Mannitolfermentering

Mannitolfermentering refers to a metabolic process where certain microorganisms convert mannitol, a sugar alcohol, into acidic byproducts. This fermentation is a characteristic trait of many bacteria, particularly staphylococci, and is often used as a key diagnostic test in microbiology. Mannitol itself is a six-carbon sugar alcohol found in various plants and is also produced commercially. The ability of a microbe to ferment mannitol is determined by the presence of specific enzymes that break down the sugar alcohol. When mannitol is fermented, it typically yields lactic acid, and sometimes other organic acids like acetic acid and ethanol, depending on the organism and conditions. This process causes a decrease in pH, which can be detected using indicator dyes in culture media. For instance, mannitol salt agar is a common medium that contains mannitol, salt, and a pH indicator. Bacteria that can ferment mannitol will produce acid, turning the indicator red to yellow. This test is invaluable for differentiating between different bacterial species, such as *Staphylococcus aureus*, which is typically mannitol-positive, and *Staphylococcus epidermidis*, which is usually mannitol-negative. The detection of mannitol fermentation aids in the identification and classification of bacteria, playing a crucial role in clinical diagnostics and food safety.