Salinisphaera

The genus Salinisphaera, classified within the family Salinisphaeraceae, order Xanthomonadales in the class Gammaproteobacteria, consists of Gram-negative cocci- or short rod-shaped cells. Strains produce colonies with a variety of pigmentations. Strains are either strictly aerobic or facultative anaerobic, and heterotrophic. S. hydrothermalis and S. shabanensis are also capable of growth on n-alkanes and acetate as sole carbon and energy sources, and chemolithoautotrophically in the presence of thiosulfate. Some are facultative chemolithoautotrophic or able to grow with n-alkanes as sole carbon and energy sources. Members of this genus usually do not reduce nitrate. Salinisphaera spp. are halophilic or halotolerant, and mesophilic. Furthermore, S. shabanensis has been reported as piezotolerant, and S. japonica as acidophilic. Poly-β-Hydroxybutyrate (PHB) is produced by several strains. All strains possess ubiquinone Q-8. The major fatty acids (detected at >10% in at least two species) are C14:0, C16:0, C18:0, C18:1ω7c, and C19:0ω8c cyclo. The major polar lipids include diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol. Six species of the genus Salinisphaera have been described to date; all of them isolated from hypersaline and marine environments.