Why Every Scientist Needs a Pressure Cooker

How would you react if you went to the dentist's office for your regular check up and instead of washing the tools they used on the last person, the hygienist just wiped them down and said "these look clean." I personally would be out of there faster than you could say "AH." It doesn't matter how clean a tool LOOKS, to make sure it is properly cleaned and ready for use again, you need to use an autoclave.

Autoclaves don't necessarily clean equipment in the sense that you put in something dirty and you come back to sparkling clean dishes. if you were to put a beaker with dirt on the bottom in the autoclave, it wouldn't become a crystal-clear glass, but instead would be a sterile beaker with sterile dirt. Instead, the autoclave sterilizes (meaning kills all living organisms) using high temperature and pressure. Most biological labs, dentists offices, and medical settings have an autoclave because they are incredibly useful for reusing equipment.

An autoclave works very similar to a pressure cooker that you would find in your kitchen. Whatever material that needs to be sterilized is loaded onto the reck of the autoclave, water is filled in below the rack, and the door is tightly closed. The autoclave then heats up, and the heats, causing the water to steam. Because this steam has high energy and nowhere to go in the sealed chamber, it builds up pressure in the chamber and forces the air int the chamber out down into the drain.

The typical setup of a steam autoclave

Typically, these autoclaves are set to reach 121°C or 135°C. These high temperatures and high pressure permanently denature the proteins in most bacteria, viruses, and eukaryotic organisms. These denatured proteins can no longer carry out their cellular functions, and because proteins are vital for just about every biological function, the autoclaved cells are unable to function and quickly begin to die. If an autoclave is set to 121°C, it must remain at that temperature for a minimum of 30 minutes, longer depending on how much material needs to be sterilized and how porous the material is. If they are set to 135°C, they usually only need about 4 minutes at this temperature to be able to fully sterilize.

High heat and pressure cause the proteins to change shape and become unable to preform their intended function

How come we don't just always have the autoclaves set to 135°C, that way we don't have to wait as long and be more efficient in the lab? 135°C works great for sterilizing tools, like scalpels or tools used by a dentist, but this high of a temperature, and its respective high temperature, can be too high for other materials, like agar, causing it to be ineffective. Just like how you cant bake a cake at 700°F for half the normal time and end up with the same results, the less abrasive temperature of 121°C is usually better for preventing damage and maximizing function of non-metal materials.

When baking, just double the heat and slash the time in half! That always works...

There is some variation in autoclaves, some being dry (don't use steam) and others use chemicals other than water to sterilize, but in typical settings steam autoclaves are used to get most jobs done. These incredibly useful tools are a staple of any biological setting and necessary for ensuring the safety of materials for repeated use.