thermotolerant and high acetic acid-producing bacterium Acetobacter sp. I14-2

A thermotolerant bacterium with high production of acetic acid was isolated from spoiled banana in Taiwan. The isolate, I14-2 ,was considered to be an Acetobacter sp. according to phenotypic and chemotaxonomic characteristics. Optimal cultural conditions for Acetobacter sp. I14-2 to produce acetic acid were studied under cultivation in a medium containing 2 mg l-1 acetic acid and 5% ethanol at 30 degrees C. Acetic acid productivity by Acetobacter sp. I14-2 was almost two and three times the amount produced by Acet. aceti IFO3283 and Acetobacter sp. CCRC 12326, respectively. The isolate retained 22% residual acetic acid-producing activity after 3 d incubation in a medium containing 8% ethanol, and produced acetic acid in a medium containing 10 g l-1 acetic acid. This bacterium is thermotolerant and retained 97% and 68% of acetic acid-producing activity after 3 d incubation at 35 degrees C and 37 degrees C, respectively, compared with that when incubated at 30 degrees C.