MICROBIAL CELL CONTROL

TERMINOLOGIES
1. a. Sterilization
  1. i. Destruction or removal
    1. - Steam under pressure or sterilizing gas
2. b. Commercial sterilization
  1. i. Limited and sufficient heat treatment
    1. - Condition not as drastic
3. c. Disinfection
  1. i. Destruction of vegetative pathogens
    1. - Chemical and physical methods
4. d. Degerming
  1. i. Removing of microbes from a limited area
    1. - Mechanical removal ( alcohol-soaked swab )
5. e. Sanitization
  1. i. To lower microbial counts on utensils
    1. - High-temperature washing
    2. - Dipping into chemical disinfectant
FACTORS
1. b. Environmental influences
2. a. Number of microbes
3. c. Time of exposure
4. d. Microbial characteristics
CHEMICAL METHODS
1. c. No single disinfectant
2. b. Reduce microbial populations
3. a. For both living tissue and inanimate objects
ACTION
1. a. Alteration of membrane permeability
  1. i. Cellular lackage
  2. ii. Interferes with the growth of cell
2. b. Damage to proteins and nucleic acids
  1. i. Breaking the bonds of proteins, enzymes
  2. ii. Changes of structures
  3. iii. Cells cannot replicate
  4. iv. Cannot carry out normal metabolic functions
3. c. Lipid dissolution
4. d. Metabolic inhibition
PHYSICAL METHODS
1. a. Heat
  1. i. Moist heat
    1. - Coagulation of proteins
    2. - Autoclaving condition
      1. • 15 psi, 121 C, 15 min
      2. • Precautions – large volume require longer sterilization time – make sure steam can contact the surface
  2. ii. Pasteurization
    1. - Sufficient heat provided - The time and temperature differ with food
    2. - Eg : pasteurization of milk • High-temperature short time pasteurization - ( 72 0C; 15s ) • Ultra-high-temperature ( UHT ) treatment – ( 140 0C;5s )
  3. iii. Dry heat sterilization
    1. - Oxidation effect
      1. • Flaming
      2. • Hot air sterilization – 170 0C; 2h – less efficient than moist heat
2. b. Filtration
  1. i. Passage of liquid or gas through a screenlike material with small pores
  2. ii. For sterilization of heat-sensitive materials
3. c. Low temperatures
  1. i. 0-7 0C - Reduce the metabolic rate
  2. ii. Below -20C - Microbes dormant
4. d. High pressure
  1. i. Change the molecular structures
  2. ii. For preservation of flavours, colours and nutrient values of perishable foods
5. e. Dessication
  1. i. Absence of water
  2. ii. In the lab : freeze dried microorganism For food : coffee, coconut powder
6. f. Osmotic pressure
  1. i. Create hypertonic environment
7. g. Radiation
  1. i. Ionizing radiation
    1. - Wavelength shorter, producing more energy
    2. - Ionizing particles hits through cells, cause damage or mutations
  2. ii. Non-ionizing radiation
    1. - UV light 260 nm
CHEMICAL AGENTS
1. f. Aldehyde
2. b. Biguanides
3. c. Halogens
4. a. Phenol and phenolics
5. e. Heavy metals and their compunds
6. d. Alcohols

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MICROBIAL CELL CONTROL

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