How to create Environmental Conditions
You can access
the "Environmental Conditions" option under the "Simulation" menu.
In the Environmental Conditions you can select the model/project to work, and set up your conditions.
In the reactions list you can search the for reactions present in the model, select and change their flux limits (lower bound / upper bound) and consequently add the new constraints to the reaction constraints list. The reactions in this list are typically extra-cellular/ drains fluxes, i.e. they can be used to define the way rates in which external metabolites are consumed or produced.
After you finish you will find a new icon representing the Environmental Conditions in the clipboard.
http://sites.google.com/site/optfluxhowtos/howtos/environmental-conditions/EnvironmentalConditionsSolution.png