De Lucca Anthony J, Boue Stephen M, Carter-Wientjes Carol, Bhatnagar Deepak
Southern Regional Research Center, USDA, New Orleans, LA, USA.
Ann Agric Environ Med. 2012;19(1):91-8.
Aspergillus flavus is a saprophytic fungus which can grow on corn and produce aflatoxins which render it unsafe for consumption as food and feed. 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. Volatiles unique to the toxigenic A. flavus isolates were determined by comparison with volatiles produced by the respective corn controls and the non-toxigenic A. flavus isolate. 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, as well as the corn control samples. Results indicate that several factors (substrate, fungal isolate, culture age) affect volatile and aflatoxin production by A. flavus.
黄曲霉是一种腐生真菌，可在玉米上生长并产生黄曲霉毒素，这使得玉米作为食品和饲料食用不安全。在本研究中，产黄曲霉毒素和不产黄曲霉毒素的黄曲霉菌株分别在湿的（添加20%水分）、无菌或非无菌破碎玉米上生长。根据需要设置湿的和干的破碎玉米对照。在12天的时间内鉴定次生代谢挥发物并测定黄曲霉毒素浓度。通过与相应的玉米对照和不产毒素的黄曲霉菌株产生的挥发物进行比较，确定产毒素黄曲霉菌株特有的挥发物。这些黄曲霉菌株产生的挥发物的数量和种类因菌株、底物是无菌还是非无菌玉米以及采样日期而异。总体而言，大多数挥发物在接种后第8天之前产生。与非无菌玉米相比，无菌玉米上的黄曲霉毒素产量低10倍。在与不产黄曲霉毒素的菌株以及玉米对照样品产生的挥发物进行比较后，在两种底物上都鉴定出了产黄曲霉毒素菌株特有的挥发物。结果表明，几个因素（底物、真菌菌株、培养时间）会影响黄曲霉的挥发物和黄曲霉毒素产量。
