The R&D Centre for Sustainable Environmental Biotechnology, Beijing University of Civil Engineering and Architecture, PR of China.
Biotechnol Bioeng. 2010 Jun 15;106(3):399-407. doi: 10.1002/bit.22703.
Decrease in bacterial activity (biomass decay) in activated sludge can result from cell death (reduction in the amount of active bacteria) and activity decay (reduction in the specific activity of active bacteria). The goal of this study was to experimentally differentiate between cell death and activity decay as the cause of decrease in bacterial activity. By means of measuring maximal anaerobic phosphate release rates, verifying membrane integrity by live/dead staining and verifying presence of 16S rRNA with fluorescence in situ hybridization (FISH), the decay rates and death rates of polyphosphate-accumulating organisms (PAOs) in a biological nutrient removal (BNR) system and a laboratory phosphate removing sequencing batch reactor (SBR) system were determined, respectively, under famine conditions. In addition, the decay rate and death rate of glycogen-accumulating organisms (GAOs) in a SBR system with an enrichment culture of GAOs were also measured under famine conditions. Hereto the maximal anaerobic volatile fatty acid uptake rates, live/dead staining, and FISH were used. The experiments revealed that in the BNR and enriched PAO-SBR systems, activity decay contributed 58% and 80% to the decreased activities of PAOs, and that cell death was responsible for 42% and 20% of decreases in their respective activities. In the enriched GAOs system, activity decay constituted a proportion of 74% of the decreased activity of GAOs, and cell death only accounted for 26% of the decrease of their activity.
活性污泥中细菌活性（生物量衰减）的降低可能是由于细胞死亡（活性细菌数量减少）和活性衰减（活性细菌比活性降低）造成的。本研究的目的是通过实验区分细胞死亡和活性衰减是导致细菌活性降低的原因。通过测量最大厌氧磷酸盐释放速率、使用活/死染色验证膜完整性以及使用荧光原位杂交（FISH）验证 16S rRNA 的存在，分别确定了在贫营养条件下生物除磷（BNR）系统和实验室除磷序批式反应器（SBR）系统中聚磷酸盐积累菌（PAOs）的衰减率和死亡率。此外，还在富积 GAOs 的 SBR 系统中测量了贫营养条件下糖原积累菌（GAOs）的衰减率和死亡率。为此，使用了最大厌氧挥发性脂肪酸摄取速率、活/死染色和 FISH。实验表明，在 BNR 和富积 PAO-SBR 系统中，活性衰减分别对 PAOs 活性降低的贡献为 58%和 80%，而细胞死亡分别对其活性降低的贡献为 42%和 20%。在富积 GAOs 系统中，活性衰减构成了 GAOs 活性降低的 74%，而细胞死亡仅占其活性降低的 26%。
