Bacteria that grow at 50° - 55°C are known as

Bacteria that grow at 50° - 55°C are known as Thermophiles.
A thermophile is an organism a type of extremophile that thrives at relatively high temperatures, between 41° and 122°C.
Thermophiles are those organisms that grow above 40°C, and have optimal growth temperatures between 50° and 55°C.
Thermophiles can survive at high temperatures, whereas other bacteria or archaea would be damaged and sometimes killed if exposed to the same temperatures.