What characterizes microbes that cannot deal with toxic oxygen?

Microbes that cannot deal with toxic oxygen are characterized by their lack of protective enzymes, which are essential for neutralizing harmful byproducts created when oxygen is utilized in cellular processes. In aerobic environments, reactive oxygen species (ROS) such as superoxide radicals and hydrogen peroxide can accumulate, and microbes that lack enzymes like superoxide dismutase and catalase cannot effectively detoxify these ROS. Consequently, these microbes are unable to survive or thrive in the presence of oxygen, which can be detrimental to their cellular integrity.

In contrast, organisms thriving in oxygen-rich environments possess mechanisms to cope with the toxic effects of oxygen. Those that utilize oxygen for energy are able to metabolize it, usually having the necessary protective strategies in place. Faculatative anaerobes are capable of switching between aerobic respiration and anaerobic processes, thus they can handle oxygen when it is available, further highlighting the distinction between those that can and cannot manage toxic oxygen.