Scientific classification e
Domain: Bacteria
Phylum: Firmicutes
Class: Negativicutes
Marchandin et al. 2010
Orders and families
  • Selenomonadales Marchandin et al. 2010 emend. Campbell et al. 2015
    • Campbell et al. 2015
    • Campbell et al. 2015
  • Campbell et al. 2015
  • Campbell et al. 2015

The Negativicutes are a class of bacteria in the phylum Firmicutes, whose members have a peculiar cell wall with a lipopolysaccharide outer membrane which stains gram-negative, unlike most other members of the Firmicutes.[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 Proteobacteria.[1][2][3][4] 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.[5]


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

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.[8][9] 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.[10][11]

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.[10][11] 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 Firmicutes, with Clostridia as their closest phylogenetic neighbours.[9][11][12][13] 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]


The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) [14] and National Center for Biotechnology Information (NCBI)[15]


Janssen and O'Farrell 1999

Acidaminococcus Rogosa 1969 emend. Jumas-Bilak et al. 2007

Del Dot et al. 1994 (type sp.)

Watanabe et al. 2012

van Gylswyk 1995


?Woo et al. 2005

?Sass et al. 2004

?Sattley et al. 2008

?Quinella ovalisKrumholz et al. 1993 (Quin’s Oval)

?Ezaki et al. 2008

Sporomusa Möller et al. 1985

Ogg and Patel 2009

Thermosinus carboxydivorans Sokolova et al. 2004

Veillonella Prévot 1933 emend. Mays et al. 1982

Megasphaera [incl. ]

Negativicoccus succinicivorans Marchandin et al. 2010

Dialister [incl. ]

Anaeromusa acidaminophila Baena et al. 1999

Anaeroarcus burkinensis (Ouattara et al. 1992) Strömpl et al. 1999

Kane and Breznak 1992

Pelosinus Shelobolina et al. 2007

Propionispora Biebl et al. 2001

(Stankewich et al. 1971) Strömpl et al. 2000

Anaerosinus glycerini (Schauder and Schink 1996) Strömpl et al. 1999

Schink et al. 1983

Zymophilus Schleifer et al. 1990

Megamonas Shah and Collins 1983

Pectinatus Lee et al. 1978 emend. Juvonen and Suihko 2006

Hungate 1966

Selenomonas [incl. , & ]

♠ 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


  1. ^ a b Sutcliffe IC (2010). "A phylum level perspective on bacterial cell envelope architecture". Trends Microbiol. 18 (10): 464–470. doi:10.1016/j.tim.2010.06.005. PMID 20637628.
  2. ^ Gupta RS (2011). "Origin of diderm (Gram-negative) bacteria: antibiotic selection pressure rather than endosymbiosis likely led to the evolution of bacterial cells with two membranes". Antonie van Leeuwenhoek. 100 (2): 171–182. doi:10.1007/s10482-011-9616-8. PMC 3133647. PMID 21717204.
  3. ^ Campbell C, Sutcliffe IC, Gupta RS (2014). "Comparative proteome analysis of Acidaminococcus intestini supports a relationship between outer membrane biogenesis in Negativicutes and Proteobacteria" (PDF). Arch Microbiol. 196 (4): 307–310. doi:10.1007/s00203-014-0964-4. PMID 24535491.
  4. ^ Tocheva EI, Matson EG, Morris DM, Moussavi F, Leadbetter JR, Jensen GJ (2011). "Peptidoglycan remodeling and conversion of an inner membrane into an outer membrane during sporulation". Cell. 146 (5): 799–812. doi:10.1016/j.cell.2011.07.029. PMC 3176627. PMID 21884938.
  5. ^ Marchandin, H.; Teyssier, C.; Campos, J.; Jean-Pierre, H.; Roger, F.; Gay, B.; Carlier, J. -P.; Jumas-Bilak, E. (2009). "Negativicoccus succinicivorans gen. Nov., sp. Nov., isolated from human clinical samples, emended description of the family Veillonellaceae and description of Negativicutes classis nov., Selenomonadales ord. Nov. And Acidaminococcaceae fam. Nov. In the bacterial phylum Firmicutes". International Journal of Systematic and Evolutionary Microbiology. 60 (6): 1271–1279. doi:10.1099/ijs.0.013102-0. PMID 19667386.
  6. ^ Sayers; et al. "Negativicutes". National Center for Biotechnology Information (NCBI) taxonomy database. Retrieved 2013-03-20.
  7. ^ a b c d Campbell C, Adeolu M, Gupta RS (2015). "Genome-based taxonomic framework for the class Negativicutes: division of the class Negativicutes into the orders Selenomonadales emend., Acidaminococcales ord. nov. and Veillonellales ord. nov". Int J Syst Evol Microbiol. 65 (9): 3203–3215. doi:10.1099/ijs.0.000347. PMID 25999592.
  8. ^ 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.
  9. ^ a b Marchandin H, Teyssier C, Campos J, Jean-Pierre H, Roger F, Gay B, Carlier JP, Jumas-Bilak E (2010). "Negativicoccus succinicivorans gen. nov., sp. nov., isolated from human clinical samples, emended description of the family Veillonellaceae and description of Negativicutes classis nov., Selenomonadales ord. nov. and Acidaminococcaceae fam. nov. in the bacterial phylum Firmicutes". Int J Syst Evol Microbiol. 60 (Pt 6): 1271–1279. doi:10.1099/ijs.0.013102-0. PMID 19667386.
  10. ^ a b Yutin N, Galperin MY (2013). "A genomic update on clostridial phylogeny: Gram-negative spore formers and other misplaced clostridia". Environ Microbiol. 15 (10): 2631–2641. doi:10.1111/1462-2920.12173. PMC 4056668. PMID 23834245.
  11. ^ a b c Vesth T, Ozen A, Andersen SC, Kaas RS, Lukjancenko O, Bohlin J, Nookaew I, Wassenaar TM, Ussery DW (2013). "Veillonella, Firmicutes: Microbes disguised as Gram negatives". Stand Genomic Sci. 9 (2): 431–448. doi:10.4056/sigs.2981345. PMC 4062629. PMID 24976898.
  12. ^ 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.
  13. ^ Yilmaz P, Parfrey LW, Yarza P, Gerken J, Pruesse E, Quast C, Schweer T, Peplies J, Ludwig W, Glöckner FO (2014). "The SILVA and "All-species Living Tree Project (LTP)" taxonomic frameworks". Nucleic Acids Res. 42 (Database issue): D643–8. doi:10.1093/nar/gkt1209. PMC 3965112. PMID 24293649.
  14. ^ J.P. Euzéby. "Negativicutes". List of Prokaryotic names with Standing in Nomenclature (LPSN). Archived from the original on 2013-01-27. Retrieved 2016-10-21.
  15. ^ Sayers; et al. "Negativicutes". National Center for Biotechnology Information (NCBI) taxonomy database. Retrieved 2013-03-20.

Comments are closed.