''Bacillus'' (Latin "stick") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

, rod-shaped

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

, a member of the phylum ''

Bacillota The Bacillota (synonym Firmicutes) are a phylum of bacteria, most of which have gram-positive cell wall structure. The renaming of phyla such as Firmicutes in 2021 remains controversial among microbiologists, many of whom continue to use the earl ...

'', with 266 named

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacilli'' is the name of the

class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used differentl ...

of bacteria to which this genus belongs. ''Bacillus'' species can be either

obligate aerobe An obligate aerobe is an organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to metabolise substances, like sugars or fats, to obtain energy. In this type of respiration, oxygen serves as the terminal e ...

s which are dependent on

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

, or

facultative anaerobes A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. Some examples of facultatively anaerobic bacteria are ''Staphylococcus' ...

which can survive in the absence of oxygen. Cultured ''Bacillus'' species test positive for the

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...

catalase Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen. It is a very important enzyme in protecting t ...

if oxygen has been used or is present. ''Bacillus'' can reduce themselves to oval

endospore An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria in the phylum Bacillota. The name "endospore" is suggestive of a spore or seed-like form (''endo'' means 'within'), but it is not a true spore (i.e., no ...

s and can remain in this dormant state for years. The endospore of one species from Morocco is reported to have survived being heated to 420 °C. Endospore formation is usually triggered by a lack of nutrients: the bacterium divides within its cell wall, and one side then engulfs the other. They are not true

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s (i.e., not an offspring). Endospore formation originally defined the genus, but not all such species are closely related, and many species have been moved to other genera of the ''Bacillota''. Only one endospore is formed per cell. The spores are resistant to heat, cold, radiation, desiccation, and disinfectants. ''Bacillus anthracis'' needs oxygen to sporulate; this constraint has important consequences for epidemiology and control. In vivo, ''B. anthracis'' produces a polypeptide (polyglutamic acid) capsule that kills it from phagocytosis. The genera ''Bacillus'' and ''Clostridium'' constitute the family ''Bacillaceae''. Species are identified by using morphologic and biochemical criteria. Because the spores of many ''Bacillus'' species are resistant to heat, radiation, disinfectants, and desiccation, they are difficult to eliminate from medical and pharmaceutical materials and are a frequent cause of contamination. Not only are they resistant to heat, radiation, etc., but they are also resistant to chemicals such as antibiotics. This resistance allows them to survive for many years and especially in a controlled environment. ''Bacillus'' species are well known in the food industries as troublesome spoilage organisms. Ubiquitous in nature, ''Bacillus'' includes

symbiotic Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasit ...

(sometimes referred to as

endophyte An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; h ...

s) as well as independent species. Two

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

ic species are medically significant: '' B. anthracis'' causes

anthrax Anthrax is an infection caused by the bacterium ''Bacillus anthracis''. It can occur in four forms: skin, lungs, intestinal, and injection. Symptom onset occurs between one day and more than two months after the infection is contracted. The sk ...

; and '' B. cereus'' causes food poisoning. Many species of ''Bacillus'' can produce copious amounts of enzymes, which are used in various industries, such as in the production of

alpha amylase α-Amylase is an enzyme (EC 3.2.1.1; systematic name 4-α-D-glucan glucanohydrolase) that hydrolysis, hydrolyses α bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose ...

used in starch hydrolysis and the

protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the ...

subtilisin Subtilisin is a protease (a protein-digesting enzyme) initially obtained from ''Bacillus subtilis''. Subtilisins belong to subtilases, a group of serine proteases that – like all serine proteases – initiate the nucleophilic attack on the p ...

used in

detergent A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more ...

s. ''

B. subtilis ''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, humans and marine sponges. As a member of the genus ''Bacillu ...

