<!-- Source: https://docs.biosimulant.com/examples/ecology-pfeiffer-atp-cooperation -->

# Ecology: ATP Pathway Cooperation

A microbial metabolic competition model. **Two populations chase ATP via different strategies — high-yield oxidative phosphorylation versus low-yield but fast substrate-level phosphorylation** — and the run reveals which strategy dominates as the shared substrate is drawn down.

## What it simulates

- A shared substrate resource and two populations with different ATP-production strategies.
- High-yield strategy (N1): more ATP per substrate, slower growth.
- Low-yield strategy (N2): faster growth, wastes substrate.
- The classic cooperation–competition tradeoff in microbial ecology.
- Dynamics solved by Tellurium directly from the original SBML file.

![Pfeiffer2001 resource, population, and strategy-fraction results](/images/examples/ecology-pfeiffer-atp-cooperation/pfeiffer2001-canvas-results.png)

## Run it on the Hub

1. Open the [Pfeiffer2001 ATP-Pathway Cooperation-Competition Model Lab](https://hub.biosimulant.com/labs/179ec6e0-8eb3-4803-b7bb-640374e4912f) on the public Hub.
2. Click **Run**. The default scenario runs for 75 time units.

## Inputs you can tune

| Input | Meaning |
|---|---|
| `integration_step` | ODE solver step size. Smaller is more precise but slower. |
| `model_path` | Relative path to the SBML file. Usually leave at the default. |

Biological parameters (rate constants, initial concentrations, stoichiometry) live in the SBML file `model/data/BIOMD0000000337.xml` — edit it directly to change the chemistry.

## What results to expect

- **Trajectories**: substrate (S), high-yield population (N1), and low-yield population (N2) over time. In the default run, N1 collapses as N2 expands.
- **Strategy fractions**: low-yield rises to 1.0 while high-yield falls to 0.0; resource-per-biomass ratio is also tracked.
- **Summary table**: final and extremal values for substrate, populations, and strategy fractions.

![Pfeiffer2001 strategy fractions and summary table](/images/examples/ecology-pfeiffer-atp-cooperation/pfeiffer2001-strategy-summary.png)

## Reference

SBML wrapper for Pfeiffer et al. (2001), [BioModels BIOMD0000000337](https://www.ebi.ac.uk/biomodels/BIOMD0000000337).

**Info:**

  Source on GitHub: [models-ecology — pfeiffer2001-atp-pathway-cooperation](https://github.com/Biosimulant/models-ecology/tree/main/labs/ecology-pfeiffer2001-atp-pathway-cooperation).