Diversity of Alicyclobacillus isolated from fruit juices and their raw materials, and emended description of Alicyclobacillus acidocaldarius

Abstract

In the course of a microbiological survey of various beverages and their raw materials, 180 moderately thermophilic, acidophilic, spore-forming bacteria were isolated from several samples. Seven representative strains, selected from 180 isolates based on morphology and the hyper-variable region of the 16S rRNA gene, were identified as Alicyclobacillus acidocaldarius, A. acidoterrestris and Alicyclobacillus genomic species 1, according to their phenotypic, chemotaxonomic, genotypic and phylogenetic features. Cellular fatty acid composition, quinone species, and DNA base composition of the seven strains were similar to those of the type/reference strains. However, physiological and biochemical characteristics were variable within each species. Moreover, sequence analyses of the 16S rRNA and partial gyrB genes revealed that, in a few strains, the phylogeny derived from both molecules was not consistent. Results of a ribotype analysis also supported this genetic heterogeneity. These results indicate a high level of diversity within species in the genus Alicyclobacillus with regards to both phenotype and genotype. In addition, an emended description of A. acidocaldarius is given on the basis of obtained polyphasic taxonomic data.