Expanding the Bio in Biogeochemistry: Cyanobacteria and the Great Oxygenation Event.

大氧化事件（GOE），即早期地球大气被氧化，被认为是一个单步事件发生约2.3 Ga。然而，最近的证据表明，在此之前，大约3 Ga就存在氧气水平升高的小生境。蓝细菌，凭借氧化光合作用，被认为是大气氧化的关键贡献者。早期地球上的生命是由太古代沉积岩中的少量叠层石层和微生物垫所证明的。现代蓝细菌的系统发育分析，使用许多基因和分子钟算法，已经确定了起源于GOE之前和之后的蓝细菌的古老谱系。目前在地球化学和地球微生物学中使用的特征分子和特征是否真的可以由古蓝细菌在被认为存在于太古代的条件下产生，尚未确定。我们的项目将解决这一研究空白，通过评估现代后代的古代蓝藻谱系的生长反应下减少O2水平，在海洋和淡水物种和相关的矿物学数据，特别是有关碳酸盐和铁循环，与现有的地球化学记录。因此，我们的目标是整合现有的地球化学记录和蓝藻系统发育史与生态生理学研究和矿物学分析的现代模拟微生物的条件下，认为已经存在的太古代结束，回答这个问题：蓝藻如何影响早期地球大气的氧化？

The Great Oxygenation Event (GOE), whereby the early Earths atmosphere was oxygenated, was thought to be a single step event occurring about 2.3 Ga. Recent evidence suggests however that niches of raised oxygen levels existed prior to this, approximately 3 Ga. Cyanobacteria, by virtue of oxidative photosynthesis, are considered a key contributor to atmospheric oxygenation. Life on early Earth is evidenced with scant stromatolitic formations and microbial mats from sedimentary rocks dating from the Archean. Phylogenetic analysis of modern-day Cyanobacteria, using many genes and molecular clock algorithms, have identified ancient lineages of Cyanobacteria that originated prior to and after the GOE. Whether the signature molecules and profiles currently utilised in biogeochemistry and geomicrobiology could actually be generated by ancient Cyanobacteria under the conditions thought to have existed during the Archean, has not been determined. Our project will address this research gap by assessing the growth responses of modern day descendants of ancient cyanobacterial lineages under reduced O2 levels, in both marine and freshwater species and to correlate the obtained mineralogic data, specifically that pertaining to carbonate and iron cycling, with the existing biogeochemical records. We thereby aim to integrate the existing biogeochemical record and cyanobacterial phylogenetic history with ecophysiological studies and mineralogic analysis of modern-day analogue micro-organisms under conditions thought to have existed towards the end of the Archean, answering the question: How did Cyanobacteria affect the oxygenation of the early Earths atmosphere?