Metalotolerance Capacity of Autochthonous Bacteria Isolated From Industrial Waste Effluent

Microbes play significant roles in remediation of heavy metal polluted industrial effluent using the mechanisms of biosorption and bioaccumulation. In the present study, six heavy metal resistant autochthonous bacteria species namely Bacillus cereus, B. megaterium, B. subtilis, Flavobacterium aquatile, Pseudomonas flourescens and Pseudomonas putida were isolated from effluent samples collected from Paper-mill industry (PMI), Paints and Chemicals Industry (PCI), and Steel-rolling Industry (SRI). The isolates were studied for their heavy metal tolerant capacities at different aqueous salt concentrations. Elemental analysis of the industrial effluent samples collected indicated the presence of heavy metals such as Copper (Cu²⁺), Manganese (Mn²⁺), Iron (Fe²⁺) and Lead (Pb²⁺) at varying concentrations in μg/ml. Generally, there were variations in the minimum inhibitory concentrations (MIC) of the heavy metal salt to each of the bacteria understudy. The MIC value of each of the bacterial isolates to aqueous solution of Cu₂SO₄ showed that B. megaterium, B. subtilis, Pseudomonas flourescens and Pseudomonas putida had the same MIC value of 20 ± 1.5 μg/mL while Bacillus cereus and Flavobacterium aquatile had MIC values of 13 ± 1.3 μg/mL and 25 ± 2.1 μg/mL respectively. This variation was also noticeable in aqueous salts of Mn₂SO₄, Fe₂SO₄ and Pb₂SO_4.The bacteria isolates showed sensitivity to heavy metals with increasing zone of inhibition as concentration increased with each isolate showing varying degree of metalotolerance. The effectiveness of the autochthonous bacteria as a means to bio-augment the remediation of heavy metal polluted industrial effluent was further proven and recommended.