What are some ways that humans are dependent on fungi and algae?

Answer 1

Fungi are also naturally used as decomposers to keep ecosystems replete with inorganic nutrients necessary for plant growth, such as carbon and nitrogen.

Fungi and plants are dependent on each other for nutrience, and we're dependent on plants for nutrience. So we are thus dependent on fungi as well.

Answer 2

Medicine:

-Fungi of the genus Penicillium are how humans discovered antibiotics - first Penicillin, and following were many, many more.

-Lovastatin is a cholesterol-lowering drug that is naturally produced in the Oyster Mushroom (Pleurotus ostreatus)

-The Reishi, or Lingzhi, mushroom (Ganoderma lucidum) is highly prized and very well known in TCM (Traditional Chinese Medicine). It is an immune system stimulant, contains natural steroidal compounds, and has mild ACE (acetylcholine esterase) inhibiting properties that may be useful in conditions like Alzheimer's Disease.

-The prized edible and well known Chanterelle has a very high level of vitamin D.

-There are many more medicinal- and health-benefiting mushrooms and fungi

Industry:

-The velvety surface of Birch Polypore (Piptoporous betulinus) after being cut has historically been used as a strop to finish the edges of the finest of razors. It has also been used as tinder, and was found being carried by a 5,000 year old mummy in Tyrol.

-Dyer's mushrooms are various fruiting bodies of fungi whose pigments are strong enough and of such chemical makeup that they are known to be effective fabric and yarn dyes.

-Some fungi are capable of absorbing toxins like crude oil and heavy metals, and store these in non-dangerous ways or expel them in safe forms.

Similar to medicine, I insist upon including psychoactive mushrooms as a tool to assist psychotherapy, personal growth, and introspect. They are possibly the oldest known 'intoxicant' used by man, and are referenced as 'Soma' in the oldest of texts, including the Rg Veda. The Aztecs refer to psilocybin-containing mushrooms as 'Teonanacatl' which literally translates to 'divine flesh' or 'God's flesh.'

Food:

Many fungi produce fruiting bodies known as mushrooms which are both delicious and health-promoting. Some of my favorites include:

-Chanterelle complex - genus Cantharellus

-Porcini - Boletus edulis

-Candy Cap (Curry Milkcap) - Lactarius fragilis, Lactarius rubidus

-Oyster Mushroom - Pleurotus ostreatus

-Shiitake mushroom - Lentinula edodes

-Reishi mushroom - Ganoderma lucidum

-Noble Rot - Botrytus cinerea is a fungus that grows on grapes, stealing moisture from them, and eventually destroying a crop. However, if conditions are right, and infected grapes are picked at a specific point (being mostly raisinated by then) they can be used to create certain varieties of very fine dessert wines, like the French - Sauternes, and the Hungarian - Tokaji.

There are many, many more important uses for fungi, but these are just the first few which came to my mind.