Worm castings (also known as vermicast or worm poop) are incredibly rich in beneficial microorganisms that help create healthy, living soil. These microbes are essential to plant health, soil structure, nutrient cycling, and disease suppression.

Below is a detailed list of the main groups of microorganisms found in worm castings, along with what they do for soil and plants:

🦠 Microorganisms in Worm Castings & Their Functions

1. Bacteria

Types Found:

  • Nitrogen-fixing bacteria (e.g., Azotobacter, Rhizobium)

  • Decomposers (e.g., Pseudomonas, Bacillus)

  • Actinomycetes

What They Do:

  • Decompose organic matter into plant-available nutrients

  • Fix nitrogen from the atmosphere into a usable form (especially in legumes)

  • Suppress pathogens through competition and antibiotic production

  • Help mineralize nutrients like phosphorus and sulfur

2. Fungi

Types Found:

  • Saprophytic fungi (e.g., Trichoderma)

  • Mycorrhizal fungi (in smaller quantities unless added externally)

What They Do:

  • Break down tough organic materials (like lignin and cellulose)

  • Form symbiotic relationships with plant roots (mycorrhizae), increasing nutrient and water uptake

  • Outcompete or inhibit harmful fungi in the soil

3. Protozoa

Types Found:

  • Amoebae

  • Flagellates

  • Ciliates

What They Do:

  • Feed on bacteria, helping to keep bacterial populations in balance

  • Release nutrients like nitrogen in plant-available forms through their waste

  • Enhance microbial turnover, increasing nutrient cycling speed

4. Nematodes (Beneficial Types)

Types Found:

  • Bacterial-feeding nematodes

  • Fungal-feeding nematodes

  • Predatory nematodes (that eat harmful nematodes)

What They Do:

  • Eat microbes and release nitrogen and other nutrients

  • Help control pathogenic nematode populations through predation

  • Improve soil porosity by moving through the soil

5. Yeasts

What They Do:

  • Assist in fermentation of organic matter

  • Compete with pathogenic fungi

  • Produce growth hormones (like auxins and cytokinins)

6. Archaea

What They Do:

  • Involved in nutrient transformations, particularly nitrogen and methane cycling

  • Thrive in extreme or low-oxygen conditions, supporting diverse soil environments

7. Enzymes (Produced by Microbes)

While not microbes themselves, worm castings are full of microbial enzymes like:

  • Amylase, protease, lipase, cellulase, chitinase

What They Do:

  • Break down organic compounds into simpler forms

  • Help suppress pathogens (e.g., chitinase breaks down fungal cell walls)

🌱 Summary Table

Microorganism Group Key Roles Bacteria Decomposition, nitrogen fixation, pathogen suppression Fungi Break down complex matter, improve root function Protozoa Eat bacteria, release nutrients Nematodes Cycle nutrients, eat pests Yeasts Fermentation, hormone production Archaea Extreme condition nutrient cycling Enzymes Breakdown of materials, pathogen suppression