Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was studied?
This original research article conducted a comprehensive metagenomic analysis of microbial community structure and functional potential in cadmium (Cd)-contaminated versus non-contaminated soils. The primary aim was to investigate how Cd contamination impacts both the diversity and metabolic capabilities of soil microorganisms. The study utilized high-throughput sequencing and bioinformatics tools to assess taxonomic composition, functional gene diversity, and key metabolic pathways based on cluster of orthologous groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations. By comparing soils from a region near phosphate rock chemical plants in Sichuan, China, the authors elucidated how heavy metal stress, particularly from cadmium, drives shifts in microbial populations and their functional attributes. The focus keyphrase, “cadmium-contaminated soil microbial community,” is central to understanding the heavy metal risk profile and potential remediation strategies for certification programs such as Heavy Metal Tested and Certified (HTMC).
Who was studied?
The study investigated soil samples from two distinct sites in Shifang County, Sichuan Province, China, near phosphate rock chemical plants. Site 1 provided non-contaminated soil, while Site 2 offered Cd-contaminated soil, both collected at a depth of 5–10 cm and processed identically for consistency. No human or animal subjects were involved; the research centered exclusively on indigenous soil microbial communities exposed to significantly different cadmium concentrations (0.072 mg/kg in S1 versus 1.639 mg/kg in S2). By examining these naturally occurring microbial assemblages, the researchers aimed to capture the real-world effects of cadmium pollution on soil ecosystems relevant to environmental risk assessment and remediation.
Most important findings
| Critical Points | Details |
|---|---|
| Microbial Diversity | Cd contamination significantly reduced microbial diversity and altered community structure. The number of taxa at both phylum and genus levels decreased in the Cd-contaminated soil compared to non-contaminated soil, with Proteobacteria becoming more dominant under contamination. |
| Community Composition | Dominant phyla in both soils included Proteobacteria, Gemmatimonadetes, Thaumarchaeota, and Acidobacteria, but Proteobacteria increased from 38.56% (non-contaminated) to 57.85% (contaminated). At the genus level, genera such as Nitrososphaera, Nitrosospira, and Sulfuricella were more abundant in contaminated soil, indicating selective enrichment of Cd-tolerant taxa. |
| Functional Shifts (COG/KEGG) | Metagenomic functional analysis revealed that metabolic gene clusters (COG Cluster III) were predominant, with their relative abundance higher in Cd-contaminated soil. KEGG pathway annotation showed a reduction in the number and diversity of metabolic pathways in contaminated soil, but certain key pathways—including those related to amino acid, fatty acid, and nucleotide metabolism—were enriched, reflecting microbial adaptation to Cd stress. |
| Detoxification Mechanisms | The most abundant pathway across both samples was ko02010 (ABC transporters), which are associated with heavy metal transport and detoxification. While overall abundance of this pathway was higher in non-contaminated soil, certain modules (e.g., peptide/nickel transport) were increased in contaminated soil, highlighting specific functional adaptations. Enzyme analysis showed increased relative abundance of oxidoreductase, transferase, and lyase in contaminated soil, all linked to heavy metal tolerance. |
| Implications for Bio-Remediation | Cd-contaminated soil harbored microbial taxa and functional gene content indicative of adaptive responses, including enhanced metabolic and detoxification pathways, suggesting that such soils may serve as reservoirs for isolating cadmium-resistant or tolerant bacteria for bioremediation or risk mitigation strategies relevant to HTMC certification. |
Key implications
The study demonstrates that cadmium-contaminated soil microbial community structure is significantly altered, with reduced diversity but selective enrichment of Cd-tolerant taxa and functional pathways. These microbial shifts can directly affect soil health and serve as critical markers for HTMC certification, and contaminated soils may be valuable sources of bioremediation agents.
Citation
Feng G, Xie T, Wang X, Bai J, Tang L, Zhao H, Wei W, Wang M, Zhao Y. Metagenomic analysis of microbial community and function involved in Cd-contaminated soil. BMC Microbiol. 2018;18:11. doi:10.1186/s12866-018-1152-5
Cadmium is a persistent heavy metal that accumulates in kidneys and bones. Dietary sources include cereals, cocoa, shellfish and vegetables, while smokers and industrial workers receive higher exposures. Studies link cadmium to kidney dysfunction, bone fractures and cancer.
