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Controlling Microbial Organisms

ethods for controlling microorganisms include chemical (antimicrobial pesticides) and non chemical approaches. Antimicrobial pesticides either destroy the microorganisms or provide barriers that exclude them from an area. Sometimes antimicrobials inhibit the growth of microorganisms. Non chemical methods include exclusion and sanitation, and may also involve modifying the envi- ronment to regulate temperature and moisture. Other methods, such as irradiation, also destroy certain microorganisms. M

In many cases, the combined use of chemical and non chemical methods is more effective because single methods of control rarely eliminate all of the organ- isms. Because of health hazards caused by certain microorganisms, total eradication or sterilization is the primary goal of a management approach, although this is very difficult to achieve.

Exclusion

Physical barriers such as walls or partitions exclude certain microorganisms from some areas. Thoroughly cleaning objects before moving them to other locations helps to prevent spreading microorganisms. Positive air pressure in a confined area also keeps airborne microorganisms out. High efficiency filters in air conditioning systems traps microorganisms and prevents their spread to other areas within a building. Special water filters remove microorganisms from water pipes.

Sanitation

The first step in sanitation involves cleaning surfaces to remove foreign materials and biofilm which can otherwise interfere with effective pest control by shielding the microor- ganisms. Cleaning usually requires washing or scrubbing with soap and water or other cleaning material. Following cleaning, treating the surfaces with a disinfectant material or heat greatly reduces the population of microbial organisms.

Modifying the Environment

Maintaining temperatures at sufficiently high or low ranges suppresses or destroys microorganisms. This is why refrigeration or heat protects foods. Some microorganisms cannot survive unless free water is available; therefore, keeping an area dry will prevent such organisms from reproducing.

Submerging objects in boiling water for several minutes kills most microorganisms, although some bacterial spores are highly resistant to boiling water. Saturated steam under pressure, known

CONTROLLING MICROBIAL ORGANISMS

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