ARS | Publication request: DETERMINATION OF AFLATOXIN PRODUCTION BY ASPERGILLUS SPECIES FROM THE MISSISSIPPI DELTA BY VARIOUS METHODS

Submitted to: Aflatoxin Elimination Workshop Proceedings
Publication Type: Proceedings
Publication Acceptance Date: September 30, 2002
Publication Date: October 23, 2002
Citation: ABBAS, H.K., ZABLOTOWICZ, R.M., HORN, B.W., XIE, W., SHIER, W.T. 2002. DETERMINATION OF AFLATOXIN PRODUCTION BY ASPERGILLUS SPECIES FROM THE MISSISSIPPI DELTA BY VARIOUS METHODS. AFLATOXIN ELIMINATION WORKSHOP PROCEEDINGS. Vol 15:110.

Technical Abstract: This study evaluated several methods to detect aflatoxins in Aspergillus. Aspergillus isolates (517) were obtained from various Mississippi Delta crops (corn, peanut, rice, cotton) and soils. Cultural methods included fluorescence on Beta-cyclodextrin media (FL), yellow pigment (YP), and color change after ammonia vapor exposure (AV) on potato dextrose agar. Aflatoxins in culture extract were confirmed by TLC and LC-MS and quantified by ELISA and HPLC. Of the 517 isolates, 314 produced greater than 20 ppb aflatoxin based on ELISA; 89%, 93% and 86% of these isolates gave positive FL, YP and AV responses respectively. Of the 203 isolates producing <20 ppb aflatoxin, 27%, 46%, and 25% gave positive FL, YP, and AV responses. This study showed a good agreement between FL and AV methods. However these cultural techniques did not detect aflatoxin in all cultures that were found to produce aflatoxin by ELISA, HPLC and TLC. Based upon LC/APC/MS analysis, aflatoxin positive A. flavus isolates only produced AFB1 and AFB2, while A. nomius and A. parasiticus produced four aflatoxins: AFB1, AFB2, AFG1, and AFG2. These methods can be used for quick screening but are not 100% reliable in detecting aflatoxin-producing Aspergillus species.