Rhodoferax sp. BLA1 Genome sequencing and assembly. Rhodoferax sp. BLA1

Photoferrotrophy is thought to have been the major pathway for primary productivity in ferruginous Precambrian oceans. However, current analogues - meromictic ferruginous lakes - either suffer from light limitation for photoferrotrophy, fix carbon through predominantly sulfurbased photosynthetic pathways, or are located in regions unsuitable for seasonal monitoring. Brownie Lake has sufficient light and an abundant community of anoxygenic phototrophs (including photoferrotrophs), and deeper Canyon Lake has an extended oxic-anoxic transition zone and much lower nutrients than Brownie Lake. Together, these lakes comprise a range of conditions to investigate the controls that varying nutrient levels, physiography, and seasonality have on photoferrotrophic primary productivity and methane cycling. The team will monitor aqueous and carbon isotope geochemistry, microbial community composition, and elemental makeup/mineralogy of particulates from the Brownie and Canyon Lake water columns in order to determine: (1) the physicochemical conditions that regulate the presence and activity of photoferrotrophs, (2) the role of resident microbes in iron and carbon cycling, (3) the inorganic and mineral biosignatures that similar microbial communities might have left in Precambrian iron-rich sediments such as Banded Iron Formations (BIF), and (4) the isotopic imprint of photoferrotrophy and methanogenesis/methanotrophy to carbon and iron cycling.