Abstract: In order to improve the biomass of Arthrobacter ureafaciens DnL1-1, the fermentation medium of the strain DnL1-1 was optimized by single factor screening and orthogonal experiment. The results showed that the best formula should be: glucose 15.0 g/L,peptone 7.5 g/L,yeast extract 0.50 g/L,K₂HPO₄ 2.0 g/L,KH₂PO₄ 1.0 g/L,CaCl₂ 0.15 g/L,MgSO₄ 0.15 g/L.Thus the strain can produce about 2.89×10¹⁰ cells in 1 mL of the culture medium under the condition of 1% inoculum, with shaking of 180 r /min at 28 ℃ for 36 hours.

Key words: Arthrobacter ureafaciens, atrazine, fermentation medium, orthogonal design