School of Ecology, Sun Yat-sen University, Guangzhou, PR China.
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, PR China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology (Sun Yat-sen University), Guangzhou, PR China.
Water Res. 2022 Sep 1;223:118995. doi: 10.1016/j.watres.2022.118995. Epub 2022 Aug 18.
The fate and removal of ciprofloxacin, a class of fluoroquinolone antibiotic, during sulfur-mediated biological wastewater treatment has been recently well documented. However, little is known regarding the genetic response of microorganisms to ciprofloxacin. Here, a lab-scale anaerobic sulfate-reducing bioreactor was continuously operated over a long term for ciprofloxacin-contaminated wastewater treatment to investigate the response of the microorganisms to ciprofloxacin by adopting a metagenomics approach. It was found that total organic carbon (TOC) removal and sulfate reduction were promoted by approximately 10% under ciprofloxacin stress, along with the enrichment of functional genera (e.g., Desulfobacter, Geobacter) involved in carbon and sulfur metabolism. The metagenomic analytical results demonstrated that ciprofloxacin triggered the microbial SOS response, as demonstrated by the up-regulation of the multidrug efflux pump genes (8-125-fold higher than that of the control) and ciprofloxacin-degrading genes (4-33-fold higher than that of the control). Moreover, the contents of ATP, NADH, and cytochrome C, as well as related functional genes (including genes involved in energy generation, electron transport, carbon metabolism, and sulfur metabolism) were markedly increased under ciprofloxacin stress. This demonstrated that the carbon and sulfur metabolisms were enhanced for energy (ATP) generation and electron transport in response to ciprofloxacin-induced stress. Interestingly, the microbes tended to cooperate while being subjected exposure to exogenous ciprofloxacin according to the reconstructed metabolic network using the NetSeed model. Particularly, the species with higher complementarity indices played more pivotal roles in strengthening microbial metabolism and the SOS response under long-term ciprofloxacin stress. This study characterized the response mechanisms of microorganisms to ciprofloxacin at the genetic level in sulfur-mediated biological wastewater treatment. These new understandings will contribute the scientific basis for improving and optimizing the sulfur-mediated bioprocess for antibiotics-laden wastewater treatment.
近年来，有关硫介导的生物废水处理过程中，环丙沙星（一种氟喹诺酮类抗生素）的命运和去除已得到充分证实。然而，对于微生物对环丙沙星的遗传响应，人们知之甚少。在这里，采用宏基因组学方法，通过实验室规模的厌氧硫酸盐还原生物反应器连续长期处理含环丙沙星的废水，研究了微生物对环丙沙星的响应。结果发现，在环丙沙星胁迫下，TOC 去除率和硫酸盐还原率分别提高了约 10%，同时富含参与碳和硫代谢的功能属（如脱硫杆菌属、地杆菌属）。宏基因组分析结果表明，环丙沙星触发了微生物 SOS 反应，多药外排泵基因（比对照高 8-125 倍）和环丙沙星降解基因（比对照高 4-33 倍）上调。此外，ATP、NADH 和细胞色素 C 的含量以及相关功能基因（包括与能量产生、电子传递、碳代谢和硫代谢相关的基因）在环丙沙星胁迫下显著增加。这表明，为了应对环丙沙星诱导的应激，微生物通过增强碳和硫代谢来产生能量（ATP）和电子传递。有趣的是，根据 NetSeed 模型构建的代谢网络，当微生物受到外源性环丙沙星的暴露时，它们倾向于合作。特别是，互补指数较高的物种在长期环丙沙星胁迫下，在强化微生物代谢和 SOS 反应方面发挥了更关键的作用。本研究从遗传水平上阐明了硫介导的生物废水处理中微生物对环丙沙星的响应机制。这些新的认识将为改进和优化含抗生素废水的硫介导生物过程提供科学依据。
