Mixotrophic Iron-Oxidizing Thiomonas Isolates from an Acid Mine Drainage-Affected Creek
Mixotrophic Iron-Oxidizing Thiomonas Isolates from an Acid Mine Drainage-Affected Creek
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DOI：
10.1128/aem.01424-20
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发表时间：
2020-12-01
影响因子：
4.4
通讯作者：
Chan, Clara S.
中科院分区：
文献类型：
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作者：
Akob, Denise M.;Hallenbeck, Michelle;Chan, Clara S.
重金属的自然衰减发生在受酸性矿山废水（AMD）影响的溪流中，通过耦合微生物铁循环和金属沉淀。在这里，我们描述了两种铁氧化细菌（FeOB）的分离，表征和基因组测序：Thiornonas ferrovorans FB-6和Thiornonas mnetallidurans FB-Cd，分离自微酸性（pH 6.3），富铁，AMD影响的小溪沉积物。这些菌株沉淀出无定形氧化铁、纤铁矿、针铁矿和磁铁矿或磁赤铁矿，并在5.5的最佳pH下生长。而硫单胞菌属（Thiomonas spp.）作为氧化剂，FB菌株氧化Fe，这表明它们可以通过共沉淀有效地去除Fe和其他金属。以前的证据硫单胞菌属。铁氧化在很大程度上是模糊的，可能是因为难以证明铁氧化在异养/兼养生物。因此，我们还进行了基因组分析，以确定铁氧化，其他金属转化和其他适应的遗传机制，将两个FB菌株基因组与其他12个硫杂菌基因组进行比较。FB菌株属于一组相对较新的硫单胞菌属菌株，其中包括另一种具有铁氧化确凿证据的菌株（b6）。大多数硫单胞菌菌株，包括FB菌株，具有推定的铁氧化基因cyc 2，但只有两个FB菌株具有推定的铁氧化酶基因rntoAB。两个FB菌株基因组含有最高数量的菌株特异性基因簇，大大增加了已知的硫杂菌遗传潜力。我们的研究结果表明，FB菌株是两个不同的新的硫单胞菌属物种的遗传潜力，通过铁氧化AMD的生物修复。重要的是，AMD通过环境移动，它会影响水生生态系统，但同时，这些生态系统可以自然地削弱污染的沃茨通过酸中和和催化金属沉淀。这是前Ronneburg铀矿区的情况，AMD影响了小溪沉积物。我们分离和鉴定了两种铁氧化硫单胞菌属，它们是轻度嗜酸性的嗜酸性的，并且具有两种铁氧化的遗传途径。这些硫单胞菌属物种很好地定位于自然衰减AMD，因为它在景观中排放。
Natural attenuation of heavy metals occurs via coupled microbial iron cycling and metal precipitation in creeks impacted by acid mine drainage (AMD). Here, we describe the isolation, characterization, and genomic sequencing of two iron-oxidizing bacteria (FeOB) species: Thiornonas ferrovorans FB-6 and Thiornonas rnetallidurans FB-Cd, isolated from slightly acidic (pH 6.3), Fe-rich, AMD-impacted creek sediments. These strains precipitated amorphous iron oxides, lepidocrocite, goethite, and magnetite or maghemite and grew at a pH optimum of 5.5. While Thiomonas spp. are known as mixotrophic sulfur oxidizers and As oxidizers, the FB strains oxidized Fe, which suggests they can efficiently remove Fe and other metals via coprecipitation. Previous evidence for Thiomonas sp. Fe oxidation is largely ambiguous, possibly because of difficulty demonstrating Fe oxidation in heterotrophic/mixotrophic organisms. Therefore, we also conducted a genomic analysis to identify genetic mechanisms of Fe oxidation, other metal transformations, and additional adaptations, comparing the two FB strain genomes with 12 other Thiornonas genomes. The FB strains fall within a relatively novel group of Thiomonas strains that includes another strain (b6) with solid evidence of Fe oxidation. Most Thiomonas isolates, including the FB strains, have the putative iron oxidation gene cyc2, but only the two FB strains possess the putative Fe oxidase genes rntoAB. The two FB strain genomes contain the highest numbers of strain-specific gene clusters, greatly increasing the known Thiornonas genetic potential. Our results revealed that the FB strains are two distinct novel species of Thiomonas with the genetic potential for bioremediation of AMD via iron oxidation.IMPORTANCE As AMD moves through the environment, it impacts aquatic ecosystems, but at the same time, these ecosystems can naturally attenuate contaminated waters via acid neutralization and catalyzing metal precipitation. This is the case in the former Ronneburg uranium-mining district, where AMD impacts creek sediments. We isolated and characterized two iron-oxidizing Thiomonas species that are mildly acidophilic to neutrophilic and that have two genetic pathways for iron oxidation. These Thiomonas species are well positioned to naturally attenuate AMD as it discharges across the landscape.