Abstract

Heavy metals are transition elements whose presence at mild doses in water bodies is deadly. Most effectively harnessed technique of their remediation is the microbial approach, also known as bio-remediation. This study is hereby aimed to investigate the potential of Klebsiella species isolated from diesel polluted soil in bioremediating the heavy metals present in effluent water.  A sample of diesel polluted soil was obtained from an automobile repair shop in Ile-Ife, Osun State Nigeria. Bacterial strains from the sample were isolated, characterized and identified by biochemical techniques. Three of the isolates were found to be Klebsiella species. Each of the strains and their consortium were administered in a 16-day bioremediation study, into sterile digested effluent water from a stream in Ile-Ife, Osun State, Nigeria. Each of the strains was tolerant to the presence of the heavy metals compared to the consortium, except with Chromium which gave consistency in both administrations. The Klebsiella species were very tolerant to Chromium. Cadmium follows suit with copper in better tolerance while there seem much resistance to Nickel. The concentration of Chromium was reduced from 2.718 to 0.046 mg L-1, 0.039, 0.041 and 0.047 mg L-1 by Klebsiella edwardsii, Klebsiella oxytoca, Klebsiella pneumoniae and the consortium of the strains, respectively. Cadmium was also reduced from 0.027 to 0.002 mg L-1, 0.001, 0.003 and 0.002 mg L-1 by K.edwardsii, K. oxytoca, K. pneumoniae and the consortium of the strains, respectively. The same list of organisms respectively reduced copper from 0.173 to 0.022 mg L-1, 0.025 0.018 and 0.030 mg L-1, and reduced Nickel from 0.103 to 0.019 mg L-1, 0.020, 0.017, and 0.017 mg L-1, respectively. It can be concluded that the trend of each microbe’s and the consortium’s affinity for the heavy metals uptake is predictably in the trend Cr > Cd > Cu > Ni.

Key words: Bio-remediation, diesel polluted soil, effluent water, tolerant, resistant, heavy metals, Klebsiella species.