Haloferax chudinovii sp. nov., a halophilic archaeon from Permian potassium salt deposits

Abstract

Three pigmented strains of halophilic archaea (RS75, RS77, RS79) were isolated from the monoliths of mottled sylvinite from the Verkhnekamsk salt deposit (Solikamsk, Russia). The cells were nonmotile, gram-negative, pleomorphic, disk-shaped or ovoid, 0.8-1.0 × 1.5-2.5 μm. The organism was a chemoorganotrophic obligate aerobe producing catalase and oxidase. A number of carbohydrates and carboxylic acids were used as growth substrates. Growth occurred in the presence of 7-27% NaCl (with the optimum at 15-18%), 0.02-20% KCl (0.2-1%), 0.2-16% MgCl2 (2-3%), in the temperature range from 23 to 51 °C (40-45 °C), and pH 5.5-8.0 (6.8-7.0). The membranes contained carotenoids of the bacterioruberin series. Phosphatidylglyceromethylphosphate (PGP-Me), phosphatidylglycerol (PG), sulfated diglycosyl diether (S-DGD-1) predominated among the polar lipids. The DNA G + C content was 64.0-65.0 mol %. Phylogenetic analysis of the 16S rRNA gene sequences showed high similarity of the new strains to Haloferax species: H. denitrificans (99.2%) and H. volcanii (99.1%), H. larsenii (96.9%) and H. elongans (96.6%). DNA-DNA hybridization revealed 93-95% similarity between strain RS75 and strains RS77 and RS79; the similarity levels between strain RS75 and the type strains of Haloferax denitrificans VKM B-1754(T) and Halobacterium salinarum VKM B-1769(T) were 50 and 10%, respectively. According to its phenotypic and genotypic characteristics, the organism was classified as a member of the genus Haloferax, forming a new species with the proposed name Haloferax chudinovii sp. nov. type strain is RS75(T) (=VKPM B-11279(T)).

Halophilic Archaea: Life with Desiccation, Radiation and Oligotrophy over Geological Times

“…This critical view has not changed, since contamination issues are being suspected and an age of millions of years for a viable microorganism is difficult to imagine. From the 1990s onward, sequences of small ribosomal RNA (16S rRNA) genes and, increasingly, full taxonomic descriptions of cultivated isolates revealed novel species of Haloarchaea in ancient rock salt [ 1 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. There is now a growing body of evidence that halophilic prokaryotes, many of them Haloarchaea, are able to survive in rock salt, most likely within brine-filled fluid inclusions [ 13 , 16 , 17 , 18 ], for very long periods of time.…”

Occurrence of viable, red-pigmented haloarchaea in the plumage of captive flamingoes

“…Carotenoid-based plumage coloration occurs through a mechanism involving carotenoid transport to blood and uptake by follicle cells in feathers 1 50 51 52 . Analysis of the major carotenoid pigments of haloarchaea 21 22 23 24 25 29 revealed that the isoprenoid-derived carotenoids, bacterioruberin and its precursors, are present in the haloarchaea membrane, giving rise to the characteristic bright pinkish-red color.…”

“…Our previous studies have characterized haloarchaeal diversity using culture-independent 6 7 and culture-dependent 8 9 10 11 12 13 14 15 16 17 18 approaches. These extremophilic microorganisms require an NaCl concentration of at least 1.5 M for proliferation, with optimal growth observed at 3.5–4.5 M 19 20 , and produce red or pink carotenoid pigments, including bacterioruberin 21 22 23 24 25 .…”

Draft Genome Sequence of Haloferax sp. Strain ATB1, Isolated from a Semi-Arid Region in the Brazilian Caatinga

“…In particular, these organisms can grow in locations with salinities ranging from 10% to 37%, pH values between 4 and 12, and temperatures between 0°C and 60°C (1). For instance, H. chudinovii grows at a pH of 6.8, 42°C, and 16% salinity (2). Halophilic species, which are resistant to dehydration, exhibit low levels of cellular macromolecule denaturation and high thermal stability (3).…”