Quantification of Persistence ofEscherichia coliO157:H7 in Contrasting Soils

[摘要] Persistence ofEscherichia coli (E. coli)O157:H7 in theenvironment is a major concern to vegetable and fruit growerswhere farms and livestock production are in close proximity. Theobjectives were to determine the effects of preplant fumigationtreatment on the survival ofE. coliO157:H7 in two soils and theeffects of indigenous bacterial populations on the survival ofthis pathogen. Real-time PCR and plate counts were used toquantify the survival ofE. coliO157:H7 in two contrasting soilsafter fumigation with methyl bromide (MeBr) and methyl iodide(MeI). Ten days after fumigation,E. coliO157:H7 counts weresignificantly lower (P=.0001) in fumigated soils than in thenon-fumigated. Direct comparison between MeBr and MeI within eachsoil indicated that these two fumigants showed similar impacts onE. coliO157:H7 survival. Microbial species diversity asdetermined by DGGE was significantly higher in clay soil thansandy soil and this resulted in higher initial decline inpopulation in clay soil than in sandy soil. This study shows thatif soil is contaminated withE. coliO157:H7, fumigation alone maynot eliminate the pathogen, but may cause decrease in microbialdiversity which may enhance the survival of the pathogen.

[学科分类] 微生物学和免疫学