Pirellula sp. strain 1
(genome size: 7.145.576 bp)

Pirellula sp. strain 1, (''Rhodopirellula baltica'') is a marine, aerobic, heterotrophic representative of the order Planctomycetales. They inhabit phytodetrital macroaggregates in marine environments and include one of the organisms known to derive energy from the anaerobic oxidation of ammonia. They catalyze important transformations in global carbon and nitrogen cycles. By their mineralization of marine snow particles planctomycetes have a profound impact on global biogeochemistry and climate by affecting exchange processes between the geosphere and atmosphere.

From the genome features it is now possible to propose a certain lifestyle of Pirellula sp. strain 1. In the water column Pirellula sp. strain 1 gains energy from the aerobic oxidation of mono- or disaccharides derived from the cleavage of sulfated polymers produced by algae. Protection systems for UV protect Pirellula sp. strain 1 from irradiation at the water surface. Nitrate transporters support growth even under limited-nitrogen conditions common in continental shelf areas. The holdfast substance enables Pirellula sp. strain 1 to attach to nutrient-rich marine snow particles slowly sedimenting to the sea floor. Anoxic conditions force Pirellula sp. strain 1 to switch to heterolactic acid fermentation or pathways involving formaldehyde conversion if not to support growth, then at least to allow basic maintenance metabolism. With the expression of genes for carbon starvation Pirellula sp. strain 1 can even outlast periods of nutrient depletion. The formation of swarmer cells helps Pirellula sp. strain 1 to reach for new resources. The high number of sigma factors allows the tight control of gene expression under changing environmental conditions.

Complete genome sequence of the marine planctomycete Pirellula sp. strain 1
F. O. Glöckner*, M. Kube ‡, M. Bauer*, H. Teeling*, T. Lombardot*, W. Ludwig § , D. Gade*, A. Beck ‡ , K. Borzym ‡ , K. Heitmann ‡ , R. Rabus*, H. Schlesner**, R. Amann*, and R. Reinhardt ‡
*Max Planck Institute for Marine Microbiology, Celsiusstrasse 1, D-28359 Bremen, Germany;
‡ Max Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany;
§ Department of Microbiology, Technical University Munich, Am Hochanger 4, D-85350 Freising, Germany;
** Department for General Microbiology, University of Kiel, Am Botanischen Garten 1-9, D-24118 Kiel, Germany

Edited by Carl R. Woese, University of Illinois at Urbana-Champaign, Urbana, IL, and approved May 6, 2003 (received for review March 12, 2003)
PNAS vol. 100, no. 14, p. 8298-8303