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Wikipedia / Fibrobacterota

Fibrobacterota is a bacterial phylum that includes cellulose-degrading bacteria associated with the digestive tracts of mammals, including ruminants. The genus Fibrobacter was separated from Bacteroides in 1988.

Phylogeny and comparative genomic studies

Although Fibrobacterota is recognized as a distinct phylum, phylogenetic studies based on RpoC and DNA gyrase B protein sequences indicate that it is related to the phyla Bacteroidota and Chlorobiota. Species from these three phyla also cluster together based on conserved signature indels in several proteins. Comparative genomic studies identified two conserved signature indels—a five- to seven-amino-acid insert in the RpoC protein and a 13- to 16-amino-acid insertion in serine hydroxymethyltransferase—and one signature protein (PG00081) shared by species from these phyla. These results support the placement of Fibrobacterota, Bacteroidota, and Chlorobiota in the FCB group.

Phylogeny

The trees below compare a 16S rRNA gene phylogeny from LTP_10_2024 with a genome-based phylogeny from GTDB release R11-RS232.GTDB treats Fibrobacter succinogenes subsp. elongatus as Fibrobacter elongatus and assigns Fibrobacter intestinalis to Hallerella as Hallerella intestinalis. LPSN retains the former as a subspecies of F. succinogenes and the latter as F. intestinalis.

Taxonomy

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

Class Chitinispirillia Sorokin et al. 2016

Order Chitinispirillales Sorokin et al. 2016

Family Chitinispirillaceae Sorokin et al. 2016

Genus Cellulosispirillum Sorokin, Merkel & Khizhniak 2025

Genus Chitinispirillum Sorokin et al. 2016

Class Chitinivibrionia Sorokin et al. 2014

Order Chitinivibrionales Sorokin et al. 2014

Family Chitinivibrionaceae Sorokin et al. 2014

Genus Chitinivibrio Sorokin et al. 2014

Class Fibrobacteria Spain et al. 2012

Order Fibrobacterales Spain et al. 2012

Family Fibrobacteraceae Spain et al. 2012

Genus Fibrobacter Montgomery et al. 1988

  • Species F. intestinalis Montgomery et al. 1988

Species F. succinogenes (Hungate 1950) Montgomery et al. 1988

  • Subspecies F. s. elongatus corrig. Montgomery et al. 1988

  • Subspecies F. s. succinogenes (Hungate 1950) Montgomery et al. 1988

Genus Hallerella Wylensek et al. 2021

  • Species H. porci Wylensek et al. 2021

  • Species H. succinigenes Wylensek et al. 2021

"Candidatus Fibrimonadales" corrig. Abdul Rahman et al. 2016

"Candidatus Fibrimonadaceae" corrig. Abdul Rahman et al. 2016

Genus "Candidatus Fibrimonas" corrig. Abdul Rahman et al. 2016

  • Species "Candidatus Fibrimonas termitidis" corrig. Abdul Rahman et al. 2016

Distribution

Fibrobacterota is part of the FCB group, which also includes Bacteroidota and Chlorobiota. Members of the genus Fibrobacter occur in the digestive tracts of mammals, including cattle and pigs. The two described species in this genus, Fibrobacter succinogenes and Fibrobacter intestinalis, are members of fibrolytic communities in mammalian digestive tracts and have been studied for their ability to degrade plant fibre.

Molecular evidence based on the amplification of 16S rRNA genes from various environments suggests that the phylum is more widespread than was initially recognized. In these studies, most clones from mammalian environments grouped with the known isolates in what was called subphylum 1. Members of the group called subphylum 2 were found in the guts of termites and some litter-feeding cockroaches. Members of subphylum 2 were abundant in fibre-associated bacterial communities in the hindguts of the wood-feeding termite Nasutitermes corniger.

See also

References

Further reading

  • List of Prokaryotic Names with Standing in Nomenclature – Genus

  • Systema Naturae 2000 classification: phylum Fibrobacteres