Reclassification of Geobacillus pallidus (Scholz et al. 1988) Banat et al. 2004 as Aeribacillus pallidus gen. nov., comb. nov.

Abstract

AlthoughAnoxybacillusandGeobacillus, two genera of thermophilic bacteria close to the genusBacillus, have only been described recently, the number of species in these genera has increased rapidly. Four thermophilic, lipolytic strains (DR01, DR02, DR03 and DR04) isolated from a hot spring in Veracruz (Mexico), which could not be identified phenotypically, were subjected to 16S rRNA gene sequence analysis. Three strains were identified as belonging to the genusAnoxybacillus, but strain DR03 was identified asGeobacillus pallidus. This result led us to perform a phylogenetic analysis of the generaAnoxybacillusandGeobacillusbased on 16S rRNA gene sequences from all the type strains of these genera. Phylogenetic trees showed three major clusters,Anoxybacillus–Geobacillus tepidamans,Geobacillussensu strictoandGeobacillus pallidus, while the 16S rRNA gene sequences ofG. pallidus(DR03 and the type strain) showed low similarity to sequences ofAnoxybacillus(92.5–95.1 %) andGeobacillus(92.8–94.5 %) species, as well as toBacillus subtilis(92.2–92.4 %). In addition,G. palliduscould be differentiated fromAnoxybacillusandGeobacilluson the basis of DNA G+C content and fatty acid and polar lipid profiles. From these results, it is proposed thatGeobacillus pallidusshould be classified in a novel genus, for which we propose the nameAeribacillus, asAeribacillus pallidusgen. nov., comb. nov. The type strain ofAeribacillus pallidusis H12T(=ATCC 51176T=DSM 3670T=LMG 19006T).