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E-Book 3rd Congress

  • Metarhizium robertsii: A Versatile Fungus for Bioremediation and Plant Growth Promotion
  • Seyed Ali Sadr Tabatabaee,1 Maliheh Entezari,2,*
    1. Bachelor’s student, Microbiology group, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran.
    2. Farhikhtegan Medical Convergence sciences Research Center , Farhikhtegan Hospital Tehran Medical sciences ,Islamic Azad University,Tehran,Iran


  • Introduction: Metarhizium robertsii is a fascinating fungus with diverse capabilities that make it a valuable asset in bioremediation and plant growth promotion. This species of fungus belongs to the genus Metarhizium, which is known for its insect-pathogenic and endophytic properties. However, recent research has unveiled the remarkable potential of M. robertsii in addressing environmental challenges and enhancing agricultural productivity. In this manuscript, we will explore the numerous attributes of M. robertsii, its mechanisms of action, and its applications in bioremediation and plant growth promotion. One of the most significant findings regarding M. robertsii is its ability to tolerate and remediate mercury pollution. Mercury contamination poses a serious threat to public health and ecosystems worldwide. M. robertsii has demonstrated its capacity to degrade methylmercury, a highly toxic form of mercury, and reduce divalent mercury, effectively decreasing the accumulation of mercury in plants and promoting their growth. The fungus achieves this through the activity of specific enzymes: methylmercury demethylase (MMD) and mercury ion reductase (MIR). These enzymes play a crucial role in the demethylation of methylmercury and the reduction of divalent mercury to volatile elemental mercury. The ability of M. robertsii to remove mercury from both soil and water makes it a promising candidate for bioremediation efforts.
  • Methods: This article uses an extensive search of PubMed - NCBI and Google Scholar databases - and the study of almost 20 articles and an analysis of the studies done in the last ten years on this issue.
  • Results: The molecular mechanisms underlying M. robertsii's mercury tolerance have been investigated extensively. The MMD enzyme is responsible for the demethylation of methylmercury, converting it into less toxic forms. Through genetic engineering, researchers have enhanced the expression of MMD in M. robertsii, resulting in improved bioremediation capabilities. Similarly, the MIR enzyme facilitates the reduction of divalent mercury to elemental mercury, which can then be volatilized. Overexpression of MIR in M. robertsii has also been shown to enhance its ability to remediate mercury-contaminated environments. Additionally, the presence of MIR homologs in various fungi suggests that the tolerance to divalent mercury is widespread in fungal species. In addition to its bioremediation potential, M. robertsii has been found to promote plant growth. The fungus forms symbiotic relationships with plants, particularly rice, and influences various aspects of plant physiology. When exposed to M. robertsii, rice plants exhibit enhanced growth characteristics, including increased height and above-ground biomass. The fungus also modulates the expression of plant defense genes and phytohormone content, leading to improved resistance against phytopathogens. These findings suggest that M. robertsii can act as a growth-promoting agent, potentially contributing to increased agricultural productivity. The unique properties and capabilities of M. robertsii have led to investigations into its potential for genetic engineering. Researchers have successfully overexpressed key enzymes involved in mercury tolerance, such as MMD and MIR, resulting in improved bioremediation capabilities. This genetic engineering approach holds promise for further enhancing the fungus's ability to remediate mercury-contaminated environments. Additionally, the identification of genes responsible for plant growth promotion and nutrient selection opens up avenues for genetic manipulation, potentially leading to the development of more efficient biofertilizers and biocontrol agents. While the research on M. robertsii has provided valuable insights, there are still many challenges and questions that need to be addressed. Further studies are needed to elucidate the specific mechanisms by which M. robertsii interacts with plants and modulates their growth and defense responses. Understanding the genetic regulation of these interactions and the underlying signaling pathways will be crucial for harnessing the full potential of M. robertsii in agriculture and environmental remediation. Additionally, field trials and long-term monitoring are necessary to assess the efficacy and sustainability of M. robertsii-based interventions.
  • Conclusion: Metarhizium robertsii is a versatile fungus with immense potential in bioremediation and plant growth promotion. Its ability to tolerate and remediate mercury pollution, as well as its capacity to enhance plant growth and defense, make it a valuable asset in addressing environmental challenges and improving agricultural productivity. The molecular mechanisms underlying M. robertsii's mercury tolerance and its interactions with plants provide a foundation for further research and potential applications. With continued investigations and advancements in genetic engineering, M. robertsii has the potential to become a powerful tool in managing environmental pollution and promoting sustainable agriculture.
  • Keywords: Metarhizium robertsii/MMD enzyme/Mercury