Final answer:
Bacteria use three enzymes to process oxygen or free radicals: superoxide dismutase, peroxidase, and catalase, each of which helps to detoxify harmful reactive oxygen species to protect the cell.
Step-by-step explanation:
The three enzymes that bacteria use to process oxygen or free radicals are superoxide dismutase, peroxidase, and catalase. Each of these enzymes plays a crucial role in detoxifying reactive oxygen species (ROS), which are harmful byproducts of aerobic respiration or can form from atmospheric oxygen. Superoxide dismutase converts superoxide radicals into less damaging molecules, like hydrogen peroxide. Then, peroxidase and catalase further process hydrogen peroxide into water and oxygen, safeguarding the bacterial cells from oxidative stress.
This detoxification is vital for many bacteria, including facultative anaerobes which thrive in both aerobic and anaerobic environments, and microaerophiles which require oxygen at lower concentrations. These enzymes are also important in the context of fermentation and anaerobic respiration, where the presence or absence of oxygen influences the pathway used for ATP production in bacteria. In addition, specific bacteria such as thermophilic bacteria produce thermostable versions of these enzymes, suitable for industrial processes at high temperatures. Understanding these enzymes is also critical for medical applications, as certain bacteria have inherent tolerance against oxidative stress, affecting the efficacy of treatments like hydrogen peroxide.