Chitosan produced from Mucorales fungi using agroindustrial by-products and its efficacy to inhibit Colletotrichum species

This study evaluated corn steep liquor (CSL) and papaya peel juice (PPJ) in mixture as substrates for the cultivation (96h, 28 degrees C, pH 5.6, 150 rpm) of Mucorales fungi for chitosan production, and determined the growth-inhibitory effect of the fungal chitosan (FuCS) obtained under optimized conditions against phytopathogenic Colletotrichum species. All Mucorales fungi tested were capable of growing in CSL-PPJ medium, showing FuCS production in the range of 5.02 (Fennelomyces heterothalicus SIS 28) - 15.63 mg/g (Cunninghamella elegans SIS 41). Highest FuCS production (37.25 mg/g) was achieved when C. elegans was cultivated in medium containing 9.43% CSL and 42.5% PPJ. FuCS obtained under these conditions showed a deacetylation degree of 86%, viscosity of 120 cP and molecular weight of 4.08 x 10(4) g/mol. FuCS at 5000, 7500 and 10,000 ppm inhibited the growth of all Colletotrichum species tested. FuCS also induced alterations in the morphology of C. fructicola hyphae. CSL-PPJ mixtures are suitable substrates for the cultivation of Mucorales fungi for FuCS production. Chitosan from C. elegans cultivated in CSL-PPJ medium is effective in inhibiting phytopathogenic Colletotrichum species. (C) 2017 Elsevier B.V. All rights reserved.