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Low Probability of Initiating nirS Transcription Explains Observed Gas Kinetics and Growth of Bacteria Switching from Aerobic Respiration to Denitrification
Figure 12
Sensitivity analysis (2): Varying initial O2 in the headspace (
(
)) within a high range.
The figure shows the impact of varying 
within a range much higher than 
(the [O2] below which recruitment of the cells to denitrification is assumed to trigger) on: A. O2 concentration in the liquid-phase 
, B. The number of aerobically growing cells (
), which do not possess denitrification enzymes, C. The rate of recruitment of 
to denitrification (
), D. The number of cells as a result of the recruitment alone (
), i.e., the denitrifying cells (
) but without aerobic and NOx-based growth, and E. Cumulated N2. The cumulated N2 reached stable plateaus at nearly the same time for all the runs (Panel E), despite the fact that the time taken to deplete O2 below 
decreased with increasing 
(Panel A). Thus, once denitrification was initiated, the rates increased with increasing initial 
due to an increasing population of oxygen-grown cells (Panels B–D). The fraction of the cells recruited to denitrification (
) declined with increasing initial O2 concentration (not shown), but this was not sufficient to compensate for the increasing number of oxygen-raised cells.
doi: https://doi.org/10.1371/journal.pcbi.1003933.g012