The three types of micro-organism are bacteria, and viruses. Bacteria are celled organisms, found everywhere and reproduce very quickly. Bacteria can cause diseases such as food , tuberculosis, pneumonia, tooth decay and . They are also used to produce , make cheese, and silage. Fungi can be single cells or exist as long such as bread mould. They do not contain . Fungi are useful in , breadmaking, producing antibiotics and some fungi such as are edible. The harmful effects of fungi are that they are poisonous, can cause food to go off and can cause disease such as foot and ringworm. are the smallest type of micro-organism. They cannot reproduce themselves. They act as living inside of other living cells which they kill and take over. Viruses can cause diseases such as , colds, flu, polio, measles mumps and chicken . Antibiotics can not work against viruses but can cure diseases caused by and fungi. is the use of living things such as micro-organisms to make useful substances. In industry, bacteria is used to make and the fungus yeast is used to make alcohol. In medicine, bacteria and fungi produce antibiotics such as and penicillin respectively.