Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, 1 Xikang Road, Nanjing 210098, China; College of Environment, Hohai University, 1 Xikang Road, Nanjing 210098, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
Water Res. 2023 May 1;234:119816. doi: 10.1016/j.watres.2023.119816. Epub 2023 Mar 2.
The massive use of zinc pyrithione (ZPT, as broad-spectrum bactericides) resulted in its high levels in waste activated sludge (WAS) and affected subsequent WAS treatment. This work revealed the effects of ZPT on the volatile fatty acids (VFAs) during WAS anaerobic digestion, in which VFAs yield was enhanced by approximately 6-9 folds (from 353 mg COD/L in control to 2526-3318 mg COD/L with low level of ZPT (20-50 mg/g TSS)). The ZPT occurred in WAS enabled the acceleration of solubilization, hydrolysis and acidification processes while inhibited the methanogenesis. Also, the low ZPT contributed to the enrichment of functional hydrolytic-acidifying microorganisms (e.g., Ottowia and Acinetobacter) but caused the reduction of methanogens (e.g., Methanomassiliicoccus and Methanothrix). Meta-transcriptomic analysis demonstrated that the critical genes relevant to extracellular hydrolysis (i.e. CLPP and ZapA), membrane transport (i.e. gltI, and gltL), substrates metabolisms (i.e. fadj, and acd), and VFAs biosynthesis (i.e. porB and porD) were all upregulated by 25.1-701.3% with low level of ZPT. Specifically, the ZPT stimulus on amino acids metabolism for VFAs transformation was prominent over carbohydrates. Moreover, the functional species enabled to regulate the genes in QS and TCS systems to maintain favorable cell chemotaxis to adapt the ZPT stress. The cationic antimicrobial peptide resistance pathway was upregulated to blunt ZPT with the secretion of more lipopolysaccharide and activate proton pumps to maintain ions homeostasis to antagonize the ZPT toxicity for high microbial activities, the abundance of related genes was up-regulated by 60.5 to 524.5%. This work enlightened environmental behaviors of emerging pollutants on WAS anaerobic digestion process with interrelations of microbial metabolic regulation and adaptive responses.
锌吡硫翁（ZPT，作为广谱杀菌剂）的大量使用导致其在废活性污泥（WAS）中含量较高，并影响随后的 WAS 处理。这项工作揭示了 ZPT 对 WAS 厌氧消化过程中挥发性脂肪酸（VFAs）的影响，其中 VFAs 的产量提高了约 6-9 倍（从对照中的 353mg COD/L 提高到低水平 ZPT（20-50mg/g TSS）下的 2526-3318mg COD/L）。WAS 中的 ZPT 加速了溶解、水解和酸化过程，同时抑制了产甲烷作用。此外，低水平的 ZPT 有助于富集功能水解酸化微生物（例如 Ottowia 和 Acinetobacter），但降低了产甲烷菌（例如 Methanomassiliicoccus 和 Methanothrix）。元转录组分析表明，与细胞外水解（即 CLPP 和 ZapA）、膜转运（即 gltI 和 gltL）、底物代谢（即 fadj 和 acd）和 VFAs 生物合成（即 porB 和 porD）相关的关键基因均被低水平 ZPT 上调了 25.1-701.3%。具体来说，ZPT 对氨基酸代谢的刺激对 VFAs 转化的影响明显大于碳水化合物。此外，功能物种能够调节 QS 和 TCS 系统中的基因，以维持有利的细胞趋化性，适应 ZPT 应激。阳离子抗菌肽抗性途径被上调，以钝化 ZPT，同时分泌更多的脂多糖并激活质子泵以维持离子平衡，以拮抗 ZPT 毒性，从而保持较高的微生物活性，相关基因的丰度上调了 60.5-524.5%。这项工作阐明了新兴污染物对 WAS 厌氧消化过程的环境行为，以及微生物代谢调节和适应反应之间的相互关系。
