These strains of bacteria have the capacity to transform sugars to acetic acid directly without creating ethanol as an intermediate (Jia et al., 2007).
The overall chemical reaction conducted by these bacteria may be represented as: C6H12O6 → 3CH3COOH. According to Jia et al., 2007 these acetogenic bacteria synthesize acetic acid from single-carbon mixtures, including methanol, carbon monoxide, or a blend of carbon dioxide and hydrogen: 2 CO2 + 4 H2 → CH3COOH + 2 H2O. It is also described in the figure below. Figure 2: Schematic outline of Vinegar Production (Wood, 1998)
The capacity of Clostridium to directly degrade complex sugars into simpler ones to produce energy, or to synthesize acetic acid from less costly inputs, suggests that these bacteria could produce acetic acid more efficiently than ethanol-oxidizers like Acetobacter (Jia et al., 2007). Despite this fact, Clostridium bacteria are more susceptible to acid than Acetobacter (Jia et al., 2007). Even the most acid-tolerant Clostridium strains can produce vinegar in concentrations of only a few per cent, compared to Acetobacter strains that can produce vinegar in concentrations up to 20%. At present, it remains more cost-effective to produce vinegar using Acetobacter, rather than using Clostridium and concentrating it. As a result, although acetogenic bacteria have been known since 1940, their industrial use is confined to a few niche applications (Jia et al., 2007).
Though the production of acetic acid is