What is the role of plant growth promoting microbes and application of plant growth-promoting rhizobacteria in bioremediation of heavy metal polluted soil?
Plant growth-promoting microbes (PGPM) are microorganisms that can enhance plant growth and development. They can do this in a variety of ways, including:
- Increasing nutrient availability
- Producing phytohormones
- Reducing plant stress
- Suppressing plant diseases
Plant growth-promoting rhizobacteria (PGPR) are a specific type of PGPM that live in the rhizosphere, or root zone, of plants. They have a particularly close relationship with plants and can play a significant role in promoting plant growth and health in metal-polluted soils.
Role of PGPM in bioremediation of heavy metal polluted soil
PGPM can play a role in the bioremediation of heavy metal polluted soil in a number of ways, including:
- Mobilization of heavy metals: PGPM can produce organic acids and other compounds that can chelate heavy metals, making them more bioavailable and easier for plants to absorb.
- Immobilization of heavy metals: PGPM can also produce extracellular polymeric substances (EPS) that can bind to heavy metals and prevent them from being absorbed by plants.
- Reduction of heavy metals: Some PGPM can reduce heavy metals to less toxic forms.
- Promotion of plant growth: PGPM can promote plant growth and development, which can help plants to better tolerate heavy metal stress.
Application of PGPR in bioremediation of heavy metal polluted soil
PGPR can be applied to metal-polluted soils in a number of ways, including:
- Seed inoculation: PGPR can be applied to seeds before planting. This will help to ensure that the plants are colonized by PGPR from the start.
- Soil application: PGPR can also be applied to the soil around existing plants. This can be done by watering or drenching the soil with a solution of PGPR.
- Biofertilizers: PGPR can also be incorporated into biofertilizers, which are slow-release fertilizers that can provide plants with nutrients and PGPR over an extended period of time.
Examples of PGPR used in bioremediation of heavy metal polluted soil
Some examples of PGPR that have been used in bioremediation of heavy metal polluted soil include:
- Azospirillum brasilense
- Pseudomonas fluorescens
- Bacillus subtilis
- Rhizobium leguminosarum
- Glomus intraradices
Conclusion
PGPM and PGPR can play a significant role in the bioremediation of heavy metal polluted soil. They can help to mobilize, immobilize, and reduce heavy metals, as well as promote plant growth and development. This can help to reduce the risk of heavy metal toxicity to plants and animals, and improve the overall health of the ecosystem.
Microorganisms have the potential to improve plant growth under abiotic stress conditions by promoting the production of low-molecular-weight osmolytes, such as glycinebetaine, proline, and other amino acids, mineral phosphate solubilization, nitrogen fixation, organic acids, and producing key enzymes. Beneficial microbes improve plant growth by enhancing the availability of nutrients, the regulation of phytohormones, and increasing plant tolerance against stresses. PGPM act as biofertilizer, increasing macro and micronutrient availability. PGPR contain nitrogen fixing and symbiotic bacteria e.g. different species of Rhizobium, Azospirillum, Azotobacter, Mycobacterium, Bacillus, Azobacter, Serratia, Xanthomonas, Proteus, Pseudomonas, Clostridium etc. Bioremediation is a process that can be applied to reduce the adverse effects of heavy metals in the soil. In this regard, bioremediation using plant growth–promoting rhizobacteria (PGPRs) as beneficial living agents can help to neutralize the negative interaction between the plant and the heavy metals. There are mainly two aspects through which biochar can effectively decrease the activities of heavy metals by precipitation. The increasing pH due to the biochar amendment of soil may lead to decreased heavy metal mobilization, thus forming heavy metal hydroxide precipitation. For remediation of wetland water, aquatic species such as hyacinth, azolla, duckweed, cattail, and poplar are commonly used due to their high accumulation of heavy metals, high tolerance, or fast growth and high biomass production. Since the enzyme ACC deaminase, when present in plant growth-promoting bacteria, can act to modulate the level of ethylene in a plant, lower the stress placed on plants by the presence of heavy metals and therefore ameliorate some of the apparent toxicity of heavy metals to plants.
- Badges
- Science topic
- Similar topics
- Biological Science
- Microbiology
- Microorganisms