The Geochemistry of a Vitamin: Vitamin B12 Cycling and Marine Microbial Community DynamicsEPA Grant Number: F6E20324
Title: The Geochemistry of a Vitamin: Vitamin B12 Cycling and Marine Microbial Community Dynamics
Investigators: Bertrand, Erin M.
Institution: Massachusetts Institute of Technology
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2006 through September 1, 2009
Project Amount: $111,172
RFA: STAR Graduate Fellowships (2006) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Aquatic Ecosystems , Fellowship - Biogeochemistry , Fellowship - Marine Chemistry
Vitamin B12 is a complex, cobalt-containing micronutrient synthesized only by prokaryotes. B12 is required by over half of all phytoplankton species. Very little is known about the role that vitamin B12 plays in oceanic nutrition, how it is connected to the biogeochemical cycling of cobalt, or how it is connected to the global cycling of major nutrients like carbon and nitrogen. This project will investigate the controls on B12 cycling in the ocean and the effect B12 has on phytoplankton and microbial population dynamics. It will explore how human activities such as vitamin supplement consumption may be adding the vitamin to coastal waters and thereby changing phytoplankton community dynamics and possibly influencing harmful algal blooms (HAB). Overall, this study will investigate the role this essential and understudied micronutrient plays in controlling primary production in the ocean, a process integral to the global carbon cycle and coastal phytoplankton dynamics.
This study will employ a range of techniques from multiple disciplines to explore vitamin B12 biogeochemical cycling. Analytical measurement of B12 in the ocean will be made using high pressure liquid chromatography coupled to mass spectrometry; measurements of cobalt will be made using adsorbtive cathodic stripping voltametry. These measurements will be paired with B12 uptake measurements to make connections between vitamin B12 and cobalt biogeochemical cycling. These analytical techniques will also be used to develop a vitamin B12 monitoring scheme in the coastal environment around Woods Hole, MA, particularly looking for an effect of the vitamin on HAB’s. Mass spectrometry-based proteomics and DNA microarray analysis will be used to investigate the vitamin B12 uptake mechanisms of several representative phytoplankton species, including cyanobacteria and several species of eukaryotic algae. Based on this, molecular probes for protein or gene expression will be developed to discover if phytoplankton are limited or stressed by vitamin B12 in the field.
Vitamin B12 cycling in the ocean is expected to play a major role in determining marine microbial community structure. Cobalt biogeochemical cycling is hypothesized to be, at least in part, controlled by biological demand for and creation of vitamin B12. Different phytoplankton species are expected to possess different vitamin B12 uptake mechanisms, such that these mechanisms might confer an ecological advantage to some species. Vitamin B12 is hypothesized to have a limiting effect on phytoplankton growth, one that could affect global carbon cycling. Increasing vitamin B12 concentrations, through pollution into coastal waters is expected along with evidence that these increases could affect coastal phytoplankton ecology and possibly play a role in HABs.