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Negativicutes

Class of bacteria From Wikipedia, the free encyclopedia

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The Negativicutes are a class of bacteria in the phylum Bacillota, whose members have a peculiar cell wall with a lipopolysaccharide outer membrane which stains gram-negative, unlike most other members of the Bacillota.[1] Although several neighbouring Clostridia species (firmicute bacteria) also stain gram-negative, the proteins responsible for the unusual diderm structure of the Negativicutes may have actually been laterally acquired from Pseudomonadota (formerly Proteobacteria).[1][2][3][4] Additional research is required to confirm the origin of the diderm cell envelope in the Negativicutes.

Quick facts Scientific classification, Orders and families ...

Most members of this class are obligate anaerobes, and occur in habitats such as rivers, lakes, and the intestines of vertebrates. They range from spherical forms, such as Megasphaera and Veillonella, to curved rods, as typified by the selenomonads. Selenomonas has a characteristic crescent shape, with flagella inserted on the concave side, while Sporomusa is similar, but nonmotile. Their names refer to this distinctive morphology: selene means moon, and musa means banana.[5]

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Taxonomy

The class currently consists of 32 validly named genera across three orders and four families.[6][7] The orders Veillonellales and Acidaminococcales each contain a single family, Veillonellaceae and Acidaminococcaceae, respectively, while the order Selenomonadales contains two families, Selenomonadaceae and Sporomusaceae.[7]

Molecular signatures

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Historically, the Negativicutes consisted of a single order, the Selenomonadales, and two families, Veillonellaceae and Acidaminococcaceae based on 16S rRNA gene sequence similarity.[8][5] However, these groupings did not include several members within the Negativicutes that branched outside of the two families. The current taxonomic view is inclusive of these members who have been validly assigned to the families Selenomonadaceae and Sporomusaceae within the emended Selenomonadales order.[7] Molecular markers in the form of conserved signature indels (CSIs) and proteins (CSPs) justify the present taxonomic divisions. These molecular markers are found at each taxonomic rank, and their distribution is in agreement with the observed phylogenetic branching.[9][10]

Many works have implicated that the Negativicutes should be reclassified as an order within the class Clostridia, based on close phylogenetic branching, and the observation that the spore-forming members of the Negativicutes share similar sporulation genes as the Clostridia, and that both stain gram-negative.[9][10] However, the heterogeneity of members within the Negativicutes, as well as the distribution of molecular signatures, supports the view that the Negativicutes are in fact an independent class within the Bacillota, with Clostridia as their closest phylogenetic neighbours.[5][10][11][12] Additionally, several CSIs and CSPs have been found to be uniquely shared among all Negativicutes, while no CSIs have been found to be shared by both Negativicutes and Clostridia.[7]

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Phylogeny

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The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[13] and National Center for Biotechnology Information (NCBI).[14]

16S rRNA based LTP_10_2024[15][16][17] 120 marker proteins based GTDB 09-RS220[18][19][20]
Acidaminococcales
Acidaminococcaceae

Succinispira

Acidaminococcus

Phascolarctobacterium

Phascolarctobacterium faecium

Succiniclasticum

Selenomonadales
Sporomusaceae
Veillonellaceae
Selenomonadaceae

Anaerosinus Strömpl et al. 1999

Propionispira

Selenomonas~1 [incl. Centipeda]

Anaerovibrio

Schwartzia

Selenomonas [incl. Mitsuokella; Selenomastix]

Veillonellales
Negativicoccaceae

Negativicoccus Marchandin et al. 2010

Dialisteraceae

Dialister Bergey et al. 1923 ex Moore & Moore 1994 [incl. Allisonella]

Dialister species-grooup 2

Megasphaeraceae

Megasphaera_C

"Caecibacter" Ricaboni et al. 2017

Megasphaera paucivorans Juvonen & Suihko 2006

Anaeroglobus Carlier et al. 2002

Megasphaera Rogosa 1971

Veillonellaceae

Veillonella Prévot 1933

Acidaminococcales
Succinispiraceae

Succinispira Janssen and O'Farrell 1999

Acidaminococcaceae

"Ca. Avacidaminococcus" Gilroy et al. 2021

Acidaminococcus Rogosa 1969

Phascolarctobacterium Del Dot et al. 1994

Phascolarctobacterium succinatutens Watanabe et al. 2012

Succiniclasticum van Gylswyk 1995

Sporomusales_A
Acetonemaceae

Anaerosporomusa Choi et al. 2016

Acetonema Kane and Breznak 1992

UPPP01
"Luciferaceae"

Lucifera Sanchez-Andrea et al. 2018

Sporomusales C
DSM15969

Anaerospora Woo et al. 2005

Thermosinaceae

Thermosinus Sokolova et al. 2004 [Sporolituus Ogg and Patel 2009]

"Sporomusales"
Sporomusaceae

Methylomusa Amano et al. 2018

Sporomusa Möller et al. 1985

UMGS1260
UMGS1260

Pelorhabdus Grässle et al. 2022

DSM13327
"Pelosinaceae"

Pelosinus Shelobolina et al. 2007

Propionisporales
Propionisporaceae

Propionispora Biebl et al. 2001

Anaeromusales
Anaeromusaceae

Anaeromusa Baena et al. 1999 (incl. Anaeroarcus Strömpl et al. 1999)

"Dendrosporobacterales"
Dendrosporobacteraceae

Dendrosporobacter Strömpl et al. 2000

Selenomonadales
"Massilibacillaceae"

"Massilibacillus" Tidjani Alou et al. 2017

ICN92133

Selenobaculum Yeo et al. 2024

Selenomonadaceae

Propionispira Schink et al. 1983

Megamonas Shah and Collins 1983

Pectinatus Lee et al. 1978

Schwartzia Gylswyk et al. 1997

Selenomonas s.s. von Prowazek 1913

Anaerovibrio Hungate 1966

Quinella Krumholz et al. 1993

Centipeda Lai et al. 1983

Selenomonas bovis Zhang & Dong 2009

Selenomastix Woodcock & Lapage 1913

Mitsuokella Shah & Collins 1983

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See also

References

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