Pseudomonas fluorescens

Introduction

Pseudomonas fluorescens is one of the most researched plant-growth-promoting and biocontrol bacteria used in agriculture. It supports plant development through hormone stimulation and nutrient mobilization, while also protecting crops from fungal and bacterial pathogens. It is a key component in integrated disease management and sustainable farming practices.

Scientific Description

Pseudomonas fluorescens is a gram-negative, rod-shaped, aerobic bacterium with a characteristic fluorescent pigment (pyoverdine) that gives colonies a greenish glow under UV light. It thrives in the rhizosphere and produces a wide variety of metabolites that suppress pathogens and promote plant health.

Key mechanisms:

• Antibiosis: Produces antibiotics like 2,4-diacetylphloroglucinol (DAPG), pyoluteorin, and phenazines.
• Siderophore Production: Sequesters iron, limiting availability to competing pathogenic microbes.
• Induced Systemic Resistance (ISR): Primes plant immune responses against foliar and root diseases.
• Phytohormone Production: Produces auxins (IAA), enhancing root growth and nutrient uptake.
• Biofilm Formation: Adheres effectively to roots, ensuring colonization and sustained activity.

Benefits

• Suppresses Soil-Borne Pathogens: Effective against Fusarium, Rhizoctonia, Pythium, Phytophthora, Sclerotinia, and more.
• Promotes Root Development: Encourages fine root proliferation and increased surface area for nutrient absorption.
• Induces Resistance in Plants: Strengthens natural immunity, reducing dependence on chemical fungicides.
• Improves Nutrient Uptake: Solubilizes phosphate and chelates iron through siderophores.
• Multipurpose Use: Works as seed treatment, soil application, and foliar spray — covering multiple disease stages.

Uses

• Crops Benefited: Rice, wheat, cotton, sugarcane, vegetables (tomato, chili, brinjal), groundnut, banana, and ornamentals.
• Target Diseases: Damping-off, wilt, root rot, sheath blight, and leaf spots.
• Application Methods:
  • Seed treatment: 5–10 g/kg seed
  • Soil drenching: 1–2 L/acre in liquid form
  • Foliar spray: 0.5% suspension during disease pressure
• Co-usage: Compatible with Trichoderma, Bacillus subtilis, and biofertilizer consortia

Trivia

• Its fluorescent pigment was first observed in spoiled meat — hence the name.
• Frequently used as a model organism in biocontrol studies.
• Forms the basis of several commercial biopesticide formulations globally.
• Can be used in both conventional and organic farming systems without residue concerns.