What Do Fungi Eat?
Most fungi are saprophytic deriving nutrition from dead matter
(organic compounds). A few are parasitics; parasites requiring
living hosts.
All fungi require an external source for organic material. To
obtain food they extrude digestive enzymes and other substances
which break down complex external nutrients. Fungi then absorb
the nutrients by "bathing" in the mixture of their secretions
and moisture from the environment. Moisture is vital for fungi
precisely because they must bathe in their nutrients to absorb
them. Although fungi also need oxygen, removing moisture is the
most effective method for halting growth.