Final answer:
Obligate anaerobes and microaerophiles would be harmed by high concentrations of oxygen; obligate anaerobes due to the absence of detoxifying enzymes, and microaerophiles due to their requirement for low levels of oxygen.
Step-by-step explanation:
Among the microbes classified as aerotolerant anaerobes, facultative anaerobes, microaerophiles, obligate aerobes, and obligate anaerobes, the ones that would be harmed by a high concentration of oxygen are the obligate anaerobes and the microaerophiles. Obligate anaerobes are harmed by oxygen because they lack the enzymes for detoxifying reactive oxygen species generated in aerobic environments. Microaerophiles, on the other hand, require a specific low level of oxygen (1%-10%) for growth and can also be adversely affected by high oxygen levels because they possess limited capacity for dealing with the toxic by-products of oxygen metabolism.
Examples of obligate anaerobes include Bacteroidetes in the human gut and Clostridium spp., while examples of microaerophiles include Campylobacter jejuni, which causes gastrointestinal infections. Aerotolerant anaerobes like lactobacilli and streptococci would not be harmed as they do not use oxygen but tolerate its presence.