THE VIRTUAL EDGE: Lab 6 Cultivation of Bacteria II

Oxygen Concentration:


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
Cell: 307-760-2942

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