Abstract: A genetically stable strain, named EW29, was obtained using Moniliella acetoabutans E54 as the starting strain by microwave- DES mutagenesis followed by screening by high osmotic plate culture and shake flask culture. The stain was further mutagenized by nitrogen ion implantation and then a strain EN59 was screened out of the resulting mutants by shake flask culture. The strain EN59 could produce 55.13 g/L erythritol after 90 h of fermentation, which was increased by 20.3% compared with EW29 and 36.9% compared with E54. The fermentation medium composition for EN59 was optimized to be 250 g/L glucose, 5 g/L yeast extract, 0.3 g/L KH2PO4, 0.04 g/L MnSO4 ·4H2O, 0.03 g/L CuSO4 ·5H2O and pH 4. The concentration of erythritol was over 69.00 g/L after 90 h fermentation under the optimal condition. The final concentration of erythritol reached up to 71.14 g/L after 126 h fermentation in 5 L fermentor.

Key words: complex mutation, N+ implantation, erythritol, Moniliella acetoabutans