Presents the whole sequenced genome of Sinorhizobium fredii. Rhizobium sp. strain NGR234 is a unique alphaproteobacterium (order Rhizobiales) that forms nitrogen- fixing nodules with more legumes than any other microsymbiont. The 3.93-Mbp chromosome (cNGR234) encodes most functions required for cellular growth. Few essential functions are encoded on the 2.43-Mbp megaplasmid (pNGR234b), and none are present on the second 0.54-Mbp symbiotic plasmid (pNGR234a).