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

Categorization of Microbes via Optimum Oxygen Concentrations

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.

Different organisms require various levels of oxygen for their metabolic processes, including some who are found in completely anaerobic ecosystems where no molecular oxygen is present. 

Environmental Oxygen Requirements for Microbial Growth

https://openstax.org/details/books/microbiology/

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.

OpenStax Microbiology Textbook

Thioglycolate Tube Cultures

Reactive oxidative species are molecules that contain oxygen that has been partially reduced, typically as a byproduct of aerobic respiration, and therefore contains a highly unstable oxygen ion. ROS are very damaging to structures they come in contact with. Some examples of ROS are peroxides, hydroxyl radical, and hypochlorite ion (household bleach).

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