阿奇霉素和铜对活性污泥古菌群落和ARGs的胁迫影响及后效应

抗生素和重金属复合污染已成为环境领域的研究热点,而关于复合污染对活性污泥系统的生态效应研究聚焦于细菌群落,忽略了仍然发挥重要作用的古菌群落.通过选择阿奇霉素(azithromycin,AZM)和金属铜(Cu)为研究对象,ρ(铜)维持在环境浓度水平(1 mg·L-1),探究低温下不同ρ(AZM)(0.05～40 mg·L-1)对古菌群落、抗生素抗性基因(antibiotic resistance genes,ARGs)及其交互作用的短期影响及其后效应.结果表明,随着AZM浓度增加,古菌多样性上升,丰富度下降,且在后效应期间有一定恢复;基于微生物全尺度分类发现不同浓度的AZM导致了微生物群落结构的改变,古菌群落结构分为3个组别,而后效应影响不明显;复合污染对丰富类群种群结构的影响大于稀有类群,其中条件稀有菌属(conditionally rare taxa,CRT)与整个古菌群落结构的变化一致;不同类型微生物中均存在抗性与恢复特性不同的特定菌属,对AZM和铜复合污染的响应不同,且丰富类群对复合污染的抗性明显高于稀有类群,其中甲烷鬃菌属(Methanosaeta)、甲烷杆菌属(Methanaohacterium)和甲烷八叠球菌属(Methanosarcina)是优势的抗性菌属;通过预测分析共得到29种ARGs,且复合污染会引起ARGs的增殖,尤其是高浓度下,但是其对各ARGs亚型的影响存在差异;在胁迫效应和后效应的交互网络中,微生物间、ARGs间及两者之间多为共现模式,其中,条件丰富菌属(conditionally abundant taxa,CAT)是微生物交互网络中的关键菌属;而稀有菌属(rare taxa,RT)在胁迫效应中处于重要生态位;ARGs间的共现与互斥模式均存在;多种古菌属与ARGs呈现正相关,是其潜在古菌宿主,且甲烷短芽孢杆菌(Methanobrevibacter)和甲烷叶菌属(Methanaolobius)可能携带多种ARGs.综上,本研究可为污水处理系统抗生素与重金属复合污染的风险评价及ARGs的削减提供新的思路与理论依据.

Stress and Post Effects of Azithromycin and Copper on Archaeal Community and ARGs in Activated Sludge

The combined pollution of antibiotics and heavy metals has become a research hotspot in the field of environmental research. However, studies on the ecological effects of the combined pollution on activated sludge systems have mainly focused on the bacterial community, ignoring the archaeal community, which plays several important roles. In this study, azithromycin (AZM) and copper (Cu) were selected to investigate the short-term and post-effect of different concentrations of AZM (0.05-40 mg·L^-1) on an archaeal community, antibiotic resistance genes (ARGs), and their interactions at low temperatures when copper was maintained at 1 mg·L^-1. The results showed that the diversity of archaea increased with the increase in AZM concentration; however, the richness decreased, and both recovered to a certain extent during the post-effect period. It was found that different concentrations of AZM led to variations in microbial community structure based on the full-scale classification method. The archaeal community structure was divided into three groups, and the post-effect influence was not obvious. The effects of combined pollution on the structure of the abundant taxa were greater than that of the rare taxa. Moreover, the variation in the conditionally rare taxa (CRT) was consistent with that of the whole archaeal community. There were specific genera with different resistance and recovery characteristics in different taxa, which had different responses to the combined pollution of AZM and copper. The resistance of abundant taxa to combined pollution was significantly stronger than that of the rare taxa, of which Methanosaeta, Methanobacterium, and Methanosarcina were the dominant resistant archaeal genera. A total of 29 ARGs were obtained using prediction analysis, and AZM caused the proliferation of ARGs, especially at high concentrations; however, the effects on each subtype of ARGs were different. The co-occurrence patterns were mainly observed among the archaeal community and ARGs during the stress-effect and post-effect periods. Among them, CAT was the core taxa in the microbial interaction network. However, rare taxa (RT) represented an important ecological niche during the stress-effect period. Meanwhile, both co-occurrence and co-exclusion patterns existed among ARGs. A variety of archaeal genera were positively correlated with ARGs, and they were the potential hosts of ARGs. In particular, Methanobrevibacter and Methanolobus may carry a variety of ARGs. Overall, this study could provide new insight and theoretical basis for the risk assessment of the combined pollution of antibiotics and heavy metals in wastewater treatment systems and the removal of ARGs.