Investigations of the capability of Fusarium isolates from corn for biosynthesis of fusariotoxins

Abstract

The aim of this paper was to investigate the potential of zearalenone (ZEN) and type A trichothecenes (T-2 toxin and diacetoxyscirpenole - DAS) for biosynthesis by Fusarium spp. isolated from corn kernels contaminated by mycotoxins. The samples of corn kernels (2004 and 2005 harvest) originating in different regions of Backa (Vojvodina, Serbia) were tested. Mycotoxicological investigations showed in most cases a significant contamination with deoxynivalenol (DON 200 - 2,460 ?g/kg) and ZEA (520 1,680 ?g/kg). Isolations and identifications of fusaria established only the presence of species F. verticillioides, after one month storage in freezer conditions, in fusariotoxin positive samples. The control cultures known as ZEA producers - F. graminearum GZ-LES, i.e. T-2 toxin and DAS producer - F. sporotrichioides KF-38/1/R were also tested. In vitro toxicological investigations of isolated fusaria were performed in liquid semisynthetic media (GPK or SPK), and on wet sterilized corn kernels, respectively. Under testing conditions, analyzed F. verticillioide and F. sporotrishioides isolates were not ZEA producers. Contrary to them, F. graminearum GZ-LES pure culture was very good producer of fusariotoxins; it biosynthesized max. 465,900 ?g/kg DON, and 4,416 ?g/kg ZEA, respectively. Cultivation conditions influenced a great deal of T-2 toxin production under laboratory conditions. In most cases, higher yields were obtained during the cultivation of F. verticillioides in liquid glucose medium (80-240 ?g/L). Contrary to the control strain F. sporotrichioides KF-38/1/R that under the same conditions synthesized, besides T-2 toxin (4.000 ?g/L) and DAS (240 ?g/L), isolates of F. verticillioides from corn grain did not show that ability.