Screening,identification and degradation efficacy evaluation of zearalenone degrading bacteria
[Objective]This study screened efficient and practical strains capable of degrading zearalenone(ZEN)and preliminarily investigated the degradation mechanism and effectiveness.[Method]Strains were screened from moldy feed and soil samples using ZEN as the sole carbon source and were identified by morphological observation and 16S rDNA genes equence analysis.The growth rate of strains and ZEN de-gradation rate were analyzed using time as a variable.The degradation active substances were preliminarily analyzed and localized through the determination of ZEN degradation rate in different active components and inactivated treatments.The extraction effects of crude degradation enzymes using ammonium sulfate(AS)precipitation(AS saturation of 30％,40％,50％,60％,70％and 80％)and tannin-polyethylene glycol method(tannin mass concentrations of 2,5,10,15 and 20 mg/mL and polyethylene glycol solution mass concentrations of 6,8,10,12 and 14 mg/mL)were compared.The molecular weights of target active pro-teins were determined by SDS-PAGE gel electrophoresis.Finally,the degradation effect of ZEN was deter-mined by adjusting moisture mass fraction of mold-contaminated cornmeal with identified strains and crude enzyme solution.[Result]The screened test strain XJ-140 was identified as Bacillus amyloliquefaciens,which could degrade 93.75％of ZEN(2 μg/mL)within 24 hours.The strain XJ-140 mainly degraded ZEN with extracellular enzymes and was complemented by cell wall adsorption.The ZEN degradation rates of crude degradative enzymes extracted by 60％saturation of AS and tannin-polyethylene glycol method(op-timal tannin concentration 10 mg/mL and optimal polyethylene glycol concentration 10 mg/mL)were 37.14％and 51.49％,respectively.The tannin-polyethylene glycol method of extraction was more favora-ble.The molecular weight of target active protein was preliminarily inferred to be 61 ku or 28 ku.Both the fermentation solution and crude enzyme solution of strain XJ-140 could degrade ZEN in mold-contaminated cornmeal.[Conclusion]The strain XJ-140 utilized extracellular enzymes to degrade ZEN and exhibited dis-cernible efficacies in reducing ZEN contamination in practical applications involving mold-contaminated cornmeal.
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维普
