Comprehensive analysis of Mithi river water quality: pollution assessment, and lead bioremediation by indigenous bacteria.

Abstract

Environmental pollution is a biggest challenge faced by whole world at current time. The natural resources are victims of pollution and contamination of natural resources with heavy metals such as Pb. Pb is a highly toxic and frequent pollutant all around the world. In present study, Mithi River, a highly polluted urban water body was physico-chemically analyzed at four different sites along its course and their association was statistically analysed. Further, Pb bioremediating bacteria were isolated from Mithi river water and analysed for their Pb remediation potential. The findings revealed consistently low water quality across all sites, indicating high pollution levels, particularly in the lower stretch of river. Mithi River exhibited a substantial total heterotrophic bacteria (THB) (Taximan- 2.89 × 10⁹ and BKC- 2.13 × 10⁹) and a prevalence of lead-resistant bacteria (Taximan- 3.16 × 10⁸ and BKC 2.24 × 10⁷). A total 21 Pb resistant bacteria were isolated and gram negative coccobacilli were the most dominant. Notably, P. mirabilis demonstrated ability to bioremediate up to 100% of lead within 48 h. The SEM-EDX analysis illustrated biosorption of Pb on cell surface. Furthermore, P. mirabilis secretes significant amount of extracellular components in Pb concentration dependent manner. The study demonstrated that P. mirabilis exhibits tolerance to a wide range of environmental conditions, including variations in pH, temperature, salinity, and resistance to various toxic pollutants like heavy metals and organic contaminants. This broad tolerance spectrum to environmental conditions, combined with its strong bioremediation potential, highlights P. mirabilis as a promising candidate for lead bioremediation. Though, real-time application of bioremediation process is still lagging behind and needs immediate attention.