Abstract:

The seed culture medium was optimized to improve the cell density of strain N24. Firstly, Plackett-Burman design was used to investigate the effects of different factors on cell density in the seed culture medium, three statistically significant factors are：peptone, K₄HPO₂ and FeSO₄ •7H₂O, and then a steepest ascent procedure were employed to define optimal response region for these three factors. Finally, Box-Behnken design and RSM were employed to define the optimal level of these three factors. The optimal seed culture medium is：peptone 6.55 g, K₂HPO₄ 0.66 g, FeSO₂₄ •7H2 ₂O 0.024 g, NaC1 0.3g, MgSO ₄•7H₂O 0.6 g, distilled water 1 000 mL, initial pH value 7.2. The bacteria concentration reached 2.4440×10¹⁰ CFU/mL at the telophase of logarithmic phase after optimization, which increased 291% than before. The cell density of strain N24 can be increased by the optimized seed culture medium through Plackett-Burman design combined with response surface analysis, which can be used industrially.

Key words: Aerobic denitrifier, Response surface methodology, Optimization, Seed culture medium