Seshan Hari, Santillan Ezequiel, Constancias Florentin, Chandra Segaran Uma Shankari, Williams Rohan B H, Wuertz Stefan
Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore; Department of Civil and Environmental Engineering, University of California, Davis, CA 95616, USA.
Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, Singapore.
Sci Total Environ. 2023 Dec 10;903:166066. doi: 10.1016/j.scitotenv.2023.166066. Epub 2023 Aug 5.
Biological wastewater treatment systems are often affected by shifts in influent quality, including the input of toxic chemicals. Yet the mechanisms underlying the adaptation of activated sludge process performance are rarely studied in a controlled and replicated experimental setting, particularly when challenged with a sustained toxin input. Three replicate bench-scale bioreactors were subjected to a chemical disturbance in the form of 3-chloroaniline (3-CA) over 132 days, after an acclimation period of 58 days, while three control reactors received no 3-CA input. Ammonia oxidation was initially affected by 3-CA. Within three weeks of the experiment, microbial communities in all three treatment reactors adapted to biologically degrade 3-CA resulting in partial ammonia oxidation recovery. Combining process and microbial community data from amplicon sequencing with potential functions gleaned from assembled metagenomics and metatranscriptomics data, two putative degradation pathways for 3-CA were identified. The first pathway, determined from metagenomics data, involves a benzoate dioxygenase and subsequent meta-cleavage of the aromatic ring. The second, determined from intensive short-term sampling for gene expression data in tandem with 3-CA degradation, involves a phenol monooxygenase followed by ortho-cleavage of the aromatic ring. The relative abundances of amplicon sequence variants associated with the genera Gemmatimonas, OLB8, and Taibaiella correlated significantly with 3-CA degradation. Metagenome-assembled genome data also showed the genus OLB8 to be differentially enriched in treatment reactors, making it a strong candidate as 3-CA degrader. Using replicated reactors, this study has demonstrated the impact of a sustained stress on the activated sludge process. The unique and novel features of this study include the identification of putative pathways and potential degraders of 3-CA using long-term and short-term sampling in tandem with multiple methods in a controlled and replicated experiment.
生物废水处理系统常常受到进水水质变化的影响，包括有毒化学物质的输入。然而，活性污泥工艺性能适应的潜在机制在可控且可重复的实验环境中很少被研究，尤其是在持续毒素输入的挑战下。在58天的适应期后，三个重复的实验室规模生物反应器在132天内受到3-氯苯胺（3-CA）形式的化学干扰，而三个对照反应器未接受3-CA输入。氨氧化最初受到3-CA的影响。在实验的三周内，所有三个处理反应器中的微生物群落适应了生物降解3-CA，导致部分氨氧化恢复。将扩增子测序的过程和微生物群落数据与从组装的宏基因组学和宏转录组学数据中收集的潜在功能相结合，确定了3-CA的两条假定降解途径。第一条途径由宏基因组学数据确定，涉及苯甲酸双加氧酶和随后的芳香环间位裂解。第二条途径由与3-CA降解同步的基因表达数据的密集短期采样确定，涉及苯酚单加氧酶，随后是芳香环邻位裂解。与Gemmatimonas、OLB8和太白菌属相关的扩增子序列变体的相对丰度与3-CA降解显著相关。宏基因组组装基因组数据还显示，OLB8属在处理反应器中差异富集，使其成为3-CA降解菌的有力候选者。本研究使用重复反应器证明了持续应激对活性污泥工艺的影响。本研究的独特新颖之处包括在可控且可重复的实验中，通过长期和短期采样与多种方法相结合，确定了3-CA的假定途径和潜在降解菌。
