title: Isotope Fractionation in Photosynthetic Bacteria during Carbon Dioxide Assimilation.
abstract: The delta (PDB) (13)C values have been determined for the cellular constituents and metabolic intermediates of autotrophically grown Chromatium vinosum. The isotopic composition of the HCO(3) (-) in the medium and the carbon isotopic composition of the bacterial cells change with the growth of the culture. The delta (PDB) (13)C value of the HCO(3) (-) in the media changes from an initial value of -6.6 per thousand to +8.1 per thousand after 10 days of bacterial growth and the delta (PDB) (13)C value of the bacterial cells change from -37.5 per thousand to -29.2 per thousand in the same period. The amount of carbon isotope fractionation during the synthesis of hexoses by the photoassimilation of CO(2) has a range of -15.5 per thousand at time zero to -22.0 per thousand after 10 days. This range of fractionation compares to the range of carbon isotope fractionation for the synthesis of sugars from CO(2) by ribulose 1,5-diphosphate carboxylase and the Calvin cycle.The amount of carbon isotope fractionation during the synthesis of aspartic acid from CO(2) is -24.9 per thousand at time zero and -15.0 per thousand after 10 days of bacterial growth. This amount of fractionation is in the range of carbon isotope fractionation for the synthesis of C(4) amino acids by a double carboxylation through ribulose 1,5-diphosphate and phosphoenolpyruvate carboxylase.
authors: Department of Oceanography, Texas A & M University, College Station, Texas 77843.
authors: W
authors: W
authors: Wong
authors: W M
authors: WM
authors: Sackett