Microorganisms as food
As we have seen in the previous section, a number of microorganisms are involved in the production of food products. Others, however, are foodstuffs! Perhaps the most obvious of these are mushrooms, the stalked fruiting bodies of certain species of basidiomycete, notably Agaricus bisporus. These are grown in the dark at favourable temperatures, in order to stimulate the production of fruiting bodies. Another fungus, Fusarium forms the basis of QuornTM, a processed mycoprotein that has been used as ameat substitute for some years in the UK. Whereas mushrooms are grown as agricultural products, QuornTM must be produced under highly regulated sterile conditions. Other microbial food sources include certain algae (seaweed), which form an important part of the diet in some parts of the world, and bacteria and yeast grown in bulk as single-cellprotein (SCP) for use as a protein-rich animal food supplement. The cyanobacterium Spirulina has been collected from dried-up ponds in parts of central Africa for use asa food supplement since time immemorial and is now available at health stores in the West.