I have read that bacteria "thrive" in warm places. Naturally, I am very interested in why this is the case. Humans for instance thrive also in relatively warm conditions if it's too cold or too warm we die. However why would this also apply to bacteria?
The idea that bacteria thrive in warm places is mostly biased from a human perspective. Human researchers will tend to care more about bacteria that cause human disease. These pathogenic bacteria can replicate in/on humans at ~37 °C (which is warm). As Dexter points out, bacteria can grow at other temperatures.
But I'd go deeper and consider proteins (and other macromolecules) in the cell. For example, the enzymes that carry out many important processes for the bacteria (such as DNA polymerases that build the DNA) are most active at certain temperatures: in E. coli or humans or dogs that's ~37 °C; for a thermophile it's warmer. See below:
Actually it's not true. It depends on species of bacteria you are talking about. Bacteria can 'thrive*' in very wide range of temperature. They can be mainly categorized according to temperature,
- Psychrophiles : live in very cold temperature. Reported lowest** temperature in which specific bacteria can 'thrive' is $-20^oC$ .
- Mesophiles : live in moderate temperature
- Thermophiles : live in very high temperature. These can 'thrive' at very high temperature like $+121^o C$
*By 'thrive' I mean they are actively dividing and metabolic process are not ceased.
**People store at bacteria at $-80^0C$ also but there they are not 'thriving' they are alive but freezed.