Do Fungi Contain Carbohydrates? The Complete Answer

December 16, 2025 •

4 min read

Carbohydrates can constitute over half of a mushroom's dry weight, demonstrating their critical role in fungal biology. Much like other eukaryotes, fungi rely on these organic compounds for energy, structural integrity, and survival.

Quick Summary

Fungi utilize carbohydrates in various ways, primarily for energy storage as glycogen and for forming rigid cell walls with chitin and glucans. These structural and storage polysaccharides are vital for fungal growth, protection, and metabolism as heterotrophic organisms. Fungi also metabolize a wide array of soluble and insoluble carbohydrates absorbed from their environment.

Key Points

Heterotrophic Nature: Fungi do not produce their own food like plants but absorb carbohydrates from the environment.
Glycogen for Storage: They store energy as glycogen, a branched glucose polymer, which is a characteristic they share with animals, not plants.
Cell Wall Composition: The rigid fungal cell wall is constructed primarily of complex carbohydrate polymers, including chitin and glucans, providing structural integrity.
Chitin for Strength: Chitin, a polymer of N-acetylglucosamine, is a major component of the fungal cell wall, offering strength comparable to the exoskeleton of insects.
Medical Relevance: The unique carbohydrate makeup of fungal cell walls makes them an excellent target for developing specific antifungal medications that do not harm human cells.
Decomposition Role: By secreting enzymes, fungi break down and absorb carbohydrates from decaying organic matter, acting as vital decomposers in the environment.

Fungal Carbohydrates: More Than Just Food

Yes, fungi do contain carbohydrates, but not in the same way that plants do. As heterotrophic organisms, fungi cannot produce their own food through photosynthesis. Instead, they absorb nutrients, including various carbohydrates, from their environment. These carbohydrates serve two primary functions in fungi: as a source of energy storage and as crucial components of their cell walls. This makes carbohydrates a fundamental part of fungal biology, from their microscopic structure to their role in the wider ecosystem as decomposers.

Energy Storage: Glycogen, the 'Animal Starch'

One of the most notable carbohydrate-related characteristics of fungi is their storage of energy in the form of glycogen, a branched polysaccharide of glucose. This is a trait they share with animals, which further highlights their evolutionary divergence from plants, which typically store energy as starch. Glycogen is stored as granules in the cytoplasm of fungal cells and can be quickly mobilized to provide glucose when the organism needs energy. This rapid-access energy reserve is vital for growth and reproduction. Fungi can also store reserve food as oil globules.

Structural Support: The Cell Wall

The cell wall is a protective, rigid layer outside the cell membrane that provides shape and protection from osmotic stress. Its composition is a key defining feature of fungi, relying heavily on carbohydrates.

Key carbohydrate components of the fungal cell wall include:

Chitin: This is the most significant structural polysaccharide in the cell walls of most fungi, particularly filamentous and mushroom-forming species. Chitin is a polymer of N-acetylglucosamine units linked together in a tough, fibrous matrix. This is the same material that forms the exoskeletons of insects and crustaceans, providing immense strength and resilience.
Glucans: These are polysaccharides made of glucose monomers linked by β-glycosidic bonds and are another major component of fungal cell walls. They cross-link with chitin to provide further rigidity and structural support. Different types of glucans, such as β-(1,3) and β-(1,6) glucans, vary in their arrangement and properties across different species.
Mannoproteins: These are glycoproteins with mannose-containing carbohydrate chains that are part of the outer cell wall layer in many fungi. They are important for adhesion, immune response modulation, and can even mask other cell wall components from detection.

Absorption and Metabolism of External Carbohydrates

As saprotrophs and parasites, fungi are experts at breaking down complex organic matter to absorb simpler carbohydrates. They secrete powerful hydrolytic enzymes into their environment to digest complex polysaccharides like cellulose, starches, and hemicelluloses into smaller, soluble sugars such as glucose, fructose, and xylose. These are then absorbed through the cell wall and used for metabolic processes. This ability makes them essential recyclers of nutrients in ecosystems. Some fungi, such as those that cause brown rot in fruits, demonstrate this by releasing enzymes that soften tissue ahead of their advancing mycelia.

Comparison of Fungal and Plant Carbohydrate Storage


Feature	Fungi	Plants
Energy Storage	Glycogen, a branched polysaccharide of glucose.	Starch, composed of amylose and amylopectin, also a glucose polymer.
Structural Component	Chitin, a polymer of N-acetylglucosamine, in the cell wall.	Cellulose, a linear polymer of glucose, in the cell wall.
Nutrient Acquisition	Heterotrophic (absorbs preformed organic matter).	Autotrophic (produces its own food via photosynthesis).
Digestion Method	Extracellular digestion by releasing enzymes into the surroundings.	Intracellular digestion in vacuoles and plastids.

The Importance of Fungal Carbohydrates for Medicine

The unique carbohydrate composition of the fungal cell wall makes it an ideal target for antifungal therapies. Since the cell wall is essential for fungal survival but absent in human cells, drugs that disrupt its synthesis, such as echinocandins which inhibit glucan synthase, are highly effective against fungal infections with minimal harm to the patient. Research into the specific types and arrangements of carbohydrates in different fungal species is also ongoing to develop more targeted treatments. For instance, certain fungal beta-glucans have shown promise in medicinal applications due to their immunomodulatory effects.

Conclusion: A World of Diverse Carbohydrates

Fungi are rich in carbohydrates, which are vital for their existence. These compounds serve dual purposes: providing energy storage in the form of glycogen, a trait shared with animals, and forming the rigid, protective cell wall with complex polysaccharides like chitin and glucans. As heterotrophs, fungi masterfully absorb and process carbohydrates from external sources, playing a crucial role as nature's recyclers. The profound differences between fungal and plant carbohydrate usage and structure provide key insights into their distinct evolutionary paths. Moreover, the uniqueness of fungal cell wall carbohydrates offers a strategic advantage in developing life-saving antifungal medicines. The next time you see a mushroom, remember that you are looking at a master of carbohydrate manipulation, finely tuned for survival and function within its ecosystem. Further understanding of fungal carbohydrates continues to open doors for medical innovations and a deeper appreciation of the kingdom of Fungi. You can learn more about mycology and fungal biology through resources like this overview on Fungal Nutrition from Britannica.

Frequently Asked Questions

Fungi store excess energy as glycogen, a highly branched polysaccharide of glucose. This is a storage method also used by animals, contrasting with plants which use starch.

Yes, chitin is a primary structural carbohydrate found in the cell walls of most fungi. It provides rigidity and strength to the cell walls and is a polymer of N-acetylglucosamine.

Fungi obtain carbohydrates by extracellular digestion. They release hydrolytic enzymes into their environment that break down complex organic compounds, such as cellulose and starches, into smaller, absorbable molecules.

While mushrooms contain carbohydrates, their content varies by species. For example, a significant portion of a mushroom's dry weight is carbohydrates, but some edible types, like cremini, have relatively low overall carbohydrate counts per serving.

Fungi differ from plants primarily in their storage carbohydrate (glycogen vs. starch) and their main cell wall component (chitin and glucans vs. cellulose).

Humans and other mammals produce chitinase enzymes that can degrade chitin, although the required chitinase activity is generally very low. For this reason, chitin often acts as a component of dietary fiber for humans.

The unique carbohydrate composition of the fungal cell wall makes it an ideal drug target. Since humans do not have cell walls, drugs that interfere with their synthesis, like echinocandins, can effectively kill fungi without harming human cells.