Query: NC_008380:4078670 Rhizobium leguminosarum bv. viciae 3841, complete genome
Lineage: Rhizobium leguminosarum; Rhizobium; Rhizobiaceae; Rhizobiales; Proteobacteria; Bacteria
General Information: This biovar nodulates legumes in the Tribe Viciae (Vicia, Pisum, Lathyrus, Lens). This strain is a spontaneous streptomycin-resistant mutant of strain 300. Nitrogen-fixing plant symbiont. This organism, like other Rhizobia, establishes a symbiotic relationship with a legume plant, providing nitrogen in exchange for a protected environment. The legume roots secrete flavonoids and isoflavonoids which the bacteria recognize and use to turn on genes involved in root nodulation. Many of the root nodulation genes are involved in synthesis and secretion of a nodule inducing signal, a lipochito-oligosaccharide molecule, which the plant recognizes, triggering nodule formation. The bacterium is endocytosed and exists inside a membrane bound organelle, the symbiosome, and fixes nitrogen for the plant cell while the host cell provides carbon compounds for the bacterium to grow on. The nitrogen fixation is important as it obviates the need for expensive and environmentally damaging fertilizer use.
Subject: NC_006397:1 Haloarcula marismortui ATCC 43049 chromosome II, complete sequence
Lineage: Haloarcula marismortui; Haloarcula; Halobacteriaceae; Halobacteriales; Euryarchaeota; Archaea
General Information: This organism was isolated from the Dead Sea and will provide information on the proteins necessary for adaptation to a high salt environment. Halophilic archaeon. Halobacterial species are obligately halophilic microorganisms that have adapted to optimal growth under conditions of extremely high salinity 10 times that of sea water. They contain a correspondingly high concentration of salts internally and exhibit a variety of unusual and unique molecular characteristics. Since their discovery, extreme halophiles have been studied extensively by chemists, biochemists, microbiologists, and molecular biologists to define both molecular diversity and universal features of life. A notable list of early research milestones on halophiles includes the discovery of a cell envelope composed of an S-layer glycoprotein, archaeol ether lipids and purple membrane, and metabolic and biosynthetic processes operating at saturating salinities. These early discoveries established the value of investigations directed at extremophiles and set the stage for pioneering phylogenetic studies leading to the three-domain view of life and classification of Halobacterium as a member of the archaeal domain. This organism is also know as "Halobacterium of the Dead Sea". Growth occurs in 1.7-5.1 M NaCl with optimum salt concentration of 3.4-3.9 M NaCl. The cytosol of this organism is a supersaturated salt solution in which proteins are soluble and active. This halophile is chemoorganotrophic and able to use a wide variety of compounds as sole carbon and energy sources.