PNNL

Abstract

A halophilic bacterial strain, HL-109T, was isolated from the unicyanobacterial consortium UCC-O, which was obtained from the photosynthetic mat of Hot Lake (Washington, USA). A polyphasic approach using phenotypic, genotypic, and chemotaxonomic data was used to classify the strain within the order “Rhizobiales”. The organism stains Gram negative and is a moderate thermophile with an optimum of 45 °C. It is an obligate aerobe, heterotrophic, and a halophile that grows in both NaCl and MgSO4 brines. The novel isolate has a polymorphic cellular morphology of short rods with occasional branching and cells were monotrichous. The major fatty acids detected were C18:1, C18:0, C16:0, and C18:cyc. Phylogenetic analysis of the 16S rRNA gene placed the strain in the order “Rhizobiales” and it shares 94% identity to its nearest relative, Salinarimonas ramus. Morphological, chemotaxonomic, and phylogenetic results did not affiliate the novel organism with any of the families in the “Rhizobiales”; therefore, HL-109T is representative of a new lineage, which we propose to be Salinivirga fredricksonii gen. nov, sp. nov., Salinivirgaceae fam. nov., with the type strain of Salinivirga fredricksonii gen. nov. sp. nov. as HL-109T (JCM TBDT and DSMZ TBDT). In addition, examination of the phylogenetics of the strain HL-109T and its nearest relatives, Salinarimonas ramus and S. rosea, demonstrate that these halophiles form a clade distinct from the families of the “Rhizobiales”. We thus recommend transferring the genus Salinarimonas to join the novel family Salinivirgaceae.