Alicyclobacillus pomorum sp nov., a novel thermo-acidophilic, endospore-forming bacterium that does not possess ω-alicyclic fatty acids, and emended description of the genus Alicyclobacillus

A thermo-acidophilic endospore-forming bacterium was isolated from a mixed fruit juice. The organism, strain 3A(T), was rod-shaped, grew aerobically at 30-60 degreesC (optimum 45-50 degreesC), pH 3.0-6.0 (optimum pH 4.0-4.5) and produced acid from various sugars. It contained menaquinone-7 as the major isoprenoid quinone. The G + C content of the DNA was 53.1 mol%. The predominant cellular fatty acids of the strain were iso-C-15:0, anteiso-C-15:0, iso-C-16:0, iso-C-17:0 and anteiSO-C-17:0, but omega-alicyclic fatty acids, which are characteristic of the genus Alicyclobacillus, were not found in the strain. Phylogenetic analyses based on both 16S rRNA and gyrB (DNA gyrase B subunit gene) gene sequences showed that strain 3A(T) falls into the Alicyclobacillus cluster, validated by significant bootstrap values. However, strain 3A(T) did not show a close relationship to the other species of the cluster. The level of 16S rDNA similarity between strain 3A(T) and other strains of the cluster was between 92.5 and 95.5%. The level of gyrB sequence similarity between strain 3A(T) and other strains of the cluster was between 68.5 and 74.4%. DNA-DNA hybridization values between strain 3A(T) and phylogenetically related strains of the genera Alicyclobacillus, Bacillus and Sulfobacillus were under 13%, indicating that strain 3A(T) represents a distinct species. On the basis of these results, strain 3A(T) should be classified as a novel Alicyclobacillus species. The name Alicyclobacillus pomorum is proposed for this organism. The type strain of Alicyclobacillus pomorum is strain 3A(T) (= DSM 14955(T) =IAM 14988(T)).