Query: NC_010556:691498 Exiguobacterium sibiricum 255-15, complete genome
Lineage: Exiguobacterium sibiricum; Exiguobacterium; Bacillales Family XII; Bacillales; Firmicutes; Bacteria
General Information: This organism was isolated from a 2-3 million-year permafrost core in Siberia, Russia and can survive and grow rapidly at low temperatures. Analysis of long-term survival of psychrophilic organisms such as this one may aid understanding of the potential growth of organisms in astrobiology. Exiguobacterium sibiricum is a psychrotolerant organism able to grow at temperatures that range from -6 to 40 degrees C. This organism is also able to survive repeated freeze/thaw cycles which may contribute to its ability to survive in cold environments.
Subject: NC_003997:4273579 Bacillus anthracis str. Ames, complete genome
Lineage: Bacillus anthracis; Bacillus; Bacillaceae; Bacillales; Firmicutes; Bacteria
General Information: This well studied laboratory strain (Porton isolate) is not virulent due to the loss of the two plasmids, pXO1 and pXO2. Under starvation conditions this group of bacteria initiate a pathway that leads to endospore formation, a process that is thoroughly studied and is a model system for prokaryotic development and differentiation. Spores are highly resistant to heat, cold, dessication, radiation, and disinfectants, and enable the organism to persist in otherwise inhospitable environments. Under more inviting conditions the spores germinate to produce vegetative cells. This organism was the first to be shown to cause disease by Dr. Louis Pasteur (the organism, isolated from sick animals, was grown in the laboratory and then used to infect healthy animals and make them sick). This organism was also the first for which an attenuated strain was developed as a vaccine. Herbivorous animals become infected with the organism when they ingest spores from the soil whereas humans become infected when they come into contact with a contaminated animal. PA/LF and PA/EF complexes are internalized by host cells where the LF (metalloprotease) and EF (calmodulin-dependent adenylate cyclase) components act. At high levels LF induces cell death and release of the bacterium while EF increases host susceptibility to infection and promotes fluid accumulation in the cells.