This is Known as Pastuerisation A process where milk is rapidly heated killing bacteria and then just as rapidly cooled again this not only protects health against bacteria but also extends the shelf life of the milk
low temp.
High temperatures kill the most bacteria. These temperatures should be at least 160 degrees Fahrenheit in foods like many meats.
Their enzymes have high optimal temperatures.
Thermophilic bacteria have growth temperatures that range from 45C to 85C, with an optimum temperature of about 60C. Thermoduric organisms can survive at extreme temperatures, e.g. pasteurization, but cannot grow.
Some bacteria are metabolically active in hot springs because they have adapted to survive and thrive in extreme temperatures. These bacteria have enzymes and metabolic pathways that are stable at high temperatures, allowing them to carry out processes like photosynthesis or chemosynthesis even in these harsh conditions.
Different temperatures can affect bacteria in different ways. Extreme temperatures (too hot or too cold) can kill bacteria by denaturing their proteins and disrupting their cell membranes. Optimal growth temperature varies between bacteria species; some thrive in high temperatures (thermophiles), while others prefer moderate temperatures (mesophiles). Cold temperatures can slow down bacterial growth but may not necessarily kill them.
It will bake the culture, and denature the proteins in the bacteria, turning them hard.
Different species of bacteria have different sensitivity to high temperatures. Fortunately practically all species of bacteria that can cause food poisoning are killed by temperatures less than 160F and most of the rest can be killed by the high pressure canning temperatures around 240F to 250F. A few species of bacteria can actually survive and grow in the high pressure, high temperature (up to 600F), high radioactivity environment inside pressurized water nuclear reactors! Most of these species of bacteria feed on metal ions not organic material and can be a serious cause of corrosion and maintenance problems in such reactors.
A thermophile is an organism - a type of extremophile - which thrives at relatively high temperatures, between 45 and 80 °C[1] (113 and 176 °F). Many thermophiles are archaea. Thermophilic bacteria is a extreme heat loving bacteria that is a member of the archaebacteria kingdom.
Halophilic bacteria thrive in high salt environments, making them challenging to eliminate. Effective methods for killing halophilic bacteria include using high concentrations of salt, desiccation, high temperatures, and disinfectants. It is essential to identify the specific type of halophilic bacteria and choose the appropriate method for eradication.
Bacteria that can thrive in harsh or extreme conditions are often categorized as extremophiles. These include thermophiles that live in high temperatures, psychrophiles in cold temperatures, acidophiles in acidic environments, alkaliphiles in alkaline environments, and halophiles in high-salt environments. These bacteria have developed specialized adaptations that allow them to survive and function in such challenging conditions.
The bacteria that live in the hot spring are of a different kind. They can survive in extreme conditions. There are also other type of bacterias that can live in salty and some which can live in acidic conditions. Also because their proteins are in their correct form when at extreme temperatures, and in fact when put at temperatures that are normal for us, their proteins would deform and they could die.