Microorganisms can be controlled by various methods.

Physical Methods

Many physical methods are applied to prevent bacteria. For example steam, dry heat, gas, filtration and radiation.

The process in which we use physical agents to control bacteria/microorganism is known as sterilization process. Sterilization is destruction of all life forms.

High Temperature Treatment:

High temperature is used in microbiological labs for control of microbes. Both dry heat and moist heat are used.

Moist Heat: Moist heat causes coagulation of proteins and kills the microbes.

Dry Heat: Dry heat causes oxidation of different chemicals of microbes and kills’ them.


Certain electromagnetic radiations below 300 nm can effectively kill the microorganisms. Gamma rays are commonly used for sterilization process.

Membrane Filters:

Heat sensitive compounds like antibiotics, seras, hormones etc., are sterilized by membrane filters.

Chemical Methods

Chemical methods for control of bacteria include antiseptics, disinfectants and chemotherapeutic agents.


These are chemical substances used on living tissues to kill and inhibit the growth of microorganism.


These chemical agents are used to inhibit the growth of vegetative cells on the nonliving materials.

These include oxidizing and reducing agents. For example halogens, phenols, hydrogen peroxide, Potassium permagnate, alcohol and formaldehyde etc.


Chemotherapeutic agents and antibiotics work with natural defense and stop the growth of bacteria and other microbes. They destroy or inhibit the growth of microorganisms in living tissues.

These are Sulfonamides, tetracycline, penicillin, etc.

Allergic Reactions:

Misuse of antibiotic like penicillin can cause allergic reactions.


Streptomycin can affect auditory nerve. The result is deafness.

Discoloration of Teeth:

Tertacycline and its related compounds cause permanent discoloration of the teeth in the young children.

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