一株氨氧化链霉菌的分类鉴定及其氨氧化特性的研究

从硝化反应器中分离获得一株链霉菌。根据其形态特征、培养特征、生理生化特性，（G+C）mol％含量以及16S rDNA序列和DNA杂交结果，将其归入链霉菌属中的比基尼链霉菌（Streptomycesbikiniensis）。该菌株既能在YD培养基上异养生长，也能在无机培养基上自养生长，异养生长速率(Vmax为0.39mg/L\5d)明显高于自养生长速率（Vmax为0.22mg/L.d）。异养生长时，氨氮主要用于合成细胞物质；自养生长时，部分氨氮用于合成细胞物质，部分氨氮转化成亚硝酸盐。在无机培养基上自养生长时，最适氨浓度为118mgN/L。最适生长pH值为9.36，最适氨氧化pH值为9.29。最适生长温度为31℃，最适氨氧化温度为40.6℃。提高溶解氧浓度有利于该菌株生长和氨氧化，菌体生长对溶解氧浓度的敏感性高于氨氧化。

Identification of ammonia oxidation Streptomyces strain A2 and study of its autotrophic ammonium oxidation characteristics

Streptomyces strain A2 was isolated from a nitrification reactor. According to the characteristics of morphology, cultivation, physiology, (G + C)mol% content, 16S rDNA sequence and DNA-DNA hybridization. it was identified as Streptomyces bikiniensis. Strain A2 could heterotrophically grow on YD medium and could also autotrophically grow on inorganic medium. The heterotrophical growth rate (0.39mg/L.d) was higher than the autotrophical growth rate (0.22mg/L.d). During heterotrophical growth ammonia was mainly assimilated. During autotrophical growth, however, one part of ammonia was assimilated and other part of ammonia was converted into nitrite. When grown on the inorganic medium, the maximum ammonium oxidation rate reached at ammonium concentration of 118mgN/L. The optimal pH for growth and ammonia oxidation was 9.36 and 9.29, respectively. The optimal temperature for growth and ammonia oxidation was 31 degrees C and 40.6 degrees C, respectively. A high concentration of dissolved oxygen was good for growth and ammonia oxidation, and growth was more sensitive to dissolved oxygen change than to ammonia oxidation.