Characterization and Bioremediation Potential of Heavy-Metal Resistant Bacteria Isolated From Agricultural Soil

Abstract

Heavy metal pollution is a major environmental issue that has a negative impact on soil quality and food security. As result, heavy metal removal or remediation from hazardous sites has become mandatory. Bioremediation based on microorganisms is promising method to remediate heavy metal-contaminated areas due to its ecofriendly, cost-effective, and highly efficient characteristics. This study aimed to isolate, identify, and characterize rhizospheric bacteria able to resist, reduce, and detoxify heavy metals [chromium (Cr), nickel (Ni), and aluminum (Al)] from agricultural soil. Two isolates were chosen due to their high level of heavy metal resistance and could serve as potential in situ remediation agents at the site of isolation. On the basis of morphological, cultural, biochemical, and molecular characterization, these two isolates were identified as Pseudomonas aeruginosa (S1) and Bacillus cereus (S2). The results revealed a minimum inhibitory concentrations (MICs) of the three heavy metals studied, ranging from 1000 to 1400 mu g/mL for the two bacterial isolates. Atomic absorption spectroscopy analysis was used to evaluate the degrading potential. B. cereus was able to reduce Cr and Al more than P. aeruginosa (42% and 67.78% vs. 38.44% and 58.85, respectively). On the other hand, P. aeruginosa showed a higher capacity to degrade Ni than B. cereus (62.33% and 50.76%, respectively). The findings of the analysis revealed information regarding the use of these heavy metal-resistant bacterial isolates as potential bioremediation agents in contaminated environments. Microbial bioremediation offers sustainable alternatives to the traditional physical or chemical remediation technologies of agricultural land.