Exploring the bioremediation potential of nonpathogenic Pb-resistant strain <i>Klebsiella pneumoniae</i> in <i>Oreochromis niloticus</i>

Lead (Pb) has been released into the environment due to increased urbanization in recent years, causing severe environmental impacts on soil and water. Therefore, the goal of the present study is to investigate the bio-remedial potential of the Pb-resistant strain <i>Klebsiella pneumoniae</i> PbS₃A₂ against Pb induced toxicity in <i>Oreochromis niloticus.</i> For this purpose, <i>O. niloticus</i> body weight (14.5 ± 0.19) and body length (9.8 ± 0.08) fishes were taken and divided into three groups (Control (T_o), lead (T₁), and Lead +<i>K. pneumoniae</i> (T₂) groups). The lead group was subjected to Pb (1 mg L⁻¹), and bacterial groups were exposed to Pb + <i>K. pneumoniae</i> (1.5 × 10⁸ CFU/ml) for four weeks. The outcomes revealed that waterborne Pb had lethal effect on Fish growth performance, body composition, hemato-biochemical parameters, enzymes activity, histopathological alteration, along with elevated Pb accumulation in various tissues (gills, liver &amp; muscles). Conversely, bioremediated with <i>K. pneumoniae</i> effectively mitigated the toxic potential of Pb and improved fish longevity. Notably, <i>K. pneumoniae</i> (1.5 × 10⁸ CFU/ml) significantly (<i>p</i> ≤ 0.05) boosted growth, body composition, reversed blood parameters, restored enzymes function in the liver and gut, reversed the histopathological alteration as well as ameliorates the Pb accumulation in tissues. Thus, the findings of the current study showed that <i>K. pneumoniae</i> is effective for the bioremediation of Pb from industrial effluent and preventing Pb induced toxicity in aquaculture.