what is facultative fermentation
A facultative anaerobe is, simply speaking, an organism which possesses the ability to survive in an environment containing oxygen while growing even more efficiently in an environment without oxygen. Facultative anaerobes can optionally function without oxygen by two main mechanisms; fermentation and alternate terminal electron acceptors. In fermentation, glycolysis is performed and pyruvate is converted to a fermentation product, reducing NAD+ back to NADH. (Note that there are likely many variations on this).