'' is a valuable model for bacterial research. Some ''Bacillus'' species can synthesize and secrete

lipopeptide A lipopeptide is a molecule consisting of a lipid connected to a peptide. They are able to self-assemble into different structures. Many bacteria produced these molecules as a part of their metabolism, especially those of the genus ''Bacillus'', ' ...

s, in particular

surfactin Surfactin is a very powerful surfactant commonly used as an antibiotic. It is a bacterial cyclic lipopeptide, largely prominent for its exceptional surfactant power. Its amphiphilic properties help this substance to survive in both hydrophilic ...

s and

mycosubtilin Mycosubtilin is a natural lipopeptide with antifungal and hemolytic activities and isolated from ''Bacillus'' species. It belongs to the iturin lipopeptide family. Definition Mycosubtilin is a natural lipopeptide. It is produced by the strains ...

s. ''Bacillus'' species are also found in marine

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

s. Marine sponge associated ''Bacillus subtilis'' (strains WS1A and YBS29) can synthesize several antimicrobial peptides. These ''Bacillus subtilis'' strains can develop disease resistance in ''

Labeo rohita The rohu, rui, ruhi or roho labeo (''Labeo rohita'') is a species of fish of the Cyprinidae, carp family, found in rivers in South Asia. It is a large omnivore and extensively used in aquaculture. Description The rohu is a large, silver-col ...

''.

Structure

Cell wall

The cell wall of ''Bacillus'' is a structure on the outside of the cell that forms the second barrier between the bacterium and the environment, and at the same time maintains the rod shape and withstands the pressure generated by the cell's

turgor Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is also called ''hydrostatic pressure'', and is defined as the pressure in a fluid measured at a certain point within itself when at equilibri ...

. The cell wall is made of teichoic and teichuronic acids. ''B. subtilis'' is the first bacterium for which the role of an

actin Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over ...

-like

cytoskeleton The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea. In eukaryotes, it extends from the cell nucleus to the cell membrane and is compos ...

in cell shape determination and

peptidoglycan Peptidoglycan or murein is a unique large macromolecule, a polysaccharide, consisting of sugars and amino acids that forms a mesh-like peptidoglycan layer outside the plasma membrane, the rigid cell wall (murein sacculus) characteristic of most ...

synthesis was identified and for which the entire set of peptidoglycan-synthesizing enzymes was localized. The role of the cytoskeleton in shape generation and maintenance is important. ''Bacillus'' species are rod-shaped, endospore-forming aerobic or facultatively anaerobic, Gram-positive bacteria; in some species cultures may turn Gram-negative with age. The many species of the genus exhibit a wide range of physiologic abilities that allow them to live in every natural environment. Only one endospore is formed per cell. The spores are resistant to heat, cold, radiation, desiccation, and disinfectants.

Origin of name

The genus ''Bacillus'' was named in 1835 by

Christian Gottfried Ehrenberg Christian Gottfried Ehrenberg (19 April 1795 – 27 June 1876) was a German naturalist, zoologist, comparative anatomist, geologist, and microscopist. Ehrenberg was an evangelist and was considered to be of the most famous and productive scie ...

, to contain rod-shaped (bacillus) bacteria. He had seven years earlier named the genus ''

Bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

''. ''Bacillus'' was later amended by Ferdinand Cohn to further describe them as spore-forming, Gram-positive, aerobic or facultatively anaerobic bacteria. Like other genera associated with the early history of microbiology, such as ''

Pseudomonas ''Pseudomonas'' is a genus of Gram-negative, Gammaproteobacteria, belonging to the family Pseudomonadaceae and containing 191 described species. The members of the genus demonstrate a great deal of metabolic diversity and consequently are able ...

'' and ''

Vibrio ''Vibrio'' is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Being highly salt tolerant and unable to survive ...

'', the 266 species of ''Bacillus'' are ubiquitous. The genus has a very large

ribosomal Ribosomes ( ) are macromolecular machines, found within all cells, that perform biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA (mRNA) molecules to for ...

16S diversity.

