Schubert, M. G.; Tang, T.-C.; Goodchild-Michelman, I. M.; Ryon, K. A.; Henriksen, J. R.; Chavkin, T.; Wu, Y.; Miettinen, T. P.; Van Wychen, S.; Dahlin, L.; Spatafora, D.; Turco, G.; Guarnieri, M.; Manalis, S. R.; Kowitz, J.; Dhir, R.; Quatrini, P.; Mason, C. E.; Church, G. M.; Milazzo, M.; Tierney, B. T.

Cyanobacteria are photosynthetic organisms that play important roles in carbon cycling as well as promising bioproduction chassis. Here, we isolate two novel cyanobacteria, UTEX 3221 and UTEX 3222, from a unique marine environment with naturally elevated CO2. We describe complete genome sequences for both isolates and, focusing on UTEX 3222 due to its planktonic growth in liquid, characterize biotechnologically-relevant growth and biomass characteristics. UTEX 3222 outpaces other fast-growing model strains on solid medium. It can double every 2.35 hours in a liquid medium and grows to high density (>31g/L biomass dry weight) in batch culture, nearly double that of Synechococcus sp. PCC 11901, whose high-density growth was recently reported. In addition, UTEX 3222 sinks readily, settling more quickly than other fast-growing strains, suggesting improved de-watering of UTEX 3222 biomass. This settling behavior can be explained in part by larger cell volume. These traits may make UTEX 3222 a compelling choice for photosynthetic bioproduction from CO2. Overall, we find that bio-prospecting in environments with naturally elevated CO2 may uncover novel CO2-metabolizing organisms with unique characteristics.