Jan 5, 2013

Control of Bacteria


Microorganisms can be controlled by physical and chemical methods.

Physical Methods

Sterilization Process: It is the process in which physical agents like steam, dry heat, gas, filtration and radiation are used to control bacteria. Sterilization is destruction to all life forms.

High Temperature: It is usually used in microbiological labs for control of microbes. Both dry heat and moist heat are effective. Moist heat causes coagulation of proteins and kills the microbes. Dry heat cause oxidation of chemical constituents of microbes and kills them.

Radiations: Certain electromagnetic radiations below 300nm are effective in killing of microorganisms. Gamma rays are in general used for sterilization process.

Membrane Filters: Heat sensitive compounds like antibiotics, seras, hormones etc can be sterilized by means of membrane filters.

Chemical Methods: Antiseptics, disinfectants and chemotherapeutic agents are used as chemical methods for microbial control.

Antiseptics: The chemical substances used on living tissues that inhibit the growth of microorganism are called antiseptics.

Joseph Lister the first person to use antiseptic.
Disinfectants: Oxidizing and reducing agents are important chemical agents for disinfection. e.g. Halogens, and phenols, hydrogen peroxide, potassium permanganate, alcohol, and formaldehyde etc. These chemicals inhibit the growth of vegetative cells and are used on nonliving material.

Chemotherapeutic Agents: These chemicals and antibiotics destroys the natural defense and stop the growth of bacteria and other microbes in the living tissues. e.g. sulfonamide, tetracycline, penicillin etc.

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