Chloroflexales

{{Short description|Order of bacteria}}

{{automatic taxobox

| taxon = Chloroflexales

| authority = Gupta et al. 2013

| subdivision_ranks = Families

| subdivision =

• Chloroflexineae
• Chloroflexaceae
• Oscillochloridaceae
• Roseiflexineae
• Roseiflexaceae

}}

Chloroflexales is an order of bacteria in the class Chloroflexia.{{cite book|last=Garrity|first=George M.|title=Bergey's manual of systematic bacteriology|url=https://archive.org/details/bergeysmanualofs00boon|url-access=registration|date=2001|publisher=Springer|location=New York|isbn=978-0-387-21609-6|pages=[https://archive.org/details/bergeysmanualofs00boon/page/427 427–446]|edition=2nd}} The clade is also known as filamentous anoxygenic phototrophic bacteria (FAP),{{cite journal |last1=Thweatt |first1=Jennifer L. |last2=Canniffe |first2=Daniel P. |last3=Bryant |first3=Donald A. |title=Biosynthesis of chlorophylls and bacteriochlorophylls in green bacteria |journal=Advances in Botanical Research |date=2019 |volume=90 |pages=35–89 |doi=10.1016/bs.abr.2019.03.002}} as the order contains phototrophs that do not produce oxygen. These bacteria are facultative aerobic.{{cite journal |vauthors=Gupta RS, Chander P, George S |title=Phylogenetic framework and molecular signatures for the class Chloroflexia and its different clades; proposal for division of the class Chloroflexia class. nov. [corrected] into the suborder Chloroflexineae subord. nov., consisting of the emended family Oscillochloridaceae and the family Chloroflexaceae fam. nov., and the suborder Roseiflexineae subord. nov., containing the family Roseiflexaceae fam. nov. |journal= Antonie van Leeuwenhoek |volume=103|issue=1|pages=99–119 |date=2013|pmid=22903492 |doi=10.1007/s10482-012-9790-3 }} They generally use chemotrophy when oxygen is present and switch to light-derived energy when otherwise. Most species are heterotrophs, but a few are capable of photoautotrophy.

The order can be divided into two suborders. Chloroflexineae ("Green FAP", "green non-sulfur bacteria") is the better-known one. This suborder uses chlorosomes, a specialized antenna complex, to pass light energy to the reaction center. Roseiflexineae ("Red FAP") on the other hand has no such ability. The named colors are not absolute, as growth conditions such as oxygen concentration will make a green FAP appear green, brown, or reddish-orange by inducing changes in pigment composition.