Final answer:
Fermentation is a type of microbial metabolism that uses hydrogen as an electron donor and carbon dioxide as an electron acceptor to produce acetate and/or acetic acid, and CO₂ as fermentation products. This process is carried out by certain microorganisms using the pentose phosphate pathway glycolysis. Fermentation is an important process in microbial metabolism, allowing the conversion of organic and inorganic compounds for energy production and growth.
Step-by-step explanation:
Fermentation is a type of microbial metabolism that uses hydrogen (H₂) as an electron donor and carbon dioxide (CO₂) as an electron acceptor to produce acetate and/or acetic acid, and CO₂ as fermentation products. This process is carried out by certain microorganisms using the pentose phosphate pathway glycolysis. These microbes generate multiple fermentation products, including lactic acid, ethanol and/or acetic acid, and CO₂. Fermenting organisms make ATP through the process of glycolysis.
In some organisms, molecules other than oxygen are used as the final electron acceptor in a process called anaerobic cellular respiration. For example, methanogens, a group of Archaea, use carbon dioxide to oxidize NADH, producing methane. These microbes are found in soil and in the digestive tracts of ruminants. Another example is sulfur bacteria, which use sulfate as a terminal electron acceptor. Fermentation is an important process in microbial metabolism, allowing the conversion of organic and inorganic compounds for energy production and growth.
During lactic acid fermentation, pyruvate accepts electrons from NADH and is reduced to lactic acid. Homolactic fermentation produces only lactic acid as a fermentation product, while heterolactic fermentation produces a mixture of lactic acid, ethanol and/or acetic acid, and CO₂ as fermentation products. Microbes in the normal microbiota typically perform lactic acid fermentation.