A spirochaete () or spirochete is a member of the

phylum In biology, a phylum (; : phyla) is a level of classification, or taxonomic rank, that is below Kingdom (biology), kingdom and above Class (biology), class. Traditionally, in botany the term division (taxonomy), division has been used instead ...

Spirochaetota (also called Spirochaetes ), which contains distinctive diderm (double-membrane)

Gram-negative bacteria Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the Crystal violet, crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelo ...

, most of which have long, helically coiled (corkscrew-shaped or spiraled, hence the name) cells. Spirochaetes are

chemoheterotroph A chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic (chemoorganotrophs) or inorganic (chemolithotrophs). The chemotroph designation is in contrast to phototroph ...

ic in nature, with lengths between 3 and 500 μm and diameters around 0.09 to at least 3 μm. Spirochaetes are distinguished from other bacterial phyla by the location of their

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

, called endoflagella, or periplasmic flagella, which are sometimes called ''axial filaments''. Endoflagella are anchored at each end (pole) of the bacterium within the periplasmic space (between the inner and outer membranes) where they project backwards to extend the length of the cell. These cause a twisting motion which allows the spirochaete to move. When reproducing, a spirochaete will undergo asexual transverse binary fission. Most spirochaetes are free-living and

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: *Adhesive#Anaerobic, Anaerobic ad ...

, but there are numerous exceptions. Spirochaete bacteria are diverse in their

pathogenic capacity In biology, a pathogen (, "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. The term ...

and the

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

s that they inhabit, as well as molecular characteristics including guanine-cytosine content and

genome size Genome size is the total amount of DNA contained within one copy of a single complete genome. It is typically measured in terms of mass in picograms (trillionths or 10−12 of a gram, abbreviated pg) or less frequently in daltons, or as the tot ...

Pathogenicity

Many organisms within the Spirochaetota phylum cause prevalent diseases. Pathogenic members of this phylum include the following: * ''

Leptospira ''Leptospira'' () is a genus of spirochaete bacteria, including a small number of pathogenic and saprophytic species. ''Leptospira'' was first observed in 1907 in kidney tissue slices of a leptospirosis victim who was described as having died ...

'' species, which causes

leptospirosis Leptospirosis is a blood infection caused by the bacterium ''Leptospira'' that can infect humans, dogs, rodents and many other wild and domesticated animals. Signs and symptoms can range from none to mild (headaches, Myalgia, muscle pains, a ...

* ''

Borrelia burgdorferi ''Borrelia burgdorferi'' is a bacterial species of the spirochete class in the genus '' Borrelia'', and is one of the causative agents of Lyme disease in humans. Along with a few similar genospecies, some of which also cause Lyme disease, it m ...

'', '' B. mayonii'', '' B. bissettiae'', '' B. garinii'', '' B. afzelii'', '' B. spielmanii'', '' B. lusitaniae'', which cause Lyme disease. * ''

Borrelia recurrentis ''Borrelia recurrentis'' is a species of ''Borrelia'', a spirochaete bacterium associated with relapsing fever Relapsing fever is a vector-borne disease caused by infection with certain bacteria in the genus '' Borrelia'', which is transmitted t ...

'', which causes

relapsing fever Relapsing fever is a vector-borne disease caused by infection with certain bacteria in the genus '' Borrelia'', which is transmitted through the bites of lice, soft-bodied ticks (genus '' Ornithodoros''), or hard-bodied ticks (Genus Ixodes). ...

* ''

Treponema pallidum ''Treponema pallidum'', formerly known as ''Spirochaeta pallida'', is a Microaerophile, microaerophilic, Gram-negative bacteria, gram-negative, spirochaete bacterium with subspecies that cause the diseases syphilis, bejel (also known as endemic ...

'' subspecies which cause treponematoses such as

syphilis Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms depend on the stage it presents: primary, secondary, latent syphilis, latent or tertiary. The prim ...

and

yaws Yaws is a tropical infection of the skin, bones, and joints caused by the spirochete bacterium ''Treponema pallidum pertenue''. The disease begins with a round, hard swelling of the skin, in diameter. The center may break open and form an ulc ...

