Phanerochaete chrysosporium

Introduction

Phanerochaete chrysosporium is a lignin-degrading fungus that plays a critical role in composting high-fiber agricultural residues and woody biomass. It belongs to the group of white-rot fungi, which are uniquely capable of degrading complex polymers such as lignin — a compound most microbes cannot process. This makes it invaluable in composting systems dealing with straw, wood chips, coir pith, and similar materials.

Scientific Description

Phanerochaete chrysosporium is a Basidiomycete fungus classified under the family Phanerochaetaceae. It is aerobic and thrives in high-carbon, low-nitrogen environments. The fungus produces extracellular oxidative enzymes such as lignin peroxidase (LiP), manganese peroxidase (MnP), and laccases, which enable it to break down lignin and related aromatic compounds.

Key biological mechanisms:

• Oxidative Lignin Degradation: Attacks lignin bonds using a radical-based mechanism that few organisms possess.
• Selective Decomposition: Degrades lignin faster than cellulose, improving C:N balance for compost microbes.
• High Carbon Tolerance: Effective in substrates with high C:N ratios such as sawdust and straw.
• Non-pathogenic: Safe for plants and soil microbiota; leaves no toxic residues.

Benefits

• Breaks Down Lignin-Rich Wastes: Enables composting of sugarcane trash, wheat straw, coir pith, sawdust, and wood shavings.
• Accelerates Decomposition: Converts slow-degrading biomass into microbial-available carbon.
• Improves Compost Structure: Contributes to finer, well-humified compost texture with good water retention.
• Supports Microbial Succession: Prepares substrate for colonization by other bacteria and fungi (e.g., Bacillus, Trichoderma).
• Safe for Use: No phytotoxic byproducts; enhances nutrient cycling.

Uses

• Waste Types: Paddy straw, wheat straw, cotton stalks, coconut coir, sugarcane bagasse, tree leaves, paper sludge.
• Application Methods:
  • Compost starter: 1–2 kg dry culture or 1–2 L liquid per ton of lignin-rich waste
  • Pre-treatment: Used in dedicated pits or heaps to pre-treat fibrous materials before main composting
  • Combined systems: Used alongside Bacillus and Trichoderma in lignocellulosic compost accelerators
• Ideal Conditions: 30–40°C, well-aerated piles, low nitrogen levels (~C:N 40–50:1) at start for efficient lignin breakdown

Trivia

• P. chrysosporium was the first fungus found capable of degrading DDT, PCBs, and other persistent organic pollutants in soil.
• It’s often used in research on bioremediation of industrial sludge and dye-contaminated wastewater.
• Unlike most fungi, it performs better in nitrogen-limited conditions.
• Inoculated straw composts treated with this fungus are notably darker and more crumbly, with higher humic acid content.