The SAR11 clade consists of very small, heterotrophic marine alphaproteobacteria that are found throughout the oceans, where they account for about 25% of all microbial cells. Pelagibacter ubique, the first cultured member of this clade, has the smallest genome and encodes the smallest number of predicted open reading frames known for a free-living microorganism. In contrast to parasitic bacteria and archaea with small genomes, P. ubique has complete biosynthetic pathways for all 20 amino acids and all but a few cofactors. P. ubique has no pseudogenes, introns, transposons, extrachromosomal elements, or inteins; few paralogs; and the shortest intergenic spacers yet observed for any cell. This project is a comparison of three different strains of SAR11, HTCC1002, HTCC1025, and HTCC1051, all isolated from the same water sample.
HTCC2148 is a member of the OM60 clade in the gammaproteobacteria division. Another member of this clade, HTCC2080, appears to be capable of aerobic anoxygenic photosynthesis (AAP) based on sequence and proteomic evidence. HTCC2148 was sequenced using 454 pyrosequencing technology to determine whether they also have the AAP gene operon.
