[Isolation and toxogenic characterization of tri5 positive Fusarium from poultry houses].

OBJECTIVE:We used tri5-PCR technique to identify the toxin-producing Fusarium strains, the toxogenic characteristics and toxicogenic condition of tri5 positive strains. We also evaluated the potential trichothecene-producing level of the Fusarium strains from the air and solid materials in poultry houses. METHODS:tri5 gene, the start gene encoding trichothecene synthase, was taken to detect 139 Fusarium isolates by PCR. Toxogenic culture was carried out for tri5 positive Fusarium strains, and the quantities of T-2 and HT-2 toxins in toxogenic cultures were measured by high performance liquid chromatography (HPLC) after immune-affinity column clear-up. RESULTS:Among the 42 tri5 positive strains determined by tri5-PCR, all 10 tri5 positive strains from the air in poultry houses were found to produce T-2 toxin (1.36-5 ng/mL) or HT-2 toxin (6.1-17.1 ng/mL) after culture. The optimal conditions for toxogenic culture were 9 days of culture with 5 degrees C-20 degrees C temperature fluctuation and light-dark alternating at 24 h intervals, shaking at early stage and non-shaking at later stage. The toxin production of tri5 positive strains was significantly affected by temperature and time, but it has no correlation with the dry mass of mycelium. CONCLUSION:In comparison with the traditional method, tri5-PCR is a rapid method for accurate detection of toxogenic Fusarium isolates in large amounts of environmental samples from poultry houses. The results provide a technical support and theoretical basis for early hazard warning and control of toxogenic Fusarium strains in animal raising environments.