Reclassification of Thermoanaerobium acetigenum as Caldicellulosiruptor acetigenus comb. nov and emendation of the genus description

Although the type species of the genus Thermoanaerobium, Thermoanaerobium brockii, was transferred to Thermoanaerobacter, Thermoanaerobium acetigenum was not transferred. Therefore, Thermoanaerobium acetigenum should be reclassified. Based on 16S rRNA gene sequence analysis and re-examination of physiological properties of the type strain, X6B(T) (= DSM 7040(T) = ATCC BAA-11149(T)), we propose that Thermoanaerobium acetigenum should be reclassified as Caldicellulosiruptor acetigenus comb. nov. Strain X6B(T) contains two separate 16S rRNA genes bracketing another species in the phylogenetic 16S rRNA gene-based tree.