High Levels of Antibiotic Resistance Genes and Their Correlations with Bacterial Community and Mobile Genetic Elements in Pharmaceutical Wastewater Treatment Bioreactors

To understand the diversity and abundance of antibiotic resistance genes (ARGs) in pharmaceutical wastewater treatment bioreactors, the ARGs in sludge from two full-scale pharmaceutical wastewater treatment plants (PWWTPs) were investigated and compared with sludge samples from three sewage treatment plants (STPs) using metagenomic approach. The results showed that the ARG abundances in PWWTP sludge ranged from 54.7 to 585.0 ppm, which were higher than those in STP sludge (27.2 to 86.4 ppm). Moreover, the diversity of ARGs in PWWTP aerobic sludge (153 subtypes) was higher than that in STP aerobic sludge (118 subtypes). In addition, it was found that the profiles of ARGs in PWWTP aerobic sludge were similar to those in STP aerobic sludge but different from those in PWWTP anaerobic sludge, suggesting that dissolve oxygen (DO) could be one of the important factors affecting the profiles of ARGs. In PWWTP aerobic sludge, aminoglycoside, sulfonamide and multidrug resistance genes were frequently detected. While, tetracycline, macrolide-lincosamide-streptogramin and polypeptide resistance genes were abundantly present in PWWTP anaerobic sludge. Furthermore, we investigated the microbial community and the correlation between microbial community and ARGs in PWWTP sludge. And, significant correlations between ARG types and seven bacterial genera were found. In addition, the mobile genetic elements (MGEs) were also examined and correlations between the ARGs and MGEs in PWWTP sludge were observed. Collectively, our results suggested that the microbial community and MGEs, which could be affected by DO, might be the main factors shaping the profiles of ARGs in PWWTP sludge.

为阐明制药废水处理生物反应器内抗生素抗性基因（antibiotic resistance genes, ARGs）的多样性与丰度特征，本研究采用宏基因组方法，对两座全规模制药废水处理厂（pharmaceutical wastewater treatment plants, PWWTPs）污泥中的ARGs进行了检测，并与三座污水处理厂（sewage treatment plants, STPs）的污泥样本开展对比分析。研究结果显示，制药废水处理厂污泥中的ARGs丰度范围为54.7~585.0 ppm，显著高于污水处理厂污泥的ARGs丰度（27.2~86.4 ppm）。此外，制药废水处理厂好氧污泥中的ARGs多样性（153种亚型）高于污水处理厂好氧污泥（118种亚型）。本研究还发现，制药废水处理厂好氧污泥的ARGs谱型与污水处理厂好氧污泥的ARGs谱型相似，但与制药废水处理厂厌氧污泥的ARGs谱型存在显著差异，提示溶解氧（dissolved oxygen, DO）可能是影响ARGs谱型的重要因素之一。在制药废水处理厂好氧污泥中，氨基糖苷类、磺胺类及多重耐药基因的检出频率较高；而在制药废水处理厂厌氧污泥中，四环素类、大环内酯-林可酰胺-链阳菌素类及多肽类耐药基因的丰度较高。此外，本研究对制药废水处理厂污泥中的微生物群落及其与ARGs的相关性进行了探究，发现ARGs类型与7个细菌属之间存在显著相关性。同时，本研究还检测了移动遗传元件（mobile genetic elements, MGEs），并观察到制药废水处理厂污泥中ARGs与移动遗传元件之间存在相关性。综上，本研究结果表明，受溶解氧调控的微生物群落与移动遗传元件，可能是塑造制药废水处理厂污泥中ARGs谱型的核心影响因素。