Abstract
Aeropyrum pernix, a strictly aerobic marine hyperthermophilic archaeon, has been studied as a potential biotechnological source. In order to clarify the phylogenetic position of A. pernix, the nearly complete nucleotide sequence of the 23S rRNA was determined and compared with the other hitherto known archaeal counterparts. To avoid the artifact caused by disparities of G+C content, transversion evolutionary distance analysis was adopted. The result confirmed that A. pernix is closely allied to the Pyrodictium-Desulfurococcus-Staphylothermus group (the order “Igneococcales”) within the kingdom Crenarchaeota. However, it also revealed that the genus Aeropyrum diverges sharply from the other genera within the family Desulfurococcaceae. Thus, we concluded that the decision to transfer the genus Aeropyrum from the family Desulfurococcaceae is reasonable in light of our present data, as well as the physiological characteristics of this archaeon reported previously.