. * '' Brachyspira pilosicoli'' and ''

Brachyspira aalborgi ''Brachyspira aalborgi'' is a species of bacteria, one of the causative agents of intestinal spirochetosis. Its cells are anaerobic, sigmoidal with tapered ends, 2 to 6 μm long. Four flagella A flagellum (; : flagella) (Latin for 'w ...

'', which cause intestinal spirochaetosis

Salvarsan Arsphenamine, also known as Salvarsan or compound 606, is an antibiotic drug that was introduced at the beginning of the 1910s as the first effective treatment for the deadly infectious diseases syphilis, relapsing fever, and African trypanosomias ...

, the first partially organic synthetic

antimicrobial drug An antimicrobial is an agent that kills microorganisms (microbicide) or stops their growth (bacteriostatic agent). Antimicrobial medicines can be grouped according to the microorganisms they are used to treat. For example, antibiotics are used aga ...

in medical history, was effective against spirochaetes and primarily used to cure

. Additionally, oral spirochaetes are known to play a significant role in the

pathogenesis In pathology, pathogenesis is the process by which a disease or disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes . Descript ...

of human

periodontal disease Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main c ...

Taxonomy and molecular signatures

The class currently consists of 14 validly named genera across four orders and five families. The orders ''

Brachyspirales Brachyspiraceae is a family of Spirochaetota. Spirochetosis of the Appendix, caused by '' Brachyspira aalborgi'' or '' Brachyspira pilosicoli'', is not associated with appendicitis. See also * List of bacteria genera * List of bacterial order ...

'', ''

Brevinematales ''Brevinema andersonii'' (Brev. i. ne' ma. L. adj. brevis, short; Gr. n. nema, thread; N.L. neut. n. Brevinema, a short thread.) (an.derso'ni.i. N.L. gen. n. andersonii, of Anderson), named for John F. Anderson, who first described the organism. ...

'' and ''

Leptospirales The Leptospiraceae are a family of spirochete bacteria. It includes the genus ''Leptospira'' which contains some pathogenic species. Phylogeny The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclatu ...

'' each contain a single family, '' Brachyspiraceae'', '' Brevinemataceae'' and '' Leptospiraceae'', respectively. The ''

Spirochaetales The Spirochaetales are an order of spirochete bacteria. Some species within this order are known to causes syphilis, Lyme disease, relapsing fever, and other illnesses. Phylogeny The currently accepted taxonomy is based on the List of Prokary ...

'' order harbours two families, ''

Spirochaetaceae The Spirochaetaceae are a family of spirochete bacteria. Some species within this family are known to causes syphilis, Lyme disease, relapsing fever, and other illnesses. Phylogeny The currently accepted taxonomy is based on the List of Prokaryo ...

'' and ''

Borreliaceae The Borreliaceae are a family of spirochete bacteria. See also * List of bacteria genera * List of bacterial orders This article lists the orders of the Bacteria. The currently accepted taxonomy is based on the List of Prokaryotic names with S ...

''. Molecular markers in the form of

conserved signature indels Conserved signature inserts and deletions (CSIs) in protein sequences provide an important category of molecular markers for understanding phylogenetic relationships. CSIs, brought about by rare genetic changes, provide useful phylogenetic markers ...

(CSIs) and CSPs have been found specific for each of the orders, with the exception of '' Brevinimetales'', that provide a reliable means to demarcate these clades from one another within the diverse phylum. Additional CSIs have been found exclusively shared by each family within the ''

''. These molecular markers are in agreement with the observed phylogenetic tree branching of two monophyletic clades within the ''

'' order. CSIs have also been found that further differentiate taxonomic groups within the ''

'' family that further delineate evolutionary relationships that are in accordance with physical characteristics such as pathogenicity (viz. ''

Borrelia ''Borrelia'' is a genus of bacteria of the spirochete phylum. Several species cause Lyme disease, also called Lyme borreliosis, a zoonotic, vector-borne disease transmitted by ticks. Other species of ''Borrelia'' cause relapsing fever, and are ...

