Biological strategy applied to maize preharvest agroecosystem in Argentina to prevent fumonisin contamination

ETCHEVERRY, M.; NESCI A; PEREIRA, P.; SARTORI, MELINA

Mycotoxins

Nova Science Publishers

Lugar: New York; Año: 2012; p. 1 - 44

Biocontrol activity of Bacillus amyloliquefaciens and Microbacterium oleovorans against F. verticillioides colonization of field-grown maize and fumonisin production in grains at harvest were investigated. Seed treatment during pre-sowing and spraying of maize ears during flowering were evaluated as inoculation methods of selected agents. The impact of inoculation of BCAs on F. verticillioides count in maize roots and grains at harvest level as well as on fumonisin content of the grains was evaluated in field trials conducted under natural fungal infection. Treatment effects on maize growth and on diversity and activity of bacterial and fungal populations naturally associated with maize roots were also assessed. Additionaly, F. verticillioides count and fumonisin B1 content were significantly reduced in grains of plants grown from B. amyloliquefaciens treated seeds. Studies on inoculum production, physiological improvement and formulation process were assessed. The viability of cells of Bacillus amyloliquefaciens and Microbacterium oleovorans of different incubation times in liquid media were evaluated. Cells of B. amyloliquefaciens grown in liquid media amended with glycerol showed better tolerance at low aw and high survival under heat stress. Furthermore, both biocontrol agents showed accumulation of betaine and ectoine improving the tolerance to water potential modifications and desiccation in the process of freeze drying and production of formulated. Bacterial growth and survival under conditions of low water availability could improve and also increase the potential for biological control of F. verticillioides in field. B. amyloliquefaciens and M. oleovorans showed highest survival in MSB medium at 0.99 aw. MSB medium was select for biomass production due to the high growth and survival after freeze-drying process. The formulates were development of fresh cells and freeze-dried of B. amyloliquefaciens and M. oleovorans. The efficacy of four stickers as seed coating was studied; the survival of B. amyloliquefaciens and M. oleovorans and the effect on seed maize were evaluated. The high count of B. amyloliquefaciens and M. oleovorans was obtained with paraffinic oil sticker using the freeze-dried formulated. Under field trial of maize, the pre-sowing application of freeze-dried formulate B. amyloliquefaciens and M. oleovorans with paraffinic oil as sticker, caused a decrease of fumonisin B1 content of harvested grains including pre-sowing inoculation of F. verticillioides.