Thermocrinis ruber gen. nov., sp. nov., A pink-filament-forming hyperthermophilic bacterium isolated from yellowstone national park

Abstract

A novel hyperthermophilic bacterium was isolated from pink filamentous streamers (pink filaments) occurring in the upper outflow channel (temperature, 82 to 88 degreesC) of Octopus Spring in Yellowstone National Park, Wyo. The gram-negative cells grew at low salinity at temperatures up to 89 degreesC in the neutral to alkaline pH range. Depending on the culture conditions, the organisms occurred as single motile rods, as aggregates, or as long filaments that formed streamer-like cell masses. The novel isolate grew chemolithoautotrophically with hydrogen, thiosulfate, and elemental sulfur as electron donors and oxygen as the electron acceptor. Alternatively, under aerobic conditions, formate and formamide served as sole energy and carbon sources. The novel isolate had a 16S rRNA sequence closely related to the 16S rRNA sequence obtained from uncultivated pink filaments. It represents a new genus in the order Aquificales, the type species of which we name Thermocrinis ruber (type strain, OC 1/4 [= DSM 12173]).

FIG. 1

Glass chamber used for Thermocrinis ruber growth studies. The chamber (160 by 20 by 20 mm) consisted of single glass plates connected by silicone rubber and a detachable glass lid. Cotton at the culture medium overflow was used for cell attachment.

FIG. 2

Scanning electron micrograph of Thermocrinis ruber rod-shaped cells grown on a silicon-coated cover glass. The flakes in the background are silicon. Bar, 2 μm.

FIG. 3

Scanning electron micrograph of long filaments of Thermocrinis ruber from the pink streamer network formed at the overflow of the glass chamber (Fig. 1). Bar, 2 μm. The granular material in the lower part of the image is precipitates containing sulfate, as determined by energy-dispersive X-ray analysis.

FIG. 4

Transmission electron micrograph of a single flagellated cell of Thermocrinis ruber that was air dried and platinum shadowed (from two directions). Bar, 1 μm.

FIG. 5

(a) Ultrathin section of a freeze-substituted cell of Thermocrinis ruber. Bar, 0.5 μm. (b) Enlarged view of the cell envelope of Thermocrinis ruber, CM, cytoplasmic membrane; PS, periplasmic space; OM, outer membrane. Bar, 0.2 μm.

FIG. 6

Effect of temperature on the growth of Thermocrinis ruber. Doubling times were calculated from the slopes of the growth curves (data not shown).

FIG. 7

Phylogenetic tree determined by neighbor-joining analysis of 16S rRNA sequences. The scale bar represents 0.10 fixed mutations per nucleotide position.