Growth of thermophilic obligately autotrophic hydrogen-oxidizing bacteria on thiosulfate

Thermophilic obligately autotrophic H2‐oxidizing bacteria from Icelandic hot springs were tested for growth on thiosulfate. Ten strains were tested and all grew on thiosulfate but not on sulfite or sulfur. The product of thiosulfate oxidation was sulfate. The growth rate on thiosulfate was slower (μ=0.12 h‐1) than on H2 (μ=0.34 h‐1). Washed cells which had been grown on thiosulfate could oxidize thiosulfate rapidly but H2‐grown cells oxidized thiosulfate much more slowly and with about a 3 h lag time. The bacteria would not grow on agar medium under H2 but grew on agar medium containing thiosulfate.