Strains C23(T) and HBSQ001 were isolated from solar salterns and are novel square-shaped, aerobic, extremely halophilic members of the domain Archaea and family Halobacteriaceae. Cells stained Gram-negative and grew optimally in media containing 18% salts at around neutral pH. Mg2+ is not required. The DNA G + C content of both isolates was 46.9 mol% and DNA-DNA cross-hybridization showed a relatedness of 80%. Their 16S rRNA gene sequences showed only 2 nucleotide differences (99.9% identity) and phylogenetic tree reconstructions with other recognized members of the Halobacteriaceae indicated that they formed a distinct clade, with the closest relative being Halogeometricum borinquense PR 3(T) (91.2% sequence identity). The major polar glycolipid of both isolates was the sulfated diglycosyl diether lipid S-DGD-1. Electron cryomicrosopy of whole cells revealed similar internal structures, such as gas vesicles and polyhydroxyalkanoate granules, but the cell wall of isolate HBSQ001 displayed a more complex S-layer compared with that of isolate C23(T). The phenotypic characterization and phylogenetic data support the placement of isolates C23(T) and HBSQ001 in a novel species in a new genus within the Halobacteriaceae, for which we propose the name Haloquadratum walsbyi gen. nov., sp. nov. The type strain of Haloquadratum walsbyi is C23(T) (= JCM 12705(T) = DSM 16854(T)).
|Number of pages||6|
|Journal||International Journal of Systematic and Evolutionary Microbiology|
|Publication status||Published - Feb 2007|