Influence of herbicide glyphosate on growth and afltoxin B1 production by Aspergillus section Flavi strains on maize grain.

MAGNOLI C.E,; MONGE M.P.,; CHIACCHIERA S.M.; BARBERIS C.L.

Minas Gerais, Bello Horizonte

Congreso; XVI Encuentro Nacional de Micotoxinas; 2018

Great quantities of pesticides are applied in maize production in Argentina. Glyphosate (PMG) is one of the main pesticides applied. The intense application produces indirect effects on the soil microbiota. The presence of pesticides is another factor that affects the development of Aspergillus section Flavi species. Aflatoxin B1 (AFB1) is the main metabolite produced by these species with the most toxicological implies. The objective of this work was to evaluate the influence of PMG on the growth and AFB1 production by A. flavus and A. parasiticus strains under different aW conditions. Maize kernels were supplied with 30, 50, 300 and 500 mM of PMG, conditioned at 0.980, 0.950 and 0.930 aW, inoculated and incubated at 25°C. Growth was registered daily and AFB1 production was determined by HPLC at 7, 14 and 21 days. Each of the factors analyzed and their interactions showed a significant effect on the growth rate, lag phase and AFB1 production. With increasing PMG concentrations, the growth rate decreased at all aW tested. In the marginal conditions (300 and 500 mM and 0.93 aW), the fungal growth was totally inhibited. AFB1 production was inhibited when the concentration of PMG increased. With 50 mM at 0.95 and 0.98 of aW the accumulation of AFB1 increased along the incubation period. These results suggest that Aspergillus section Flavi species can increase their growth and the AFB1 accumulation when there are exposed to PMG under favorable environmental conditions, which imply a potential risk of contamination of the maize kernels.