thermoanaerobacterales family iv thermoanaerobacterales family iv thermoanaerobacterales family iv is a family of rod-shaped, motile bacteria in the order thermoanaerobacterales of the phylum bacillota. these microorganisms are spore-forming, anaerobic and moderately thermophilic (growing at optimal temperatures about 50°c) and stain gram-positive. because of uncertainty in the taxonomic assignment of its members, this family is referred to as "incertae sedis". thermoanaerobacterales family iv. incertae sedis scientific classification domain: bacteria phylum: bacillota class: clostridia order: thermoanaerobacterales family: thermoanaerobacterales family iv. incertae sedis genera mahella bonilla salinas et al. 2004