Submitted to: American Society of Pharmacognosy
Publication Type: Abstract Only
Publication Acceptance Date: 7/30/1997
Publication Date: N/A
Technical Abstract: A new method of growing Aspergillus flavus for experimental studies was used to evaluate the effect of different groups of compounds occurring in the corn kernel on growth and aflatoxin B1 formation. The culture system (suspended disc method) consists of a humidified vial with a thick septum pierced by a pin on which a glass fiber disc is affixed. The disc contains the test solution, inoculum, and medium. Cultures reach maximum growth and aflatoxin in five days at 25 deg C. Growth is determined gravimetrically. Discs of glass fiber, quartz fiber, and filter paper were evaluated for AFT B1 production and coefficient of variation (CV). The best overall performance was obtained with glass fiber filters containing binder. AFT B1 production was ca. five times greater than for liquid medium layers with equivalent surface area to volume. Discs as small as 6 mm, using 8 ul of medium, had a lower CV (15%) than liquid cultures with 20-30 times more medium. The method allows replicate testing with sub mg amounts and accommodates compounds over a range of solubilities. It is particularly useful for testing hydrophobic compounds without solubilizers and compounds available in very small amounts. Corn kernel metabolites and related compounds which have been studied with this system include the following: benzoxazolinones, anthocyanins, flavonoids, tocopherols, carotenes, ionones, retinoids, amides, sterol esters, fatty acids and triglycerides.