Microbes as Bio-Control Agents and Bio-Fertilisers

Introduction

Microbiological tools such as biofertiliser and biocontrol agents are bacteria and fungi which are capable of promoting plant growth and health, they have been produced and are being used for many decades now. Biofertilizers have the potential to increase agricultural yields and they are also proven environmentally very beneficial. Biofertilizers are living microorganisms containing substances that take over the rhizosphere, internal parts of the plant and help in the growth of the plant when applied to soil, seeds, or plant surfaces. Bacteria or fungi capable of nitrogen fixation, phosphate solubilization, sulphur oxidation, plant hormone synthesis, or organic compound decomposition are commonly used as biofertilisers. Biocontrol agents are microorganisms that can potentially replace hazardous pesticides. Biological control is a non-chemical way of controlling plant diseases that involve the use of other living organisms such as bacteria. Hence the Microbes being bio-control agents and bio-fertilizers are important for farmers. 

Plant-Growth-Promoting Rhizobacteria (PGPR)

Plant-growth-promoting rhizobacteria is a bacteria used as a potent biofertilizer and very effective biocontrol agent. PGPR invades the rhizosphere of many plant species, causing favourable and positive benefits like improved plant growth, reduced susceptibility to illnesses and diseases caused by the plant pathogens such as nematodes, fungus, bacteria, and viruses. Alcaligenes, Arthrobacter, Azospirillum, Azotobacter, Bacillus, and Burkholderia are the genera with the most well-known PGPR. Enterobacter, Klebsiella, Pseudomonas, Rhizobium, and Serratia are some of the most common bacteria. Increased seed germination rate, better growth of root, good yield, increased leaf area, increased chlorophyll content and nutrient uptake, protein content, hydraulic activity, abiotic stress tolerance, increased weight of shoot and root and delaying of senescence are some of the advantages of PGPR.

Rhizobia

Rhizobia are one of the oldest agricultural tools used in day-to-day agricultural practices. The commercial manufacturing of rhizobia began out at the starting of the 19th century. The Rhizobia can shape nodules with legumes. Whereas their agricultural use is as a substitute constrained to the leguminous crop plants, Also the nitrogen-solving cyanobacterial symbiosis with Azolla is very much used as manure in rice cultivation Fields. Nitrogen-fixating bacteria can expand nodules within legumes. Although its agricultural use is restricted to leguminous crop plants, the nitrogen-solving cyanobacterial symbiosis with Azolla is typically used as inexperienced manure in rice cultivation.

Mycorrhizal Fungi

Apart from PGPR, mycorrhizal fungi are the most widely used biofertilizers on the earth. They help the crop plants acquire water and nutrients, mainly phosphorus; they reduce abiotic stress; and they work as biocontrol agents against root-damaging diseases from the genera Fusarium, Pythium, and Phytophthora, as well as nematodes. By raising the antioxidant and vitamin content of edible sections, mycorrhizal fungus improves the food-quality qualities of crop plants.

The Importance Bio-Fertilizers and Its Advantages

• The Biofertilizer Microbes are used to fix nutrients in the soil, particularly when there is a lack of nitrogen

• The use of microorganisms as fertilizers greatly aids plant growth while also retaining soil richness

• The Biofertilizer is a live creature that contributes to the conversion of complex organic materials into simpler molecules. This allows the plants or trees to absorb the nutrients more easily

• Rather than restricting growth, microorganisms aid in the escalation of the process of growth within plants, particularly when it comes to the growth of new seeds

Microbes as Biocontrol

Plant pathogens are biologically controlled by microbial biological control agents, which work in a variety of ways. Without any direct contact with the intended pathogen, some interact with plants via developing resistance or priming them. Others modulate the pathogen’s development environment through nutritional competition or other ways. Antibiotics work by interfering with the pathogen directly through hyperparasitism and antibiosis. These interactions are tightly controlled metabolic pathways that frequently combine many mechanisms of action.

There are 3 basic bio-pest control strategies: classical or importation, in which a pest’s natural enemy is introduced in high hopes of achieving control; inductive or augmentation, in which a huge population of natural enemies is introduced for faster pest control; and inoculative or conservation, in which natural enemies are maintained through the regular introduction. 

Conclusion

Microbial inoculants, in general, are potential tools for sustainable agriculture because, when used properly, they can promote plant health and also stimulate plant growth and improve nutrient availability and uptake by the plant.