Query: NC_004061:31500 Buchnera aphidicola str. Sg (Schizaphis graminum), complete genome Lineage: Buchnera aphidicola; Buchnera; Enterobacteriaceae; Enterobacteriales; Proteobacteria; Bacteria General Information: This strain is the symbiont of the aphid Schizaphis graminum and contains a large circular chromosome. 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.
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General Information: This strain is a type A isolate from the soil. It can establish gas gangrene in a murine experimental model. Causative agent of gas gangrene. This genus comprises about 150 metabolically diverse species of anaerobes that are ubiquitous in virtually all anoxic habitats where organic compounds are present, including soils, aquatic sediments and the intestinal tracts of animals and humans. This shape is attributed to the presence of endospores that develop under conditions unfavorable for vegetative growth and distend single cells terminally or sub-terminally. Spores germinate under conditions favorable for vegetative growth, such as anaerobiosis and presence of organic substrates. It is believed that present day Mollicutes (Eubacteria) have evolved regressively (i.e., by genome reduction) from gram-positive clostridia-like ancestors with a low GC content in DNA. This organism is a causative agent of a wide spectrum of necrotic enterotoxicoses. It also causes such animal diseases as lamb dysentery, ovine enterotoxemia (struck), pulpy kidney disease in lambs and other enterotoxemias in lambs and calves. It is commonly found in the environment (soil, sewage) and in the animal and human gastrointestinal tract as a member of the normal microflora. It is a fast growing (generation time 8-10 min) anaerobic flesh-eater. Active fermentative growth is accompanied by profuse generation of molecular hydrogen and carbon dioxide. It is also oxygen tolerant which makes it an easy object to work with in laboratories. Known isolates belong to five distinct types (A, B, C, D, and E) that are distinguished based on the specific extracellular toxins they produce. Known isolates belong to five distinct types (A, B, C, D, and E) that are distinguished based on the specific extracellular toxins they produce. All types produce the alpha toxin (phospholipase C). Type A strains that cause gas gangrene produce alpha toxin, theta (hemolysin), kappa (collagenase), mu (hyaluronidase), nu (DNAse) and neuraminidase which are all the enzymatic factors aiding the bacterium in invading and destruction of the host tissues. Type C strains produce alpha toxin, beta toxin and prefringolysin enteritis. In addition to alpha toxin, Type B strains produce beta toxin, types B and D produce the pore forming epsilon toxin and type E strains produce iota toxin.