摘要
      水生生态系统被认为是抗生素和金属抗性基因的枢纽。恒河是印度独特的河流系统，具有社会文化和经济意义。然而，在其受人类遗传学影响的过程中，对其微生物组和相关耐药性的研究仍然不足。本研究利用纳米孔测序方法来描述恒河沉积物中的微生物群落结构，该结构在已知人为影响的较低河段携带抗生素和金属抗性基因（a/MRG）。综合微生物组分析揭示了对23种不同类型的金属和28类抗生素的耐药性基因。最主要的ARG类别是多药耐药性，而最普遍的MRG赋予了对铜和锌的耐药性。季节差异严重影响了恒河的微生物群。然而，膦霉素和四环素的抗性基因随季节方差分析而变化，p<0.05。有趣的是，在季风前和季风后的所有位置分别观察到333和334个ARG亚型。与显性ARGs和MRGs相关的分类群是假单胞菌和伯克霍尔德菌，它们是重要的医院病原体。致病细菌和腐败细菌在所有地方的大量噬菌体多样性因其用于解决抗生素和金属耐药细菌的传播而引起关注。这项研究表明，抗生素和金属的积累是耐药基因出现的驱动力，以及运输这些基因的附属细菌。目前的宏基因组评估强调，需要对这条全国重要河流中与ARGs和MRGs相关的污染物进行全面、长期的生物和物理化学监测和缓解策略。
Abstract
Aquatic ecosystems are regarded as a hub of antibiotic and metal resistance genes. River Ganges is a unique riverine system in India with socio-cultural and economic significance. However, it remains underexplored for its microbiome and associated resistomes along its anthropogenically impacted course. The present study utilized a nanopore sequencing approach to depict the microbial community structure in the sediments of the river Ganges harboring antibiotic and metal resistance genes (A/MRGs) in lower stretches known for anthropogenic impact. Comprehensive microbiome analyses revealed resistance genes against 23 different types of metals and 28 classes of antibiotics. The most dominant ARG category was multidrug resistance, while the most prevalent MRGs conferred resistance against copper and zinc. Seasonal differences dismally affected the microbiota of the Ganges. However, resistance genes for fosmidomycin and tetracycline varied with season ANOVA, p < 0.05. Interestingly, 333 and 334 ARG subtypes were observed at all the locations in pre-monsoon and post-monsoon, respectively. The taxa associated with the dominant ARGs and MRGs were Pseudomonas and Burkholderia, which are important nosocomial pathogens. A substantial phage diversity for pathogenic and putrefying bacteria at all locations attracts attention for its use to tackle the dissemination of antibiotic and metal-resistant bacteria. This study suggests the accumulation of antibiotics and metals as the driving force for the emergence of resistance genes and the affiliated bacteria trafficking them. The present metagenomic assessment highlights the need for comprehensive, long-term biological and physicochemical monitoring and mitigation strategies toward the contaminants associated with ARGs and MRGs in this nationally important river.

https://www.sciencedirect.com/science/article/abs/pii/S0048969723007416