The optimum temperature for the survival of the bacterium is about 45o C. Some of the microbes like bacteria and archaebacteria can survive in high-temperature zones. These organisms are known as thermophiles which can tolerate the temperature of about 100o C. These organisms have developed certain thermo-resistant enzymes which help them to carry out the normal metabolism at higher temperatures without getting degraded. Some of the bacteria can form bacterial endospores which are resistant structures. These endospores are not degraded or damaged by heat and other stressful environments.