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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 4
A stock and flow diagram of the model's structure.
The squares represent the state variables, the circles the rate of change in the state variables, the shaded ovals the auxiliary variables, the arrows dependencies between the variables, and the edges represent flows into or out of the state variables. A. The panel represents the structure that governs the O2 kinetics. Briefly, it shows that O2 in the vial's headspace (
) is transported (
) to the liquid-phase (
), where it is consumed (
) by both 
and 
populations with an identical cell-specific velocity of O2 consumption (
). 
represents net marginal changes in 
due to sampling. B. The panel represents the structural basis for population dynamics of the cells without (
) and with (
) denitrification enzymes. Briefly, it shows that both the populations are able to grow by aerobic respiration (
and 
, respectively). The growth rate of 
, however, is primarily based on denitrification (
). Initially, 
= 0 and is populated through recruitment (
) of the cells from 
, where the recruitment is a function of 
and an [O2] dependent specific-probability of the recruitment 
for any 
cell. C. The panel represents the structural basis for the 
/N2 kinetics. Briefly, it illustrates that 
control the consumption rate of 
(
), recovered as N2, in proportion to a cell-specific velocity of 
consumption (
).
doi: https://doi.org/10.1371/journal.pcbi.1003933.g004