COMPARATIVE DETECTION OF FUMONISIN BY HPLC, ELISA, AND IMMUNOCYTOCHEMICAL LOCALIZATION IN FUSARIUM CULTURES

Fumonisins are a group of mycotoxins that are elaborated by Fusarium m oniliforme and Fusarium proliferatum and that have recently been assoc iated with animal and human disease. In this study, the time course of fumonisin B-I (FB1) production in corn was monitored in five Fusarium cultures using high-performance liquid chromatography (HPLC), enzyme- linked immunosorbent assay (ELISA), and in situ localization by an enz yme-linked immunocytochemical technique (ELICT). Using HPLC on culture extracts prepared with 50% (vol/vol) acetonitrile in water, FB1 was d etectable at 3 days with maximal FB, (ranging from 230 to 3,000 ppm) o ccurring between 14 and 28 days. Although there was a positive correla tion between FB1 detected by HPLC and ELISA, the latter consistently y ielded higher results than HPLC. Maximal FB1 ''equivalents'' detected by ELISA ranged from 12,000 to 35,000 ppm. Following fixation of Fusar ium from cultures, ELICT revealed the presence of large deposits indic ative of fumonisin or fumonisin-like cross-reacting compounds in mycel ia, microconidia, and microconidia. Prior to fixation, these compounds were extractable in 50% (vol/vol) acetonitrile in water, ELICT result s qualitatively correlated with HPLC and ELISA over the time course of the cultures. Taken together, the results suggest that (a) ELISA or E LICT could be used for qualitative screening of FB1 producing cultures , and (b) in addition to FB1, the monoclonal antibody-based ELISA dete cted one or more compounds that structurally resemble FB1 and occur co ncurrently with FB1.