Chapter 7: The _______ of Microbial Growth Microorganisms and Microbial Growth Figure 7.11.

Chapter 7: The _______ of Microbial GrowthMicroorganisms and Microbial Growth

Figure 7.11

Terminology Related to the __________ Microbial Growth

• ___________: Removal of all microbial life• ___________: Removal of pathogens• __________: Removal of pathogens from living

tissue• __________: Removal of microbes from a limited

area• Sanitization: Lower microbial counts on eating

utensils• _____________________: Kills microbes• Bacteriostasis: Inhibiting, not killing, microbes

Effectiveness of antimicrobial treatment depends on:

• ______ of microbes• Environment:

Ex. temperature• ______ of exposure• Microbial

characteristics

Microbial Control Agents

______________Heat, Filtration, Low Temperature, Pressure,

Dessication, Radiation______________

Phenols, Chlorhexidine, ________, Halogens, Heavy Metals, Surface Active Agents

Various Effects of Microbial Control Agents• Alteration of membrane permeability• Damage to proteins• Damage to _____________ acids

Physical Method of Microbial Control: Moist Heat

• Moist heat denatures proteins

• Autoclave: _______ under pressure

Figure 7.2

Physical Methods of Microbial Control: Dry Heat

• Dry Heat Sterilization kills by ______________– ______________– Incineration– Hot-air sterilization

Hot-air Autoclave

Equivalent treatments 170˚C, 2 hr 121˚C, 15 min

Physical Methods of Microbial Control______________

_____________ reduces spoilage organisms and pathogens•Methods used in pasteurization:

– ____________________– High-temperature short-time 72°C for 15 sec– Ultra-high-temperature: _______________– Thermoduric organisms survive

_____Methods of Microbial Control cntd.• _____________

removes microbes

• _____________: inhibits microbial growth

– Refrigeration– Deep freezing– Lyophilization

• _________________ denatures proteins

• _________________ prevents metabolism

• _________________ causes plasmolysis

________________ damages DNA

Physical Methods of Microbial Control______________

• Radiation damages _________• Types of radiation:

– Ionizing radiation (X rays, gamma rays, ____________) – Nonionizing radiation (__) – (___________ kill by heat; not especially antimicrobial)

Chemical Methods of Microbial Control

Types of Disinfectants___________ – disrupt plasma membranesIodine, Chlorine, Bleach – _____________ agents_________ – denature proteins, dissolve lipids________________ – denature proteinsPeroxides – oxidizing agents

Principles of effective disinfection– ________________ of disinfectant– Organic matter– pH– Time

______ Methods of Microbial Control

Types of Disinfectants___________ – disrupt plasma membranesIodine, Chlorine, Bleach, Peroxides – ________ agentsAlcohols – denature proteins,

dissolve lipidsHeavy metals – denature

____________Principles of effective disinfection

– _______________ of disinfectant

– Organic matter– pH– Time

Types of Disinfectants• Surface-Active Agents or Surfactants__________ Degerming

Acid-anionic _______________ Sanitizing

Quarternary ammonium compoundsCationic detergents

Bactericidal, Denature proteins, disrupt plasma membrane

Evaluating a Disinfectant• __________________ method

FOOD PRESERVATION

• Chemical Food Preservatives– _________ Acids: sorbic acid, benzoic acid,

calcium propionateInhibit metabolism

Control molds and bacteria in foods and cosmetics

– __________: prevents endospore germination– __________: Nisin and natamycin prevent spoilage

of cheese