Query: NC_007426:205390 Natronomonas pharaonis DSM 2160, complete genome
Lineage: Natronomonas pharaonis; Natronomonas; Halobacteriaceae; Halobacteriales; Euryarchaeota; Archaea
General Information: Isolated from Lake Gabara in Egypt. Extreme haloalkaliphilic archeon. Natronomonas pharaonis is able to survive at high salt and pH conditions which results in limited nitrogen availability through ammonium. In order to compensate for this, Natronomonas pharaonis has developed three systems to promote nitrogen assimilation: direct uptake of ammonia, uptake of nitrate, and uptake of urea. Another problem with high pH environments is the use of a proton gradient for the generation of ATP, which other alkaliphiles have adapted to by substitution of sodium ions for protons. However, this organism utilizes protons for ATP generation as determined by experimental data.
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.