Isolation of indigenous microorganisms from soil contaminated with metal scraps for the uptake of selected heavy metals in constituted growth media

Abstract

Indigenous bacteria and fungi were isolated from soil obtained from a metal scrap dumpsite in Ibadan, Nigeria. Soil sample analyses showed presence of calcium, iron, magnesium, zinc, manganese and copper. A selective isolation of microorganisms was done using heavy metal constituted growth media at concentration of 25 mg/L. Lactobacillus casei was isolated from cadmium and lead composed growth media, Corynebacterium xerosis and Corynebacterium kutsceri from nickel composed growth media. Aspergillus niger and Histoplasma capsulatum were isolated from growth media composed of nickel and lead respectively at a 25 mg/L concentration. Growths were observed for all isolates at 50mg/L, 100mg/L and 400mg/L composed growth media. A 7 day bio-treatment process with isolates for uptake of heavy metals from growth media solution at 50 mg/L concentration of heavy metal was done. Histoplasma capsulatum, Aspergillus fumigatus and Aspergillus niger reduced the heavy metal concentrations in lead, nickel and cadmium to 6, 18.12 and 12.45 mg/L respectively. Lactobacillus casei, and C. xerosis reduced the heavy metal concentration of cadmium, lead and nickel to 13.55, 33, 25, 22.38, 15.45 and 29.11 mg/L respectively. These microorganisms reduced the initial concentration of heavy metals and could thus be used for bioremediation processes.