Bioremediation of industrial wastewater heavy metals using solo and consortium Enterobacter spp

Abstract

Heavy metals are considered the most common pollutants in industrial wastewater areas. Out of thirty bacterial isolates, only 3 isolates sighted the highest metal resistance activity for Zn⁺², Fe⁺², Pb⁺², Co⁺², Mn⁺², Ni⁺², and Cd⁺². The biochemical and DNA homology identification with similarities 99.58%, 99.79%, and 99.86% of those isolates was identified and deposited in WDCM, respectively, as Enterobacter kobei OM144907 SCUF0000311, Enterobacter cloacae OM180597 SCUF0000312, and Enterobacter hormaechei OM181067 SCUF0000313. The minimum tolerance activity (MIC) of heavy metal concentrations against E. kobei and E. cloacae was 25, 15, and 15 mmol/l for Ni⁺², Fe⁺², and Mn⁺², respectively, and 10 mmol/l for Zn⁺², Pb⁺², Co⁺², and Cd⁺², while against E. hormaechei, it is 15 mmol/l for Ni⁺², Fe⁺², and Mn⁺² and 10 mmol/l for Zn⁺², Pb⁺², Co⁺², and Cd⁺². The consortium and solitary application of bacterial isolates towards heavy metal removal at 100%, 200%, and 300% industrial wastewater concentrations were conducted and showed that more than 90% removal of Zn⁺², Fe⁺², Pb⁺², Mn⁺², Ni⁺², and Cd⁺² from a non-concentrated polluted sample (100%) was reported by the three strains. With doubling the polluted sample concentration (200%), the highest removal efficiency for Zn⁺², Pb⁺², Mn⁺², Ni⁺², and Cd⁺² was reported by E. cloacae as 70. 75, 66, 65, and 57%, respectively. Removal efficiency after increasing the polluted sample concentration to 300% showed that E. cloacae removed above 45% of all tested heavy metals except Pb⁺². Ultimately, E. cloacae exposed the highest efficiency with recommendations for heavy metals removal under higher concentrations.

Keywords: Bioremediation; Enterobacter spp.; Heavy metal; Industrial waste; Suez Gulf.