PNNL

Abstract

An obligately thermophilic, chemolithotrophic, microaerophilic bacterium, designated strain GBS1T, was isolated from the water column of Great Boiling Spring, Nevada, USA. Thiosulfate was required for growth. Although capable of autotrophy, growth of GBS1T was enhanced in the presence of acetate, peptone, or Casamino acids. Growth occurred at 70-85 °C with an optimum at 80 °C, at pH 6.5-7.75 with an optimum at pH 7.25, at 0.5-8% oxygen with an optimum at 1-2%, and at =200 mM sodium chloride. The doubling time under optimal growth conditions was 1.3 hrs, with a final cell density of 6.2±0.5 x 107 cells/mL. Non-motile, rod-shaped cells 1.4-2.4 x 0.4-0.6 µm occurred singly or in pairs. Major cellular fatty acids (>5% of total) were C20:1?9c (44.8%), C18:0 (26.0%), C16:0 (9.9%) and C20:0 (5.4%). Phylogenetic analysis of the GBS1T 16S rRNA gene sequence indicated an affiliation with Thermocrinis ruber and other Thermocrinis spp., but comparisons of 16S rRNA gene identity (=97.10%) and in silico estimated DNA-DNA hybridization values (=18.4%) with Thermocrinis spp. indicate that his strain is distinct from described species. Based on phenotypic, genotypic, and phylogenetic characteristics, the name Thermocrinis jamiesonii sp. nov. is proposed, with GBS1T (= JCM 19133T = DSM 27162T) as the type strain.