Methods of Microbial Control

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Methods of Microbial Control

• Chapter 9

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Microbial Control

• Microorganisms ? vital link in the web of life
• Couldnt live without microbes
• Why do we need to control?
• Human health
• Food spoilage
• Rotting decaying of materials

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How Microbes Affect Humans

• Beneficial

• Harmful

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Microbial Control

• Great deal of time has been spent towards
  understanding how to control microorganisms
• Interested in how the treatment affects the
  entire population of microbes

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Death Rate

• Not all cells die at the same time
• Cell die as they grow- exponentially
• D-Value? time in minutes it takes to kill 90of
  cells in a population
• TDP? lowest temp reqd. to kill all orgs. in 10
  mins
• TDT? minimal time reqd. to kill all org. at a
  given temp

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Microbial DeathD-Value ?
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Key Terms

• Sterilization ? destroys all microbial life
• Disinfection ?reduces the of pathogens
• Antiseptic ?kills microbes on living tissue
• Microbiocidal ? kills all microbes
• Microbiostatic? inhibits growth
• Germicide? kills microbes
• Bactericide
• Fungicide
• Virucide

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Physical Methods of Control

• Heat
• Cold? microbiostatic
• Radiation
• Filtration
• Drying
• Osmotic pressure

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Chemical Methods of Control

• Chemotherapeutic agents
• Antibiotics
• Other chemicals
• Alcohols
• Halogens H2O2
• Surfactants
• Heavy metals
• Formalin

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Selecting a Germicide

• Depends on
• Damage to object or tissue
• Control of target organism
• Purpose of treatment

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