Abstract

Soil contamination with heavy metals, particularly in rhizosphere regions, presents significant environmental and ecological challenges. Diverse bacterial communities found in the rhizosphere, the small area of soil that is impacted by plant roots, are critical for metal detoxification, organic matter breakdown, and nutrient cycling. This research investigates the bacterial community dynamics in the Cu (copper)-contaminated rhizosphere of Elsholtzia splendens. Using metagenomic analysis, 28 bacterial phyla were identified, with 7 dominant phyla found in contaminated soils. The composition and diversity of bacterial communities were found to be most significantly influenced by pH out of all the environmental parameters examined, including Cu concentration, Total Organic Carbon (TOC), total nitrogen, pH, soil moisture content, temperature, and soil texture. Changes in microbial composition in those environmental parameters can be efficiently evaluated using Bray-Curtis dissimilarity, which is used to quantify differences between microbial communities based on species abundance. The findings reveal the taxonomic composition; Proteobacteria was the most abundant phylum, constituting 45.2% of the bacterial community in contaminated soils. Furthermore, Firmicutes increased from 18.3% to 22.1% in contaminated soils, while Pseudomonas abundance rose from 11.5% to 18.3%. Metagenomic profiling also revealed functional gene pathways associated with metal tolerance and detoxification, including those related to copper efflux and oxidative stress responses, which were found to be more prevalent in contaminated soils. This research highlights the bacterial diversity and functions in metal-contaminated rhizospheres, enhancing the understanding of microbial adaptation and bioremediation potential.