Mollicutes

Abstract

Mol.li.cu'tes. L. adj.mollissoft, pliable; L. fem. n.cutisskin; N.L. fem. pl. n.Mollicutesclass with pliable cell boundary.Tenericutes / MollicutesWithin the phylumTenericutesthe classMollicutesaccommodates small wall‐less prokaryotes with small (usually 0.5–1.5 Mb) genomes and low (usually 25–30 mol%) G + CDNA. The genomes of more than 65 species have been completely sequenced and annotated to date. These bacteria are distributed among the ordersMycoplasmatales,Entomoplasmatales,Acholeplasmatales, andAnaeroplasmatalesaccording to polyphasic taxonomic standards established and refined over many years by the International Committee on Systematics of Prokaryotes' Subcommittee on the Taxonomy ofMollicutes. The class is best known for its members in the genusMycoplasmaand related organisms that are commensals or parasites of humans, animals, insects, or plants. A number of “Candidatus” species have been proposed but not yet cultivated axenically. In the distant past, there was some risk of confusing mollicutes with wall‐less variants of other bacteria, but simplePCR‐based analyses of16S rRNAor other gene sequences now obviate that problem. Members of theErysipelothrixline of descent, formerly grouped with theMollicutesas “walled relatives,” are now assigned to the classErysipelotrichiin the phylumFirmicutes. The proliferation in recent years of new names appearing in the literature to accommodate alleged novel taxa of mollicutes whose existence has been inferred principally from singularDNAsequences in metagenomic studies is a current concern.DNA G + C content (mol%): 60–79.Type order:MycoplasmatalesFreundt 1955, 71ALemend. Tully, Bové, Laigret and Whitcomb 1993, 382.