Variation in bacterial flora with nickel and <i>in vitro</i> analysis of the phytotoxic and genotoxic potential and oxidative stress induced by the lake sediments

Present study aims to evaluate the quality of freshwater lake sediments for physico-chemical parameters, inorganic and organic contaminants, variation in bacterial populations in different seasons as well as evaluating their biological effects through phytotoxic (<i>Vigna radiata</i>), and mutagenic (Ames <i>Salmonella</i> tester strains) assessments. Sediment samples contained potentially toxic elements (Cd, Cr, Cu, Pb, Ni and Zn) and organic pollutants including pharmaceutical drugs (spironolactone and kendomycin), phenylpropanes (2,4-di-tert-butylphenol), personal care items (17-pentatriacontene), aromatic hydrocarbons (1,7-diisopropyl naphthalene), and insecticides (chlorpyrifos). These pollutants are considered to be toxic to the biological system. Total aerobic heterotrophic counts ranged from 5.53 ± 0.2 × 10⁵ to 27.60 ± 0.64 × 10⁵ CFU/ml during summer. In view of the detrimental impact of contaminants, <i>V. radiata</i> seeds germinated at varying concentrations of sediment extract, showed reduced seedling vigor index, radicle and plumule length. Root tips of <i>V. radiata</i> seeds revealed oxidative damage. Solvent (hexane, chloroform, ethyl acetate) extracted sediments induced mutagenicity in Ames <i>Salmonella</i> tester strains, with TA98 being the most sensitive. Sediment extract of chloroform revealed the maximum mutagenic potential compared to hexane and ethyl acetate. These findings highlight the ecological and genotoxic risk impact of sediment pollution, stressing the need for monitoring and prevention. ICP-AES revealed the presence of PTEs. Organic contaminants were identified using GC-MS. Metal tolerant bacteria have been found. CLSM showed oxidative damage in the root tips <i>of V. radiata</i>. <i>Salmonella typhimurium</i> strains revealed significant mutagenic potential.