A bioremediation approach of some selected heavy metal detected from Bishoftu and Mojo industrial effluents in Ethiopia

Various heavy metals (HM) can be removed from the environment due to the diversity of bacterial species capable of developing resistance against them. Bacteria can accumulate HMs within their cellular structures. This study aimed at a bioremediation approach of some selected HM detected from the Bishoftu and Modjo industries. Bacteria were characterized and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) based on protein profile. Biodegradation efficiency was assessed using atomic absorption spectroscopy (AAS). The optimal conditions for carbon and nitrogen sources, pH, and temperature were evaluated. Aeromonas hydrophila, Bacillus spp ., Delftia acidovorans, Exiguobacterium aurantiacum , Pseudomonas putida, and others’ Pseudomonas spp. were identified as the best HM bioremediation. Aeromonas hydrophila- HMRBI-12 and Delftia acidovorans -HMRBI-17 showed good Cd and Zn removal abilities, with biodegradation rates of 65.02 ± 0.002 % and 70.04 ± 0.001 %, respectively. Similarly, Exiguobacterium aurantiacum -HMRBI-7 was most effective for removing Cu and Cr with a biodegradation rate of 65.13 ± 0.004 % and 65.03 ± 0.004 %. The isolate likely utilized intracellular and extracellular biosorption mechanisms to biodegrade HMs. 16S rRNA gene analysis identified isolates as Paraclostridium benzoelyticum strain of HMRBI-1 with 60.49 ± 0.002 % of Co biodegradation. This study effectively identified bacterial species from industrial effluents in Bishoftu and Modjo, Ethiopia, demonstrating their potential HM bioremediation. The identification of HM-resistant and biodegrading bacteria could form the basis for developing local bioremediation formulations for treating toxic pollutants.