TMPD and DMPD can be used to test if an organism possesses an enzyme that reduces this compound, which helps identify if non-lactose-fermenting gram negative rods are pseudomonas. Requirements for this molecule can be approximated by growing an organism in thioglycolate broth. A lack of access to this molecule may have led to the evolution of the hydrogenosome. (15[1])Organisms that (*) tolerate this molecule detoxify its reactive byproducts using SOD and catalase, (10[1])thus avoiding a namesake form of stress. Organisms which do not metabolize this molecule either use alternative electron acceptors for respiration or fermentation (10[1])to generate ATP. For 10 points, obligate anaerobes cannot tolerate atmospheric concentrations of what gaseous molecule? ■END■