ABSTRACT

 Industrialization and anthropogenic activities have led to release of large amount of effluents and wastes that contain heavy metals into waterbodies. The capacity of selected isolates from Umudiawa stream to remove heavy metal in form of their salts was investigated. Heavy metal content of water samples was quantified using atomic absorption spectrophotometer and their values were 0.84±0.0lmg/L for iron, 0.25±0.0lmg/L for copper, 0.03±0.00mg/L for cadmium, 2.06± 0.0lmg/L for zinc, 0.05±0.00mg/L for arsenic,0.06±0.01mg/L for lead, 0.04±0.0lmg/L for chromium, 0.05±0.00mg/L for nickel and O.02±0.0.00mg/L for cobalt respectively while mercury was not detected in water samples. Zinc and Iron had the highest concentration while Cobalt and Cadmium had the lowest concentration in the water samples from Umudiawa stream. Isolation of bacteria from Umudiawa stream was done by the standard microbiological techniques. Bacteria isolates were identified and characterized by series of biochemical tests. Enterobacter cloacae, Bacillus subtilis, Salmonella enterica and Kiebsiella aerogenes were identified with a total count of log₁₀ 5.43CFU/m1. These bacteria isolates were used to reduce heavy metal in form of their salts at different concentrations. Starting with initial concentration of mercury chloride of 0.001mg/L, 0.04mgIL, 0.008mg/L and 0.Ol2mg/L, Enterobacter cloacae, Bacillus subtilis, Salmonella enterica and Klebsiella aero genes reduced mercuric chloride completely. E. cloacae, B. subtilis, S. enterica and K. aero genes reduced copper sulphate at higher rate from the initial concentration of 4mg/L whereas B. subtilis and S. enterica at concentration of 1 6mg/L reduce copper sulphate at lower rate, E. cloacae, B. subtilis and S. enterica reduce zinc sulphate at a maximum rate from all the initial concentrations of 0.2mg/L, 0.4mgIL, 0.6mglL and 0.8mg/L. Kiebsiella aerogenes reduced zinc sulphate at a lower range ,E. cloacae, B. subtilis and K aero genes reduced iron sulphate at higher rate from all concentrations. S. enterica could not reduce iron sulphate from the initial concentration of 0.8mglL. The bacterial isolates used in this study have the potential in reducing or completely removing heavy metals in polluted waters.