Microbial Oceanography: From Genomes to Geochemical Cycles
Sonya Dyhrman, Woods Hole Oceanographic Institution
25 Jan 2008
Microbes dominate the planet, especially our oceans. They produce and consume green house gases, process organic matter, and account for roughly half of total global primary production. In this talk I will delve into the world of this “unseen majority”, focusing on the nitrogen-fixing cyanobacteria (Trichodesmium and Crocosphaera) that play such a critical role in the marine carbon and nitrogen cycles. Results to date bring together comparative genomics, gene expression profiling, and field observations, to highlight how these genera scavenge phosphorus from their environment. The data suggests that Trichodesmium, unlike Crocosphaera, is able to acquire phosphorus from refractory forms of dissolved organic phosphorus. This work, and other studies, also suggest that phosphorus availability may limit the growth and N fixation of Trichodesmium populations in the Sargasso Sea, and the South Atlantic.