Biological interactions to select biocontrol agents against toxigenic strains of A. flavus and F. verticillioides from maize

ETCHEVERRY, M.; SCANDOLARA, A.; NESCI, A.; VILAS BOAS RIBEIRO, M.S.; PEREIRA, P.; BATTILANI, P.

Estanbul, Turquía

Simposio; XII International IUPAC Symposium on Mycotoxins and Phycotoxins; 2007

Biological control is an alternative to pesticides for protection against crop diseases. A key to progress in the field of biological control to protect maize against Fusarium verticillioides and Aspergillus flavus is to select in vitro the best agent to be applied in the field. The aim of this study was to examine the antagonistic activity of bacterial and yeasts against F. verticillioides and A. flavus toxigenic strains. The first study showed the impact of Bacillus amyloliquefaciens (BA-S13), Microbacterium oleovorans (DMS 16091), Enterobacter hormomaechei (EM – 562T) and Kluyveromyces spp. (K14, K16) on mycelial growth of 2 strains of A. flavus (MPVPA 2092, 2094) and 3 strains of F. verticillioides (MPVPA 285, 289 and 294) on 3% maize meal extract agar at different water activities (0.99, 0.97, 0.95 and 0.93). From this first assay, M. oleovorans, B. amyloliquefaciens and Kluyveromyces spp. (K16) produced an increase of lag phase and decreased growth rate of all strains. These isolates were selected for further studies. In vitro maize ears (apex sprayed inoculated) and non-rhizospheric maize soil (centrally and sprayed inoculated) were treated with antagonists and pathogenic strains alone and in co-inoculated cultures. Overall, Kluyveromyces spp. (K16) was the most effective treatment at inhibiting infection percentage of F. verticillioides and A. flavus strains on maize ears. Microbacterium oleovorans significantly reduced F. verticillioides count in maize soil inoculated centrally while Kluyevoromyces spp. completely inhibited F. verticillioides and A. flavus count in maize soil inoculated by spray.