Molecular Assessment of Dominant Genus in Heavy Metal Contaminated Soil from Selected Dumpsites in Port Harcourt, Nigeria

Abstract

Heavy metal contamination distorts and diminishes microbial diversity due to their inhibitory effects on bacteria, resulting in the elimination of susceptible bacteria and the proliferation of resistant strains, which eventually become dominant. Consequently, this study seeks to characterize the dominant bacteria (RCBBR_B37 and RCBBR_B38) isolated from soil at a dump site contaminated with heavy metals. DNA extraction from the isolates was performed using the Zymo Quick DNA Fungal/Bacterial Kit, and the purity of the extracted DNA was assessed using a NanoDrop 2000c spectrophotometer. Gel electrophoresis confirmed the presence of DNA bands, including a control band. Subsequently, PCR amplification using 27F and 1492R complementary primers was carried out on the extracted DNA. The PCR products underwent sequence analysis followed by BLAST search in the National Center for Biotechnology Information (NCBI) database. A phylogenetic tree was constructed based on the BLAST results. Isolate RCBBR_B37 exhibited a 98% similarity index to Bacillus fungorum, while RCBBR_B38 showed a 97% similarity index to Bacillus paramycoides. The prevailing presence of Bacillus in heavy metal contaminated dumpsite is a signature, representing the difference mechanisms of microbial interaction for heavy metals amelioration, including but not limited to bioaccumulation, sequestration, redox transformation, neutralization, metabolization, and detoxification.