Louis pasteur demonstrated that fermentation to produce alcohol is caused by

facultative anaerobes

Explanation:

Facultative anaerobes -

It is an organism, which is capable to prepare ATP via aerobic respiration, in the presence of oxygen, and can start the process of fermentation in the absence of oxygen, is the facultative anaerobes.

In the famous work by Louis pasteur, he was capable to ferment alcohol in the presence of facultative anaerobes.

Hence, from the given statement of the question,

The correct term is facultative anaerobes.