2. Give examples to prove that microbes release gases during metabolism.
When any bacteria grows on any material, it uses that material as the substratum to acquire food and starts metabolising that material to release some products. For example, the puffed appearance of the dough of dosa is due to the release of gases like CO2 by the bacteria growing on them. Large holes in Swiss cheeses are also due to the release of gases produced by bacteria growing on them. All these examples collectively point towards the gaseous exchange that takes place during metabolism.