Abstract: The quality of chicken and eggs are significantly improved by adding Sphingomonas Sp in drinking water of poultry. However, the cell density under traditional fermentation is low, which cannot meet the needs of poultry farming. To improve the cell density of Sphingomonas Sp, firstly, the growth curve was measured. Then the medium and culture conditions were optimized by single factor experiment and orthogonal experiment. The optimum medium and culture conditions was determined: sucrose 20.0 g/L, yeast extract 25 g/L, NaCl 10.0 g/L, KH₂PO₄ 2.0 g/L, pH was 6.0, inoculation amount was 3%, temperature was 30℃. Based on the results, the number of colonies reached 51.7×10⁹ CFU/mL through high density culture of microencapsulation after four generations of continuous cultivation, which was increased by 3.64 times as compared to that normal culture by optimized medium, and 29.4 times as compared to that that of normal culture by basic medium. Therefore, in this experiment, not only the culture medium and culture conditions were optimized, but also the cell density was greatly improved through high density culture of microencapsulation.

Key words: Sphingomonas sp., Microencapsulation, High density culture