ROMEO: Metagenomic and Metatranscriptomic response of riverine microbial communities to seasonal changes in the composition of dissolved organic matter.

Rivers are the principle conduits between the major global organic carbon stores on land and those in the ocean. Dissolved organic matter (DOM) is a master variable in rivers, impacting light attenuation, metal transport, and metabolism. Riverine bacteria rely on DOM for sustenance and, in using DOM, respire a fraction and alter the composition of the remaining DOM. The relationship between microbes and DOM is a crucial but poorly understood shaper of river ecosystem function. One major gap is our understanding of specific metabolic capabilities of bacteria and how they interact with organic matter quality to carry out the key ecosystem function of transforming and metabolizing riverborne DOM. The ROMEO project (River Organic Matter and Environmental 'Omics) integrates new and cutting-edge tools in genetics and DOM geochemistry to describe in molecular detail the ecological and genetic mechanisms by which terrestrial DOM is modified and mineralized to carbon dioxide during transport from land to sea by determining the interactions and feedbacks between microbial functional diversity, gene expression, and DOM metabolism in U.S. rivers.