Food is important basic substance for humans which provide nutrients for survival. 

Household food processing- some of the microorganisms like bacteria and fungi play variety of roles in formation of household food. 

Example- Lactobacillus is the bacteria involved in formation of curd from milk and yoghurt is produced by bacteria, Lactobacillus bulgaricus. 

Industrial production- Food engineering is one of the advance methods to improve the quality and quantity of food by using organisms. 

Examples- 

1. Microorganisms involved in commercial production of enzyme like production of lipases. 

2. Ethanol is one of the important commercial chemical produced by saccharomyces cerevisiae 

3. Penicillin is one of the important antibiotic and it is produced from the bacteria, penicillium notatum.