Isolation and identification

Established methods for isolating ''Bacillus'' species for culture primarily involve suspension of sampled soil in distilled water, heat shock to kill off vegetative cells leaving primarily viable spores in the sample, and culturing on agar plates with further tests to confirm the identity of the cultured colonies. Additionally, colonies which exhibit characteristics typical of ''Bacillus'' bacteria can be selected from a culture of an environmental sample which has been significantly diluted following heat shock or hot air drying to select potential ''Bacillus'' bacteria for testing. Cultured colonies are usually large, spreading, and irregularly shaped. Under the microscope, the ''Bacillus'' cells appear as rods, and a substantial portion of the cells usually contain oval

s at one end, making them bulge.

Characteristics of ''Bacillus'' spp.

S.I. Paul et al. (2021) isolated and identified multiple strains of ''Bacillus'' species (strain
WS1AYBS29KSP163AOA122ISP161AOI6WS11KSP151ES8
from marine sponges of the Saint Martin's Island Area of the

Bay of Bengal The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line between ...

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...

. Based on their study, colony, morphological, physiological, and biochemical characteristics of ''Bacillus'' spp. are shown in the Table below. Note: + = Positive, – =Negative, O= Oxidative, F= Fermentative

Phylogeny

Three proposals have been presented as representing the phylogeny of the genus ''Bacillus''. The first proposal, presented in 2003, is a ''Bacillus''-specific study, with the most diversity covered using 16S and the ITS regions. It divides the genus into 10 groups. This includes the nested genera ''

Paenibacillus ''Paenibacillus'' is a genus of facultative anaerobic, endospore-forming bacteria, originally included within the genus ''Bacillus'' and then reclassified as a separate genus in 1993.Ash C, Priest FG, Collins MD: Molecular identification of rRNA ...

Brevibacillus ''Brevibacillus'' is a genus of Gram-positive bacteria in the family Paenibacillaceae The Paenibacillaceae are a family of Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain tes ...

Geobacillus ''Geobacillus'' is a bacterial genus from the family of Bacillaceae The Bacillaceae are a family of gram-positive, heterotrophic, rod-shaped bacteria that may produce endospores. Motile members of this family are characterized by peritrichou ...

, Marinibacillus'' and ''

Virgibacillus ''Virgibacillus'' is a genus of Gram-positive, rod-shaped ( bacillus) bacteria and a member of the phylum Bacillota. ''Virgibacillus'' species can be obligate aerobes (oxygen reliant), or facultative anaerobes and catalase enzyme Enzyme ...

''. The second proposal, presented in 2008, constructed a 16S (and 23S if available) tree of all validated species. The genus ''Bacillus'' contains a very large number of nested taxa and majorly in both 16S and 23S. It is

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

to the

Lactobacillales Lactobacillales are an order of gram-positive, GC-content, low-GC, acid-tolerant, generally nonsporulating, Aerotolerant anaerobe, nonrespiring, either rod-shaped (bacillus (shape), bacilli) or spherical (cocci) bacteria that share common metabo ...

(''Lactobacillus, Streptococcus, Staphylococcus, Listeria'', etc.), due to ''

Bacillus coahuilensis ''Bacillus coahuilensis'' is a rod-shaped, Gram-positive, motile, spore-forming bacterium. This species was isolated from water samples taken from a highly saline desert lagoon in Coahuila, Mexico Mexico (Spanish: México), officially ...

'' and others. A third proposal, presented in 2010, was a gene

concatenation In formal language theory and computer programming, string concatenation is the operation of joining character strings end-to-end. For example, the concatenation of "snow" and "ball" is "snowball". In certain formalisations of concatenat ...

study, and found results similar to the 2008 proposal, but with a much more limited number of species in terms of groups. (This scheme used ''Listeria'' as an outgroup, so in light of the ARB tree, it may be "inside-out"). One clade, formed by ''Bacillus anthracis'', ''Bacillus cereus'', ''Bacillus mycoides'', ''Bacillus pseudomycoides'', ''Bacillus thuringiensis'', and ''Bacillus weihenstephanensis'' under the 2011 classification standards, should be a single species (within 97% 16S identity), but due to medical reasons, they are considered separate species (an issue also present for four species of ''

Shigella ''Shigella'' is a genus of bacteria that is Gram-negative, facultative anaerobic, non-spore-forming, nonmotile, rod-shaped, and genetically closely related to '' E. coli''. The genus is named after Kiyoshi Shiga, who first discovered it in 1 ...

