Screening and identification of T-2 toxin-degrading strains from natural environment

Abstract:

[Objective] This study was to find the T-2 toxin-degrading strains, which were isolated and identified from natural environment. [Methods] Fusarium producing T-2 toxin were isolated from the samples of shrimp culture pond water, pond sediment and shrimp mixed feed, respectively. When it was cultured in GYM medium for 14 days, the airborne bacteria in nature environment were inoculated. The content of T-2 toxin was detected by LC-MS/MS at 28 day in its cultivation. T-2 toxin-degrading strains were screened from the bacteria suspension in which the content of T-2 toxin has obviously decreased with dilution spread method, plat streaking method, Gram stain method and microscopic examination. And then the identification and phylogenetic analysis of the screened strains were performed by 16S rRNA method. The method was also used to validate the toxin-degrading capacities of the screened strains respectively and the combined effect of them in different matrixes. [Results] Two T-2 toxin-degrading strains were screened out during the cultivation of five Fusarium strains which were isolated as indicator bacteria from shrimp culture environment. The results of 16S rRNA analysis showed that they were Pseudomonas geniculate and Staphylococcus nepalensis, and their degradation rates to T-2 toxin were 90.9% and 85.5% respectively. But there was no significant difference between the degradation effects of the two strains (P>0.05). In addition, the combined effect was good but had no significant difference with the single strain’s degradation effect (P>0.05). And the combined degradation effects were not much affected by different matrixes (P>0.05). [Conclusion] This new discovery established a basis for further ascertaining T-2 toxin degrading genes and developing T-2 toxin degrading enzymes.

Key words:T-2 toxin, Fusarium, Degrading strains