Abstract:Objective This study aims to breed an elite strain of acetic acid bacteria with ethanol tolerance and suitable for malt vinegar brewing, thereby improving the utilization of raw materials, the yield of acetic acid, and the quality of the final vinegar product.Method The fermentation capacity of Acetobacter tropicalis J-22, Gluconacetobacter saccharivorans J-15, and Acetobacter pasteurianus HN 1.01 in beer with different volume fractions (6%~10%) of ethanol was compared. Based on the acetic acid yield (acetic acid mass concentration), ethanol conversion rate, and sensory evaluation, Acetobacter tropicalis J-22 , which achieved the highest overall assessment, was identified as the original strain. Acetobacter tropicalis J-2276 was finally bred through atmospheric and room temperature plasma (ARTP) mutagenesis combined with high-throughput screening (HTS). The growth curves and malt vinegar fermentation performance of the mutant strain Acetobacter tropicalis J-2276 and the original strain Acetobacter tropicalis J-22 under different volume fractions of ethanol further verified the ethanol tolerance and fermentation capacity of the mutant strain.Result The mutant strain Acetobacter tropicalis J-2276 exhibited significantly improved growth under ethanol stress at various volume fractions and tolerated the ethanol volume fraction up to 11%. Compared with the original strain Acetobacter tropicalis J-22, the mutant strain Acetobacter tropicalis J-2276 increased the acetic acid mass concentration of malt vinegar by 65.0%. Furthermore, the mutant strain Acetobacter tropicalis J-2276 with higher ethanol tolerance produced richer flavor compounds, with the mass concentrations of total organic acids and total volatile compounds increasing by 45.3% compared with the original strain Acetobacter tropicalis J-22.Conclusion This study demonstrates the successful breeding of an ethanol-tolerant strain, Acetobacter tropicalis J-2276, by ARTP mutagenesis and HTS. The strain exhibits stable genetic traits after seven successive generations, effectively increases the acid yield in malt vinegar fermentation, and improves the flavor quality of malt vinegar products, demonstrating broad application prospects.
