aerotaxis

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Movement of an organism, especially a bacterium, toward or away from air or oxygen.

from The Century Dictionary.

• noun The movement of cells or organisms in relation to a source or supply of air.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bacteriology) The positive or negative stimulus exerted by oxygen on aërobic and anaërobic bacteria.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biology Movement of an organism either towards or away from a region of higher oxygen content.