Amongst iron-oxidizing bacteria playing a key role in the natural attenuation of arsenic in acid mine drainages (AMDs), members of the Ferrovum genus were identified in mine effluent or water treatment plants, and were shown to dominate biogenic precipitates in field pilot experiments. In order to address the question of the in situ activity of the uncultivated Ferrovum sp. CARN8 strain in the Carnoulès AMD, we assembled its genome using metagenomic and metatranscriptomic sequences and we determined standardized expression values for protein-encoding genes. Our results showed that this microorganism was indeed metabolically active and allowed us to sketch out its metabolic activity in its natural environment. Expression of genes related to the respiratory chain and carbon fixation suggests aerobic energy production coupled to ferrous iron oxidation and chemolithoautotrophic growth. Notwithstanding the presence of nitrogenase genes in its genome, expression data also indicated that Ferrovum sp. CARN8 relied on ammonium import rather than nitrogen fixation. The expression of flagellum and chemotaxis genes hints that at least a proportion of this strain population was motile. Finally, apart from some genes related to metal resistance showing surprisingly low expression values, genes involved in stress response were well expressed as expected in AMDs.

中文翻译：

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未经培养的Ferrovum sp。的原位代谢活性。转录组分析证实了CARN8。

在氧化性矿井排水中的砷自然衰减中起关键作用的铁氧化细菌中，在矿井废水或水处理厂中鉴定出了Ferrovum属的成员，并在野外试验实验中显示出其占主导地位。为了解决未培养的Ferrovum sp。的原位活性的问题。在CarnoulèsAMD中的CARN8菌株中，我们使用宏基因组和元转录组序列组装了其基因组，并确定了蛋白质编码基因的标准化表达值。我们的结果表明，这种微生物确实具有代谢活性，并允许我们勾勒出其在自然环境中的代谢活性。与呼吸链和碳固定相关的基因的表达表明，有氧能量的产生与亚铁的氧化和化能自养的生长有关。尽管在其基因组中存在固氮酶基因，表达数据也表明Ferrovum sp。CARN8依赖进口铵，而不是固氮。鞭毛和趋化基因的表达暗示该菌株群体中至少一部分是能动的。最后，除了一些与金属抗性有关的基因显示出令人惊讶的低表达值外，与应激反应有关的基因也如AMD所预期的那样被很好地表达。CARN8依赖进口铵，而不是固氮。鞭毛和趋化基因的表达暗示该菌株群体中至少一部分是能动的。最后，除了一些与金属抗性有关的基因显示出令人惊讶的低表达值外，与应激反应有关的基因也如AMD所预期的那样被很好地表达。CARN8依赖进口铵，而不是固氮。鞭毛和趋化性基因的表达暗示该菌株群体中至少一部分是能动的。最后，除了一些与金属抗性有关的基因显示出令人惊讶的低表达值外，与应激反应有关的基因也如AMD所预期的那样被良好表达。