Media sterlization

Hello everyone,

You must have seen food get spoiled within 1-2 day  when kept outside. but why this happens ?

The most probable reason is presence of spoilage microorganisms in air . It is very important that such organism should not be present in medias , reagents etc , which can lead to error in analysis . hence all these materials  should be sterilized before use .

It is very important than every material used in microbiological laboratory whether it be water, media , glassware etc  should be sterile. Hence every microbiological laboratory contains an equipment known as AUTOCLAVE. So in this section I will be dealing with basic principle and working of Laboratory autoclave .

An autoclave is a pressure chamber is used to sterilize equipment and supplies by subjecting them to high pressure (15 atmosphere) steam at 121  °C for around 15-20 mins. Typically the chambers in autoclaves are cylindrical, because cylinders are better able to withstand extreme pressures than boxes, whose edges become points of weakness that can break.

 Principle of autoclave 

You've probably heard of pressure cookers? They were all common in use until microwave ovens became popular. They're like over-sized saucepans with lids that seal on tightly and, when you fill them with water, they produce lots of high-pressure steam that cooks your food more quickly .

Autoclaves work in a similar way, but they're typically used in a more extreme form of cooking: to kill all the microorganisms on things with steam long enough to sterilize them. 

You can try at home by boiling one potato in pressure cooker and other on open pan , and the interpret which cooks potato early, obviously the the answer is pressure cooker .

The extra pressure in an autoclave means that water boils at a temperature higher than its normal boiling point—roughly 20°C hotter—so it holds and carries more heat and kills microbes more effectively. A lengthy blast of high-pressure steam is much more effective at penetrating and sterilizing things than a quick wipe in ordinary hot water!

Working of autoclave :

most autoclaves contain a sterilizing chamber into which articles are placed and o steam jacket where steam is maintained. as steam flows from from steam jacket into steam chamber, cool air is forced out and a special valves increases the pressure above the normal pressure .The super heated water molecules conduct heat to microorganism.

Uses of autoclave :

In a microbiology lab an autoclave is used mainly to sterilize  medias, buffer , reagents etc. we can also sterilize small apparatus , certain glassware , heat resistant plastic containers , micro pipette tips etc.

Thank you,

Hope you understand 

with love 

-Dixy