The Thermoanaerobacteriales are an order

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 of bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 placed within the class clostridia

Clostridia

The Clostridia are a class of Firmicutes, including Clostridium and other similar genera. They are distinguished from the Bacilli by lacking aerobic respiration. They are obligate anaerobes and oxygen is toxic to them. Species of the genus Clostridium are all Gram-positive and have the ability to...

, and encompassing three families, the Thermoanaerobacteriaceae, the Thermodesulfobiaceae and Thermoanaerobacterales Family III. Incertae Sedis. This order is noted for the species abilities to survive in environments of extreme elevated temperature. An example organism in this order is Thermoanaerobacteriium autearoensis.(C.Michael Hogan)