Heavy Metals in Soils and the Remediation Potential of Bacteria Associated With the Plant Microbiome
| Autor: | Thaura Ghneim-Herrera, Sarah González Henao |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Environmental remediation
Microbacterium chemistry.chemical_element bacteria-assisted phytoremediation 010501 environmental sciences 01 natural sciences 03 medical and health sciences Bioremediation minimum inhibitory concentration (MIC) bioremediation heavy metals lcsh:Environmental sciences 030304 developmental biology 0105 earth and related environmental sciences General Environmental Science lcsh:GE1-350 0303 health sciences Cadmium biology Pseudomonas Mesorhizobium Enterobacter biology.organism_classification plant microbiome Phytoremediation chemistry Environmental chemistry |
| Zdroj: | Frontiers in Environmental Science, Vol 9 (2021) |
| DOI: | 10.3389/fenvs.2021.604216/full |
| Popis: | High concentrations of non-essential heavy metals/metalloids (arsenic, cadmium, and lead) in soils and irrigation water represent a threat to the environment, food safety, and human and animal health. Microbial bioremediation has emerged as a promising strategy to reduce the concentration of heavy metals in the environment due to the demonstrated ability of microorganisms, especially bacteria, to sequester and transform these compounds. Although several bacterial strains have been reported to be capable of remediation of soils affected by heavy metals, published information has not been comprehensively analyzed to date to recommend the most efficient microbial resources for application in bioremediation or bacterial-assisted phytoremediation strategies that may help improve plant growth and yield in contaminated soils. In this study, we critically analyzed eighty-five research articles published over the past 15 years, focusing on bacteria-assisted remediation strategies for the non-essential heavy metals, arsenic, cadmium, and lead, and selected based on four criteria: i) The bacterial species studied are part of a plant microbiome, i.e., they interact closely with a plant species ii) these same bacterial species exhibit plant growth-promoting characteristics, iii) bacterial resistance to the metal(s) is expressed in terms of the Minimum Inhibitory Concentration (MIC), and iv) metal resistance is related to biochemical or molecular mechanisms. A total of sixty-two bacterial genera, comprising 424 bacterial species/strains associated with fifty plant species were included in our analysis. Our results showed a close relationship between the tolerance level exhibited by the bacteria and metal identity, with lower MIC values found for cadmium and lead, while resistance to arsenic was widespread and significantly higher. In-depth analysis of the most commonly evaluated genera, Agrobacterium, Bacillus, Klebsiella, Enterobacter, Microbacterium, Pseudomonas, Rhodococcus, and Mesorhizobium showed significantly different tolerance levels among them and highlighted the deployment of different biochemical and molecular mechanisms associated with plant growth promotion or with the presence of resistance genes located in the cad and ars operons. In particular, the genera Klebsiella and Enterobacter exhibited the highest levels of cadmium and lead tolerance, clearly supported by molecular and biochemical mechanisms; they were also able to mitigate plant growth inhibition under phytotoxic metal concentrations. These results position Klebsiella and Enterobacter as the best potential candidates for bioremediation and bacteria-assisted phytoremediation strategies in soils contaminated with arsenic, cadmium, and lead. |
| Databáze: | OpenAIRE |
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