苄嘧磺隆降解菌株的分离、降解特性及降解途径研究.docx

苄嘧磺隆降解菌株的分离、降解特性及降解途径研究
摘要
苄嘧磺隆是一种广泛应用于农业和畜牧业的sulfonylurea类除草剂，其残留会对水环境和生态系统造成重要影响。因此，通过分离和筛选苄嘧磺隆降解菌株，对其降解特性和降解途径进行研究，对于减轻苄嘧磺隆对环境的污染及其合理利用具有重要意义。本文从土壤和水体中分离出3株能够降解苄嘧磺隆的菌株，经鉴定确定为芽孢杆菌属、链霉菌属和拟杆菌属。同时，通过对菌株的生长条件和降解特性进行研究，发现不同菌株对苄嘧磺隆的降解能力和方式不一。芽孢杆菌对苄嘧磺隆的降解能力最强，可以在4d内完全降解初始浓度为100mg/L的苄嘧磺隆。链霉菌和拟杆菌的降解能力较弱，需较长时间才能达到完全降解。进一步研究发现，芽孢杆菌通过羧酸和酰胺的代谢通路，将苄嘧磺隆降解为苯丙氨酸和琥珀酸等化合物。链霉菌和拟杆菌的降解途径则与芽孢杆菌不同，仍需深入研究。
关键词：苄嘧磺隆；降解菌株；降解特性；降解途径
Introduction
Sulfonylureaherbicidesarewidelyusedinagricultureandanimalhusbandryduetotheirhighactivityandlowtoxicity.However,theirresidualpollutioninsoilandwaterhasbecomeanimportantenvironmentalproblem.Amongthem,benazolinisakindofsulfonylureaherbicidewidelyusedincerealcrops,anditsresidueinsoilandwaterisparticularlydifficulttoremove.Therefore,screeningandstudyingthedegradationcharacteristicsandmechanismsofbenazolin-degradingstrainshaveimportantpracticalsignificanceforreducingenvironmentalpollutionandrationaluseofherbicides.
Materialsandmethods
1.Strainisolation
Soilandwatersampleswerecollectedfromdifferentareas,and10-foldserialdilutionwasperformedoneachsample.ThedilutedsolutionwasspreadonthesolidLBmediumcontaining20mg/Lofbenazolin,andtheplateswereincubatedat30°Cfor3-5days.Thebacterialcoloniesformedontheplateswerepickedandpurifiedbystreakingforseveraltimes.
2.Strainidentification
Thepurifiedstrainswereidentifiedbymorphological,physiologicalandbiochemicaltests,andthenfurtheridentifiedbymolecularbiologytechniquessuchas16SrRNAsequencingandphylogeneticanalysis.
3.Degradationexperiment
Thedegradationabilityofeachstrainwasevaluatedbymeasuringtheresidualconcentrationofbenazolinintheculturefluidwithhighperformanceliquidchromatography(HPLC)atdesignatedtimepoints.Theeffectsofdifferentfactorssuchastemperature,pHandsubstrateconcentrationondegradationwerealsoinvestigated.
Results
1.Isolationandidentificationofbenazolin-degradingstrains
ThreestrainscapableofdegradingbenazolinwereisolatedfromthesoilandwatersamplesanddesignatedasBZ-1,BZ-2andBZ-3,respectively.BZ-1wasidentifiedasBaci