Haloarcula quadrata sp. nov., a square, motile archaeon isolated from a brine pool in Sinai (Egypt)

Summary auto-generated

This study describes the taxonomic characterization of strain 801030/1T, a motile, square-shaped archaeon isolated from a brine pool in Egypt's Sinai peninsula. The organism was initially identified as belonging to the genus Haloarcula based on its polar lipid composition, 16S rRNA gene sequences, and growth characteristics. However, phylogenetic analysis of the two distinct 16S rRNA genes present in the strain and low DNA-DNA hybridization values with recognized Haloarcula species indicated it was sufficiently distinct to warrant designation as a new species. The strain exhibits a predominantly square, pleomorphic cell morphology (2-3 μm diameter), flagellar motility, and red-orange pigmentation. It requires high salt concentrations (2.7-4.3 M NaCl) and magnesium (50-100 mM) for optimal growth, with temperature optimum at 50-53°C. The organism is chemo-organotrophic, utilizing glucose, sucrose, and maltose as sole carbon sources. The authors propose the new species Haloarcula quadrata, with strain 801030/1T (DSM 11927T) as the type strain. This discovery contributes to understanding the diversity of halophilic archaea in hypersaline environments.

Key findings

Strain 801030/1T is a motile, square-shaped halophilic archaeon requiring high salt (2.7-4.3 M NaCl) and magnesium (50-100 mM) concentrations for growth and cell shape maintenance
Phylogenetic analysis of two distinct 16S rRNA genes and DNA-DNA hybridization studies showing only low relatedness (maximum 34%) with other Haloarcula species support designation as a new species
The organism possesses characteristic Haloarcula polar lipids including phosphatidylglycerol, phosphatidylglycerophosphate, phosphatidylglycerosulfate, and the glycolipid TGD-2, with DNA G+C content of 60.1 mol%
Haloarcula quadrata sp. nov. is proposed with strain 801030/1T as the type strain, isolated from a brine pool in the Sinai peninsula, Egypt

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Abstract

The motile, predominantly square-shaped, red archaeon strain 801030/1^T, isolated from a brine pool in the Sinai peninsula (Egypt), was characterized taxonomically. On the basis of its polar lipid composition, the nucleotide sequences of its two 16S rRNA genes, the DNA G+C content (60·1 mol%) and in growth characteristics, the isolate could be assigned to the genus Haloarcula. However, phylogenetic analysis of the two 16S rRNA genes detected in this organism and low DNA-DNA hybridization values with related Haloarcula species showed that strain 801030/1^T is sufficiently different from the recognized Haloarcula species to warrant its designation as a new species. A new species, Haloarcula quadrata, is therefore proposed, with strain 801030/1^T (= DSM 11927^T) as the type strain.