Microbe Control Environmental Controls  Temperature  Radiation  Pressure  pH  Moisture Control Methods

Temperature Growth Temperature  Maximum  Optimum  Minimum Heat Cold

Radiation Blue Light UV X-rays Gamma Rays Photoreactivation

Pressure Obligate barophiles  10m = 1 atm  100m = 10 atm  1000m = 100 atm  3000m = 300 atm  10000m = 1000 atm Pseudomonas bathecetes

pH Most Marine Commensal or parasitic Molds vs. Bacteria

Moisture Osmosis  Hyper- vs Hypo-osmotic Bacteria vs Molds Food Preparation  Dried Foods  Freeze-Dried Foods  “Cured” Foods

Microbe Control Methods TERMS:  Sterilize Kill or remove all life present  Disinfect Kill pathogens present

Microbe Control Methods TERMS:  Germicide Kill harmful microbes: fungicide, bacteriocide  Antiseptic Prevents sepsis or putrefaction Inhibits growth  Sanitize Make safe to use or eat from

Ways to Sterilize Burning Boiling Autoclave (pressure cook) Filtration Irradiation Chemicals

Pasteurization Internal temperature Batch vs Flow through methods

Disinfectant Action Injure cell membrane  Change permeability  Lyse Denature proteins

Disinfectant Action Factors Affecting Effectiveness:  Concentration  Duration of Contact  Temp., pH  Media  Microbe  Circadian Cycles

Disinfectant Action Detergents and Soaps Acids and Bases Alcohols Iodine, Chlorine

Disinfectant Action Mercury Cresols Hydrogen peroxide (H 2 O 2 ) Formalin Antibiotics