S. Skirnisdottir et al., A new ecological adaptation to high sulfide by a Hydrogenobacter sp growing on sulfur compounds but not on hydrogen, MICROBI RES, 156(1), 2001, pp. 41-47
Thermophilic bacteria were isolated from a sulfide-rich, neutral hot spring
in Iceland on gelrite minimal medium with 16 mM thiosulfate. The isolates
were aerobic, obligate chemolithoautotrophs and used thiosulfate and sulfur
as electron donors, producing sulfate from both substrates. No growth was
observed with hydrogen as the sole electron donor, and no hydrogenase activ
ity was detected. The cells were gram-negative and usually single, 4-5 mum
long and 0.7 mum in diameter and formed sulfur globules after a few days of
incubation. By SSU rRNA sequence comparisons, the bacterium was placed in
the genus Hydrogenobacter with the closest relative to be Calderobacterium
hydrogenophilum with 98.3% sequence similarity. This novel bacterium shows
an ecological adaptation to high sulfide springs and is differentiated from
its closest known relatives by lack of H-2 oxidation, deposition of sulfur
and lower growth temperature.