Ex-situ Bioremediation of Heavy Metal-Contaminated Soil Using Bacillus cereus and Micrococcus luteus Consortium: A Phytotoxicity Assessment

Abstract

Pollution by arsenic, lead, and mercury poses an environmental and health risk. Microbial bioremediation is an environmentally benign process for remediating contaminated soils. The purpose of this study was to assess the influence of two bacterial strains isolated and identified from the soil at Gevra coal mine, Korba, and Mand coalfield, Raigarh: Bacillus cereus and Micrococcus luteus on the rate of depollution of arsenic, lead, and mercury-contaminated soils. To test this effect, sterile soil was bioaugmented with B. cereus and M. luteus strains individually and in combination for 25 days at 30˚C. The bioaugmentation of the sterile soil with a mixture of B. cereus and M. luteus strains resulted in the highest rate of reduction of Pb²⁺ (80.33%), Hg²⁺ (79.42%), and As³⁺ (74.77%) compared to the rate of bioaugmentation by each bacterial strain individually. These findings are supported by the study of sterile soil, which revealed an increase in the mobility and bioavailability of Pb²⁺, As³⁺, and Hg²⁺. Ecotoxicological responses indicated lower heavy metal concentrations were not associated with lower soil toxicity. These promising results provide another perspective for a soil bioremediation bioprocess that employs bacterial bioremediation.