Winderl Christian, Schaefer Sabine, Lueders Tillmann
Institute of Groundwater Ecology, GSF - National Research Center for Environment and Health, Neuherberg, Germany.
Environ Microbiol. 2007 Apr;9(4):1035-46. doi: 10.1111/j.1462-2920.2006.01230.x.
Benzylsuccinate synthase (Bss) is the key enzyme of anaerobic toluene degradation and has been found in all anaerobic toluene degrading bacterial isolates tested. However, only a few pure cultures capable of anaerobic toluene oxidation are available to date, and it is important to understand the relevance of these model organisms for in situ bioremediation of hydrocarbon-contaminated aquifers. Due to their phylogenetic dispersal, it is not possible to specifically target anaerobic toluene degraders using marker rRNA genes. We therefore established an assay targeting a approximately 794 bp fragment within the Bss alpha-subunit (bssA) gene, which allows for the specific detection and affiliation of both known and unknown anaerobic degraders. Three distinct tar-oil-contaminated aquifer sites were screened for intrinsic bssA gene pools in order to identify and compare the diversity of hydrocarbon degraders present at these selected sites. We were able to show that local diversity patterns of degraders were entirely distinct, apparently highly specialized and well-adapted to local biogeochemical settings. Discovered at one of the sites were bssA genes closely related to that of Geobacter spp., which provides evidence for an importance of iron reduction for toluene degradation in these sediments. Retrieved from the other two sites, dominated by sulfate reduction, were previously unidentified bssA genes and also deeply branching putative bssA homologues. We provide evidence for a previously unrecognized diversity of anaerobic toluene degraders and also of other hydrocarbon degraders using fumarate-adding key reactions in contaminated aquifers. These findings enhance our current understanding of intrinsic hydrocarbon-degrading microbial communities in perturbed aquifers and may have potential for the future assessment and prediction of natural attenuation based on degradation genes.
苄基琥珀酸合酶（Bss）是厌氧甲苯降解的关键酶，在所有测试过的厌氧甲苯降解细菌分离物中均有发现。然而，迄今为止，仅有少数能够进行厌氧甲苯氧化的纯培养物，了解这些模式生物对于烃类污染含水层的原位生物修复的相关性非常重要。由于它们在系统发育上的分散性，不可能使用标记rRNA基因特异性地靶向厌氧甲苯降解菌。因此，我们建立了一种针对Bssα亚基（bssA）基因内约794 bp片段的检测方法，该方法能够对已知和未知的厌氧降解菌进行特异性检测和归属。为了识别和比较这些选定地点存在的烃类降解菌的多样性，我们对三个不同的焦油污染含水层地点的内在bssA基因库进行了筛选。我们能够证明，降解菌的局部多样性模式完全不同，显然高度专业化且非常适应当地的生物地球化学环境。在其中一个地点发现了与地杆菌属密切相关的bssA基因，这为铁还原在这些沉积物中甲苯降解中的重要性提供了证据。从以硫酸盐还原为主的另外两个地点检索到的是以前未鉴定的bssA基因以及深度分支的假定bssA同源物。我们提供了证据，证明在受污染含水层中使用添加富马酸盐的关键反应的厌氧甲苯降解菌以及其他烃类降解菌存在以前未被认识到的多样性。这些发现增进了我们目前对受干扰含水层中内在烃类降解微生物群落情况的了解，并可能对未来基于降解基因的自然衰减评估和预测具有潜在意义。
