Original Contribution to Forensic Soil Analysis: Microbial Community Profiling as a Geographic Provenance Tool Across Nigerian Ecological Zones

Microbial community profiling through metagenomic analysis represents a cutting-edge frontier in forensic soil science, offering provenance determination capabilities that transcend the discriminatory resolution of conventional mineralogical and chemical methods. This doctoral study makes an original scientific contribution by characterising soil microbial community profiles as geographic provenance indicators across Nigeria's six ecological zones: the Guinea Savanna, Sudan Savanna, Sahel, Rainforest, Freshwater Swamp, and Mangrove zones. A multi-site empirical experimental design was employed, collecting 360 systematically georeferenced soil samples from twelve states representing all ecological zones, applying 16S rRNA amplicon sequencing and ITS sequencing for bacterial and fungal community characterisation, and developing a multivariate discriminant analysis classification model. The model's geographic attribution accuracy was validated using a blind test set of forty-five independently collected samples. The study demonstrates that microbial community profiling achieves correct ecological zone attribution in ninety-one percent of blind test cases, significantly outperforming mineral composition analysis, which achieved sixty-seven percent attribution accuracy on the same sample set. Significant inter-zone microbial differentiation was observed even between ecologically similar zones, driven by soil pH, organic matter content, and land use history. An original Nigeria Forensic Soil Microbiome Reference Database comprising the full sample dataset is proposed. Recommendations include the formalisation of this method within Nigerian forensic soil examination protocols and continued investment in environmental forensic microbiomics research. Keywords: forensic soil analysis, microbial community profiling, geographic provenance, Nigeria, metagenomics.