产多聚唾液酸的菌种筛选及产酸条件

通过对40株大肠杆菌进行产多聚唾液酸的筛选，得到一株高产多聚唾液酸菌株C-8，对该菌的一系列培养条件进行了研究。最佳培养基为：山梨醇2.5％，硫酸铵0.5％，磷酸氢二钾90mmol／L，胰蛋白陈1.5％，硫酸镁0.04％，pH7．8。在37℃，250r／min摇床培养65h，可使菌体在每毫升培养液中产多聚唾液酸1200μg。

STUDIES ON THE SELECTION OF STRAINS PRODUCING COLOMINIC ACID AND CULTURE CONDITIONS

One strain E. coli C-8, the highest yield of colominic acid, was selected from 40 E. coli strains in the medium in which glucose and ammonium sulfate were the only carbon and nitrogen resources. An optimum medium for the growth and colominic acid production of E. coli C-8 was studied. The optimum carbon resources for colominic acid production was sorbitol selected from 16 kinds of carbons, and its optimum concentration was 2.5%. The optimum inorganic and organic nitrogen resources for colominic acid production were ammonium sulfate (0.5%) and tryptone (1.5%), respectively. The optimum concentration of K2 HPO4 was 90 mmol/L. The optimum culture temperature was 37 degrees C, but no colominic acid was produced below 20 degrees C. The optimum pH range was 7.5-8.2. The strain growth in the optimum medium kept logarithmic phase in 40 h (maxim A = 22). The colominic acid secreted into medium was much lower before 20 h, but high biosynthetic rate of colominic acid was detected after 40 h, the colominic acid reached the highest level (1,200 micrograms/ml) at 65 h.