H aloferax

Abstract

Ha.lo.fe'rax. Gr. n. hals, halos salt; L. neut. adj. ferax fertile; N.L. neut. n. Haloferax salt (requiring) and fertile. Euryarchaeota / Halobacteria / Haloferacales / Haloferacaceae / Haloferax The genus Haloferax is classified within the family Haloferacaceae and the order Haloferacales , in the class Halobacteria . The cells are extremely pleomorphic (most commonly flattened disks or cups) and stain Gram‐negative. Nonmotile or motile; motility often difficult to observe. Colonies are red to red‐orange, red‐pink, or beige‐orange pigmented and may have a mucoid appearance. They are neutrophilic (optimal growth at pH 6.5–8.0) and extremely halophilic Archaea, growing in media containing 1.0–5.1 M NaCl. The polar lipids are characterized by the presence of C 20 C 20 glycerol diether derivatives of phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP‐Me), sulfated diglycosyl diether (S‐DGD‐1), and DGD‐1 and the absence of phosphatidylglycerol sulfate (PGS). The DNA G + C content is between 59.1 and 65.5 mol%. Currently, the genus includes 13 species: Haloferax volcanii (type species of the genus), Haloferax alexandrinus , Haloferax chudinovii , Haloferax denitrificans , Haloferax elongans , Haloferax gibbonsii , Haloferax larsenii , Haloferax lucentense, Haloferax mediterranei, Haloferax mucosum, Haloferax namakaokahaiae, Haloferax prahovense , and Haloferax sulfurifontis . The strains of these species were isolated from salt lakes, salterns, and other saline habitats. DNA G + C content (mol % ) : 59.1–65.5. The DNA may contain major and minor components. Type species : Haloferax volcanii Torreblanca et al. 1986, VL22 (Basonym: Halobacterium volcanii Mullakhanbhai and Larsen 1975).

Lipidomic chemotaxonomy aligned with phylogeny of Halobacteria

“…asiatica and has a low amount in Hf. mediterranei, which are extreme salt-adapted strains (Merino et al, 2019) that have the highest optimum NaCl concentrations (3.4 M and 4.0 M, respectively) among the 7 strains (Figure 3C) (Hezayen et al, 2001;Ventosa et al, 2009). Accordingly, we inferred that strains thriving under such extreme salt conditions may not favor the production of bacterioruberin.…”

“…The annotation results referred to 107 unique lipids, encompassing the majority of lipids previously reported in Halobacteria. These included unsaturated and extended diether core structures; IPLs of PG, Me-PGP, DGD and S-DGD; cardiolipins of both BPG and glycocardiolipins; non-bilayer forming lipids of MK and bacterioruberin (Kamekura and Kates, 1999;Ventosa et al, 1999;Hezayen et al, 2001;Sprott et al, 2003;Xu et al, 2007;Tapingkae et al, 2008;Minegishi and Kamekura, 2009;Ventosa et al, 2009;Elling et al, 2016).…”

Effects of chaotropic salts on global proteome stability in halophilic archaea: Implications for life signatures on Mars

“…Interestingly, H. salinarum proteome was destabilized by chaotropic salts, MgCl 2 as well as (per)chlorate salts. By comparison, H. sodomense and H. volcanii optimally grow at lower NaCl concentrations (McGenity & Grant, 2015; Ventosa et al, 2015) and showed proteomes that are the least destabilized and even distinctively stabilized in some occasions by chaotropic salts. Moreover, H. mediterranei has the largest NaCl concentration range compatible with growth and tolerates both high and low NaCl concentrations (Oren, 2017; Oren & Hallsworth, 2014) and showed a proteome with intermediary behaviour in our measurements.…”