Enzymes Responsible for Acetate Oxidation by Acetic Acid Bacteria

Area of Science:

• Microbiology
• Biochemistry

Background:

• Acetic acid bacteria, including Acetobacter species, can oxidize acetate.
• Excessive acetate oxidation is undesirable in vinegar manufacturing.
• Acetobacter rancens SKU 1111 is identified as a strong acetate oxidant.

Purpose of the Study:

• To investigate the acetate oxidation capabilities of Acetobacter rancens SKU 1111.
• To understand the effect of glycerol on acetate oxidation and biomass production in A. rancens.
• To elucidate the enzymatic mechanisms underlying acetate metabolism and glycerol catabolism.

Main Methods:

• Culturing Acetobacter rancens SKU 1111 and Acetobacter aceti IFO 3284.
• Monitoring growth curves and acetate consumption.
• Analyzing enzyme activities (acetyl-CoA synthetase, phosphotransacetylase, phosphoenolpyruvate carboxylase) under different conditions.
• Investigating the effect of glycerol addition.

Main Results:

• Acetobacter rancens SKU 1111 exhibited biphasic growth and consumed acetate in the second phase.
• Glycerol addition enhanced acetate oxidation and biomass yield in A. rancens.
• High activities of acetyl-CoA synthetase and phosphotransacetylase were observed during acetate oxidation.
• Phosphoenolpyruvate carboxylase activity was stimulated by acetyl-CoA, showing sigmoidal kinetics.

Conclusions:

• Acetobacter rancens SKU 1111 efficiently uses acetate for biomass, particularly when glycerol is present.
• The combined activities of acetate-metabolizing enzymes and phosphoenolpyruvate carboxylase contribute to increased biomass production.
• Understanding these metabolic pathways is crucial for controlling acetate oxidation in industrial applications like vinegar production.