Phylogenetic analysis of the Alicyclobacillaceae, including the genera Sulfobacillus and Alicyclobacillus. Sequences for each of the 11 species type strains of Alicyclobacillaceae available in release 5.0 of Bergey's taxonomic outline, along with additional sequences for four Alicyclobacillaceae species type strains that became available after the release of the outline (marked with an asterisk), and two Bacillus species type strains were analyzed using the weighted neighbor-joining method (5). The tree is rooted using Escherichia coli sequence J01695 as the outgroup. Bootstrap confidence estimates above 85% are shown. Three misclassifications made by the RDP Classifier are highlighted, with the original (release 5.0) description appended with a corrected description. S. disulfidooxidansT became A. disulfidooxidansT. In 2005, S. disulfidooxidans was formally reclassified as a new combination, A. disulfidooxidans (14). S. thermosulfidooxidans VKM 1269T became “A. tolerans K1.” In release 5, sequence Z21979 was listed as coming from the type strain (VKM 1269) of S. thermosulfidooxidans. This agrees with the original publication for the sequence (25). The same group later reported that the sequence was probably from S. thermosulfidooxidans strain K1, not VKM 1269 (15). Two independent sequences (X91080 and AB089844) for the type strain of S. thermosulfidooxidans are available. They are nearly identical to each other (0.2% difference) and 19% different from Z21979. In 2005, S. thermosulfidooxidans strain K1 was reclassified as the type strain of a new species, A. tolerans (14). In our analysis, however, the sequence for K1 given in the naming paper (accession number AF137502) is 8% different from that for Z21979. Although still listed in the GenBank record as from A. tolerans strain K1, Z21979 is most probably not from strain K1 and not even from a member of the species A. tolerans. A. acidoterrestrisT became Bacillus sp. Sequence X60602 was published in 1991 as from the type strain (DSM 3922) for A. acidoterrestris (1). The GenBank record also lists this as from strain DSM 3922, but a strain mix-up in the culture supplied by the DSMZ was reported in 1992 (27). The type strain (ATCC 49025, listed by the DSMZ as equivalent to DSM 3922) was resequenced in 2005 (AY573797 [9]). These two sequences are 14% different, and X60602 is now described by GenBank as from a Bacillus sp.