Which metabolic process is primarily used by bacteria to break down glucose anaerobically?

Bacteria primarily utilize fermentation as the metabolic process to break down glucose in the absence of oxygen. During fermentation, glucose undergoes glycolysis to produce a small amount of ATP, and the pyruvate generated is then converted into various byproducts, such as lactic acid or ethanol, depending on the type of bacteria and the specific conditions. This process allows bacteria to regenerate NAD+, which is essential for maintaining glycolysis under anaerobic conditions.

In contrast, cellular respiration requires oxygen as the final electron acceptor, which is not available in anaerobic environments. Oxidative phosphorylation is a key component of aerobic cellular respiration and also relies on oxygen. Glycolysis itself is a universal process that occurs in both aerobic and anaerobic respiration; however, it does not exclusively indicate the method by which anaerobic metabolism continues beyond initial glucose breakdown. Thus, fermentation is specifically responsible for the anaerobic breakdown of glucose in bacteria.