'' emend. '' Borreliella'' gen. nov.). However, this study has been criticized, and other studies using different approaches do not support the proposed split. The new naming system for the Lyme and relapsing fever ''Borrelia'' has not been adopted by the scientific literature. A CSI has also been found exclusively shared by all Spirochaetota species. This CSI is a three-amino-acid insert in the flagellar

basal body A basal body (synonymous with basal granule, kinetosome, and in older cytological literature with blepharoplast) is a protein structure found at the base of a eukaryotic undulipodium (cilium or flagellum). The basal body was named by Theodor Wi ...

rod protein FlgC which is an important part of the unique endoflagellar structure shared by Spirochaetota species. Given that the CSI is exclusively shared by members within this phylum, it has been postulated that it may be related to the characteristic flagellar properties observed among Spirochaetota species. Historically, all families belonging to the Spirochaetota phylum were assigned to a single order, the ''

''. However, the current taxonomic view is more connotative of accurate evolutionary relationships. The distribution of a CSI is indicative of shared ancestry within the clade for which it is specific. It thus functions as a

synapomorphic In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ...

characteristic, so that the distributions of different CSIs provide the means to identify different orders and families within the phylum and so justify the phylogenetic divisions.

Phylogeny

Taxonomy

The currently accepted taxonomy is based on the

List of Prokaryotic names with Standing in Nomenclature List of Prokaryotic names with Standing in Nomenclature (LPSN) is an online database that maintains information on the naming and taxonomy of prokaryotes, following the taxonomy requirements and rulings of the International Code of Nomenclatu ...

(LPSN) and

National Center for Biotechnology Information The National Center for Biotechnology Information (NCBI) is part of the National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The NCBI is lo ...

(NCBI). * Phylum Spirochaetota Garrity and Holt 2021 ** Genus ?"'' Spirosymplokos''" Guerrero et al. 1993 ** Class Leptospiria Chuvochina et al. 2024 *** Order Turneriellales Chuvochina et al. 2024 **** Family Turneriellaceae Chuvochina et al. 2024 ***** Genus '' Turneriella'' Levett et al. 2005 *** Order

Gupta et al. 2014 **** Family Leptonemataceae Chuvochina et al. 2024 ***** Genus '' Leptonema'' Hovind-Hougen 1983 **** Family Leptospiraceae Hovind-Hougen 1979 ***** Genus ''

'' Noguchi 1917 ** Class Brachyspiria Chuvochina et al. 2024 *** Order

corrig. Gupta et al. 2014 **** Family Brachyspiraceae Paster 2012 ***** Genus ?"''Ca.'' Maribrachyspira" Matsuyama et al. 2017 ***** Genus ''

Brachyspira ''Brachyspira'' is a genus of bacteria classified within the phylum Spirochaetota.See the List of Prokaryotic names with Standing in Nomenclature. Data extracted from See the National Center for Biotechnology Information, NCBI]webpage on Spiro ...

'' Hovind-Hougen et al. 1982 non Foliella non Pfeiffer 1855 ** Class Brevinematia Chuvochina et al. 2024 *** Order

Gupta et al. 2014 **** Family "Longinemataceae" Karnachuk et al. 2021 ***** Genus ?"'' Longinema''" corrig. Karnachuk et al. 2021 **** Family Brevinemataceae Paster 2012 ***** Genus '' Brevinema'' Defosse et al. 1995 **** Family Thermospiraceae Ben Ali Gam et al. 2023 ***** Genus '' Thermospira'' Ben Ali Gam et al. 2023 ** Class Spirochaetia Paster 2020 *** Order

Buchanan 1917 **** Family " Pillotinaceae" Margulis & Hinkle 1992 ***** Genus ?'' Pillotina'' Hollande and Gharagozlou 1967 ex Bermudes et al. 1988 **** Family

Swellengrebel 1907 Pallen, Rodriguez-R & Alikhan 2022">Thiospirochaetaceae" Pallen, Rodriguez-R & Alikhan 2022***** Genus ?"''Ca.'' Allospironema" Paster & Dewhirst 2000 ***** Genus ?"'' Canaleparolina''" Wier, Ashen & Margulis 2000 ***** Genus ?'' Clevelandina'' Bermudes et al. 1988 ***** Genus ?'' Diplocalyx'' Gharagozlou 1968 ex Bermudes et al. 1988 non Richard 1850 non Presl 1845 ***** Genus ?"''Candidatus'' Haliotispira" Sharma et al. 2024 ***** Genus ?'' Hollandina'' To et al. 1978 ex Bermudes et al. 1988 non Haynes 1956 ***** Genus ?"'' Mobilifilum''" Margulis et al. 1990 ***** Genus '' Oceanispirochaeta'' Subhash & Lee 2017b ***** Genus ?''

