Abstract: By utraviolet radiation treatment,two superior erythritol-producing strains were screened out from twenty-eitht strains isolated from honey,wastewater from sugar factory and decayed fruits in Changchun suburbs,and the protoplasts of the two strains were used to construct high erythritol-producing strain by means pf elecrofusion.The results showed that the optimal conditions for preparing the protoplasts are as follows:snailase amount 0.25%,treatment time 20min,temperature 35℃,and pH 5 to 6.The optiaml electrofusion parameters are as follows:alternating electric field intensity 250V/cm,impulse intensity 6 kV/cm,impulse time 30 s,and impulse number 5.The erythritol productivity of the construted strain is 120.6 g/L,and the consumed glucose is 53.2%.

Key words: erythritol, electrofusion