Sustainable chitosan production by mucoralean fungi using waste post-frying oils and corn steep liquor as substrates

This study aimed to evaluate three industrial wastes as alternative sources of carbon and nitrogen in the production of chitosan by Cunninghamella bertholletiae URM 7658, Rhizopus arrhizus URM 7651 and Mucor subtilissimus URM 7659. A 23 full-factorial design (FFD) was used to determine the effect of wastes (oily emulsion from collectors wash -OECW-, mixture of waste post-frying oils -MWPO- and corn steep liquor -CSL-) in biomass and chitosan production by the Mucoralean fungi. The obtained biomasses were lyophilized and submitted to a chitosan extraction process using alkali-acid treatment. The polymers were characterized for degree of deacetylation using Fourier transform infrared spectroscopy (FT-IR), crystallinity index by X-ray diffraction and viscosity. The results showed that both C. bertholletiae URM 7658 and M. subtilissimusURM 7659 obtained the highest yields of biomass (25.95 and 8.74 g/L, respectively) and chitosan (69.05 and 41.90 mg/g, respectively) in condition 7 of FFD (1% OECW, 5% MWPO and 5% CSL). However, for R. arrhizus URM 7651, the highest biomass production (12.28 g/L) was found in assay 8 (5% OECW, 5% MWPO and 5% CSL) and chitosan (103.54 mg/g) in assay 5 of FFD (1% OECW, 1% MWPO and 5% CSL). The chitosans obtained presented 75-87% deacetylation degree.