Haloplasma

Ha.lo.plas’ma. Gr. n. hals, salt; Gr. neut. n. plasma, some- thing formed or molded, a form; N.L. neut. n. Halo- plasma, a salt-loving form. The genus Haloplasma, classified within the family Haloplasmataceae and order Haloplasmatales within the phylum Firmicutes, consists of Gram-negative cells with characteristic contractile cellular protrusions. Cells are pleomorphic, wall-less, and non-spore-forming. When grown on solid media they produce very small colonies with a “fried-egg” appearance. Members of this genus are strictly anaerobic. They are also strictly organotrophic, using a very limited range of substrates, under denitrifying and fermentative conditions. Halo- plasma contractile, the single species of the genus, is moderately halophilic and mesophilic. The major res- piratory lipoquinone is MK-4, and phosphatidylglycerol and bisphosphatidylglycerol are the major polar lipids. Major fatty acids (>10%) are C16:0, C18:0, C18:1ω9c, and summed feature 5 (most likely C18:2ω6,9c). Only one species of the genus Haloplasma has been described to date. H. contractile has been isolated from the brine–sediment interface of deep-sea brine. DNA G+C content: 33.6mol% (based on HPLC); 33.0 mol% (based on the draft genome sequence). Type species: Haloplasma contractile Antunes, Rainey, da Costa and Huber 2008a, 2476VP (Effective publi- cation: Antunes, Rainey, Wanner, Taborda, Pätzold, Nobre, da Costa and Huber 2008b, 3586).