Query: NC_002607:1868371 Halobacterium sp. NRC-1, complete genome
Lineage: Halobacterium; Halobacterium; Halobacteriaceae; Halobacteriales; Euryarchaeota; Archaea
General Information: Chemoheterotrophic obligate extreme halophilic archeon. This microbe (strain ATCC 700922) is an obligately halophilic archeon that has adapted to growth under conditions of extremely high salinity. Motility is via tufts of polar flagella and intracellular gas vesicles are used for buoyancy. This organism grow aerobically and its ease of culturing combined with the availability of established methods of genetic manipulation in the laboratory make it an ideal model organism for study of the archaea.
Subject: NC_008380:58232 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.