Study of the Effect of Methyl Jasmonate Concentration on AflatoxinB1Biosynthesis byAspergillus parasiticusin Yeast Extract Sucrose Medium

Aflatoxin B 1 (AFB 1 ) is a carcinogenic metabolite produced by certain Aspergillus species on agricultural commodities. AFB 1 biosynthesis is affected by jasmonic acid and also by its methylester (MeJA), a plant growth regulator derived from linoleic acid. This study reports the effect of MeJA on the growth of A. parasiticus and AFB 1 output in yeast extract sucrose (YES) medium when added at three different concentrations; namely, 10 −2  M, 10 −4  M, and 10 −6  M. AFB 1 determination was performed by immunoaffinity and HPLC. MeJA at 10 −4 and 10 −6 M concentrations had no significant effect on mycelial growth but did affect AFB 1 production after the 7th day of incubation; on the 12th day, AFB 1 production was increased by 212.7% and 141.6% compared to the control samples (addition of 10 −6  M and 10 −4  M MeJA, resp.). Treatment of A. parasiticus cultures with 10 −2  M MeJA inhibited mycelial growth and AFB 1 production as well. These results suggest that the effect of MeJA on AFB 1 biosynthesis by A. parasiticus depends on the MeJA concentration used.