'' and ''

Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escher ...

''). A phylogenomic study of 1104 ''Bacillus'' proteomes was based on 114 core proteins and delineated the relationships among the various species, defined as ''Bacillus'' from the NCBI taxonomy. The various strains were clustered into species, based on Average Nucleotide identity (ANI) values, with a species cutoff of 95%.

Species

* '' B. Symun'' * '' B. acidicola'' * '' B. acidiproducens'' * '' B. acidocaldarius'' * '' B. acidoterrestris'' * '' B. aeolius'' * '' B. aerius'' * '' B. aerophilus'' * '' B. agaradhaerens'' * '' B. agri'' * '' B. aidingensis'' * '' B. akibai'' * '' B. albus'' * '' B. alcalophlus'' * '' B. algicola''i * '' B. alginolyticus'' * '' B. alkalidiazotrophicus'' * '' B. alkalinitrilicus'' * '' B. alkalisediminis'' * '' B. alkalitelluris'' * '' B. altitudinis'' * '' B. alveayuensis'' * '' B. alvei'' * '' B. amyloliquefaciens'' ** ''B. a. ''subsp.'' amyloliquefaciens'' ** ''B. a. ''subsp.'' plantarum'' * '' B. aminovorans'' * '' B. amylolyticus'' * '' B. andreesenii'' * '' B. aneurinilyticus'' * '' B. anthracis'' * '' B. aquimaris'' * '' B. arenosi'' * '' B. arseniciselenatis'' * '' B. arsenicus'' * '' B. aurantiacus'' * '' B. arvi'' * '' B. aryabhattai'' * '' B. asahii'' * '' B. atrophaeus'' * '' B. axarquiensis'' * '' B. azotofixans'' * '' B. azotoformans'' * '' B. badius'' * '' B. barbaricus'' * '' B. bataviensis'' * '' B. beijingensis'' * '' B. benzoevorans'' * '' B. beringensis'' * '' B. berkeleyi'' * '' B. beveridgei'' * '' B. bogoriensis'' * '' B. boroniphilus'' * '' B. borstelensis'' * '' B. brevis'' * '' B. butanolivorans'' * '' B. canaveralius'' * '' B. carboniphilus'' * '' B. cecembensis'' * '' B. cellulosilyticus'' * '' B. centrosporus'' * '' B. cereus'' * '' B. chagannorensis'' * '' B. chitinolyticus'' * '' B. chondroitinus'' * '' B. choshinensis'' * '' B. chungangensis'' * '' B. cibi'' * '' B. circulans'' * '' B. clarkii'' * '' B. clausii'' * '' B. coagulans'' * '' B. coahuilensis'' * '' B. cohnii'' * '' B. composti'' * '' B. curdlanolyticus'' * '' B. cycloheptanicus'' * '' B. cytotoxicus'' * '' B. daliensis'' * '' B. decisifrondis'' * '' B. decolorationis'' * '' B. deserti'' * '' B. dipsosauri'' * '' B. drentensis'' * '' B. edaphicus'' * '' B. ehimensis'' * '' B. eiseniae'' * '' B. enclensis'' * '' B. endophyticus'' * '' B. endoradicis'' * '' B. farraginis'' * '' B. fastidiosus'' * '' B. fengqiuensis'' * '' B. filobacterium rodentuim'' * '' B. firmus'' * '' B. flexus'' * '' B. foraminis'' * '' B. fordii'' * '' B. formosus'' * '' B. fortis'' * '' B. fumarioli'' * '' B. funiculus'' * '' B. fusiformis'' * '' B. gaemokensis'' * '' B. galactophilus'' * '' B. galactosidilyticus'' * '' B. galliciensis'' * '' B. gelatini'' * '' B. gibsonii'' * '' B. ginsengi'' * '' B. ginsengihumi'' * '' B. ginsengisoli'' * '' B. glucanolyticus'' * '' B. gordonae'' * '' B. gottheilii'' * '' B. graminis'' * '' B. halmapalus'' * '' B. haloalkaliphilus'' * '' B. halochares'' * '' B. halodenitrificans'' * '' B. halodurans'' * '' B