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首页> 外文期刊>Applied Microbiology >Extraintestinal Escherichia coli Carrying Virulence Genes in Coastal Marine Sediments
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Extraintestinal Escherichia coli Carrying Virulence Genes in Coastal Marine Sediments

机译：沿海海洋沉积物中携带毒力基因的肠外大肠杆菌

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Despite the recognized potential of long-term survival or even growth of fecal indicators bacteria (FIB) in marine sediments, this compartment is largely ignored by health protection authorities. We conducted a large-scale study over approximately 50 km of the Marche coasts (Adriatic Sea) at depths ranging from 2 to 5 m. Total and fecal coliforms (FC) were counted by culture-based methods. Escherichia coli was also quantified using fluorescence in situ hybridization targeting specific 16S rRNA sequences, which yielded significantly higher abundances than culture-based methods, suggesting the potential importance of viable but nonculturable E. coli cells. Fecal coliforms displayed high abundances at most sites and showed a prevalence of E. coli. FC isolates ( n = 113) were identified by API 20E, additional biochemical tests, and internal transcribed spacer-PCR. E. coli strains, representing 96% of isolates, were then characterized for genomic relatedness and phylogenetic group (A, B1, B2, and D) of origin by randomly amplified polymorphic DNA and multiplex-PCR. The results indicated that E. coli displayed a wide genotypic diversity, also among isolates from the same station, and that 44 of the 109 E. coli isolates belonged to groups B2 and D. Further characterization of B2 and D isolates for the presence of 11 virulence factor genes ( pap , sfa/foc , afa , eaeA , ibeA , traT , hlyA , stx _(1), stx _(2), aer , and fyuA ) showed that 90% of B2 and 65% of D isolates were positive for at least one of these. Most of the variance of both E. coli abundance and assemblage composition (>62%) was explained by a combination of physical-chemical and trophic variables. These findings indicate that coastal sediments could represent a potential reservoir for commensal and pathogenic E. coli and that E. coli distribution in marine coastal sediments largely depends upon the physical and trophic status of the sediment. We conclude that future sampling designs aimed at monitoring the microbiological quality of marine coastal areas should not further neglect the analysis of the sediment and that monitoring of these environments can be improved by including molecular methods as a complement of culture-based techniques.
机译：尽管公认的海洋沉积物中可能存在长期生存甚至是粪便指示菌（FIB）增长的潜力，但卫生防护部门很大程度上忽略了该隔室。我们在马尔凯海岸（亚得里亚海）约50公里处进行了大规模研究，深度为2至5 m。通过基于培养的方法对大肠菌群和粪大肠菌群（FC）进行计数。还使用针对特定16S rRNA序列的荧光原位杂交技术对大肠埃希氏菌进行了定量，与基于培养的方法相比，其产生的丰度明显更高，这表明有活力但不可培养的大肠杆菌细胞的潜在重要性。粪大肠菌在大多数地方都显示出高丰度，并显示出大肠杆菌的流行。通过API 20E，其他生化测试和内部转录间隔区PCR鉴定了FC分离株（n = 113）。然后，通过随机扩增的多态性DNA和多重PCR对代表96％分离株的大肠杆菌菌株进行基因组相关性分析和起源的系统发育组（A，B1，B2和D）。结果表明，大肠杆菌也表现出广泛的基因型多样性，在同一站点的分离株中也是如此，并且109个大肠杆菌分离株中有44个属于B2和D组。对于11种存在的B2和D分离株的进一步表征毒力因子基因（pap，sfa / foc，afa，eaeA，ibeA，traT，hlyA，stx _（1），stx _（2），aer和fyuA）显示90％的B2和65％的D分离株至少其中之一是积极的。大肠杆菌丰度和组合物组成（> 62％）的大部分变化是通过理化和营养变量的组合来解释的。这些发现表明，沿海沉积物可能是共生性和致病性大肠杆菌的潜在库，而海洋沿海沉积物中的大肠杆菌分布在很大程度上取决于沉积物的物理和营养状态。我们得出的结论是，未来旨在监测海洋沿海地区微生物质量的采样设计不应进一步忽视对沉积物的分析，并且可以通过包括分子方法作为基于文化的技术的补充来改善对这些环境的监测。

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