How do bacteria and fungi digest food outside their cells?

Bacteria and fungi digest food outside their cells through a process known as extracellular digestion or osmotrophic nutrition. Because these organisms lack the specialized structures required to ingest bulk food, they rely on the direct absorption of small nutrient molecules.12

To obtain these nutrients, bacteria and fungi secrete enzymes directly onto the organic material in their environment. These biological catalysts break down large, complex molecules—such as proteins, starches, and cellulose—into smaller, simpler units like amino acids and simple sugars.3124

Once the food is broken down into these smaller, soluble molecules, it can be absorbed directly through the cell walls or membranes of the organism. This process is essential for decomposition and nutrient cycling, as it allows these microorganisms to transform complex organic matter into substances that they, and other organisms, can utilize for growth and energy.31256