mikroaerofiler

Mikroaerofiler are microorganisms that require oxygen at lower-than-atmospheric levels for growth. They proliferate best in environments containing roughly 1 to 10 percent oxygen, with many species preferring about 5 percent. Atmospheric oxygen at about 21 percent is typically inhibitory or lethal to them. In addition to reduced O2, many microaerophiles grow better in the presence of elevated carbon dioxide (often several percent).

Physiology and metabolism: Microaerophiles respire using oxygen but are damaged by higher oxygen concentrations due to the formation of reactive oxygen species. They generally possess antioxidant defenses, though often not as robust as those of strict aerobes, and their enzyme systems are adapted to low-oxygen conditions. Their growth is sensitive to oxygen levels and environmental stress.

Habitat and examples: They occur in diverse habitats, including soils, sediments, aquatic environments, and mucosal surfaces of animals. Clinically important microaerophiles include Campylobacter jejuni and Campylobacter fetus, which cause gastroenteritis, and Helicobacter pylori, a stomach pathogen associated with gastritis and ulcers.

Culturing: In the laboratory, microaerophiles are cultivated under reduced oxygen using devices such as candle jars, gas-pak systems, or specialized incubators that deliver about 5% O2, 10% CO2, and 85% N2. Growth media are often enriched with blood or other nutrients to support their metabolism. They are typically inhibited by standard aerobic incubation.

Significance: Mikroaerofiler are important in clinical microbiology and environmental microbiology due to their roles as pathogens and environmental residents. Their study informs understanding of host–pathogen interactions and the structure of microbial communities that thrive under low-oxygen conditions.