title: Haloquadratum walsbyi gen. nov., sp. nov., the square haloarchaeon of Walsby, isolated from saltern crystallizers in Australia and Spain.
abstract: 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).
authors.affiliation: Department of Microbiology and Immunology, University of Melbourne, Victoria 3010, Australia.
authors.forename: David G
authors.initials: DG
authors.lastname: Burns
authors.affiliation: Department of Microbiology and Immunology, University of Melbourne, Victoria 3010, Australia.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Janssen
authors.affiliation: Japan Collection of Microorganisms, RIKEN BioResource Center, Saitama 351-0198, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Itoh
authors.affiliation: Noda Institute for Scientific Research, 399 Noda, Noda-shi, Chiba-ken 278-0037, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kamekura
authors.affiliation: California Institute of Technology, Mail code 114-96, Pasadena, CA 91125, USA.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Li
authors.affiliation: California Institute of Technology, Mail code 114-96, Pasadena, CA 91125, USA.
authors.forename: Grant
authors.initials: G
authors.lastname: Jensen
authors.affiliation: Universidad Miguel Hernandez, 03550 San Juan de Alicante, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Rodríguez-Valera
authors.affiliation: Department of Microbial Ecology, University of Groningen, 9751 NN Haren (Gn), The Netherlands.
authors.forename: Henk
authors.initials: H
authors.lastname: Bolhuis
authors.affiliation: Department of Microbiology and Immunology, University of Melbourne, Victoria 3010, Australia.
authors.forename: Mike L
authors.initials: ML
authors.lastname: Dyall-Smith
mesh_terms: D000332:Aerobiosis; D001315:Australia; D001482:Base Composition; D002473:Cell Wall / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D019641:DNA, Archaeal / Q000737:chemistry / Q000302:isolation & purification; D020459:Genes, rRNA; D006216:Halobacteriaceae / Q000145:classification* / Q000166:cytology / Q000302:isolation & purification* / Q000502:physiology; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000378:metabolism; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D015388:Organelles / Q000648:ultrastructure; D010743:Phospholipids / Q000032:analysis / Q000737:chemistry; D010802:Phylogeny; D019642:RNA, Archaeal / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012492:Salts; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013030:Spain; D014871:Water Microbiology
chemical_list: D019641:DNA, Archaeal; D010743:Phospholipids; D019642:RNA, Archaeal; D012336:RNA, Ribosomal, 16S; D012492:Salts; D008274:Magnesium