Submitted to: Aflatoxin Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 10/27/2000
Publication Date: N/A
Technical Abstract: Corn germ triglycerides are a major factor in aflatoxin B1 formation by A. flavus-infected corn kernels. Results are presented on the effect of glycerol and the sugar D-talose on aflatoxin formation from triglycerides (TGs) and free fatty acids. Media containing 5% free oleic acid and either glycerol or glucose as the carbon sources were compared. Glycerol increased net aflatoxin B1 (AFB1) production from free oleic acid at concentrations up to 286 mM. AFB1 content at 286 mM was 207 ug/ml more than for oleic acid alone and 49 ug/ml more than 5% triolein alone. Glucose produced a maximum increase of 20 ug/ml. The effect of glycerol on AFB1 from oleic acid medium was synergistic and not due to its role as a carbon source. D-talose was tested in medium using 10% corn oil (CO medium), 5% sucrose (S medium) or sucrose plus corn oil (SO) as carbon sources. AFB1 from CO was 95% inhibited at 249 ug/ml talose and completely inhibited at 556 ug/ml along with most of the growth. Inhibition was similar on both S and SO but much less than on CO medium. AFB1 on SO was higher than on S due to the contribution of oil, but toxin formation fell in parallel on both media indicating that TG utilization for AFB1 was not affected by talose. Talose did not affect growth on either medium. Sucrose down to 1.25% showed no inhibition of TG from talose. Sucrose at a concentration of 1.25% or higher blocks D-talose inhibition of TG metabolism. alpha-Carotene and delphinidin have been shown to effectively inhibit AFB1 formation. Using a modified suspended disc method, these compounds were found to produce volatiles which could account for at least part their inhibition.