LIMOS, Nancy Université, CNRS UMR 7137, Faculté des Sciences, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex, France.
Environ Microbiol. 2011 Mar;13(3):722-36. doi: 10.1111/j.1462-2920.2010.02376.x. Epub 2010 Nov 18.
To determine whether the diversity of phenanthrene-degrading bacteria in an aged polycyclic aromatic hydrocarbon (PAH) contaminated soil is affected by the addition of plant root exudates, DNA stable isotope probing (SIP) was used. Microcosms of soil with and without addition of ryegrass exudates and with ¹³C-labelled phenanthrene (PHE) were monitored over 12 days. PHE degradation was slightly delayed in the presence of added exudate after 4 days of incubation. After 12 days, 68% of added PHE disappeared both with and without exudate. Carbon balance using isotopic analyses indicated that a part of the ¹³C-PHE was not totally mineralized as ¹³CO₂ but unidentified ¹³C-compounds (i.e. ¹³C-PHE or ¹³C-labelled metabolites) were trapped into the soil matrix. Temporal thermal gradient gel electrophoresis (TTGE) analyses of 16S rRNA genes were performed on recovered ¹³C-enriched DNA fractions. 16S rRNA gene banding showed the impact of root exudates on diversity of PHE-degrading bacteria. With PHE as a fresh sole carbon source, Pseudoxanthomonas sp. and Microbacterium sp. were the major PHE degraders, while in the presence of exudates, Pseudomonas sp. and Arthrobacter sp. were favoured. These two different PHE-degrading bacterial populations were also distinguished through detection of PAH-ring hydroxylating dioxygenase (PAH-RHD(α)) genes by real-time PCR. Root exudates favoured the development of a higher diversity of bacteria and increased the abundance of bacteria containing known PAH-RHD(α) genes.
为了确定植物根分泌物的添加是否会影响老化多环芳烃（PAH）污染土壤中菲降解菌的多样性，采用 DNA 稳定同位素探针（SIP）法进行了研究。监测了添加和不添加黑麦草分泌物且添加 ¹³C 标记菲（PHE）的土壤微宇宙 12 天。在添加分泌物后，培养 4 天后 PHE 降解略有延迟。12 天后，添加的 PHE 有 68%在有无分泌物的情况下消失。利用同位素分析的碳平衡表明，¹³C-PHE 的一部分没有完全矿化为 ¹³CO₂，而是被未鉴定的 ¹³C 化合物（即 ¹³C-PHE 或 ¹³C 标记代谢物）捕获到土壤基质中。对回收的 ¹³C 富集 DNA 进行了 16S rRNA 基因的时间温度梯度凝胶电泳（TTGE）分析。16S rRNA 基因带显示了根分泌物对 PHE 降解菌多样性的影响。以 PHE 为新鲜的单一碳源时，假单胞菌属和微杆菌属是主要的 PHE 降解菌，而在有分泌物的情况下，假单胞菌属和节杆菌属则占优势。通过实时 PCR 检测多环芳烃环羟化双加氧酶（PAH-RHD(α)）基因，还区分了这两种不同的 PHE 降解细菌种群。根分泌物有利于形成更高多样性的细菌，并增加了含有已知 PAH-RHD(α)基因的细菌的丰度。
