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Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants and humans. A member of the genus Bacillus, B. subtilis is rod-shaped, and can form a tough, protective endospore, allowing it to tolerate extreme environmental conditions. B. subtilis has historically been classified as an obligate aerobe, though evidence exists that it is a facultative anaerobe.
This lesson will discuss the characteristics of the bacterium Bacillus subtilis, including its microscopic characteristics, its metabolism, and its...
Originally named Vibrio subtilis in 1835, this organism was renamed Bacillus subtilis in 1872. Other names for this bacteria also include Bacillus uniflagellatus, Bacillus globigii, and Bacillus natto. Bacillus subtilis bacteria were one of the first bacteria to be studied. These bacteria are a good model for cellular development and differentiation (Entrez Genome Project).
Bacillus subtilis helps support digestion and enzyme production. It also encourages gut health while inhibiting harmful organism growth.
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J Appl Bacteriol. 1993 May;74(5):588-94. Research Support, Non-U.S. Gov't
Bacillus subtilis StoA is an extracytoplasmic thiol-disulfide oxidoreductase (TDOR) important for the synthesis of the endospore peptidoglycan
cortex protective layer. Here we demonstrate that StoA is membrane-associated in B. subtilis and report the crystal structure of the soluble protein lacking its membrane anchor. This showed that StoA adopts a thioredoxin-like
fold with N-terminal and internal additions that are characteristic of extracytoplasmic TDORs. The CXXC active site of the crystallized protein was found to be in a mixture of oxidized and reduced states, illustrating that there
is little conformational variation between redox states. The midpoint reduction potential was determined as -248 mV versus normal hydrogen electrode at pH 7 consistent with StoA fulfilling a reductive role in endospore biogenesis. pKa values of the active site cysteines, Cys-65 and Cys-68, were determined to be 5.5 and 7.8. Although Cys-68 is buried within
the structure, both cysteines were found to be accessible to cysteine-specific alkylating reagents. In vivo studies of site-directed variants of StoA revealed that the active site cysteines are functionally important, as is Glu-71,
which lies close to the active site and is conserved in many reducing extracytoplasmic TDORs. The structure and biophysical
properties of StoA are very similar to those of ResA, a B. subtilis extracytoplasmic TDOR involved in cytochrome c maturation, raising important general questions about how these similar but non-redundant proteins achieve specificity. A
detailed comparison of the two proteins demonstrates that relatively subtle differences, largely located around the active
sites of the proteins, are sufficient to confer specificity.
What makes Bacillus subtilis unique?
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Mol Microbiol. 2005 May;56(4):845-57. Review
Unique Spore formation in Bacillus subtilis acts as a survival mechanism against extreme/ adverse conditions :
Can relaxation make you tougher? Yes, research shows, if you are a bacterial endospore (also simply referred to as a “spore”). Endospores are tough dormant structures that form inside the cell wall of certain types of bacteria, such as Bacillus bacteria. These tough capsules form in response to adverse conditions such as drought or high temperatures. They are also resistant to ultraviolet radiation, desiccation, extreme freezing, and chemical disinfectants. Analysis of enzyme structures within endospores suggests that reversible relaxation of their three-dimensional structure is the strategy Bacillus bacteria use to survive at temperatures deadly to non-spore forming cells.
