Principle Microbiology

Steam under pressure is used for the purpose of sterilization as it gives the object totally free of living organisms. Steam under pressure provides the temperatures above that can be obtained by free flowing steam. The laboratory apparatus designed for steam under pressure is an AUTOCLAVE. The autoclave is a double-jacketed steam chamber which can be filled with steam. The autoclave has some devises which can maintain desired temperature and pressure for any period of time. For the operation of autoclave the air in the chamber should be completely replaced by the saturated steam. The steam gives more temperature than the air at the same pressure. Generally the autoclave is operated at a pressure of 15 lbs/in2 and at temperature of 121 degree C.

The time to achieve sterility depends on the nature of material being sterilized, the type of container, and the volume.
This is the method of sterilization.

Control of microorganisms by use of temperature can be classified in High temperature and low temperature. In some of the method in high temperature we get sterilization and in some we get disinfection. Low temperature however extreme can not be used as the method of sterilization.