chitin with 5% LiCl/DMAc solvent. Chitin isolates from the shells were found to have a protein content of less than 5%, while chitin isolates fro m the three fungal mycelia strains had protein content in the range of 10-1 5%. The relative molecular weights as estimated by GPC for all chitin sampl es were in the 10(5) dalton range. All samples displayed characteristic pro files for chitin in their FTIR and solid-state NMR spectra. All chitin samp les evaluated with MTT and Neutral Red assays with three commercial cell li nes did not display cytotoxic effects. (C) 2001 Elsevier Science Ltd. All r ights reserved.