Agriculture microbiology: Introduction, Function and interaction

Introduction

Agricultural microbiology is a field of science focused on examining various microorganisms that relate to plants, the health of soil, and diseases in animals. For the past ten years, agricultural microbiology has received a lot of attention because it clarifies how important specific microbial strains are for farming. This knowledge aims to reduce losses in agriculture, enhance soil fertility, and improve crop yields. Agricultural microbiology aids in understanding the unique needs of plants, which involve soil type, nutrients in the soil, moisture levels, and the microorganisms that are linked to them.

The primary type of microorganisms in soil and plants is bacteria. These bacteria exist in a mutually beneficial connection with plants, assisting in important processes such as nitrogen fixation and the supply of minerals.

Functions of microorganisms in agriculture:

• Microorganisms mainly break down organic matter, but they also contribute in various ways, such as supplying nitrogen through fixation for plant growth, breaking down harmful toxins, fighting off disease causing organisms, and creating substances that may enhance plant growth.
• Additionally, soil microorganisms have another critical role for humans, They are the source of most antibiotics that we rely on to combat illnesses.
• Microorganisms linked to farming activities are crucial for soil nutrition, plant well-being, compost making, pest management, and eco-friendly agriculture.

There are various branches of agriculture microbiology:

Soil microbiology focuses on microorganisms that are in soil, these microorganisms use to improve the soil health, soil fertility. Soil has micronutrients & Macronutrients that are direct or indirectly play role to improve soil health & fertility in nutrients the mains are carbon nitrogen, phosphorus, potassium, sulphur & zinc are most important for plant health.

Soil microbial communities

• Bacterial communities: Types of bacteria in soil.
  • Decomposers: They break down organic substances into humus (for example, Bacillus, Pseudomonas).
  • Nitrogen-Fixing Bacteria: They change nitrogen from the atmosphere into forms that plants can use.
    • Symbiotic: Rhizobium (found in legumes), Frankia (associated with actinorhizal plants).
    • Free-living: Azotobacter, Azospirillum.
  • Phosphate-Solubilizing Bacteria (PSB): They convert inorganic phosphate into usable forms (like Bacillus, Pseudomonas, and Serratia).
  • Potassium-Solubilizing Bacteria (KSB): They help release potassium from minerals (such as Bacillus mucilaginosus).
  • Sulfur-Oxidizing Bacteria: They transform sulfur into sulfate (like Thiobacillus).
  • Pathogenic Bacteria: They lead to diseases in plants (such as Xanthomonas).
• Fungal communities: Types of fungus in soil.
  • Decomposers (Saprophytic Fungi): They break down organic matter, cellulose, and lignin. Trichoderma, Penicillium, Aspergillus.
  • Mycorrhizal Fungi: They create beneficial partnerships with roots of plants, helping in the absorption of nutrients.
    • Arbuscular Mycorrhizal Fungi (AMF): They improve the uptake of phosphorus (Glomus, Rhizophagus).
    • Ectomycorrhizal Fungi: They connect with trees (Pisolithus, Suillus).
• Pathogenic Fungi: They lead to diseases in plants.
  • Fusarium (root rot), Phytophthora (late blight), Rhizoctonia (damping-off).
• Biocontrol Fungi: They reduce plant pathogens.
  • Trichoderma (fights against fungal pathogens), Beauveria bassiana (used for controlling insects).
• Actinomycete communities: Actinomycetes are thread-like bacteria similar to fungi. They create antibiotics and enzymes that operate outside their cells. These bacteria are mainly found in dry, alkaline, and low-nutrient soils.
  • Functions of Actinomycetes in Soil:
    • Decomposers: They dismantle complex organic materials (for example, Streptomyces, Micromonospora).
    • Antibiotic Producers: They help control plant diseases (like how Streptomyces makes streptomycin).
    • Nitrogen Fixation: Certain actinomycetes, such as Frankia, help convert atmospheric nitrogen in partnership with plants.

Plant microbe interaction

This area examines both positive and negative interactions between plants and microorganisms.

It consists of useful Microorganisms:

• Rhizobium and legumes: Rhizobium bacteria create nodules on the roots of legumes and help in nitrogen fixation from the air.
• Mycorrhizal fungi: These types of fungi improve the absorption of nutrients, particularly phosphorus.
• Phosphate-Solubilizing Bacteria (PSB): Microorganisms such as Bacillus, Pseudomonas, and Azospirillum dissolve phosphate, making it accessible for plants.
• Endophytic Microbes: Certain bacteria and fungi reside within plant tissues, aiding in growth or providing protection from diseases.
• Plant Growth-Promoting Rhizobacteria (PGPR): Bacteria, including Bacillus subtilis and Azospirillum brasilense, generate plant hormones like auxins and gibberellins.

Bio pesticides & Bio fungicides

This area is dedicated to utilizing helpful microbes to manage plant diseases, insects, and weeds instead of relying on chemical pesticides.

• Bacterial Biocontrol Agents: Bacillus thuringiensis (BT) generates toxins that are harmful to insects. Pseudomonas fluorescens fights against plant diseases by producing antibiotics.
• Fungal Biocontrol Agents: Trichoderma species work against fungal diseases such as Fusarium and Phytophthora.
• Viral Biocontrol Agents: Baculoviruses are designed to specifically attack insect pests.
• Nematode Control Microbes: Pasteuria penetrans feeds on nematodes that harm plants.

Compost & Waste Management Microbiology

Composting and Waste Management microorganisms are essential in breaking down organic materials, creating compost, and restoring nutrients.

Microorganisms in Composting:

• Bacteria: Bacillus, Pseudomonas, and Actinomycetes.
• Fungi: Aspergillus and Penicillium.
• Decomposition of Cellulose and Lignin: Trichoderma and Phanerochaete chrysosporium are involved in breaking down plant materials.
• Production of Biogas: Anaerobic organisms such as Methanobacterium turn organic substance into methane gas.
• Treatment of Industrial Waste: Certain bacteria can break down harmful substances found in industrial waste.

Reference and Sources:

• https://quizlet.com/107306418/nitrogen-cycle-flash-cards/
• https://microbiologynotes.org

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