Integrated physicochemical and metagenomic analysis of the Ganges River water

The perennial River Ganges, one of India's most vital freshwater resources, is increasingly threatened by growing human activities. The present study provides an integrated assessment of water quality, heavy metal pollution, antibiotic resistance, and microbial community dynamics along a culturally important section of the river. Physicochemical parameters showed seasonal variations, with higher pH, TDS, nitrate, and sulfate levels, indicating significant human activities. ICP-AES analysis of heavy metals revealed high levels of Cr and Cd, with a contamination degree of 38.25, indicating a very high pollution level. Antibiotic susceptibility testing of 84 bacterial isolates demonstrated 64.28% multidrug resistance, mainly against β-lactam antibiotics. Although the Water Quality Index was 43.43 (classified as good), microbial and metal contamination indicated hidden ecological risks. 16S rRNA gene-based metagenomic profiling showed dominance of pollution-tolerant bacterial groups, especially Pseudomonadota, Bacillota, and Fusobacteriota. Genera like Brevundimonas, Methylobacterium, Pseudomonas, and Acinetobacter were most common, indicating microbial shifts due to ongoing human activities. Functional predictions (KEGG) suggested enrichment in pathways for xenobiotic degradation, energy production, and environmental information processing. These findings highlight the importance of comprehensive monitoring that combines chemical, microbiological, and genomic tools to better assess the river pollution and efforts to reduce public health risks.