摘要

      新型污染物如药物、抗药性细菌（ARB）和抗药性基因（ARGs）由于在农业生态系统中的数量迅速增加而受到越来越多的关注。由于食品消费是药物、ARB和ARGs对人类的直接接触途径，因此了解受污染土壤和水体生产的粮食作物中细菌群落和ARG谱的变化非常重要。本研究分别采用高通量qPCR和16srrna扩增子测序技术，检测了土壤、莴苣地上部和根中的ARGs水平和类型以及细菌群落组成。在土壤、莴苣地上部和根部共检测到52个ARG亚型，其中以大环内酯类林可酰胺链霉素B（MLSB）和多药耐药（MDR）基因为主。土壤表层灌溉条件下，莴苣芽中ARGs和细菌的总体丰度和多样性均低于架空灌溉条件下，说明土壤表层灌溉对高ARGs含量粮食作物的生产风险较低。ARG谱和细菌群落对药物暴露敏感，但没有观察到一致的变化模式。与没有药物的情况相比，MGE intl1在药物暴露的情况下始终更为丰富。药物暴露丰富了蛋白质细菌（尤其是嗜甲基菌科）并降低了细菌α多样性。最后，细菌群落、抗生素浓度和精氨酸丰度之间存在显著的相互作用，可能涉及到包括鞘氨醇单胞菌科、水飞蓟科和甲壳虫科在内的热点、MGEs（intl1和tnpA_1）和MDR基因（mexF和oprJ）。

      New classes of emerging contaminants such as pharmaceuticals, antibiotic resistant bacteria (ARB), and antibiotic resistance genes (ARGs) have received increasing attention due to rapid increases of their abundance in agroecosystems. As food consumption is a direct exposure pathway of pharmaceuticals, ARB, and ARGs to humans, it is important to understand changes of bacterial communities and ARG profiles in food crops produced with contaminated soils and waters. This study examined the level and type of ARGs and bacterial community composition in soil, and lettuce shoots and roots under soil-surface or overhead irrigation with pharmaceuticals-contaminated water, using high throughput qPCR and 16S rRNA amplicon sequencing techniques, respectively. In total 52 ARG subtypes were detected in the soil, lettuce shoot and root samples, with mobile genetic elements (MGEs), and macrolide-lincosamide-streptogramin B (MLSB) and multidrug resistance (MDR) genes as dominant types. The overall abundance and diversity of ARGs and bacteria associated with lettuce shoots under soil-surface irrigation were lower than those under overhead irrigation, indicating soil-surface irrigation may have lower risks of producing food crops with high abundance of ARGs. ARG profiles and bacterial communities were sensitive to pharmaceutical exposure, but no consistent patterns of changes were observed. MGE intl1 was consistently more abundant with pharmaceutical exposure than in the absence of pharmaceuticals. Pharmaceutical exposure enriched Proteobacteria (specifically Methylophilaceae) and decreased bacterial alpha diversity. Finally, there were significant interplays among bacteria community, antibiotic concentrations, and ARG abundance possibly involving hotspots including Sphingomonadaceae, Pirellulaceae, and Chitinophagaceae, MGEs (intl1 and tnpA_1) and MDR genes (mexF and oprJ).

       https://www.sciencedirect.com/science/article/pii/S016041201931270X?via%3Dihub