Abstract: The degradation potential of Issatchenkia terricola fermentation to L-malic acid and citric acid was explored. The maximum concentrations of SO2 and alcohol and the minimum pH level that the strain could tolerate were 450 mg/L, 5% and 2, respectively. The medium and fermentation conditions for the degradation of both acids by the strain were optimized based on deacidification rate. When the concentration of the determined optimum nitrogen source tryptone was 0.5 g/100 mL, the deacidification rate reached its maximum level, over 90%. The optimum inoculum size and incubation duration were 1.25 × 106－7.5 × 106 CFU/mL and 60 h, respectively, and the resulting degradation rates of 8－20 g/L L-malic acid and 8－12 g/L critic acid reached over 90%.

Key words: Issatchenkia terricola, degradation, L-malic acid, critic acid