Fractionation of Stable Carbon Isotopes during Chemoautotrophic Growth of Sulfur-Oxidizing Bacteria

Laboratory-grown strains of chemoautotrophic Thiomicrospira sp. strain L-12 and Thiobacillus neapolitanus produced cell carbon that was 24.6 to 25.1 ppt (24.6 to 25.1 mg/g) lower in ¹³C isotope abundance than the ambient source of carbon dioxide and bicarbonate. This degree of ¹³C isotope depletion was comparable to that found in organic material produced in deep-sea hydrothermal-vent communities.