Table 1 Growth parameters and sulfur isotope effects during the growth of DA on sulfide and nitrate in three replicate experiments.

Substrate consumption ratios, yields, and cell-specific consumption rates highlight the differences in nitrate and sulfide consumption. Calculated 34ε values varied depending on whether the substrate (sulfide) or product (sulfate) was used. Uncertainty was propagated from regression uncertainties (see the Supplementary Materials).

ExperimentGrowth rate
(day−1)
Substrate
consumption ratio
Yield estimates
[mol C (mol NO3)−1]
Cell-specific consumption rates
(fmol cell−1 day−1)
Sulfur
isotope
enrichment
factor*
kσHS:NO3σYsσYcσHSσNO3σ34εσ
10.140.011.420.030.840.060.200.019.80.56.90.3+13.10.7
20.250.021.410.050.840.090.390.039.00.86.40.6
30.240.031.450.030.900.070.360.029.41.16.40.8+12.00.5

*34ε reported in this table is based on Rayleigh enrichment of the substrate pool. See Supplementary Materials and Materials and Methods.