Brazilian Journal of Microbiology
Print version ISSN 1517-8382
OLIVEIRA JUNIOR, Enio N.; GUEDDARI, Nour E. El; MOERSCHBACHER, Bruno. M. and FRANCO, Telma T.. Growth rate inhibition of phytopathogenic fungi by characterized chitosans. Braz. J. Microbiol. [online]. 2012, vol.43, n.2, pp. 800-809. ISSN 1517-8382. http://dx.doi.org/10.1590/S1517-83822012000200046.
The inhibitory effects of fifteen chitosans with different degrees of polymerization (DP) and different degrees of acetylation (FA) on the growth rates (GR) of four phytopathogenic fungi (Alternaria alternata, Botrytis cinerea, Penicillium expansum, and Rhizopus stolonifer) were examined using a 96-well microtiter plate and a microplate reader. The minimum inhibitory concentrations (MICs) of the chitosans ranged from 100 µg × mL-1 to 1,000 µg × mL-1 depending on the fungus tested and the DP and FA of the chitosan. The antifungal activity of the chitosans increased with decreasing FA. Chitosans with low FA and high DP showed the highest inhibitory activity against all four fungi. P. expansum and B. cinerea were relatively less susceptible while A. alternata and R. stolonifer were relatively more sensitive to the chitosan polymers. Scanning electron microscopy of fungi grown on culture media amended with chitosan revealed morphological changes.
Keywords : chitosan; antifungal activity; fungal morphology; phytopathogenic fungi.