亚硝化单胞菌（Nitrosomonas sp．）THD-1分离鉴定及高密度培养

从浙江舟山桃花岛近海海域分离筛选到一株高活性氨氧化细菌，命名为THD-1。菌株THD-1为革兰氏阴性，球状至椭球状，大小约为（0．5～0．8）μm×（0．7～1．3）μm；菌落呈无色透明状，针尖大小，边缘光滑；可在盐度为0～50％0的培养基中生长。16SrDNA序列比对表明，菌株THD—1与Nitrosomonas europaea ATCC25978^T的相似性为96．3％。培养液的pH值对菌体生长和氨氧化活性影响明显，当pH值降至6．0以下时，菌株的生长和氨氧化活性几乎完全被抑制，但这种抑制可通过回调pH值的方法解除；在所试的4种碱液中，碳酸氢铵调节pH值对菌体生长和氨活性改善效果最好。建立了菌株THD-1的分批补料式高密度培养方法，最终OD600可达0．214，最大活菌数可达7．5×10^8cells／mL。

Isolating and high-density culturing of Nitrosomonas sp. THD-1

A strain of ammonia-oxidizing bacteria, THD-1, was isolated from the coastal surface sediment of Taohua Island in Zhoushan. Its cell is spherical or short rod with a size of 0. 5 - 0. 8 μm×0. 7 - 1.3 μm, gram-negative, and the colony is colorless and transparent, needle size with a smooth edge. The similarity between the 16S rDNA sequence of the srain THD-1 and that of Nitro- somonas europaea ATCC25978^T is 96. 3%. The pH of culture solution significantly affects cell growth and ammonia oxidation of strain THD-1. Ammonia bicarbonate could improve the growth and ammonia oxidation activity when used for pH controlling. High-density culture for strains THD-1 was obtained by fed-batch adding of ammonia bicarbonate, with a maximum of 0. 214 OD600 and 7.5 × 10^8 cells/mL.