Effect of Temperature on Bacteria Growth

Bacteria are micro-organisms, which need the right conditions to grow. One of the main factors affecting their growth is temperature.
Bacteria can be categorised based on their temperature requirements into three main groups: psychrophiles (cold-loving bacteria), mesophiles (moderate-temperature-loving bacteria), and thermophiles (heat-loving bacteria).
Psychrophiles thrive in temperatures below 15 degrees Celsius, mesophiles prefer temperatures between 20-45 degrees Celsius, and thermophiles can live in temperatures above 45 degrees Celsius.
Mesophiles, which include most human pathogens, have their optimal growth temperature between 20 degrees Celsius and 40 degrees Celsius, typically at human body temperature (37 degrees Celsius).
When the temperature is too low, bacterial growth can slow down or stop as the metabolic reactions needed for growth slow down or stop too.
When the temperature is too high, similarly, bacterial growth can slow down or stop, as the proteins and enzymes essential for their growth can lose their shape (denature) and become non-functional.
If the temperature is excessively high, bacteria can be killed. This process is utilised in sterilisation methods such as autoclaving.
Certain heat-resistant bacteria can form endospores, a type of dormant state, when exposed to extreme heat, which allows them to survive until conditions become favourable again.
In a laboratory, scientists control the temperature of bacterial cultures using an incubator, in order to optimise their growth and study them effectively.