What Microorganisms Drive the Terramation Process? The Biology Explained (colloquially referred to as human composting)

The microorganisms that drive the terramation process are primarily bacteria — specifically a group called thermophilic bacteria — working alongside fungi in a carefully managed aerobic environment. These microorganisms are not added artificially. They are already present in the organic materials placed in the vessel (wood chips, straw, and similar amendments) and on and within the human body itself. Together, under the right conditions of heat, moisture, and oxygen, they break down organic material into stable, nutrient-rich soil. The result is a process that is both biologically ancient and scientifically precise — the same fundamental microbiology as industrial composting, applied and regulated for human remains.

What microorganisms drive the terramation process?

Terramation is driven primarily by thermophilic bacteria — heat-loving organisms that thrive above 131°F and perform the bulk of organic breakdown — working alongside mesophilic bacteria in early and curing phases, and fungi that break down lignin in wood chips. All of these microorganisms are naturally present in the body and in bulking materials; none are artificially introduced.

Thermophilic bacteria (active above 131°F / 55°C) are the primary decomposers during the active phase, breaking down proteins, fats, and complex organic molecules rapidly.
Mesophilic bacteria initiate the process before temperatures rise and re-establish dominance during the curing phase after the thermophilic phase concludes.
Fungi — especially white-rot fungi — produce ligninase enzymes that break down lignin in wood chips, unlocking carbon that bacteria cannot access on their own.
No microorganisms are artificially added; they come from the organic bulking materials and the body itself.
Sustained thermophilic temperatures eliminate pathogens because pathogenic organisms are adapted to body temperature (98.6°F), not the 131–160°F of the active NOR phase.
The two-phase structure (thermophilic then curing) mirrors high-quality industrial composting and is consistent with established aerobic composting science.

What Types of Microorganisms Are Involved in Terramation?

Terramation relies on two main categories of microorganisms: bacteria and fungi. Bacteria do the heaviest lifting. Fungi play a supporting role, particularly with materials that are harder to break down.

Within the bacterial category, there are two important sub-groups defined by the temperature at which they do their best work.

Mesophilic bacteria are active at moderate temperatures — roughly 50°F to 110°F (10°C to 45°C). These are the organisms that are everywhere in the natural environment: in soil, in compost piles, and in the human gut. They are the first to get to work at the start of the terramation process, when temperatures in the vessel are still building. Think of them as the opening act — essential for getting the biological process started, but not capable of driving the intense decomposition that the main phase requires.

Thermophilic bacteria are the primary drivers of terramation. These organisms thrive at high temperatures — above 131°F (55°C), with some species active at temperatures as high as 160°F (71°C). The name comes from the Greek thermos (heat) and philos (loving). Where mesophilic bacteria slow down and become inactive in intense heat, thermophilic bacteria accelerate. They are specifically adapted to the high-temperature conditions that develop inside a well-managed NOR vessel, and they are responsible for the rapid, thorough breakdown of organic material that defines the active phase of the process.

Fungi contribute primarily by breaking down lignin — the tough structural compound that gives wood its rigidity. Wood chips are a primary amendment material in terramation vessels, and lignin is resistant to bacterial degradation. Fungi produce enzymes that can penetrate and break apart lignin’s molecular structure, making the carbon and nutrients within it available to bacteria. Fungi are most active early in the process and during the curing phase; they become less dominant once temperatures climb into the thermophilic range.

How Do Bacteria Drive the Active Decomposition Phase?

The active decomposition phase — sometimes called the thermophilic phase — is where most of the biological transformation happens.

When remains and organic amendment materials are loaded into the vessel, mesophilic bacteria begin metabolizing the available organic matter almost immediately. Their activity generates heat as a byproduct, raising the temperature inside the vessel. As temperature climbs past roughly 110°F (45°C), mesophilic bacteria slow down — and thermophilic bacteria take over. They metabolize organic material far more rapidly, generating even more heat and driving temperatures into the 131–160°F (55–71°C) range. The system creates the conditions that sustain itself.

This is an aerobic process — it requires oxygen. NOR operators manage airflow within the vessel to keep oxygen available throughout the materials. This distinguishes NOR from anaerobic decomposition (decomposition without oxygen), which produces methane, hydrogen sulfide, and the foul odors of unmanaged biological breakdown. By keeping the process aerobic, NOR avoids those byproducts and maintains an environment where thermophilic bacteria remain in control.[^1]

What Role Do Fungi Play in the Terramation Process?

Fungi are less talked about in discussions of terramation, but they serve an important function — one that bacteria largely cannot perform on their own.

Wood chips are among the most common amendment materials used in NOR vessels. They provide structure (keeping the material aerated so oxygen can move through it), moisture regulation, and a carbon-rich energy source for microbial activity. But wood chips contain significant amounts of lignin, and lignin is chemically resistant. Bacteria struggle to break it down efficiently, particularly in the early stages of the process.

