[Direct detection of T-2- and HT-2-mycotoxins producers of fungi the genus Fusarium in food grain by PCR (report 2)].

The improvement of the Fusarium DNA extraction method has been undertaken in order to reduce the error of PCR analysis for detection of toxigenic Fusarium species, including those contained in the grain in the uncultureted state, directly in the grain. The efficiency of Fusarium DNA extraction methods (nucleotides sorption and CTAB method) has been compared. The efficiency of CTAB method combined with 10-fold weight increase of milled grain sample has been demonstrated. This approach revealed a greater number of Fusarium species, than PCR analysis of combined Fusarium mycelium from the same samples. The uncultureted F. langsethiae was detected in the DNA extract from a sample of barley, which was not identified in the combined sample of the mycelium. This sample of the grain has the highest levels of T-2/NT-2-toxins--0,075/0,345 mg/kg (determined by HPLC) among positive samples. F. sporotrichioides--a potential producer of T-2- and HT-2-toxins has been revealed by PCR method in other grain samples both containing and not containing these toxins. The biosynthesis of T-2- and HT-2-toxins on the PSA-medium in vitro has been studied for 10 single-spores F. sporotrichioides isolates, allocated from grain. Synthesized T-2-toxin content (measured by ELISA) ranged from 0.4 to 184.5 mg per l of medium. Three strains showed very high levels from 117.2 to 184.4 mg/l, two of which have been isolated from barley which don't contain these toxins. The absence of the toxin in grain samples does not guarantee the absence of high-level producers of mycotoxins. The direct detection of Fusarium spp. in grain by PCR analysis with extraction of fungal DNA by CTAB method along with increased sample weight has been shown to make possible the detection of a more number of species of Fusarium (including uncultureol strains) compared with mycological method with PCR analysis of the combined sample of the mycelium.