Oxygen Concentration:

Procedure

Bacteria vary considerably in their requirements for oxygen.  Molecular oxygen (O₂) is usually thought to be necessary for life.  This is not always the case, however, since many microorganisms thrive in the absence of O₂ and some microorganisms are actually inhibited or killed by toxic derivatives of this gas.  According to their O₂ requirement, bacteria are classified as:

• aerobes:  organisms that require atmospheric O₂ for growth.
• anaerobes:  organism that are killed or inhibited by the presence of atmospheric O₂.
• facultative anaerobes:  organisms that do not require O₂ for growth, but do grow better when it is present.
• microaerophiles:  organisms that require low concentrations of O₂, generally between 2 and 10%.
• aerotolerant anaerobes:  anaerobic organisms that can survive in the presence of O₂, but do not use it in their metabolism.

Rachel Watson, M.S.
AG 5010
766-3524
Cell: 307-760-2942
rwatson@uwyo.edu