Agroindustrial waste as ecofriendly and low-cost alternative to production of chitosan from Mucorales fungi and antagonist effect against Fusarium solani (Mart.) Sacco and Scytalidium lignicola Pesante.

This study aimed to evaluate the production of fungal chitosan (FuChi) from Mucorales fungi cultivated in a cashew apple juice (CAJ) and cheese whey (CW) mixture, and to determine the growth-inhibitory effect of this biopolymer against Fusarium solani CFF109 and Scytalidium lignicola CMM1098, which cause root rot disease in cassava plants. Cunninghamella phaeospora UCP 1303 and Cunninghamella elegans UCP 1306 showed the highest FuChi production in screening assay, being selected to a CCRD 22 design to analyze the influence of different CAJ and CW concentrations in the increase of FuChi production. All nine Mucorales fungi cultivated in CAJ-CW medium, showing FuChi production in the range of 27.58 (Mucor hiemalis UCP 1309) to 65.40 mg/g (C. elegans UCP 1306). During CCRD 22 design, the highest FuChi production (64.09 mg/g) was achieved by C. elegans UCP 1306 cultivated in medium containing 40% (v/v) of CAJ and 30% (v/v) of CW, presenting 75% deacetylation degree and crystallinity indexes of 41.50%. FuChi at 16000 μg/mL showed a better inhibition against S. lignicola mycelial growth (81.70%) when compared with F. solani (22.13%) and induced alterations in hyphae morphology on both strains. CAJ and CW are promising substrates for FuChi production, and this biopolymer shows antimicrobial effect against F. solani and S. lignicola.