Query: NC_004545:15650 Buchnera aphidicola str. Bp (Baizongia pistaciae), complete genome
Lineage: Buchnera aphidicola; Buchnera; Enterobacteriaceae; Enterobacteriales; Proteobacteria; Bacteria
General Information: This organism is found in the aphid Baizongia pistaciae. Aphid endosymbiont. 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.
Subject: NC_002932:296557 Chlorobium tepidum TLS, complete genome
Lineage: Chlorobaculum tepidum; Chlorobaculum; Chlorobiaceae; Chlorobiales; Chlorobi; Bacteria
General Information: This green-sulfur bacterium is a thermophile and was isolated from a New Zealand high-sulfide hot spring. Photosynthetic thermophile. Chlorobium tepidum is a member of the green-sulfur bacteria. It has been suggested that the green-sulfur bacteria were among the first photosynthetic organisms since they are anaerobically photosynthetic and may have arisen early in the Earth's history when there was a limited amount of oxygen present. This organism utilizes a novel photosynthetic system, and harvests light energy using an unusual organelle, the chlorosome, which contains an aggregate of light-harvesting centers surrounded by a protein-stabilized galactolipid monolayer that lies at the inner surface of the cytoplasmic membrane. Unlike many other photosynthetic organisms, the green-sulfur bacteria do not produce oxygen and tolerate only low levels of the molecule. This organism also fixes carbon dioxide via a reverse tricarboxylic acid cycle, using electrons derived from hydrogen or reduced sulfur to drive the reaction, instead of via the Calvin cycle like many other photosynthetic organisms.