Evidence for cutinase production by Aspergillus flavus and its possible role in infection of corn kernels

Aspergillus flavus can infect nondamaged corn kernels and produce aflatoxins before harvest. Experiments were conducted to determine if A. flavus produces cutinase and, if so, to investigate its possible role in kernel infection. Plate assays in vitro showed that A. flavus can grow on purified cutin as the sole carbon source and that it secretes extracellular cutinase. A. flavus grew better in Liquid culture at pH 8 than at pH 6. Most cutinase substrate (p-nitrophenyl butyrate [PNB]) hydrolysis activity was in the 30% ammonium sulfate fraction. Two proteins with different PNB hydrolysis activity, designated C-1 and C-2, were isolated from A, flavus culture filtrates using native polyacrylamide gel electrophoresis.