Pacific Northwest Laboratory, m/s K4-06, P.O. Box 999, 99352, Richland, Washington, USA.
Microb Ecol. 1993 Jan;25(1):35-50. doi: 10.1007/BF00182128.
The microbial diversity in two deep, confined aquifers, the Grande Ronde (1270 m) and the Priest Rapids (316 m), Hanford Reservation, Washington, USA, was investigated by sampling from artesian wells. These basaltic aquifers were alkaline (pH 8.5 to 10.5) and anaerobic (Eh -200 to -450 mV). The wells were allowed to free-flow until pH and Eh stabilized, then the microflora was sampled with water filtration and flow-through sandtrap methods. Direct microscopic counts showed 7.6 × 10(5) and 3.6 × 10(3) bacteria ml(-1) in water from the Grande Ronde and Priest Rapids aquifers, respectively. The sand filter method yielded 5.7 × 10(8) and 1.1 × 10(5) cells g(-1) wet weight of sand. The numbers of bacteria did not decrease as increasing volumes of water were flushed out. The heterotrophic diversity of these bacterial populations was assessed using enrichments for 20 functional groups. These groups were defined by their ability to grow in a matrix of five different electron acceptors (O2, Fe(III), NO3 (-), SO4 (2-), HCO3 (-)) and four groups of electron donors (fermentation products, monomers, polymers, aromatics) in a mineral salts medium at pH 9.5. Growth was assessed by protein production. Culture media were subsequently analyzed to determine substrate utilization patterns. Substrate utilization patterns proved to be more reliable indicators of the presence of a particular physiological group than was protein production. The sand-trap method obtained a greater diversity of bacteria than did water filtration, presumably by enriching the proportion of normally sessile bacteria relative to planktonic bacteria. Substrate utilization patterns were different for microflora from the two aquifers and corresponded to their different geochemistries. Activities in the filtered water enrichments more closely matched those predicted by aquifer geochemistry than did the sand-trap enrichments. The greatest activities were found in Fe(III)-reducing enrichments from both wells, SO4-reducing enrichments from the Grande Ronde aquifer, and methanogenic enrichments from the Priest Rapids aquifer. Organisms from these aquifers may be useful for high-pH bioremediation applications as well as production of biotechnological products. These organisms may also be useful for modeling potential reactions near buried concrete, as might be found in subsurface waste depositories.
对美国华盛顿汉福德保留地两个深层封闭含水层——大仑德（1270 米）和普里斯特里普斯（316 米）——的微生物多样性进行了研究，采样来自自流井。这些玄武岩含水层呈碱性（pH8.5 至 10.5）且无氧（Eh-200 至-450mV）。这些井在 pH 和 Eh 稳定后允许自由流动，然后用过滤水和流动砂阱法采样微生物群。直接显微镜计数显示，大仑德和普里斯特里普斯含水层的水中分别有 7.6×10(5)和 3.6×10(3)个细菌/ml。砂滤法得到的湿砂中分别有 5.7×10(8)和 1.1×10(5)个细胞/g。随着冲洗出的水量增加，细菌数量并没有减少。通过对 20 个功能群的富集，评估了这些细菌种群的异养多样性。这些群是根据它们在 pH9.5 的矿物盐培养基中生长的能力来定义的，使用五种不同的电子受体（O2、Fe(III)、NO3(-)、SO4(2-)、HCO3(-))和四组电子供体（发酵产物、单体、聚合物、芳烃）。通过蛋白质产量来评估生长情况。随后对培养基进行分析以确定底物利用模式。与蛋白质产量相比，底物利用模式是存在特定生理群的更可靠指标。砂阱法比水过滤法获得了更多的细菌多样性，这可能是因为它富集了相对于浮游细菌而言通常处于静止状态的细菌的比例。两个含水层的微生物群的底物利用模式不同，与它们不同的地球化学特征相对应。过滤水的富集物中的活性更接近含水层地球化学预测的活性，而砂阱的富集物则不然。最大的活性出现在两个井的 Fe(III)还原富集物、大仑德含水层的 SO4 还原富集物和普里斯特里普斯含水层的产甲烷富集物中。这些含水层中的生物体可能可用于高 pH 值生物修复应用以及生物技术产品的生产。这些生物体也可能有助于模拟地下废物储存库中可能发现的埋藏混凝土附近的潜在反应。
