Abstract
Addition of chitosan, either native (from crab) or a chemically-derived derivative (N-carboxymethyl chitosan), to liquid fungal culture at certain concentrations markedly reduced growth of Aspergillus flavus and A. parasiticus. The effect of chitosans on aflatoxin production varied based on the type and concentration of the material. Reduced levels of native chitosan inhibited fungal growth, whereas the chitosan-derivative stimulated synthesis of the toxin. After 8 days, A. flavus treated with the chitosan derivative produced 345.96μg aflatoxin B1/g mycelia, whereas control cultures without chitosan produced 10μg toxin/g mycelia. Elevated concentrations of either chitosan inhibited aflatoxin production. Chitosan exhibited the greatest effect on fungal growth when it was added to culture flasks during the early fermentation phase. Aflatoxin production by both Aspergillus species was inversely related to fungal growth in cultures containing lower concentrations of chitosan-derivative.
