Bacillus subtilis
A Microbial Biorealm page on the genus Bacillus subtilis
Classification
Higher order taxa
Domain: Bacteria, phylum: Firmicutes, class: Bacilli, order: Bacillales, family: Bacillaceae
Genus
Bacillus subtilis
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NCBI: Taxonomy |
Description and significance
Originally named Vibrio subtilis in 1835, this organism was renamed Bacillus subtilis in 1872. Bacillus subtilis bacteria were one of the first bacteria to be studied, and it is a good model for cell development and differentiation. Bacillus subtilis cells are rod-shaped, Gram-positive bacteria that are naturally found in the soil. Bacillus subtilis grow in the mesophilic temperature range. The optimal temperature is 25-35 degrees Celsius. Stress and starvation is common in this environment, therefore, Bacillus subtilis has evolved a set of strategies that allow survival under these harsh conditions. One strategy, for example, is the formation of stress-resistant endospores. Another strategy is the uptake of external DNA, which allow the bacteria to adapt by recombination. However, these strategies are time-consuming. Bacillus subtilis can also gain protection more quickly against many stress situations such as acidic, alkaline, osmotic, or oxidative conditions, and heat or ethanol. The alternative sigma factor ςB is a global regulator of stress response. Heat, acid, or ethanol and glucose or phosphate starvation are all stimuli that activate ςB.
Genome structure
Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?
Cell structure and metabolism
Bacillus subtilis are rod-shaped bacteria that are Gram-positive. The cell wall is a rigid structure outside the cell. It is composed of peptidoglycan, which is a polymer of sugars and amino acids. The peptidoglycan that is found in bacteria is known as murein. Other constituents that extend from the murein are teichoic acids, lipoteichoic acids, and proteins. The cell wall forms the barrier between the environment and the bacterial cell. It is also responsible for maintaining the shape of the cell and withstanding the cell's high internal turgor pressure.
Bacillus subtilis bacteria have been considered strictly aerobic, meaning that they require oxygen to grow and they cannot undergo fermentation, however, recent studies show that they can indeed grow in anaerobic conditions. Bacillus subtilis can use nitrite or nitrate as a terminal acceptor of electrons. They can also ferment. Bacillus subtilis contains to unique nitrate reductases. one is used for nitrate nitrogen assimilation and the other is used for nitrate respiration. However, there is only one nitrite reductase that serves both purposes. Bacillus subtilis is different from other anaerobes in that it undergoes fermentation without external acceptors of electrons. The cells use pyruvate dehydrogenase for pyruvate metabolism. they do not use pyruvate formate lyase like other bacteria do.
Bacillus subtilis contain catalase, an enzyme that is responsible in the catalysis of the decomposition of hydrogen peroxide to water and oxygen, and superoxide dismutase, an enzyme that catalyzes the breakdown of superoxide into oxygen and hydrogen peroxide.
Ecology
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.
Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Application to Biotechnology
Does this organism produce any useful compounds or enzymes? What are they and how are they used?
Current Research
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References
http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=139561 Bandow, J.E., H. Brötz, M. Hecker. "Bacillus subtilis Tolerance of Moderate Concentrations of Rifampin Involves the ςB-Dependent General and Multiple Stress Response". Journal of Bacteriology. 2002 January, 184(2): 459–467.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=genomeprj&cmd=Retrieve&dopt=Overview&list_uids=76 Entrez Genome Project
http://arjournals.annualreviews.org/doi/abs/10.1146%2Fannurev.micro.52.1.165 Nakano, M.M., P. Zuber. "Anaerobic Growth of a 'Strict Aerobe' (Bacillus subtilis)". Annual Review of Microbiology. 1998 October, Vol. 52: 165-190.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=94387 Perez, A.R., A. Abanes-De Mello, K. Pogliano. "SpoIIB Localizes to Active Sites of Septal Biogenesis and Spatially Regulates Septal Thinning during Engulfment in Bacillus subtilis". Journal of Bacteriology. 2000 February; 182(4): 1096–1108.
Schaechter, M., J.L. Ingraham, F.C. Neidhardt. Microbe. (ASM Press, Washington, DC, 2006).
Edited by Margo Ucar, student of Rachel Larsen and Kit Pogliano
