Abstract: Gluconacetobacter sp. A4 (G. sp. A4), which has strong ability to produce D-saccharic acid 1, 4 lactone (DSL), is the key functional bacteria isolated from the kombucha preserved. This studay investigated the effect of temperature, pH, folic acid,xylitol and fermentation time on the growth of A4 and DSL production. The results showed that the optimum conditions are as follows: black tea 0.5% (W/V), glucose 5% (W/V), and xylitol 1.5% (W/V); the inoculation quantity 10% (V/V); pH maintaining at 4.0 and fermenting at 30 ℃ for 8 d. At the end of fermentation, the rate of glucose consumption is 82%, and DSL concentration reaches 4.69 mg/ml.

Key words: kombucha, Gluconacetobacter sp. A4, D-saccharic acid 1,4 lactone, gas chromatography