Low Probability of Initiating nirS Transcription Explains Observed Gas Kinetics and Growth of Bacteria Switching from Aerobic Respiration to Denitrification
Figure 7
Simulations of the treatments with ∼0 vol.% using
= 0.0052 h−1.
The figure compares the measured and simulated O2 depletion (mol vial−1) and N2 accumulation (molN vial−1) for the ∼0 vol.% O2 treatments of Bergaust et al. [4], [8], i.e., the vials with near-zero O2 in the headspace () at the time of inoculation. Separate plots are shown for each initial concentration of
(0.2, 1, and 2 mM). The measured initial O2 was somewhat erratic due to episodes of needle clogging and/or high O2 leakage during sampling, so the initial
used in the simulations is chosen somewhat ad lib so that the simulated O2 depletion coincides with that measured. The discrepancy compared to the measured O2 seems to be significant for 2 mM
treatment. That is most likely due to the inhibitory effect of nitrite on aerobic respiration, which is not taken into account; all simulations are run with an identical
. Near exhaustion, the simulated O2 increases slightly at each sampling time; that is due to the leakage of O2 via the injection system exceeding dilution of the headspace (with He) during each sampling.