Table of Contents
Advances in Oceanography
Volume 2014, Article ID 706082, 12 pages
Review Article

Patterns of Microbially Driven Carbon Cycling in the Ocean: Links between Extracellular Enzymes and Microbial Communities

Department of Marine Sciences, University of North Carolina at Chapel Hill, 3117 Venable/Murray Hall, Chapel Hill, NC 27599-3300, USA

Received 4 February 2014; Revised 12 June 2014; Accepted 16 June 2014; Published 26 June 2014

Academic Editor: Christos Panagiotopoulos

Copyright © 2014 Carol Arnosti. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Heterotrophic microbial communities play a central role in the marine carbon cycle. They are active in nearly all known environments, from the surface to the deep ocean, in the sediments, and from the equator to the Poles. In order to process complex organic matter, these communities produce extracellular enzymes of the correct structural specificity to hydrolyze substrates to sizes sufficiently small for uptake. Extracellular enzymatic hydrolysis thus initiates heterotrophic carbon cycling. Our knowledge of the enzymatic capabilities of microbial communities in the ocean is still underdeveloped. Recent studies, however, suggest that there may be large-scale patterns of enzymatic function in the ocean, patterns of community function that may be connected to emerging patterns of microbial community composition. Here I review some of these large-scale contrasts in microbial enzyme activities, between high-latitude and temperate surface ocean waters, contrasts between inshore and offshore waters, changes with depth gradients in the ocean, and contrasts between the water column and underlying sediments. These contrasting patterns are set in the context of recent studies of microbial communities and patterns of microbial biogeography. Focusing on microbial community function as well as composition and potential should yield clearer understanding of the factors driving carbon cycling in the ocean.