. halophilus'' * '' B. halosaccharovorans'' * '' B. hemicellulosilyticus'' * '' B. hemicentroti'' * '' B. herbersteinensis'' * '' B. horikoshii'' * '' B. horneckiae'' * '' B. horti'' * '' B. huizhouensis'' * '' B. humi'' * '' B. hwajinpoensis'' * '' B. idriensis'' * '' B. indicus'' * '' B. infantis'' * '' B. infernus'' * '' B. insolitus'' * '' B. invictae'' * '' B. iranensis'' * '' B. isabeliae'' * '' B. isronensis'' * '' B. jeotgali'' * '' B. kaustophilus'' * '' B. kobensis'' * '' B. kochii'' * '' B. kokeshiiformis'' * '' B. koreensis'' * '' B. korlensis'' * '' B. kribbensis'' * '' B. krulwichiae'' * '' B. laevolacticus'' * '' B. larvae'' * '' B. laterosporus'' * '' B. lautus'' * '' B. lehensis'' * '' B. lentimorbus'' * '' B. lentus'' * '' B. licheniformis'' * '' B. ligniniphilus'' * '' B. litoralis'' * '' B. locisalis'' * '' B. luciferensis'' * '' B. luteolus'' * '' B. luteus'' * '' B. macauensis'' * '' B. macerans'' * '' B. macquariensis'' * '' B. macyae'' * '' B. malacitensis'' * '' B. mannanilyticus'' * '' B. marisflavi'' * '' B. marismortui'' * '' B. marmarensis'' * '' B. massiliensis'' * '' B. megaterium'' * "'' B. mesentericus''" * '' B. mesonae'' * '' B. methanolicus'' * '' B. methylotrophicus'' * '' B. migulanus'' * '' B. mojavensis'' * '' B. mucilaginosus'' * '' B. muralis'' * '' B. murimartini'' * '' B. mycoides'' * '' B. naganoensis'' * '' B. nanhaiensis'' * '' B. nanhaiisediminis'' * '' B. nealsonii'' * '' B. neidei'' * '' B. neizhouensis'' * '' B. niabensis'' * '' B. niacini'' * '' B. novalis'' * '' B. oceanisediminis'' * '' B. odysseyi'' * '' B. okhensis'' * '' B. okuhidensis'' * '' B. oleronius'' * '' B. oryzaecorticis'' * '' B. oshimensis'' * '' B. pabuli'' * '' B. pakistanensis'' * '' B. pallidus'' * '' B. pallidus'' * '' B. panacisoli'' * '' B. panaciterrae'' * '' B. pantothenticus'' * '' B. parabrevis'' * '' B. paraflexus'' * '' B. pasteurii'' * '' B. patagoniensis'' * '' B. peoriae'' * '' B. persepolensis'' * '' B. persicus'' * '' B. pervagus'' * '' B. plakortidis'' * '' B. pocheonensis'' * '' B. polygoni'' * '' B. polymyxa'' * '' B. popilliae'' * '' B. pseudalcalophilus'' * '' B. pseudofirmus'' * '' B. pseudomycoides'' * '' B. psychrodurans'' * '' B. psychrophilus'' * '' B. psychrosaccharolyticus'' * '' B. psychrotolerans'' * '' B. pulvifaciens'' * '' B. pumilus'' * '' B. purgationiresistens'' * '' B. pycnus'' * '' B. qingdaonensis'' * '' B. qingshengii'' * '' B. reuszeri'' * '' B. rhizosphaerae'' * '' B. rigui'' * '' B. ruris'' * '' B. safensis'' * '' B. salarius'' * '' B. salexigens'' * '' B. saliphilus'' * '' B. schlegelii'' * '' B. sediminis'' * '' B. selenatarsenatis'' * '' B. selenitireducens'' * '' B. seohaeanensis'' * '' B. shacheensis'' * '' B. shackletonii'' * '' B. siamensis'' * '' B. silvestris'' * '' B. simplex'' * '' B. siralis'' * '' B. smithii'' * '' B. soli'' * '' B. solimangrovi'' * '' B. solisalsi'' * '' B. songklensis'' * '' B. sonorensis'' * '' B. sphaericus'' * '' B. sporothermodurans'' * '' B. stearothermophilus'' * '' B. stratosphericus'' * '' B. subterraneus'' * ''

