The processes often involve some kind of chemical change - a building up or breaking down of materials. These are the scientists who work out how microorganisms can be used in a controlled way in industry and the health services. They tend to work in laboratories, with specialised equipment. Return to index Yeasts and moulds Both of these are types of fungus. Each individual is too small to see without using a microscope, but in a mass they are easy to see.
Yeasts feed on sugar.
If there is no air in their environment, they turn the sugar into alcohol and carbon dioxide gas after removing some energy. There are many different kinds - many living on the skins of fruits. Moulds occur naturally in the soil and elsewhere, feeding mostly on dead organic material. They can grow in quite cool conditions - even in a refrigerator. Their minute spores float around in the air.