Anaerobic fermentation of Acetic Acid
Anaerobic fermentation of Acetic Acid
Species of anaerobic bacteria, including members of the genus Clostridium, can convert sugars to acetic acid directly, without using ethanol as an intermediate. The overall chemical reaction conducted by these bacteria may be represented as:
C6H12O6 → 3 CH3COOH
It is interesting to note that, from the point of view of an industrial chemist, these acetogenic bacteria can produce acetic acidfrom one-carbon compounds, including methanol, carbon monoxide, or a mixture of carbon dioxide and hydrogen:
2 CO2 + 4 H2 → CH3COOH + 2 H2O
This ability of Clostridium to utilize sugars directly, or to produce acetic acid from less costly inputs, means that these bacteria could potentially produce acetic acid more efficiently than ethanol-oxidizers like Acetobacter. However, Clostridium bacteria are less acid-tolerant than Acetobacter. Even the most acid-tolerant Clostridium strains can produce vinegar of only a few per cent acetic acid, compared to Acetobacter strains that can produce vinegar of up to 20% acetic acid. At present, it remains more cost-effective to produce vinegar-using Acetobacter than to produce it using Clostridium and then concentrate it. As a result, although acetogenic bacteria have been known since 1940, their industrial use remains confined to a few niche applications.
C6H12O6 → 3 CH3COOH
It is interesting to note that, from the point of view of an industrial chemist, these acetogenic bacteria can produce acetic acidfrom one-carbon compounds, including methanol, carbon monoxide, or a mixture of carbon dioxide and hydrogen:
2 CO2 + 4 H2 → CH3COOH + 2 H2O
This ability of Clostridium to utilize sugars directly, or to produce acetic acid from less costly inputs, means that these bacteria could potentially produce acetic acid more efficiently than ethanol-oxidizers like Acetobacter. However, Clostridium bacteria are less acid-tolerant than Acetobacter. Even the most acid-tolerant Clostridium strains can produce vinegar of only a few per cent acetic acid, compared to Acetobacter strains that can produce vinegar of up to 20% acetic acid. At present, it remains more cost-effective to produce vinegar-using Acetobacter than to produce it using Clostridium and then concentrate it. As a result, although acetogenic bacteria have been known since 1940, their industrial use remains confined to a few niche applications.