'' ** ''B. s. ''subsp.'' inaquosorum'' ** ''B. s. ''subsp.'' spizizenii'' ** ''B. s. ''subsp.'' subtilis'' * '' B. taeanensis'' * '' B. tequilensis'' * '' B. thermantarcticus'' * '' B. thermoaerophilus'' * '' B. thermoamylovorans'' * '' B. thermocatenulatus'' * '' B. thermocloacae'' * '' B. thermocopriae'' * '' B. thermodenitrificans'' * '' B. thermoglucosidasius'' * '' B. thermolactis'' * '' B. thermoleovorans'' * '' B. thermophilus'' * '' B. thermoproteolyticus'' * '' B. thermoruber'' * '' B. thermosphaericus'' * '' B. thiaminolyticus'' * '' B. thioparans'' * ''

B. thuringiensis ''Bacillus thuringiensis'' (or Bt) is a gram-positive, soil-dwelling bacterium, the most commonly used biological pesticide worldwide. ''B. thuringiensis'' also occurs naturally in the gut of caterpillars of various types of moths and butterfl ...

'' * '' B. tianshenii'' * '' B. trypoxylicola'' * '' B. tusciae'' * '' B. validus'' * '' B. vallismortis'' * '' B. vedderi'' * '' B. velezensis'' * '' B. vietnamensis'' * '' B. vireti'' * '' B. vulcani'' * '' B. wakoensis'' * '' B. xiamenensis'' * '' B. xiaoxiensis'' * '' B. zanthoxyli'' * '' B. zhanjiangensis

Ecological and clinical significance

''Bacillus'' species are ubiquitous in nature, e.g. in soil. They can occur in extreme environments such as high pH ('' B. alcalophilus''), high temperature ('' B. thermophilus''), and high salt concentrations ('' B. halodurans''). They also are very commonly found as

s in plants where they can play a critical role in their

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

, nutrient absorption and

nitrogen fixing Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the Atmosphere of Earth, air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but al ...

capabilities. ''

'' produces a toxin that can kill insects and thus has been used as insecticide. ''B. siamensis'' has antimicrobial compounds that inhibit plant pathogens, such as the fungi '' Rhizoctonia solani'' and ''

Botrytis cinerea ''Botrytis cinerea'' is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or ...

'', and they promote plant growth by volatile emissions. Some species of ''Bacillus'' are naturally competent for DNA uptake by

transformation Transformation may refer to: Science and mathematics In biology and medicine * Metamorphosis, the biological process of changing physical form after birth or hatching * Malignant transformation, the process of cells becoming cancerous * Trans ...

. *Two ''Bacillus'' species are medically significant: '' B. anthracis'', which causes

; and '' B. cereus'', which causes food poisoning, with symptoms similar to that caused by '' Staphylococcus''. **''B. cereus'' produces toxins which cause two different set of symptoms: ***emetic toxin which can cause vomiting and nausea ***diarrhea * ''

'' is an important

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...

pathogen, and is sometimes used to control insect pests. *''B. subtilis'' is an important

model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

. It is also a notable food spoiler, causing ropiness in bread and related food. **''B. subtilis'' can also produce and secrete antibiotics. *Some environmental and commercial strains of '' B. coagulans'' may play a role in food spoilage of highly acidic, tomato-based products.

