Civil and Environmental Engineering, Rutgers, The State University of New Jersey, 96 Frelinghuysen Rd, Piscataway, NJ, USA,
Microb Ecol. 2014 Oct;68(3):453-62. doi: 10.1007/s00248-014-0421-6. Epub 2014 Apr 24.
Small-scale geochemical gradients are a key feature of aquifer contaminant plumes, highlighting the need for functional and structural profiling of corresponding microbial communities on a similar scale. The purpose of this study was to characterize the microbial functional and structural diversity with depth across representative redox zones of a hydrocarbon plume and an adjacent wetland, at the Bemidji Oil Spill site. A combination of quantitative PCR, denaturing gradient gel electrophoresis, and pyrosequencing were applied to vertically sampled sediment cores. Levels of the methanogenic marker gene, methyl coenzyme-M reductase A (mcrA), increased with depth near the oil body center, but were variable with depth further downgradient. Benzoate degradation N (bzdN) hydrocarbon-degradation gene, common to facultatively anaerobic Azoarcus spp., was found at all locations, but was highest near the oil body center. Microbial community structural differences were observed across sediment cores, and bacterial classes containing known hydrocarbon degraders were found to be low in relative abundance. Depth-resolved functional and structural profiling revealed the strongest gradients in the iron-reducing zone, displaying the greatest variability with depth. This study provides important insight into biogeochemical characteristics in different regions of contaminant plumes, which will aid in improving models of contaminant fate and natural attenuation rates.
小规模地球化学梯度是含水层污染物羽流的一个关键特征，突出了需要在类似尺度上对相应微生物群落进行功能和结构剖析。本研究的目的是描述在比奇迪石油泄漏点的烃羽流和相邻湿地的代表性氧化还原带中，随着深度的变化，微生物功能和结构多样性的特征。定量 PCR、变性梯度凝胶电泳和焦磷酸测序相结合，应用于垂直采样的沉积物芯。靠近油体中心的位置，产甲烷标志物基因甲基辅酶 M 还原酶 A（mcrA）的水平随深度增加而增加，但在进一步向下的位置，其深度变化不定。偶氮arcus 属等兼性厌氧微生物的苯甲酸盐降解 N（bzdN）烃降解基因存在于所有位置，但在油体中心附近含量最高。在沉积物芯中观察到微生物群落结构差异，并且发现已知烃类降解菌的细菌类群相对丰度较低。功能和结构的深度解析揭示了铁还原带中最强的梯度，显示出随深度变化最大的可变性。本研究为污染物羽流不同区域的生物地球化学特征提供了重要的见解，这将有助于改进污染物归宿和自然衰减率模型。
