Researchers from the Department of Biotechnology at Khon Kaen University studied acetic acid production using Acetobacter pasteurianus. They tested different temperatures and aeration conditions and found that a temperature of 30°C with 2 vvm aeration and 20% dissolved oxygen in a 2-L fermenter resulted in the highest acetic acid productivity of 20.7 g/L, while temperature most affected productivity and not final concentration. Aeration allowed for better productivity but with substrate loss.

1. M. Boonmee , S. Intarapanich, O. Cotano Department of Biotechnology Faculty of Technology, Khon Kaen University

2. Cane sugar sugar Chemicals Ethanol Ethyl acetate Acetic acid

3. Strain selection (TISTR) Batch fermentation Fed-batch fermentation Initial ethanol concentration Productivity (flask) Aeration study pH study

4. 46.0 44.3 42.6 19 ± 2 °C 23 ± 2 °C 26 ± 2 °C 38 h 40 h Acetic acid production at room temperature (flask shaking at 200 rpm)

5. Effect of controlled temperature (acetic acid concentration) 44.6 44.4 46.0 44.3 42.6 44.9

6. Effect of controlled temperature (acetic acid yield) 1.02 0.97 0.94 0.97 0.93 0.92

7. Effect of controlled temperature (acetic acid productivity) 0.59 0.86 0.57 0.70 0.35 0.87

8. Acetic acid production in 2–L fermenter (2 vvm, pO 2 20% , 30°C) 19.7

9. Acetic acid production in 2–L fermenter (2 vvm, pO 2 20% , 30°C) 18.8

10. Acetic acid production in 2–L fermenter (2 vvm, pO 2 20% , 30°C) 20.7

14. M. Boonmee , S. Intarapanich, O. Cotano Department of Biotechnology Faculty of Technology, Khon Kaen University