Fungi — specifically the category known as lignin-degrading fungi or white-rot fungi — produce a specialized enzyme called ligninase that dismantles lignin’s complex molecular structure. This enzymatic action makes the carbon locked within wood chips accessible to the broader microbial community. Without fungal activity, the carbon in wood chips would remain largely unavailable, slowing the overall process and reducing the richness of the resulting soil.[^2]

Fungi are most active during two windows: early in the process, before temperatures rise into the thermophilic range, and again during the curing phase at the end (more on that below). During the thermophilic phase — when temperatures exceed 131°F — most fungi become inactive. They are mesophilic or moderately thermotolerant organisms, not extreme thermophiles. This is fine: by the time the thermophilic phase is well underway, the fungi have already done much of their lignin-breakdown work.

Why Does Temperature Matter So Much to Microbial Activity?

Temperature is the central variable in terramation — the condition that determines which microorganisms are active, how fast they work, and critically, which organisms do not survive.

The thermophilic phase serves two purposes simultaneously. First, it accelerates decomposition. Thermophilic bacteria metabolize organic material at a rate that would take months under ambient conditions and compress it into the active decomposition window. Second, and equally important, sustained high temperatures eliminate pathogens.

Pathogens — disease-causing microorganisms — are generally not thermophilic. They are adapted to the temperature environment of a living human body (around 98.6°F / 37°C) or the cooler temperatures of soil and water. When temperatures in the NOR vessel sustain above 131°F (55°C) for an extended period, these organisms cannot survive. This is the same principle behind pasteurization, autoclaving, and — in composting — the EPA’s Process to Further Reduce Pathogens (PFRP) standards, which require sustained thermophilic temperatures as proof of pathogen reduction.[^3]

Washington State, the first to legalize NOR in 2019, built this principle directly into its regulatory framework. The state’s rules specify minimum time-temperature requirements for NOR vessels — ensuring that the thermophilic phase is sustained long enough to achieve pathogen elimination before the resulting soil can be returned to families or used in memorialization.[^4] Other states with operational NOR programs have adopted similar standards.

This temperature requirement is also why the process duration cannot be arbitrarily shortened. The thermophilic phase must be sustained — not merely reached — for the process to be both complete and safe. NOR operators monitor vessel temperatures throughout the process to confirm compliance with these standards. For a detailed look at how NOR eliminates pathogens and what makes the resulting soil safe, see our article on terramation safety and pathogen elimination.

Have questions about the terramation process? Our team works with families and funeral professionals across the 14 states where NOR is currently legal. Learn more about terramation providers near you

What Happens During the Curing Phase?

After the thermophilic phase, the process enters a curing phase — a period of lower-temperature activity that stabilizes the material into finished soil.

Mesophilic bacteria and fungi re-establish dominance. These organisms work through the more resistant organic compounds that remain after the thermophilic phase, building the stable humus — the dark, rich organic fraction of soil — that gives finished terramation soil its characteristic structure and nutrient density.[^5] The microbial community reaches biological equilibrium, transitioning from an intense decomposition environment to something resembling mature compost.

This two-phase structure mirrors what happens in high-quality industrial composting operations. The Washington State University Extension, which conducted early applied research on NOR, noted explicitly that NOR’s biological mechanics are consistent with established aerobic composting science, adapted for human remains.[^6]

The total process — active phase through curing — typically takes several weeks to a few months, depending on the system. To understand how NOR unfolds step by step, see: How Does Natural Organic Reduction Work?

Curious about NOR for yourself or someone you love? Natural organic reduction is now legal in 14 states, with more states considering legislation. Ready to explore terramation options? Contact TerraCare Partners

Sources

Rynk, R., et al. The Composting Handbook: A Practical Guide to Making and Using Compost. Academic Press, 2022.
Hatakka, A. “Lignin-modifying enzymes from selected white-rot fungi: production and role in lignin degradation.” FEMS Microbiology Reviews, 13(2–3), 1994, pp. 125–135.
United States Environmental Protection Agency. Environmental Regulations and Technology: Control of Pathogens and Vector Attraction in Sewage Sludge. EPA/625/R-92/013.
Washington State Department of Ecology. Natural Organic Reduction: Overview and Regulatory Framework. Olympia, WA: Washington DOE, 2020.
Epstein, E. Industrial Composting: Environmental Engineering and Facilities Management. CRC Press, 2011.
Washington State University Extension. Natural Organic Reduction of Human Remains: A Review of the Science. WSU Extension Publication, 2019.
Haug, R.T. The Practical Handbook of Compost Engineering. CRC Press/Lewis Publishers, 1993.
Neher, D.A., et al. “Biological indices differentiate broad categories of land use on composted and non-composted soils.” Applied Soil Ecology, 5(3), 1997, pp. 241–251.

For a broader look at how NOR works from the first step to soil return, visit our complete guide to natural organic reduction. For a state-by-state overview of where NOR is currently legal, see our state guides.

TerraCare Partners | Last Updated: April 2, 2026