Industrial significance

Many ''Bacillus'' species are able to

secrete 440px Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...

large quantities of enzymes. ''

Bacillus amyloliquefaciens ''Bacillus amyloliquefaciens'' is a species of bacterium in the genus ''Bacillus'' that is the source of the BamHI restriction enzyme. It also synthesizes a natural antibiotic protein barnase, a widely studied ribonuclease that forms a famously t ...

'' is the source of a natural antibiotic protein

barnase Barnase (a portmanteau of "BActerial" "RiboNucleASE") is a bacterial protein that consists of 110 amino acids and has ribonuclease activity. It is synthesized and secreted by the bacterium '' Bacillus amyloliquefaciens'', but is lethal to the cel ...

ribonuclease Ribonuclease (commonly abbreviated RNase) is a type of nuclease that catalyzes the degradation of RNA into smaller components. Ribonucleases can be divided into endoribonucleases and exoribonucleases, and comprise several sub-classes within ...

used in starch hydrolysis, the

used with detergents, and the BamH1 restriction enzyme used in DNA research. A portion of the ''Bacillus thuringiensis'' genome was incorporated into corn (and cotton) crops. The resulting GMOs are resistant to some insect pests. ''Bacillus subtilis'' (natto) is the key microbial participant in the ongoing production of the soya-based traditional natto fermentation, and some ''Bacillus'' species are on the Food and Drug Administration's GRAS (generally regarded as safe) list. The capacity of selected ''Bacillus'' strains to produce and secrete large quantities (20–25 g/L) of extracellular enzymes has placed them among the most important industrial enzyme producers. The ability of different species to ferment in the acid, neutral, and alkaline pH ranges, combined with the presence of thermophiles in the genus, has led to the development of a variety of new commercial enzyme products with the desired temperature, pH activity, and stability properties to address a variety of specific applications. Classical mutation and (or) selection techniques, together with advanced cloning and protein engineering strategies, have been exploited to develop these products. Efforts to produce and secrete high yields of foreign recombinant proteins in ''Bacillus'' hosts initially appeared to be hampered by the degradation of the products by the host proteases. Recent studies have revealed that the slow folding of heterologous proteins at the membrane-cell wall interface of Gram-positive bacteria renders them vulnerable to attack by wall-associated proteases. In addition, the presence of thiol-disulphide oxidoreductases in ''B. subtilis'' may be beneficial in the secretion of disulphide-bond-containing proteins. Such developments from our understanding of the complex protein translocation machinery of Gram-positive bacteria should allow the resolution of current secretion challenges and make ''Bacillus'' species preeminent hosts for heterologous protein production. ''Bacillus'' strains have also been developed and engineered as industrial producers of nucleotides, the vitamin riboflavin, the flavor agent ribose, and the supplement poly-gamma-glutamic acid. With the recent characterization of the genome of ''B. subtilis'' 168 and of some related strains, ''Bacillus'' species are poised to become the preferred hosts for the production of many new and improved products as we move through the genomic and proteomic era.

Use as model organism

''Bacillus subtilis'' is one of the best understood prokaryotes, in terms of molecular and cellular biology. Its superb genetic amenability and relatively large size have provided the powerful tools required to investigate a bacterium from all possible aspects. Recent improvements in fluorescent microscopy techniques have provided novel insight into the dynamic structure of a single cell organism. Research on ''B. subtilis'' has been at the forefront of bacterial molecular biology and cytology, and the organism is a model for differentiation, gene/protein regulation, and cell cycle events in bacteria.

References

External links

Bacillus
genomes and related information a
PATRIC
a Bioinformatics Resource Center funded b
NIAID
{{Authority control Bacillus, Bacteria genera Gram-positive bacteria