Corrosion Behavior of Galvanized Steel Exposed to Fusarium oxysporum f. sp. cumini Isolated from a Natural Biofilm

Abstract

Fusarium spp. are prevalent fungi in water systems and also in biofilm layers developing upon metal surfaces associated with these systems. The present study investigated (i) the presence of Fusarium sp. in biofilms on galvanized steel surface exposed to potable water, and (ii) the effect of Fusarium sp. on corrosion behaviour of galvanized steel by electrochemical methods. The natural biofilm was formed on the galvanized steel surface in a laboratory-scaled test system. Molecular characterization of the tentative Fusarium isolate was carried out by sequencing of the internal transcribed spacer (ITS) regions. The metal coupons were exposed for 336 h to potato dextrose broth medium inoculated with Fusarium sp. The biofilm formation and corrosion products on the metal surfaces were investigated by scanning electron microscopy. The ITS sequences showed that the Fusarium sp. isolate was closely related to Fusarium oxysporum f. sp. cumini (98.97%). The electrochemical analysis revealed that although the test medium was corrosive for the metal, the presence of F. oxysporum f. sp. cumini accelerated the corrosion of galvanized steel. According to the results, this is the first study showing the presence of Fusarium sp. in the natural biofilm formed on the galvanized steel surface and also the effect of Fusarium sp. on corrosion behavior of the galvanized steel in aqueous environment.