A High-temperature, Hydrogen-oxidizing Bacterium—Hydrogenomonas thermophilus, n.sp.

Abstract

WE have succeeded in isolating in pure culture from petroliferous soil a thermophilic bacterium which utilizes hydrogen. The isolation was accomplished by streaking material from a soil enrichment culture on to Repaske's mineral salts medium prepared by mixing equal volumes of a sterile 4 per cent agar solution in water and a sterile, double-strength solution of mineral salts containing ammonium chloride, MgSO₄·7H₂O, CaCl₂·2H₂O, potassium dihydrogen phosphate, sodium monohydrogen phosphate, and several trace elements. On cooling to about 50° C, 1 ml. of a solution of ferrous ammonium sulphate was added, the plates poured, allowed to solidify and immediately streaked. The plates were incubated in an atmosphere containing 70 per cent hydrogen, 20 per cent oxygen, and 10 per cent carbon dioxide at 50° C. By picking the minute, flat, smooth, translucent colonies into liquid mineral salts medium and incubating in the 70–20–10 gas mixture, a pure culture was obtained.