ABSTRACT

Sulfur isotope compositions (δ³⁴S) were analysed on elemental sulfur and cellular protein in sulfur-oxidizing bacterial mats and on hydrogen sulfide and sulfate in the associated geothermal waters which were collected from nine locations in central and northeastern Japan. The δ³⁴S values of elemental sulfur and cellular protein in the mats were comparable to those of hydrogen sulfide, but far from the associated sulfate in the waters, indicating the positive use of dissolved hydrogen sulfide. There could be observed slightly negative (rod-shaped bacteria) and positive (sickle-formed bacteria) sulfur isotope fractionations (up to 2‰) during the bacterial use of hydrogen sulfide.