Negativicutes Marchandin et al., 2010
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- Negativicutes
Abstract
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. 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). Additional research is required to confirm the origin of the diderm cell envelope in the Negativicutes. 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.
Molecular signatures
Historically, the Negativicutes consisted of a single order, the Selenomonadales, and two families, Veillonellaceae and Acidaminococcaceae based on 16S rRNA gene sequence similarity.Ludwig W, Schleifer K-H, Whitman, WB (2009) Revised road map to the phylum Firmicutes. In: Bergey’s Manual of Systematic Bacteriology, vol. 3, 2nd edn. pp. 1–13. Eds P. De Vos, G. M. Garrity, D. Jones, N. R. Krieg, W. Ludwig, F. A. Rainey, K. H. Schleifer & W. B. Whitman Springer-: New York. 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. 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. 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. 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.Merchandin H, Jumas-Bilak E (2014) The family Veillonellaceae. In: The Prokaryotes, vol. 7, 4th edn. pp. 433–453. Eds E. Rosenberg, E. DeLong, S. Lory, E. Stackebrandt & F. Thompson Springer-: Berlin, Heidelberg. 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.
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)
Selenomonadales Marchandin et al. 2010 emend. Campbell et al. 2015 Selenomonadaceae Campbell et al. 2015 Anaerovibrio Hungate 1966 Centipeda (bacteria) Lai et al. 1983 Megamonas Shah and Collins 1983 Mitsuokella Shah and Collins 1983 Pectinatus Lee et al. 1978 emend. Juvonen and Suihko 2006 Propionispira Schink et al. 1983 Schwartzia van Gylswyk et al. 1997 Selenomonas von Prowazek 1913 Zymophilus Schleifer et al. 1990 Sporomusaceae Campbell et al. 2015 Acetonema Kane and Breznak 1992 Anaeroarcus Strömpl et al. 1999 Anaeromusa Baena et al. 1999 Anaerosinus Strömpl et al. 1999 Anaerospora ♠ Woo et al. 2005 Dendrosporobacter Strömpl et al. 2000 Desulfosporomusa ♠ Sass et al. 2004 Lucifera Sánchez-Andrea et al. 2019
Pelosinus Shelobolina et al. 2007
Propionispora Biebl et al. 2001 Psychrosinus ♠ Sattley et al. 2008 Sporolituus Ogg and Patel 2009 Sporomusa Möller et al. 1985 Thermosinus Sokolova et al. 2004 Acidaminococcales Campbell et al. 2015 Acidaminococcaceae Marchandin et al. 2010 emend. Campbell et al. 2015 Acidaminococcus Rogosa 1969 emend. Jumas-Bilak et al. 2007 Phascolarctobacterium Del Dot et al. 1994 Succiniclasticum van Gylswyk 1995 Succinispira Janssen and O'Farrell 1999 Veillonellales Campbell et al. 2015 Veillonellaceae Rogosa 1969 emend. Campbell et al. 2015 Allisonella Garner et al. 2003 Anaeroglobus Carlier et al. 2002 Dialister (ex Bergey et al. 1923) Moore and Moore 1994 emend. Morotomi et al. 2008 Megasphaera Rogosa 1971 emend. Marchandin et al. 2003 Negativicoccus Marchandin et al. 2010 Veillonella Prévot 1933 emend. Mays et al. 1982 Unclassified
Quinella ♪ Krumholz et al. 1993
Notes: ♠ Strains found at the National Center for Biotechnology Information (NCBI), but not listed in the List of Prokaryotic names with Standing in Nomenclature (LPSN) ♪ Prokaryotes where no pure (axenic) cultures are isolated or available, i. e. not cultivated or can not be sustained in culture for more than a few serial passages
Selenomonadales Marchandin et al. 2010 emend. Campbell et al. 2015 Selenomonadaceae Campbell et al. 2015 Anaerovibrio Hungate 1966 Centipeda (bacteria) Lai et al. 1983 Megamonas Shah and Collins 1983 Mitsuokella Shah and Collins 1983 Pectinatus Lee et al. 1978 emend. Juvonen and Suihko 2006 Propionispira Schink et al. 1983 Schwartzia van Gylswyk et al. 1997 Selenomonas von Prowazek 1913 Zymophilus Schleifer et al. 1990 Sporomusaceae Campbell et al. 2015 Acetonema Kane and Breznak 1992 Anaeroarcus Strömpl et al. 1999 Anaeromusa Baena et al. 1999 Anaerosinus Strömpl et al. 1999 Anaerospora ♠ Woo et al. 2005 Dendrosporobacter Strömpl et al. 2000 Desulfosporomusa ♠ Sass et al. 2004 Lucifera Sánchez-Andrea et al. 2019
Pelosinus Shelobolina et al. 2007
Propionispora Biebl et al. 2001 Psychrosinus ♠ Sattley et al. 2008 Sporolituus Ogg and Patel 2009 Sporomusa Möller et al. 1985 Thermosinus Sokolova et al. 2004 Acidaminococcales Campbell et al. 2015 Acidaminococcaceae Marchandin et al. 2010 emend. Campbell et al. 2015 Acidaminococcus Rogosa 1969 emend. Jumas-Bilak et al. 2007 Phascolarctobacterium Del Dot et al. 1994 Succiniclasticum van Gylswyk 1995 Succinispira Janssen and O'Farrell 1999 Veillonellales Campbell et al. 2015 Veillonellaceae Rogosa 1969 emend. Campbell et al. 2015 Allisonella Garner et al. 2003 Anaeroglobus Carlier et al. 2002 Dialister (ex Bergey et al. 1923) Moore and Moore 1994 emend. Morotomi et al. 2008 Megasphaera Rogosa 1971 emend. Marchandin et al. 2003 Negativicoccus Marchandin et al. 2010 Veillonella Prévot 1933 emend. Mays et al. 1982 Unclassified
Quinella ♪ Krumholz et al. 1993
Notes: ♠ Strains found at the National Center for Biotechnology Information (NCBI), but not listed in the List of Prokaryotic names with Standing in Nomenclature (LPSN) ♪ Prokaryotes where no pure (axenic) cultures are isolated or available, i. e. not cultivated or can not be sustained in culture for more than a few serial passages
Taxonomy
The class currently consists of 32 validly named genera across three orders and four families. The orders Veillonellales and Acidaminococcales each contain a single family, Veillonellaceae and Acidaminococcaceae, respectively, while the order Selenomonadales contains two families, Selenomonadaceae and Sporomusaceae.