Why does a microaerophilic organism grow only in the middle depth region of a Fluid Thioglycollate Medium tube

A microaerophilic organism grows only in the middle depth area of a Fluid Thioglycollate Medium tube because the mid area of the tube has moderate levels of oxygen and significantly higher amounts of carbon dioxide.

Explanation:

A microaerophile organism is one that cannot survive or thrive in a region with normal levels of atmospheric oxygen. It prefers environments with a lower concentration of oxygen and higher amounts of carbon dioxide.

Fluid Thioglycollate Medium tube is used during experiments to determine which organisms are aerobes (that is can thrive well in and require oxygen to survive), from those which are anaerobes (cannot tolerate oxygen and may die in its presence) and microaerophilic organisms.

At the bottom of the Fluid Thioglycollate Medium tube, there is zero oxygen whilst at the top, there is lots of oxygen. Towards the midsection, there is less oxygen and more carbon dioxide. The Thioglycollate mixture contains the following:

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