Query: NC_007484:2665195 Nitrosococcus oceani ATCC 19707, complete genome
Lineage: Nitrosococcus oceani; Nitrosococcus; Chromatiaceae; Chromatiales; Proteobacteria; Bacteria
General Information: Found in marine or saline environments. Ammonia-oxidizing bacterium. This species, along with Nitrosococcus halophilus, are ammonia-oxidizing bacteria found within the gamma subdivision of Proteobacteria. This organism has two surface layers, and produces a central stack of intracytoplasmic membranes (flattened vesicles).
Subject: NC_008513:13484 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.