Obligate aerobes require abundant levels of environmental oxygen levels to grow. Therefore they can be observed growing at the top of Thioglycolate tubes where oxygen levels are the highest. 

Obligate Aerobes

Obligate anaerobes cannot grow in the presence of oxygen, which is why they grow densest at the bottom of the Thioglycolate tube. In nature, they can be found in places like deep in the ocean or in anaerobic environments inside of our bodies. 

Obligate Anaerobes

Facultative anaerobes thrive in aerobic environments with abundant oxygen, but have the means to conduct anaerobic respiration or fermentation so that they can grow it absence of oxygen as well. 

Facultative Anaerobes

Aerotolerant anaerobes utilize anaerobic respiration or fermentation, but are indifferent to the presence of oxygen.

Aerotolerant Anaerobes

Microaerophiles thrive in areas of oxygen concentrations below the typical 21% in the Earth's atmosphere. They grow best in ranges closer to 1%-10% oxygen concentration.

Microaerophiles

Capnophiles thrive in environments of high CO<sub>2</sub> concentrations and oxygen concentrations lower than atmospheric.

Capnophiles

- Obligate Aerobes 
- Obligate Anaerobes
- Facultative Anaerobes
- Aerotolerant Anaerobes
- Microaerophiles

Thioglycolate tube cultures allow labs to distinguish the oxygen requirements for microorganisms. the oxygen begins diffusing at the top of the test tube, but because the Thioglycolate medium in the tube has strong reducing properties not many oxygen molecules reach the bottom. The microbes will grow densest in the areas of optimum oxygen concentration.

Thioglycolate Tube Cultures

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Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

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