Aquatic Sciences Meeting, Albuquerque 2001

SS04 Environmental Microbial Genomics (Environmental and Disciplinary Connections)

Date: Wednesday, February 14, 2001, Time: 10:30:00 AM

Location: Brazos

Rocap, G, , MIT, Cambridge, USA, scratch@mit.edu

Larimer, F, W, Oak Ridge National Laboratory, Oak Ridge, USA, larimerfw@ornl.gov

Lamerdin, J, E, Joint Genome Institute, Walnut Creek, USA, lamerdin1@llnl.gov

Stilwagon, S, , Joint Genome Institute, Walnut Creek, USA, stilwagen1@llnl.gov

Chisholm, S, W, MIT, Cambridge, USA, chisholm@mit.edu

FROM BASE PAIRS TO NICHE DIFFERENTIATION: ECOLOGICAL INSIGHTS FROM TWO COMPLETE GENOMES OF PROCHLOROCOCCUS

The genome sequence of the marine cyanobacterium Prochlorococcus strain MED4 has been determined by the Department of Energy's Microbial Genome Program. The complete genome is less than 1.7 Mbp and encodes only about 1700 genes, the smallest known for a phototroph. The MED4 genome lacks genes for nitrite and nitrate reductases, consistent with the inability of this strain to grow on these nitrogen sources. MED4 also lacks a gene for the alpha subunit of phycoerythrin and possesses a highly degenerate beta phycoerythrin gene. Complete genome sequencing of Prochlorococcus strain MIT9313 is also underway. Although more than 97% identical to MED4 in 16S rDNA sequence, MIT9313 is physiologically very different. It is capable of growing at lower light levels than MED4 and can utilize nitrite as its sole nitrogen source. Preliminary data indicate that MIT9313 has a larger genome (2.4 Mbp) with a significantly higher %GC content (50%, compared to 30% for MED4). An update on the MIT9313 project and the effects of the genetic complement on the differential distribution of these strains in the ocean will be discussed.

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Aquatic Sciences Meeting, Albuquerque 2001

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