Effects of cadmium and copper mixtures on antibiotic resistance genes in rhizosphere soil Original paper
Researched by:
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Divine Aleru
ID
Divine Aleru
Read MoreI am a biochemist with a deep curiosity for the human microbiome and how it shapes human health, and I enjoy making microbiome science more accessible through research and writing. With 2 years experience in microbiome research, I have curated microbiome studies, analyzed microbial signatures, and now focus on interventions as a Microbiome Signatures and Interventions Research Coordinator.
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Metals
Metals
OverviewHeavy metals play a significant and multifaceted role in the pathogenicity of microbial species. Their involvement can be viewed from two primary perspectives: the toxicity of heavy metals to microbes and the exploitation of heavy metals by microbial pathogens to establish infections and evade the host immune response. Understanding these aspects is critical for both […]
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Divine Aleru
Read More
Researched by:
-
Divine Aleru
ID
Divine Aleru
Read More
Microbiome Signatures identifies and validates condition-specific microbiome shifts and interventions to accelerate clinical translation. Our multidisciplinary team supports clinicians, researchers, and innovators in turning microbiome science into actionable medicine.
Divine Aleru
What was studied?
This study investigates how cadmium (Cd) and copper (Cu), both individually and in combination, influence the distribution of antibiotic resistance genes (ARGs) in rhizosphere soil. The research aims to examine how these heavy metals impact the abundance of specific bacterial communities and ARGs, including multidrug resistance genes and metal resistance genes. It explores whether metals like Cd and Cu, through interactions, contribute to the co-selection of resistance genes in the soil, which could have implications for human health via agricultural systems.
Who was studied?
The study primarily focuses on the bacterial communities in rhizosphere soil, which is the region of soil surrounding plant roots. These bacteria are directly influenced by soil contamination with heavy metals, specifically Cd and Cu. The experiment was conducted using agricultural soil samples treated with varying concentrations of these metals. The bacteria studied include those from key phyla like Proteobacteria and Actinobacteria, known for hosting various antibiotic resistance and metal resistance genes. The research also investigates the relationship between metal concentrations and the presence of resistance genes, linking these findings to environmental risks.
Most important findings
The study reveals that both Cd and Cu, when present in high concentrations, significantly influence the distribution and abundance of antibiotic resistance genes in rhizosphere soil. Key genes like acrA (multidrug resistance), intI-1 (integron), and sul3 (sulfonamide resistance) were found to be more abundant in soils contaminated with these metals. Interestingly, while cadmium had a direct effect on the presence of certain genes like acrA, copper primarily influenced genes like intI-1. The research also identified that most of the resistance genes were hosted by bacterial taxa such as Proteobacteria, Actinobacteria, and Bacteroidetes. The combination of Cd and Cu showed interactive effects on gene abundance, suggesting that these metals co-select ARGs.
Structural equation modeling showed that cadmium had a more direct effect on the abundance of ARGs compared to copper, which impacted them more indirectly by altering soil properties like pH and organic matter content. The study also noted that while microbial community diversity didn’t significantly affect the ARG distribution, mobile genetic elements (MGEs) played a crucial role in facilitating the horizontal gene transfer of ARGs between bacterial species.
Key implications
The findings of this study highlight the growing concern over the co-selection of antibiotic resistance genes in environments contaminated with heavy metals. The results emphasize the need to consider both metal pollution and antibiotic resistance when assessing environmental risks, especially in agricultural soils. Heavy metal contamination could be contributing to the spread of antibiotic resistance in the environment, which may ultimately impact human health. The research calls for more comprehensive environmental monitoring and management strategies to mitigate the risks posed by metal pollution, focusing on both heavy metal and antibiotic resistance.
Cadmiun (Cd)
Cadmium (Cd) is a highly toxic heavy metal commonly found in industrial, agricultural, and environmental settings. Exposure to cadmium can occur through contaminated water, food, soil, and air, and it has been linked to a variety of health issues, including kidney damage, osteoporosis, and cancer. In agriculture, cadmium is often present in phosphate fertilizers and can accumulate in plants, entering the food chain. Its toxicity to living organisms makes cadmium a subject of regulatory concern worldwide, particularly in industrial waste disposal and environmental monitoring.
Copper (Cu)
Copper serves as both a vital nutrient and a potential toxin, with its regulation having profound effects on microbial pathogenesis and immune responses. In the body, copper interacts with pathogens, either supporting essential enzyme functions or hindering microbial growth through its toxicity. The gastrointestinal tract, immune cells, and bloodstream are key sites where copper plays a crucial role in controlling infection and maintaining microbial balance. Understanding copper’s interactions with the microbiome and host defenses allows for targeted clinical strategies.