How can facultative anaerobes exist without catalase?

Question

>Catalase-negative bacteria may be anaerobes, or they may be **facultative anaerobes** that only ferment and do not respire using oxygen as a terminal electron acceptor<br />A facultative anaerobe is an organism that makes ATP by aerobic respiration if **oxygen is present**, but is capable of switching to fermentation or anaerobic respiration if oxygen is absentBut if facultative anaerobes can be present in oxygen rich environments, don't they have to have catalase in order not to die?

Answer 1

In general organisms without catalase get away with it using a few methods.

They can retune the pathways in which electrons flow during the electron transport chain to minimize the amount of peroxides formed. This is done by either more carefully regulating the use of oxygen (by holding it still or just having a lower internal concentration of oxygen) or changing the electron receptors so that the oxidative differences are lower

They may have a different enzyme that does a similar job at removing peroxides, but not nearly as efficiently as catalase

Finally, they could just deal with the damage resulting from low levels of peroxides being formed. There's a large difference quantities when you compare what is made during respiration, and the challenges bacteria undergo during the catalase test.

If you have more questions let me know and we can schedule time to discuss this further.