Aerobic & Anaerobic Respiration Yeast & Bacteria

What is the yeast and bacteria in anaerobic respiration, and what is it in aerobic respiration?

Yeast are facultatively anaerobic which means that they perform fermentation only under anaerobic conditions. In the presence of O2, the yeast will perform aerobic metabolism.

Bacteria can be either aerobic or anaerobic..
Aerobic bacteria requires oxygen to perform cellular respiration, which is a means to derive energy. In short, aerobic bacteria grows and multiplies only in the presence of oxygen