Fig 5.

Variations in ³⁴ε and cell-specific sulfate reduction rate (csSRR) in DMSS-1 cultures limited by iron or ammonium (this study) or various electron donors (62, 63). Iron deficiency reduced csSRR and led to increasing fractionation factors. A similar relationship between csSRR and ³⁴ε is observed when the csSRR rates in DMSS-1 are changed by changing the concentration of a single electron donor or changing the type of organic electron donor (62, 63). In contrast, nitrogen limitation increased both csSRR and ³⁴ε.