Isolation and Diversity Analysis of Heavy Metal-Tolerant Bacteria from Ganga River Across Seasonal Gradients

The Ganga River, a vital water resource in India, faces significant challenges due to increasing pollution, particularly from heavy metals. The present study explores the bacterial diversity and heavy metal tolerance of microorganisms in the Ganga River at Haridwar. Water samples were collected from four locations (Bhimgoda, Kankhal, Prem Nagar, and Jwalapur) during three seasons (monsoon, winter, and summer). Physio-chemical parameters, including pH, conductivity, turbidity, dissolved oxygen, and biochemical oxygen demand, were analyzed, revealing notable seasonal and spatial variations. Heavy metal-tolerant bacteria were isolated and characterized using morphological, biochemical, and molecular techniques. Fifteen bacterial strains were identified, including Bacillus subtilis, Klebsiella pneumoniae , and Delftia tsuruhatensis , demonstrating diverse survival strategies and potential for bioremediation. The highest bacterial diversity and evenness were observed during the monsoon season, as indicated by various ecological indices. Screening for heavy metal tolerance revealed that isolate HGB1 exhibited the highest tolerance to arsenic, cadmium, chromium, copper, nickel, and iron, up to 100 ppm. Antibiotic sensitivity assays further highlighted the resistance profiles of the isolates. The existence of bacteria exhibiting tolerance to heavy metals in the Ganga River underscores the impact of anthropogenic activities on microbial communities and emphasizes the necessity for regular monitoring and sustainable remediation techniques to preserve the river's ecological integrity and mitigate public health risks. This study contributes crucial findings regarding the complex interplay between physicochemical parameters, microbial diversity, and heavy metal tolerance in the Ganga River ecosystem.