利用分子生物等技术确定活性污泥硝化细菌的衰减特征

通过常规耗氧速率（OUR）测定方法、荧光原位杂交技术（FISH）和LIVE/DEAD细胞活性实验，分别研究了序批式反应器（SBR）硝化系统和生物营养物去除（BNR）系统中硝化细菌的好氧衰减特征.实验结果表明，SBR硝化系统中硝化细菌在衰减过程中由细胞死亡引起的衰减分别占细胞总衰减的33%（SRT=10 d）和50%（SRT=40 d）；相应地，由活性降低引起的衰减分别占细胞总衰减的67%（SRT=10 d）和50%（SRT=40 d）.长SRT可能会选择出能够更好地适应饥饿状态的硝化菌种，使细菌能够迅速地做出紧迫反应，从而降低其衰减速率.在BNR系统中（SRT=15 d），硝化细菌在衰减过程中由细胞死亡引起的衰减约占细胞总衰减的45%，由活性降低引起的衰减约占细胞总衰减的55%.两种系统中硝化细菌由细胞死亡引起的衰减比例不同是由于两种系统中不同微生物组成所致.

Determining the decay characteristics of nitrifying bacteria in activated sludge using molecular biological techniques

The aerobic decay characteristics of nitrifying bacteria in a nitrifying sequencing batch reactor (SBR) and a biological nutrient removal (BNR) system were investigated by measuring maximal oxygen uptake rates (OURs), analyzing 16S rRNA with fluorescence in-situ hybridization (FISH) and observing membrane integrity by LIVE/DEAD staining. The experimental results reveal that in the nitrifying SBR system, cell death was responsible for 33% of cell decay at SRT=10 d and for 50% at SRT = 40 d. In other words, the activity decay contributed 67% and 50% of the total cell decay at SRT=10 and 40 d respectively. A longer SRT should select for nitrifying bacteria better adapted to starvation conditions, and thus the selected nitrifying bacteria could quickly produce a stringent response. As a result, a reduced decay rate of the selected nitrifying bacteria is expected. In the BNR system (SRT=15 d), the cell death was responsible for 45% of the total cell decay for nitrifying bacteria, and thus the activity decay accounted for 55% of the total cell decay. The different fractions of cell death of nitrifying bacteria in the two systems could be caused by different microbial compositions in the SBR and BNR systems.