6.16—Microorganisms in decomposition and carbon recycling

Bacteria and fungi secrete enzymes that digest large molecules in dead tissue into smaller molecules. They absorb and respire these products, releasing carbon dioxide and sometimes methane.

Decomposition returns carbon to the atmosphere and leaves nutrients available for reuse. Oxygen availability changes the pathway and the gases produced.

In an aerobic compost heap, decomposers release carbon dioxide while breaking down plant material; an anaerobic saturated site can produce methane instead.

Decomposers do not “destroy” carbon; they transfer it between organic matter, gases and soil. Gas output depends on conditions, not a fixed single product.