Query: NC_007964:717590 Nitrobacter hamburgensis X14, complete genome
Lineage: Nitrobacter hamburgensis; Nitrobacter; Bradyrhizobiaceae; Rhizobiales; Proteobacteria; Bacteria
General Information: Nitrobacter hamburgensis X14 was isolated from soil. Nitrite-oxidizing soil bacterium. Members of this genus are found in marine, freshwater, and terrestrial habitats, often in association with ammonia-oxidizing bacteria. These organisms oxidize nitrite, generated by the oxidation of ammonia, to nitrate and play an important role in the global nitrogen cycle. The enzyme involved in nitrite oxidation, nitrite oxidoreductase, can also reduce nitrate to nitrite in the absence of oxygen, allowing Nitrobacter sp. to grow anaerobically. Nitrobacter hamburgensis is commonly isolated from freshwater, soil, and sewage sludge. This organism has been used in biofilms to remove nitrogen from wastewater.
Subject: NC_008513:343540 Buchnera aphidicola str. Cc (Cinara cedri), complete genome
Lineage: Buchnera aphidicola; Buchnera; Enterobacteriaceae; Enterobacteriales; Proteobacteria; Bacteria
General Information: This strain is found in the cedar aphid, Cinara cedri. Aphid endosymbiont. Almost all aphids contain maternally transmitted bacteriocyte cells, which themselves contain bacteria called Buchnera. The aphids live on a restricted diet (plant sap), rich in carbohydrates, but poor in nitrogenous or other essential compounds. It is believed that the Buchnera provide the essential nutrients the host lacks. Besides a nutritional co-dependence, due to a co-existence of millions of years, Buchnera have lost the ability to produce cell surface components such as lipopolysaccharides. This makes for an obligate endosymbiont relationship between host and Buchnera. Buchnera are prokaryotic cells which belong to the gamma-Proteobacteria, closely related to the Enterobacteriaceae family. Phylogenetic studies using 16S rRNA indicate that the symbiotic relationship was established around 200-250 million years ago. Since Buchnera are closely related to Escherichia coli and Haemophilus influenzae, comparative genomic studies can shed light on the evolutionary mechanisms of intracellular endosymbiosis as well as the different underlying molecular basis between organisms with parasitic behavior and symbionts.