Characterization of Environmentally Persistent Escherichia coli Isolates Leached from an Irish Soil
Characterization of Environmentally Persistent Escherichia coli Isolates Leached from an Irish Soil
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DOI：
10.1128/aem.01944-09
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发表时间：
2010-04-01
影响因子：
4.4
通讯作者：
O'Flaherty, Vincent
中科院分区：
文献类型：
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作者：
Brennan, Fiona P.;Abram, Florence;O'Flaherty, Vincent
土壤通常被认为是肠道微生物的次优环境，但越来越多的证据表明，在有利的条件下，大肠杆菌种群可以在土壤中栖息。以前的工作报道了原生大肠杆菌在海洋温带Luvic Stagnosol土壤中的生长，本研究旨在通过分子和生理手段表征从土壤中淋洗的环境持久性大肠杆菌分离株的遗传多样性和生理学特征。分子分析(16S rRNA测序、肠杆菌重复基因间一致性聚合酶链式反应、脉冲场凝胶电泳法和多重聚合酶链式反应)确定了菌株(n=7)的遗传多样性，而生理学方法确定了菌株在测试条件下相对于实验室菌株的代谢能力和环境适宜性。基因分型分析表明，浸出的菌株并不形成单一的遗传类群，但多个基因类群能够在该环境中生存和增殖。在生理学研究中，与实验室菌株的生长相比，环境菌株在广泛的温度和介质范围内生长良好。这些发现表明，某些大肠杆菌菌株可能具有定居和适应土壤条件的能力。由此导致的粪便特异性的缺乏意味着使用大肠杆菌作为环境中粪便污染的指示器。
Soils are typically considered to be suboptimal environments for enteric organisms, but there is increasing evidence that Escherichia coli populations can become resident in soil under favorable conditions. Previous work reported the growth of autochthonous E. coli in a maritime temperate Luvic Stagnosol soil, and this study aimed to characterize, by molecular and physiological means, the genetic diversity and physiology of environmentally persistent E. coli isolates leached from the soil. Molecular analysis (16S rRNA sequencing, enterobacterial repetitive intergenic consensus PCR, pulsed-field gel electrophoresis, and a multiplex PCR method) established the genetic diversity of the isolates (n = 7), while physiological methods determined the metabolic capability and environmental fitness of the isolates, relative to those of laboratory strains, under the conditions tested. Genotypic analysis indicated that the leached isolates do not form a single genetic grouping but that multiple genotypic groups are capable of surviving and proliferating in this environment. In physiological studies, environmental isolates grew well across a broad range of temperatures and media, in comparison with the growth of laboratory strains. These findings suggest that certain E. coli strains may have the ability to colonize and adapt to soil conditions. The resulting lack of fecal specificity has implications for the use of E. coli as an indicator of fecal pollution in the environment.