%0 Journal Article %A Burns, David G. %A Janssen, Peter H. %A Itoh, Takashi %A Kamekura, Masahiro %A Li, Zhuo %A Jensen, Grant %A Rodríguez-Valera, Francisco %A Bolhuis, Henk %A Dyall-Smith, Mike L. %T Haloquadratum walsbyi gen. nov., sp. nov., the square haloarchaeon of Walsby, isolated from saltern crystallizers in Australia and Spain %D 2007 %J International Journal of Systematic and Evolutionary Microbiology, %V 57 %N 2 %P 387-392 %@ 1466-5034 %R https://doi.org/10.1099/ijs.0.64690-0 %K SHOW, square haloarchaea of Walsby %K PHA, polyhydroxyalkanoate %I Microbiology Society, %X Strains C23T 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 3T (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 C23T. The phenotypic characterization and phylogenetic data support the placement of isolates C23T 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 C23T (=JCM 12705T=DSM 16854T). %U https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.64690-0