20th century Cultures of
B. subtilis were popular worldwide, before the introduction of
antibiotics, as an immunostimulatory agent to aid treatment of
gastrointestinal and
urinary tract diseases. It was used throughout the 1950s as an
alternative medicine, which upon digestion has been found to significantly stimulate
broad-spectrum immune activity including activation of secretion of specific
antibodies IgM,
IgG and
IgA and release of
CpG dinucleotides inducing
interferon IFN-α/
IFNγ producing activity of
leukocytes and
cytokines important in the development of
cytotoxicity towards
tumor cells. It was marketed throughout America and Europe from 1946 as an immunostimulatory aid in the treatment of gut and urinary tract diseases such as
Rotavirus and
Shigellosis. In 1966, the U.S. Army dumped
Bacillus subtilis onto the grates of New York City subway stations for five days in order to observe how a biological agent dispensed around the subway trains would disperse and potentially affect unsuspecting passengers. Due to its ability to survive, it is thought to still be present there. The antibiotic
bacitracin was first isolated from a variety of
Bacillus licheniformis named "Tracy I" in 1945, then considered part of the
B. subtilis species. It is still commercially manufactured by growing the variety in a container of liquid
growth medium. Over time, the bacteria synthesize bacitracin and secrete the antibiotic into the medium. The bacitracin is then extracted from the medium using chemical processes. Since the 1960s
B. subtilis has had a history as a test species in spaceflight experimentation. Its
endospores can survive up to 6 years in space if coated by dust particles protecting it from solar UV rays. It has been used as an
extremophile survival indicator in
outer space such as
Exobiology Radiation Assembly,
EXOSTACK, and
EXPOSE orbital missions. Wild-type natural isolates of
B. subtilis are difficult to work with compared with laboratory strains that have undergone domestication processes of
mutagenesis and selection. These strains often have improved capabilities of transformation (uptake and integration of environmental DNA), growth, and loss of abilities needed "in the wild". And, while dozens of different strains fitting this description exist, the strain designated '168' is the most widely used. Strain 168 is a
tryptophan auxotroph isolated after X-ray mutagenesis of
B. subtilis Marburg strain and is widely used in research due to its high transformation efficiency. in a
molecular biology laboratory Bacillus globigii, a closely related but
phylogenetically distinct species now known as
Bacillus atrophaeus was used as a biowarfare
simulant during
Project SHAD (aka
Project 112). Subsequent genomic analysis showed that the strains used in those studies were products of deliberate enrichment for strains that exhibited abnormally high rates of
sporulation. A strain of
B. subtilis formerly known as
Bacillus natto is used in the commercial production of the Japanese food
nattō, as well as the similar Korean food
cheonggukjang.
21st century • As a
model organism,
B. subtilis is commonly used in laboratory studies directed at discovering the fundamental properties and characteristics of Gram-positive spore-forming bacteria. •
B. subtilis is used as a
soil inoculant in
horticulture and
agriculture. • It may provide some benefit to
saffron growers by speeding corn growth and increasing stigma biomass yield. • It is used as an "indicator organism" during gas sterilization procedures, to ensure a sterilization cycle has completed successfully. Specifically
B. subtilis endospores are used to verify that a cycle has reached spore-destroying conditions. •
B. subtilis has been found to act as a useful bioproduct fungicide that prevents the growth of
Monilinia vaccinii-corymbosi, a.k.a. the mummy berry fungus, without interfering with pollination or fruit qualities. • Both metabolically active and non-metabolically active
B. subtilis cells have been shown to reduce gold (III) to gold (I) and gold (0) when oxygen is present. This biotic reduction plays a role in gold cycling in geological systems and could potentially be used to recover solid gold from said systems. • Pairing bacillus subtilis with chitosan has been shown to reduce green mold decay in citrus fruits.
Novel and artificial substrains • Novel strains of
B. subtilis that could use 4-fluorotryptophan (4FTrp) but not canonical tryptophan (Trp) for propagation were isolated. As
Trp is only coded by a single codon, there is evidence that Trp can be displaced by 4FTrp in the genetic code. The experiments showed that the canonical genetic code can be mutable. • Recombinant strains pBE2C1 and pBE2C1AB were used in production of
polyhydroxyalkanoates (PHA), and malt waste can be used as their carbon source for lower-cost PHA production. • It is used to produce
hyaluronic acid, which is used in the joint-care sector in healthcare and cosmetics. •
Monsanto has isolated a gene from
B. subtilis that expresses cold shock protein B and spliced it into their drought-tolerant corn hybrid MON 87460, which was approved for sale in the US in November 2011. • A new strain has been modified to convert nectar into
honey by secreting enzymes. ==Safety==