Effects of clarified neem oil on growth and aflatoxin B sub(1) formation in submerged and plate cultures of aflatoxigenicAspergillus spp

An increase of 11-31% of dry mycelial mass was observed along with a slight decrease (5-10%) in aflatoxin Bi production in 5-day-old aflatoxigenicAspergillus spp. submerged cultures containing either 0.5 ml or 1.0 ml clarified neem oil (CNO) in 0.1 % Triton solution. Fungal growth and aflatoxin B sub(1) production were also determined in potato-dextrose-agar petri plate cultures inoculated with aflatoxigenicAspergillus spp. containing an atmosphere of volatiles emitted from 0.25 ml, 0.5 ml, and 1.0 ml CNO added to the plates. After 5 days' incubation, fungal radial growth was reduced by 7-29% and aflatoxin B sub(1) production by 0-67%. GC/MS analysis of the head space volatiles of the CNO indicated that the reduction of fungal growth and aflatoxin B sub(1) was probably due to low molecular weight hydrocarbons, aldehydes, alcohols, and sulfur compounds emitted at 30C in the dry culture. These results suggest that volatiles emitted from CNO at 30 C in plate cultures were more fungistatic and consequently inhibited aflatoxin production more than neem oil added in liquid cultures.