Vanessa Michelou

composite image

bull kelp

Vanessa Michelou
michelou //at// stanford.edu
Postdoctoral Scholar, CV

Ph.D. in Oceanography, University of Delaware, 2009

Dissertation: "Uptake of organic matter compounds by heterotrophic and autotrophic bacteria: exploring photoheterotrophy by marine cyanobacteria."
Advised by David Kirchman.

B.S. in Marine Science, University of South Carolina, 2004.

CURRENT RESEARCH
My research interests lie in understanding the forces that shape bacterial community structures and dynamics, microbial diversity, and the roles of microbial species in biogeochemical fluxes of nutrients.  I use innovative, multi-disciplinary approaches for assessing the link between bacterial community structure and ecosystem function.

Microbial ecology of photoheterotrophic bacteria
My Ph.D. research, in Dr. David Kirchman’s lab, focused on assessing the heterotrophic capabilities of photoautotrophic marine cyanobacteria and explored their role in the water column. I compared the uptake of organic matter by strictly heterotrophic bacteria and cyanobacteria.  My main goal was to determine the element (carbon or nitrogen) being used for the observed heterotrophy.  I tracked the uptake of glucose, a common carbon-only compound used by marine prokaryotes.  In addition to carbon compounds I am also interested in the uptake of organic and inorganic phosphorus compounds by these same groups of bacteria.

Microbial ecology of Macrocystis pyrifera-associated bacteria
I came to Hopkins Marine Station as a postdoctoral scholar to study the seasonal variation of the phylogenetic, taxonomic and functional diversity of microorganisms associated with the most important kelp species around Monterey Bay, CA, Macrocystis pyrifera.  I am using genomics and high-throughput sequencing technologies to examine the metabolic potential, biogeography, and evolution of uncultured microbes from this unique aquatic environment.  Kelp forests represent one of the largest preserves of biodiversity, and understanding the role and value of this vast diversity requires that microbiological studies be conducted at the level of the individual organism in order to determine the metabolic capabilities of the uncultured majority of microbes in such a complex community.  My work involves applying my scientific background and experience to not only help determine microbial trophic interactions that form the basis of kelp forest ecosystems (thus helping in the conservation of these habitats), but also in the discovery of novel genes for the benefit of our society.  An important part of my research program is to use these data to determine the time-dependent changes in microbial community composition and to try to learn what physical, chemical, and biological factors regulate that composition (http://mlo.stanford.edu/microbial.htm).  Measuring bacterial production and abundance is very important, but over time and space, these parameters appear very constant.  Community composition on the other hand, might tell us something more about environmental change.

So far I have characterized the microbial communities from Kelp biofilm across both space and time, using 454-pyrosequencing, in order to shed some insight on how the free-living microbial community in the water compares to that on the biofilm of the kelp.  Initial results suggest a wide range of diversity that may be related to seasonal changes in the environment (free-living microbial community) as well as age of the kelp (biofilm microbes).  The coming months will be spent increasing the temporal resolution of the study and finalizing the analyses for publication in 2011.  This work has led to productive collaborations with some of the other microbial diversity labs in the area at University of California Santa Cruz (Dr. John Zher) and the Monterey Bay Aquarium Research Institution (Dr. Chris Scholin and Dr. Francisco Chavez).

Future Directions
In continuing to build upon the recently established investigation into the mechanisms of
microbial-kelp interactions, I plan to address some of the fundamental questions of taxonomic and functional diversity of microbial ecology: What species are present?  How do they respond to alterations in the chemical and physical environment?  What role do they play in biogeochemical cycling, food webs, and maintenance of global climate?  Can we use specific organisms as indicators of environmental change?  Are harmful or toxic microorganisms present, and if so, which species and how many?

Outreach
I work with the Montery Bay Aquarium within the community (mostly Hispanic) to facilitate family science nights, pre-school programming and youth support.  See these programs at:

http://education.mbayaq.org/.

Michelou, V.K., Lomas, M.W., Kircman, D.K. 2010. Phosphate and Adenosine-5'-triphosphate uptake by cyanobacteria and heterotrophic bacteria in the Sargasso Sea. Limnology and Oceanography. In press.

Michelou, V.K., Lomas, M.W., Kircman, D.K. 2010. Amino Acid and Glucose Uptake by Autotrophic and Heterotrophic Bacteria in the Sargasso Sea. Submitted.

Michelou, V.K. Cottrell, M.T., Kirchman, D.L., 2007. Light-stimulated Organic Matter Assimilation by Cyanobacteria and Other Microbes in the North Atlantic Ocean. Applied and Environmental Microbiology 73(17): 5539-5546.

Cottrell, M.T.,Michelou, V.K., Nemeck, N., DiTullio , G., Kirchman, D.L. 2008. Carbon Cycling by Microbes influenced by Light in the Northeast Atlantic Ocean. Aquatic Microbial Ecology. 50(3): 239-250.

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