South Asian Journal of Research in Microbiology

Heavy metals are resistant to degradation and can remain in the environment, posing long-term risks to human health. This study aimed to isolate and characterize bacteria capable of utilizing heavy metals from dumpsites within Keffi Metropolis. A total of forty-eight (48) soil samples were randomly collected from Babale, Yankari, Angwan Nepa, and Majema dumpsites, and transported to the Microbiology Laboratory of Nasarawa State University, Keffi, for bacteriological assessment using standard techniques. Atomic absorption spectrophotometer (AAS) was used to measure the amounts of the metals. The analysis confirmed the presence of diverse bacterial species across all sampled locations, including Klebsiella spp., Pseudomonas aeruginosa, and Bacillus spp. The prevalence data indicated that Klebsiella spp. was the most dominant (45.8%), followed by Pseudomonas spp. (39.5%) and Bacillus spp. (31.2%). When exposed to selected heavy metals at 0.05 mg/mL, Pseudomonas spp. showed the greatest resistance to ferric chloride and lead sulfate (21.0%), whereas Bacillus spp. exhibited notable tolerance to zinc sulfate and ferric chloride (20.0%). Regarding metal reduction potential, Bacillus spp. achieved the highest decrease in zinc (1.21 mg/mL) and lead (1.81 mg/mL), reflecting strong metabolic activity toward these metals. Pseudomonas spp. demonstrated the highest reduction in ferric chloride (1.11 mg/mL) along with a significant decrease in nickel (1.0 mg/mL), highlighting its role in iron and nickel detoxification. In contrast, Klebsiella spp. displayed weak reduction capabilities, with no significant activity against zinc and lead. Overall, the findings suggest that Bacillus spp. is particularly effective against zinc and lead contamination, making it a valuable candidate for bioremediation of heavy metal–polluted sites. Focus should therefore be directed toward metals that showed the highest bacterial utilization namely lead, ferric chloride, and zinc. Bioremediation remains a sustainable strategy for mitigating environmental heavy metal pollution, and future studies should explore advanced approaches for targeting these metals, considering their significant public health implications.