The selection of thermotolerant acetic acid bacteria and their applications for acetic acid fermentation

Abstract

Acetic acid is an important organic acid used in many industries, especially in food processing. The objectives of this study were to select the thermotolerant acetic acid bacteria having the high acid producing capacity and to study the fermentation conditions for acetic acid production at high temperature. In this study, nine thermotolerant acetic acid bacterial isolates were selected from 20 strains based on their high acetic acid production ranging from 1.72% to 2.04% (w/v) at 37°C. These strains were dominated by representatives from the Acetobacter genus including A. pasteurianus, A. tropicalis, A. orientalis, and A. sicerae. Strain A18 was determined as the most effectively fermentative bacterial strain at 39°C with the acetic acid production of 2.56% (w/v) and productivity of 62.19%.  The favorable conditions for acetic acid fermentation by the selected target strain Acetobacter sicerae A18 were determined at the pH of 4.0, the ethanol concentration of 4.32% (v/v), and the starter density of 105 cells/ml. The total acid content of 2.61% (w/v) was achieved after 6 days of fermentation at 39°C.