Bacillus stearothermophilus
Thermophilic Bacillus
Bacillus stearothermophilus — High-temperature Compost Specialist
Thermophilic bacilli such as Bacillus stearothermophilus (some strains reclassified as Geobacillus) thrive at 55–65°C during aerobic composting. They generate heat, degrade organic matter in the thermophilic phase, and help maintain pathogen-reduction windows — key process strains for industrial and farm-scale compost.
Mechanisms of Action
Thermophilic Activity
Optimal around 55–65°C — active in the compost thermophilic phase, unlike mesophilic Bacillus.
Heat Maintenance
Works with B. subtilis: mesophiles kick-start heating; thermophiles help hold core pile temperature.
Hot-phase Breakdown
Degrades protein, starch, and some fiber at high temperature, softening feedstock and reducing volume.
Heat-tolerant Spores
Heat-stable spores suit process inoculation and storage; dormant after cooling, minimal carryover to cropping.
Product Specifications
Application Methods
Pile inoculation: 0.1-1% of feedstock, expand on bran or mature compost 24-48 h, mix at build
Blend option: Pair with B. subtilis at ~3:7 to 4:6 for start-up plus heat holding
Thermophilic phase: Turn and aerate once core reaches 55°C; avoid sealed anaerobic conditions
Stop after cooling: Below 45°C core, switch to mesophilic maturation or stop re-inoculation
Application Scenarios
Aerobic high-temperature composting of manure, straw, food waste, and blended organics — a process inoculant, not a primary field biocontrol product