Roze et al. (2004) developed a novel flow-through system
to monitor the effects of ethylene on aflatoxin biosynthesis
by A. parasiticus grown on a defined solid culture medium
(GMS). Ethylene treatment reduced aflatoxin accumulation
in a dose-dependent manner; the greatest reduction
(10-fold) was observed when the fungus was treated with
146 ppm ethylene. CO2 at 0.1% also reduced aflatoxin
accumulation (about 5-fold); adding more CO2 (0.7% or
3.0%) reversed the inhibitory effect. Co-treatment with
CO2 and ethylene resulted in an additive inhibitory effect.
Ethylene decreased the level of transcription of the nor-1
gene in A. parasiticus (encodes an early enzyme in aflatoxin
synthesis), suggesting that ethylene acts directly or
indirectly on aflatoxin promoter function. In this same
study, treatment of peanut seeds with a single concentration
of ethylene (2 ppm) and/or two concentrations of CO2
(0.05% or 0.1%) inhibited aflatoxin accumulation up to 5-fold (Roze et al., 2004).