Beneficial Soil Bacteria can increase the plant’s ability to absorb nutrients and/or promote plant growth. Through direct competitive effects, they produce antimicrobial substances and protect the root surfaces of plants from pathogenic microbes. These bacteria can affect plant growth either right away or incidentally.
The benefits of having these bacterial populations in the soil are numerous. They can help to improve the availability of nutrients for the plants, increase plant growth, and protect plants from disease. In addition, they can also help to break down organic matter, which helps to improve nutrient availability.
Soil organisms and their beneficial and harmful roles
The increase in nutrient availability is primarily due to the production of enzymes by these bacteria. Specifically, they are able to break down compounds that are insoluble to plants, which results in them becoming available for uptake. Some of these compounds include organic matter and certain minerals such as iron. They also produce siderophores, which are compounds that can attach to iron molecules in the soil. This enables plants to absorb the iron directly from the rhizospheric bacteria.
While these populations tend to be higher in soils where plants are growing (i.e., plant-associated bacteria), they increase their activity when plants are decomposing (i.e., common in the rhizosphere).
Pineapple plant roots are full of beneficial bacteria.
When added to soils, these populations can quickly out-compete other soil microbes and thus control soil quality. They also produce metabolites that can suppress plant pathogens and nematodes.
The use of beneficial soil bacteria is a key part of sustainable agriculture. By increasing nutrient availability and promoting plant growth, these populations can help to improve crop yields while reducing the need for fertilizers and pesticides. In addition, they can also help to improve the soil quality, which is important for
Plant growth-promoting rhizobacteria, (PGPR), integrate phytohormones and distribute them in their surroundings and rhizospheric environment. These phytohormones are known as plant growth regulators. These microorganisms can play a huge regulatory role in plant developmental and growth-related processes. PGRs are organic compounds having a profound effect on the functional processes of plants at exceptionally lower levels.
There are five main classes of PGRs including auxins, gibberellins, cytokinin, and ethylene. The role of the phytohormone auxin has received much attention. Indole-3-acetic Acid (IAA) is physiologically the most effective auxin for plants. It is well-known to encourage both short-term (e.g. cell elongation) and long-term (e.g. cell division and differentiation).
These compounds have huge potential to indirectly improve plant growth on a sustainable basis. It is therefore difficult to detect and quantify them for proper studies. Cytokinin has a noticeable effect on plants, with an increase in cell division.
However, it can also have an impact on root development and root hair growth. Over 30 growth-stimulating compounds belonging to the cytokinin family have been discovered in plants and microorganisms that are plant-associated. In vitro culture of microorganisms in the rhizosphere has shown that up to 90% can release cytokinin.
Sustainable Approach of Using Bacteria for Soil
Many bacteria species can produce ethylene. Ethylene can be used to regulate plant growth and development and it also affects senescence. Ethylene is recognized as a ripening hormonal. It encourages the formation of adventitious roots and root hairs, accelerates germination, and breaks down dormancy in seeds.
Feeding Soil Microbes for Removing Soil Contaminants
PGPR can also be used to treat contaminated soils as it mineralizes organic compounds in conjunction with plants. The combined use of PGPR and particular contaminant-damaging bacteria can efficaciously remove multifaceted pollutants. Certain rhizobacteria may increase Ni uptake from soils by changing the phase of the bacteria and Bacillus and Pseudomonads are most important in this regard.
They are used in bioremediation and can further be used for cleaning up pollutants from iron, copper, and silver mines. Some bacteria can remove carbon, nitrogen, and phosphorous compounds. Others can remove toxic metals as well as pesticides and herbicides. These multi-step processes involve both anaerobic and aerobic metabolisms.
Beneficial Soil Microorganisms
Indirect plant growth promotion is related to the inhibition of harmful impacts from phytopathogenic organisms. The use of siderophores is essentially an important way to achieve this growth improvement and development.
The production of siderophores allows bacteria to fight against pathogens by eradicating iron from their surroundings or the environment. Pseudomonads and Frankia are very familiar with siderophore production. They also produce iron-chelating compounds. Many bacterial species are also capable of synthesizing antibiotics and soil-borne pathogens. Rhizobacteria also prevent phytopathogens through the production of hydrogen cyanide (HCN), and/or fungal wall-destroying enzymes, such as chitinase, ss-1, and 3-glucanase.
Microbial Soil Amendments A Significant Sustainable Approach
Research has demonstrated the feasibility of introducing beneficial soil microbes to marketable peat-based substrates used for vegetable and fruits production. Trials on muskmelon and watermelon showed that a variety of PGPR formulations reduced the severity of root-knot nematode diseases.
Beneficial Soil Organisms
Soil microorganisms and soil biota have a direct role to improve plant growth, development, and nutritional contents of produce on a sustainable basis. To develop targeted products and meet specific consumer demands, strategies that focus on understanding the potential actions of microbes are crucial.
It is important to foster closeness to growers as farmers’ acceptance must be a priority. It is also important to note that the success of subsequent generation agro-inputs using microbial inoculants will depend on regulatory clarity and a cooperative mindset. This is where farmers, scientists, advisors, and policymakers can all work together. This will allow us to move towards integrated, profitable ecosystems that use all inputs following healthy principles.
It also helps us to optimize nutrient utilization efficiency in an environment where climate changeability is constantly endangering our food productivity. Therefore, there is a dire urgent need for strong and efficient collaboration between researchers, leading scientists, governments, international organizations, and policymakers to promote the use of beneficial microbial strains all over the globe.