Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/20/2002
Publication Date: 6/30/2002
Citation: ABBAS, H.K., ZABLOTOWICZ, R.M., HORN, B.W., XIE, W., SHIER, W.T. 2002. CULTURAL AND ANALYTICAL METHODS TO DETERMINE AFLATOXIN PRODUCTION BY ASPERGILLUS SPECIES FROM THE MISSISSIPPI DELTA. PHYTOPATHOLOGY. 92:81. Interpretive Summary:
Technical Abstract: Several methods were used to detect aflatoxin production by various Aspergillus species. Isolates (n = 786) were obtained from crops (including corn, peanut, cotton) and soils from the Mississippi Delta. Cultural methods for assessing aflatoxin production on potato dextrose agar included yellow pigment (YP) production and color change with exposure to ammonia vapor (AV). The presence of aflatoxins in culture extract was confirmed by TLC and LC-MS and quantified by ELISA and HPLC. Fifty-one percent of isolates produced YP, and all were positive for the presence of aflatoxins. Forty-seven percent of isolates changed color with AV, and all were positive for aflatoxins. Thus, positive YP and AV responses were highly correlated with aflatoxin production. However, both methods failed to detect aflatoxins in all cultures that tested positive using ELISA, HPLC and TLC. Cultures that produced less than 250 ppb were typically negative by the AV method. A. flavus isolates positive for aflatoxins produced AFB1 and AFB2 only, whereas A. nomius and A. parasiticus produced all four aflatoxins (AFB1, AFB2, AFG1, and AFG2). Fifty-one percent of 341 soil isolates and 55% of 250 corn isolates produced aflatoxins. This study showed that YP and AV methods can be used for rapid screening but are not reliable in detecting low producers of aflatoxins.