Collaborative research: BEE: Discovery and characterization of novel microbial lineages in an early Earth analog sulfur-based ecosystem.

Evolution of life on Earth is closely linked to geological changes occurring at its surface. Changes in early Earth's geology and atmosphere drove the evolution of new microorganisms adapted to the prevailing new conditions. Consequently, growth of these newly-evolved microorganisms was associated with the production of new end products such as oxygen, carbon dioxide, and sulfides, that in turn greatly impacted the physical conditions on Earth in a never-ending feedback loop between biology and geology. So far, it is not clearly understood what types of microorganisms inhabited early Earth. Early unicellular lifeforms are fragile, boneless, and have not been preserved. Since direct sampling is impossible, an alternative approach based on the identification of current locations with conditions paralleling those prevailing in past eons is warranted. The researchers have identified a unique site in southwestern Oklahoma (Zodletone spring), where physical conditions at various locations in the spring remarkably correspond to conditions prevalent at various geological eons throughout Earth's history. Therefore, spatial sampling in Zodletone spring can substitute for inaccessible temporal time scales. The project will utilize a range of cutting-edge laboratory methodologies to characterize the microbial community in this unique site. This knowledge will contribute to our understanding of how life evolved on Earth, and the prerequisites for its potential evolution on other planets and celestial objects within the solar system and beyond. The research will contribute to workforce training of multiple high-school, undergraduate, and graduate students in two states with special emphasis on students from groups that are underrepresented in science.

The overall goal of this project is to identify and characterize novel bacterial lineages prevalent in Zodletone spring: a surficial, light-exposed, and euxinic (anoxic, sulfide-rich) habitat representing an early Earth analog. The researchers will characterize novel yet-uncultured bacterial lineages encountered in the spring using a combination of genome-resolved metagenomics, metabolic reconstruction, community transcriptomics, targeted isolation, and global diversity and pangenomic surveys. This will be achieved by: 1) Metabolic reconstruction to deduce the metabolic potential and physiological preferences of uncultured lineages recovered from various locations in the spring; 2) Validating the proposed metabolic capabilities and ecological roles using expression studies and reverse-genomics based isolation strategies, and; 3) Assessing the global distribution patterns and pangenomic diversity of the identified lineages using data mining approaches and comparative genomics strategies to trace the ecological success/retreat/extinction of these novel lineages.

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.