Okabe S, Naitoh H, Satoh H, Watanabe Y
Department of Urban and Environmental Engineering, Graduate School of Engineering, Hokkaido University, Sapporo, Japan.
Water Sci Technol. 2002;46(1-2):233-41.
The phylogenetic diversity of a nitrifying bacterial community of two types of nitrifying biofilms, a domestic wastewater biofilm and an autotrophic nitrifying biofilm grown on rotating disk reactors (RDR), was characterized by 16S ribosomal DNA (rDNA)-cloning analysis. Thereafter, successional development of nitrifying the bacterial community within both biofilms was visualized in situ by fluorescent in situ hybridization (FISH) wih a set of fluorescently labeled 16S rRNA-targeted DNA probes. In situ hybridization revealed that Nitrosomonas ureae was the numerically dominant species of the ammonia-oxidizing population in the domestic wastewater biofilm and that a population shift from N. urea to N. europaea and N. eutropha occurred when the culture medium was switched to the synthetic media from the domestic wastewater. After reaching the steady-state condition, microprofiles of NH4+, NO2-, NO3-, and O2 in the biofilms were measured by use of microsensors, and the spatial distributions of in situ nitrifying activities were determined. The relationship between the spatial organization of nitrifying bacterial populations and the in situ activity of these populations within the biofilms was discussed. Microelectrode measurements revealed that the active ammonia-oxidizing zone was vertically separated from the active nitrite-oxidizing zone. This vertical separation became more evident with increase of the substrate C/N ratio, leading to deterioration of nitrification efficiency. The combined use of these techniques made it possible to relate in situ nitrifying activity directly to the occurrence of nitrifying bacterial populations.
通过16S核糖体DNA（rDNA）克隆分析，对两种硝化生物膜（生活污水生物膜和在转盘反应器（RDR）上生长的自养硝化生物膜）中硝化细菌群落的系统发育多样性进行了表征。此后，利用一组荧光标记的靶向16S rRNA的DNA探针，通过荧光原位杂交（FISH）对两种生物膜中硝化细菌群落的演替发展进行了原位观察。原位杂交显示，脲硝化螺菌是生活污水生物膜中氨氧化菌群数量上占优势的物种，当培养基从生活污水切换到合成培养基时，发生了从脲硝化螺菌到欧洲亚硝化单胞菌和嗜中温亚硝化单胞菌的种群转变。达到稳态条件后，使用微传感器测量生物膜中NH4+、NO2-、NO3-和O2的微剖面，并确定原位硝化活性的空间分布。讨论了硝化细菌种群的空间组织与这些种群在生物膜中的原位活性之间的关系。微电极测量显示，活性氨氧化区与活性亚硝酸盐氧化区在垂直方向上是分开的。随着底物碳氮比的增加，这种垂直分离变得更加明显，导致硝化效率降低。这些技术的联合使用使得将原位硝化活性与硝化细菌种群的出现直接联系起来成为可能。
