Final answer:
An obligate anaerobe is a type of bacteria that cannot survive in the presence of oxygen and lacks SOD. They use alternative methods such as anaerobic respiration or fermentation to obtain energy. They lack enzymes that protect cells from oxidative stress caused by oxygen free radicals, making oxygen lethal to them.
Step-by-step explanation:
A bacteria that lacks SOD and is killed by the presence of oxygen is an obligate anaerobe. These bacteria can only survive in environments lacking oxygen and use alternative methods such as anaerobic respiration or fermentation to produce energy. They lack enzymes that protect cells from oxidative stress caused by oxygen free radicals, making oxygen lethal to them. Bacteria that lack superoxide dismutase (SOD) and are susceptible to being killed by the presence of oxygen are typically classified as obligate anaerobes. Superoxide dismutase is an enzyme that plays a crucial role in protecting cells from the toxic effects of reactive oxygen species (ROS), which are produced during the normal metabolism of oxygen.
Obligate anaerobes are organisms that cannot survive in the presence of oxygen because they lack the necessary enzymes to neutralize ROS. Exposure to oxygen can lead to the accumulation of toxic reactive oxygen species, causing damage to cellular components. These bacteria thrive in environments devoid of oxygen or with very low oxygen concentrations. Examples of obligate anaerobic bacteria include some species of Clostridium and Bacteroides.