There are a total of 5 reversible oxygen-containing reactions (13.16% of all oxygen-containing reactions): MOX, EX_o2_e, O2Stex, O2tpp, O2tex

The directionality of oxygen-producing/-consuming reactions affects the model's ability to grow anaerobically i.e. create faux-anaerobic organisms. This test reports how many of these oxygen-containing reactions are reversible. This test does not have any mandatory 'pass' criteria. Implementation: First, find the metabolite representing atmospheric oxygen in the model on the basis of an internal mapping table or by specifically looking for the formula "O2". Then, find all reactions that produce or consume oxygen and report those that are reversible.