Arsenic is best known as an environmental toxin, but this element could also serve as a metabolic energy source to certain microorganisms. Moreover, As cycling may have driven microbial life on early Earth prior to oxygenation of the atmosphere. Still, little is known about the arsenic cycling processes occurring in the presence of microorganisms and the possible traces that could be preserved in the rock record. To advance our understanding of this we studied the geochemical proxies of microbial As metabolism in living microbialites from Laguna Diamante, a likely Precambrian ecosystem analogue (Catamarca, Argentina). In this study, we show that the coexistence of As(III) and As(V) strongly supports the presence of active microbially arsenic cycling in these microbialites. In addition, we propose a model by which arsenic metabolic processes can be preserved and interpreted as biosignatures in modern systems as well as in the rock record.

中文翻译：

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高海拔安第斯湖（拉古纳迪亚曼特，阿根廷）活微生物岩中砷循环的地球化学证据

砷是众所周知的环境毒素，但这种元素也可以作为某些微生物的代谢能源。此外，在大气氧化之前，As 循环可能驱动了早期地球上的微生物生命。尽管如此，人们对在微生物存在下发生的砷循环过程以及岩石记录中可能保留的痕迹知之甚少。为了加深我们对此的理解，我们研究了来自 Laguna Diamante 的活微生物岩中微生物 As 代谢的地球化学代理，Laguna Diamante 是一种可能的前寒武纪生态系统类似物（阿根廷卡塔马卡）。在这项研究中，我们表明 As(III) 和 As(V) 的共存强烈支持这些微生物岩中存在活跃的微生物砷循环。此外，