Isolation and Characterization of a Thermotolerant Acetic Acid Bacteria Strain for Improved Zhenjiang Aromatic Vinegar Production

This study aimed to isolate a thermotolerant acetic acid bacteria (AAB) strain from Zhenjiang aromatic vinegar (ZAV) and evaluate its potential as a starter culture for high-temperature solid-state vinegar fermentation. <i>Acetobacter pasteurianus</i> TCBRC 103 was successfully isolated and demonstrated superior thermotolerance compared to the industrial strain <i>A. pasteurianus</i> Huniang 1.01. <i>A. pasteurianus</i> TCBRC 103 exhibited robust growth and acetic acid production at 42 °C. When employed in the solid-state fermentation of ZAV, inoculation with <i>A. pasteurianus</i> TCBRC 103 resulted in higher fermentation temperatures, leading to enhanced accumulation of organic acids and volatile compounds. Notably, the concentrations of flavor compounds such as isoamyl acetate, acetic acid 2-phenylethyl ester, and acetoin were significantly higher in vinegar fermented by <i>A. pasteurianus</i> TCBRC 103 compared to those fermented by <i>A. pasteurianus</i> Huniang 1.01. Orthogonal partial least squares-discriminant analysis (OPLS-DA) identified 14 discriminative flavor compounds that could serve as potential markers for distinguishing between vinegars fermented by <i>A. pasteurianus</i> TCBRC 103 and <i>A. pasteurianus</i> Huniang 1.01. These findings highlight the promising application of <i>A. pasteurianus</i> TCBRC 103 as a starter culture for the production of high-quality ZAV under high-temperature conditions, with implications for reducing cooling costs and improving vinegar productivity in industry.