The acetyl group in acetic acid is the basis of all life in biochemistry. When combined with Coenzyme A, it becomes the center of carbohydrate and fat metabolism. However, the concentration of acetic acid in the cells is strictly controlled to a very low range, avoiding damaging changes in the pH of the cytoplasm. Unlike other long chain carboxylic acids, acetic acid is not present in triglycerides. However, artificial acetic acid-containing triglycerides, also known as glycerol acetate (triacetin), are important food additives and are also used in the manufacture of cosmetics and topical drugs.
Acetic acid is produced or secreted by some specific bacteria. Of note is the bacterium Acetobacter clostridium, which is widely found in food, water and soil worldwide. Acetate is naturally produced when fruit or other food is spoiled. Acetic acid is also an integral part of the vaginal lubricating fluid of all primates, including humans, and is considered a mild antibacterial agent.