Spirochaeta ''Spirochaeta'' is a genus of bacteria classified within the phylum Spirochaetota. Phylogeny The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology I ...

'' Ehrenberg 1835 em. Pikuta et al. 2009 non Turczaninow 1851 ***** Genus ?"''Candidatus'' Thalassospirochaeta" Pragya et al. 2024 ***** Genus '' Thiospirochaeta'' Dubinina et al. 2020 **** Family Alkalispirochaetceae Chuvochina et al. 2024 ***** Genus '' Alkalispirochaeta'' Sravanthi et al. 2016 **** Family Salinispiraceae Chuvochina et al. 2024 ***** Genus '' Salinispira'' Ben Hania et al. 2015 *** Order "Exilispirales" Pallen, Rodriguez-R & Alikhan 2022 **** Family "Exilispiraceae" Pallen, Rodriguez-R & Alikhan 2022 ***** Genus '' Exilispira'' Imachi et al. 2008 *** Order Borreliales Chuvochina et al. 2024 **** Family

Gupta et al. 2014 ***** Genus ''

'' Swellengrebel 1907 (relapsing fever Borrelia, reptile-associated Borrelia and Echidna-associated Borrelia) ***** Genus '' Borreliella'' Adeolu & Gupta 2015 (Lyme disease Borrelia) ***** Genus ?'' Cristispira'' Gross 1910 *** Order "Entomospirales" Pallen, Rodriguez-R & Alikhan 2022 **** Family "Entomospiraceae" Pallen, Rodriguez-R & Alikhan 2022 ***** Genus '' Entomospira'' Grana-Miraglia et al. 2024 non Enderlein 1917 *** Order "Marispirochaetales" Pallen, Rodriguez-R & Alikhan 2022 **** Family Marispirochaetaceae Chuvochina et al. 2024 ***** Genus '' Marispirochaeta'' Shivani et al. 2017 *** Order "Sediminispirochaetales" Pallen, Rodriguez-R & Alikhan 2022 **** Family Sediminispirochaetaceae Chuvochina et al. 2024 ***** Genus '' Sediminispirochaeta'' Shivani et al. 2016 *** Order Sphaerochaetales Chuvochina et al. 2024 **** Family Sphaerochaetaceae Hördt et al. 2020 ***** Genus '' Bullifex'' Wylensek et al. 2021 Gilroy et al. 2021">ncl. "''Ca.'' Aphodenecus" Gilroy et al. 2021***** Genus "''Ca.'' Ornithospirochaeta" Gilroy et al. 2021 ***** Genus '' Parasphaerochaeta'' Bidzhieva et al. 2020 ***** Genus "''Ca.'' Physcosoma" Gilroy et al. 2022 ***** Genus '' Pleomorphochaeta'' Arroua et al. 2016 ***** Genus '' Sphaerochaeta'' Ritalahti et al. 2012 *** Order Treponematales Chuvochina et al. 2024 **** Family Rectinemataceae Brune et al. 2022 ***** Genus '' Rectinema'' Koelschbach et al. 2017 **** Family Breznakiellaceae Brune et al. 2022 ***** Genus '' Breznakiella'' Song et al. 2022 ***** Genus '' Gracilinema'' Brune et al. 2022 ***** Genus '' Helmutkoenigia'' Brune et al. 2022 ***** Genus '' Leadbettera'' Brune et al. 2022 ***** Genus '' Zuelzera'' Brune et al. 2022 **** Family Treponemataceae Robinson 1948 ***** Genus "''Ca.'' Avitreponema" Gilroy et al. 2021 ***** Genus '' Brucepastera'' Song et al. 2023 ***** Genus "''Ca.'' Gallitreponema" Gilroy et al. 2021 ***** Genus '' Teretinema'' Song et al. 2023 ***** Genus ''

Treponema ''Treponema'' is a genus of spiral-shaped bacteria. The major treponeme species of human pathogens is ''Treponema pallidum'', whose subspecies are responsible for diseases such as syphilis, bejel, and yaws. '' Treponema carateum'' is the cause ...

'' Schaudinn 1905 em. Abt et al. 2013

References

External links

Introduction to the Spirochetes
University of California Museum of Paleontology (UCMP) {{Taxonbar, from=Q12673555 Bacteria phyla