Nine pure cultures of neutrophilic haloaloarchaea capable of anaerobic growth by carbohydrate dependent sulfur respiration were isolated from hypersaline lakes in southwestern Siberia and southern Russia. According to phylogenomic analysis the isolates were closely related to each other and formed a new species within the genus Halapricum (family Haloarculaceae). They have three types of catabolism: fermentative, resulting in H2 formation; anaerobic respiration using sulfur compounds as e-acceptors and aerobic respiration. Apart from elemental sulfur, all isolates can also use three different sulfoxides as acceptors and the type strain also grows with thiosulfate, reducing it partially to sulfide and sulfite. All strains utilized sugars and glycerol as the e-donors and C source for anaerobic growth and some can also grow with alpha-glucans, such as starch and dextrins. The major respiratory menaquinones are MK-8:8 and MK-8:7, but 5–19% consists of ‘‘thermoplasmata” quinones (MMK-8:8 and MMK-8:7), whose occurrence in haloarchaea is unprecedented. On the basis of their unique physiological properties and results of phylogenomic analysis, the isolates are suggested to be classified into a novel species Halapricum desulfuricans sp. nov. (type strain HSR12-2T = JCM 34032T = UNIQEM U1001T).@en

Ha.lo.de.sul.fur.ar.chae’um. Gr. n. hals, halos salt of the sea; L. pref. de-, from; L. n. sulfur , sulfur; N.L. neut. n. archaeum archaeon from Gr. adj. archaios-ê-on ancient; N.L. neut. n. Halodesulfurarchaeum sulfur-reducing haloarchaeon. The genus Halodesulfurarchaeum, classified within the family Halobacteriaceae, order Halobacteriales, and in the class Halobacteria, consists of obligately anaerobic extremely halophilic euryarchaea that grow by oxidation of H2 or formate with elemental sulfur, DMSO, or thiosulfate (some strains) as the electron acceptor, representing a first example of lithoheterotrophy in the class Halobacteria. Strains have been isolated from sediments of various terrestrial hypersaline chloride-sulfate lakes, marine solar salterns, and deep-sea hypersaline brines in the Mediterranean. The genus consists of one species Halodesulfurarchaeum formicicum, which is the type species of the genus. DNA G+C content (mol%): 63.6–63.8 mol% (genome). Type species: Halodesulfurarchaeum formicicum.@en