Bioremediation of lead contaminated environment by Bacillus cereus strain BUK_BCH_BTE2: Isolation and characterization of the bacterium

Abstract

Lead is one of the most toxic heavy metals ever known by man today, which has zero biological role. It is known to cause anemia and affect the nervous and reproductive systems with irreversible effects. Its continual usage leads to its high accumulation polluting the soil and water bodies with devastating health effects. This research, aimed at isolation and characterization of indigenous lead tolerant bacteria from contaminated soil of Anka. Results of Atomic Absorption Spectrophotometry (AAS) showed high concentration of lead (738 mg/kg) of the affected sites above the EPA standard (400 mg/kg). Similarly, a mineral salt media was used to isolate the bacteria following serial dilution. An indigenous bacterial isolate (Ac) with potential to tolerate up to 3000 mg/L Pb(NO3)2 was isolated and molecularly identified based on 16s rRNA sequencing as Bacillus cereus strain BUK_BCH_BTE2 with the accession number MT160412. The isolate was further characterized for its optimum growth and tolerance conditions using one factor at a time (OFAT). Sucrose with an optimum concentration of 5 g/L was the best carbon source for the isolate. The isolate was found to utilize ammonium sulphate as the best nitrogen source at a concentration of 2.5 g/L, with an optimum pH and tempertaure of 7.0 and 37 °C respectively. A concentration of 1000 mg/L Pb(NO3)2 was found to be the optimum concentration for the isolate. The optimum incubation time and inoculum size were found to be 48 hrs and 100 μL respectively. The fact that the isolate could tolerate high Pb(NO3)2 concentration makes it suitable for future bioremediation work involving lead.

Keywords

• Lead
• Heavy metals
• Isolation
• Bacteria
• Lead-tolerant