Characterization of Tetragenococcus strains from sugar thick juice reveals a novel species, Tetragenococcus osmophilus sp. nov., and divides Tetragenococcus halophilus into two subspecies, T. halophilus subsp. halophilus subsp. nov. and T. halophilus subsp. flandriensis subsp. nov.

摘要

Most bacteria recovered so far from sugar thick juice during storage represent strains of thespecies Tetragenococcus halophilus. Recently, several Gram-positive, non-motile, non-sporeformingcocci with other physiological and genetic traits were isolated from sugar thick juicesamples from different origins. In this study, representative isolates were investigated using apolyphasic taxonomic approach. The 16S rRNA gene sequence similarity between these isolatesand their closest relative, Tetragenococcus muriaticus, was 97.4 %. The level of DNA–DNArelatedness between isolate T1T, representing the newly found Tetragenococcus isolates, and T.muriaticus was 57 %. Isolate T1T had a DNA G+C content of 36.7 mol%. Phylogenetic data andgenomic and phenotypic features demonstrated that the isolates represent a novel species, forwhich the name Tetragenococcus osmophilus sp. nov. is proposed with T1T as the type strain(LMG 26041T 5DSM 23765T). Additionally, T. halophilus isolates from high-salt and highsugarenvironments showed clear differences in several physiological and genetic characteristicslike RAPD fingerprints and 16S rRNA gene sequences. DNA–DNA hybridizations, however,showed 79 to 80% relatedness between osmophilic and halophilic T. halophilus isolates,demonstrating that the different strains belong to the same species. Based on the phenotypic andgenotypic differences observed, as well as the different origins of the strains and the industrialrelevance of thick juice degradation, two subspecies of T. halophilus are described in thismanuscript: T. halophilus subsp. halophilus subsp. nov. for the strains isolated from salt mediaand T. halophilus subsp. flandriensis subsp. nov. for the strains isolated from sugar-richenvironments, which were first isolated in Flanders, Belgium. The type strains for the subspeciesare IAM 1676T (5LMG 11490T 5DSM 20339T) and T5T (5LMG 26042T 5DSM 23766T),respectively.