Optimization of culture conditions for levansucrases by Bacillus methylotrophicus SK 21.002

The culture medium and culture conditions of Bacillus methylotrophicus SK 21.002 producing levansucrases were investigated.By single-factor experiment and orthogonal test, the optimal culture medium was determined as follows:sucrose 80g/L, yeast extract 10g/L, tryptone 10g/L, K₂HPO₄ 8g/L, MgSO₄ 1g/L, NaCl 2g/L, while the optimal culture conditions were initial pH6.5, fermentation temperature 30℃, medium volume 30%, inoculation ratio 2%, fermentation time 21h.Under these conditions, the yield of levansucrases reached 9.76U/mL, which was 3.75 times higher than it before optimization.