ARS | Publication request: Volatile profiles and aflatoxin production by toxigenic and non-toxigenic isolates of Aspergillus flavus grown on sterile and non-sterile cracked corn

Submitted to: Annals of Agriculture and Environmental Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 14, 2012
Publication Date: April 3, 2012
Citation: De Lucca II, A.J., Boue, S.M., Carter Wientjes, C.H., Bhatnagar, D. 2012. Volatile profiles and aflatoxin production by toxigenic and non-toxigenic isolates of Aspergillus flavus grown on sterile and non-sterile cracked corn. Annals of Agriculture and Environmental Medicine. 19(1):91-98.

Interpretive Summary: The fungus Aspergillus flavus is a common soil inhabitant, including soil in corn growing areas. This fungus produces toxins, called aflatoxins, which cause liver cancer when contaminated food is eaten. Under the right conditions of moisture and temperature, A. flavus can infect and grow on corn kernels while still on the plant or in storage after harvest. Such contaminated corn is a large economic loss to the United States grain industry as well as a nutritional loss to national and international food and feed markets, so it is important to detect A. flavus growth to allow rapid removal of the contaminated corn. The research described in this manuscript shows aflatoxin-producing A. flavus isolates produce a number of unique volatile compounds not produced by corn. The identity of these unique volatiles could be used to design sensors to detect A. flavus growth and alert workers that a contaminated corn batch is present and must be removed.

Technical Abstract: Aspergillus flavus is a saprophytic fungus which can grow on corn and produce aflatoxins which render it unsafe for food and feed consumption. In this study, aflatoxin and non-aflatoxin producing isolates of A. flavus were grown separately on wet (20% water added), sterile or non-sterile cracked corn. Wet and dry cracked corn controls were included as needed. Secondary metabolic volatiles were identified and aflatoxin concentrations determined over a 12-day period. The number and identity of the volatiles produced by these A. flavus isolates varied by isolate, whether sterile or non-sterile corn was the substrate, and the sampling day. Overall, most of the volatiles were produced before day 8 after inoculation. Aflatoxin production was 10-fold lower on the sterile corn compared to the non-sterile corn. Volatiles unique to the aflatoxin producing isolates were identified on both substrates after comparison with those produced by the non-aflatoxin producing isolate. Results indicate that several factors (substrate, fungal isolate, culture age) affect volatile and aflatoxin production by A. flavus.