Water Resources Research Center, University of Hawai'i at Mānoa, Honolulu, HI, United States of America.
Institute of Technology, Tartu University, Tartu, Estonia.
PLoS One. 2020 Apr 30;15(4):e0232265. doi: 10.1371/journal.pone.0232265. eCollection 2020.
The groundwater biome is a poorly characterized habitat hypothesized to harbor uniquely diverse bacterial communities; the degree to which these communities differ from associated soils is a central question in environmental microbiology. We characterized the Bacterial community composition in 37 aquifer and 32 surface soil samples across the island of O'ahu, Hawai'i. Several bacterial phyla (Acetothermia, Omnitrophica, Parcubacteria, Peregrinibacteria) relatively abundant in the aquifer samples were rare to absent in the soils. Immense bacterial diversity detected in the deep aquifers indicates that these environments are not as homogenous as expected, but provide various niches and energy sources for wide variety of bacteria. A small proportion of OTUs were widespread in all the basal (0.63%) and all the dike aquifer (0.31%) samples. However, these core bacteria comprised an average of 31.8% (ranging 16.2%-62.0%) and 15.4% (0.1%-31.5%) of all sequences isolated from the basal and dike aquifers respectively. Bacterial community composition correlated significantly with the sodium, sulfate, potassium, total dissolved solids, nitrate, conductivity, and pH in the basal aquifers, while phosphate and bicarbonate levels were also highly important when dike water samples were included in the analyses. This was consistent with high relative abundance of putative chemolithoautoroph taxa in the aquifer communities relative to soils. Targeted molecular and culture-based fecal indicator microbial analyses indicated good water quality of aquifers. The dominance of unique, deeply branching lineages in tropical aquifers emphasizes a large adaptive potential in O'ahu's aquifers; variability among groundwater samples suggests that aquifer habitats are surprisingly variable potentially harboring a variety of chemolithotrophic energy sources. Although parallel analyses of conventional and alternative indicators indicated good groundwater quality, this study calls for groundwater monitoring programs which would consider public as well as ecosystem health.
地下水生物群是一个特征描述较差的栖息地，据推测其中存在独特多样的细菌群落；这些群落与相关土壤的差异程度是环境微生物学中的一个核心问题。我们对夏威夷欧湖岛的 37 个含水层和 32 个表层土壤样本中的细菌群落组成进行了描述。在含水层样本中相对丰富的几个细菌门（醋热菌门、全氮营养菌门、Parcubacteria 门、Peregrinibacteria 门）在土壤中很少或不存在。在深部含水层中检测到的巨大细菌多样性表明，这些环境并不像预期的那样同质，而是为各种细菌提供了不同的小生境和能源。一小部分 OTUs 在所有基岩（0.63%）和所有岩脉含水层（0.31%）样本中都广泛存在。然而，这些核心细菌分别占基岩和岩脉含水层中所有分离序列的平均 31.8%（范围为 16.2%-62.0%）和 15.4%（0.1%-31.5%）。细菌群落组成与基岩含水层中的钠、硫酸盐、钾、总溶解固体、硝酸盐、电导率和 pH 值显著相关，而当包括岩脉水样进行分析时，磷酸盐和碳酸氢盐水平也非常重要。这与含水层群落中假定的化能自养类群的相对丰度较高相一致。针对分子和基于培养的粪便指示微生物的靶向分析表明，含水层的水质良好。热带含水层中独特的、深分支谱系的优势强调了奥胡岛含水层具有很大的适应性潜力；地下水样本之间的变异性表明，含水层栖息地具有很大的可变性，可能蕴藏着各种化能营养能源。尽管对常规和替代指标的平行分析表明地下水质量良好，但本研究呼吁制定地下水监测计划，将公众健康和生态系统健康都纳入考虑范围。
