Facultative:  Growth has occurred essentially throughout the entire tube.  Although there is a small zone at the bottom where no growth occurs, this is probably due to incomplete mixing of the original inoculum into the medium.

Obligate aerobe:  Growth is restricted to the surface and, at most, a small depth into the medium (indicated with the bracket).

Anaerobe: An obligate anaerobe leaves a distinct zone below the surface (bracketed) of the medium where no growth occurs.  Although the depth of the zone will differ among species depending upon how inhibitory oxygen is to their growth, typically the zone is only a few millimeters deep.

Note: There are gas pockets in two of these tubes, produced by the release of gases during bacterial fermentation.  It is best to not allow the media to culture too long, since these gas pockets can become so large as to make interpretation of the results difficult.

Question: What pattern would you expect for a microaerophile?