The application of antagonistic yeasts and bacteria: An assessment of in vivo and under field conditions pattern of Fusarium mycotoxins in winter wheat grain

Abstract

Bacteria of the genus Sphingomonas, Aureobasidium pullulans yeast-like fungus and yeast Debaryomyces hansenii naturally colonize wheat grain. Selected isolates of these microorganisms, antagonistic against Fusarium spp., can be applied to wheat spikes to complement chemical control methods. The aim of this study was to determine the content of Fusarium mycotoxins in winter wheat grain in vivo and under field conditions, and to analyze the interactions between antagonistic microorganisms and F. culmorum and F. avenaceum pathogens in dual cultures. Seventeen toxic metabolites produced by Fusarium fungi were identified in grain: deoxynivalenol, deoxynivalenol-3-glucoside, culmorin, 15-hydroxyculmorin, 5-hydroxyculmorin, HT-2 toxin, nivalenol, nivalenol-3-glucoside, aurofusarin, enniatins, zearalenone, moniliformin, equisetin, and apicidin. Integrated fungicide and biological treatments decreased deoxynivalenol levels in grain in the field conditions from 141.36 to 72.76 μg/kg. Deoxynivalenol was not detected in grain treated with D. hansenii suspension, and culmorin content was 38 times lower than in unprotected grain. Fungicides and integrated treatments involving D. hansenii also decreased enniatin A1 content by 76.61 and 48.17%. In vitro yeasts considerably reduced moniliformin and enniatin concentrations by 7.67–92.87%. Antagonistic microorganisms, which inhibit the growth of Fusarium fungi through antibiosis and competition for nutrients, can effectively reduce the production of selected Fusarium toxins when combined with fungicides in the integrated approach.