Collaborative Research: PurSUiT: Uncovering the hidden diversity of Gloeobacteria, an enigmatic lineage crucial for understanding the early evolution of cyanobacteria

The emergence of cyanobacteria approximately 2 billion years ago was a pivotal moment in Earth's history. Cyanobacteria increased the amount of oxygen in the atmosphere from nearly none to over 10% of modern levels through the process of oxygenic photosynthesis. This oxygen-rich atmosphere allowed for the evolution of aerobic respiration and complex life forms. However, tracing the early evolution of cyanobacteria has been challenging because cyanobacteria rarely ever form fossils. In addition, most modern cyanobacteria are Phycobacteria, and their sister lineage, Gloeobacteria, are very rare – until 2020 we only knew of two species. The poor representation of Gloeobacteria has made it difficult to determine if their unique features were ancestral or results of specific evolutionary paths. Recent discoveries, however, have revealed a much greater diversity within Gloeobacteria than previously recognized, especially in high-latitude and high-altitude habitats. This project aims to comprehensively characterize the hidden diversity of Gloeobacteria, which will shed new light on the early evolution of oxygenic photosynthesis, a process that fundamentally shifted the trajectories of life on Earth. The first aim involves isolating new Gloeobacteria cultures through targeted fieldwork and real-time nanopore sequencing. These cultures will be characterized in the second aim based on their genomic, phylogenetic, morphological, and physiological traits, leading to detailed taxonomic descriptions. The third aim focuses on fostering interdisciplinary research by organizing a workshop to unite experts from various fields. This study is crucial for comprehending the evolution of cyanobacteria, as Gloeobacteria hold key insights into the origins of oxygenic photosynthesis. The project plans to increase the number of known Gloeobacteria strains tenfold and significantly expand the number of described species, bridging hundreds of millions of years of evolutionary history. Further, given that polar regions are disproportionately threatened by climate change, this work will help document and conserve key microbial diversity before these habitats disappear. Student training opportunities will be provided at various academic levels, and by partnering with Let’s Botanize, the findings of this research will be broadly communicated to the public. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.