Monster Seminar Jam - Microbial Population Structure of the World's Oceans: an underexplored rare biosphere
Dr. Mitchell Sogin, Marine Biological Laboratory (Woods Hole) Department of Molecular and Cellular Biology (Brown University)
Microorganisms of untold diversity are usually members of complex communities that dominate every corner of our biosphere. They orchestrate key processes in geochemical cycling, biodegradation and in the protection of entire ecosystems from major environmental shifts. Within the oceans, nominal cell counts greater than 105/ml predict an estimated 3.6 x 1029 microbial cells with cellular carbon of ~3 x 1017 grams. Given the enormous number of microbes and their vast metabolic diversity, the accumulation of mutations during the past 3.5 billion years should have led to very high levels of genetic and phenotypic variation. Molecular techniques reveal that microbial diversity is at least 100 times greater than estimates based upon traditional cultivation-dependent surveys but these new approaches rarely inform us about the relative population numbers for different kinds of microbes. By adopting a massively parallel pyro-sequencing strategy to interrogate microbial populations fro mthe sea, we discovered a spectacular wealth of previously unknown diversity. A relatively small number of different populations dominate all samples, but thousands of low-abundance populations account for most of the observed phylogenetic diversity. This rare biosphere is very ancient and may represent a nearly inexhaustible source of genomic innovation. Members of the rare biosphere are highly divergent from each other and at different times in earths history may have had a profound impact on shaping planetary processes.
Date and Time:
May 1, 2008,
10:30 am - 1:00 pm
206-860-3380 send email