Iron and Cobalt Limitation in Atlantic Prochlorococcus MIT9301

Abstract

Prochlorococcus is an abundant marine microorganism playing a vital role in the Earth’s carbon cycle and therefore climate. This organism is a cyanobacteria meaning it obtains energy through photosynthesis. A large portion of the ocean’s phytoplankton populations are limited by low concentrations of trace metals such as iron and cobalt. Future climate change will likely alter ocean circulation and supply of trace metals to the surface ocean, and may impact Prochlorococcus populations, which can affect marine food webs. We only have information on iron and cobalt requirements for a few strains of Prochlorococcus. Therefore, we performed culturing experiments to understand the growth and decay of Prochlorococcus in a lab environment with changes in levels of iron and cobalt. Iron limitation on Atlantic Prochlorococcus did not have a significant impact on growth rates, while cobalt limitation experiments did significantly impact the growth of these phytoplankton when lowered. The growth rates resulting from these experiments can be used to model future changes in Prochlorococcus populations as the impacts of climate change become more prevalent.

Keywords: Prochlorococcus, trace metal, cobalt, iron, growth rate, limitation