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Sterilization
Complete Absence of life
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Commercial Sterilzation
complete absense of any pathogen
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Disinfectant
- Used on inanimate surfaces
- kills microbes
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Antiseptic
Kills bacteria on living tissues
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Biocide
A substance capable of killing microorganisms
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Germicide
A substance capable of killing microorganisms
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Bateriostatic
Stops growth of bacteria
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Sepsis
Bacterial contamination
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Antisepsis
Absense of Bacterial contamination
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Rate of Microbial Death is dependent on 4 Factors:
- 1) Number of microbes
- 2) Presense of organic matter (blood, vomit, etc)
- 3) Time of exposureof antimicrobial
- 4) Microbial characteristics
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Time and Temperature to kill Endospores with Moist Heat
121o C (250o F) for 15 minutes
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Phenol
- Disruption of plasma membrane
- Denaturation of enzymes
- Rarely used-smells bad
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Bisphenols
- Disruption of plasma membrane
- Denaturation of enzymes
- Thymol (in 1% of Listerine)
- O-Pheynlphenol
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Bisphenols
- Disrupts plasma membrane
- In a lot of soaps and lotions
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Biguanides
- Plasma membrane disruption
- Skin disinfections (especially for surgical scrubs)
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Halogens
Chlorine and Iodine
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Chlorine
- Protein denaturation
- Strong oxidizer
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Bleach
- 5% NaOCl- (sodium hypochlorite)
- Chlorine kills
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Iodine
- Protein denaturation
- Antiseptic
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Alcohols
- Protein denaturation
- Lipid Dissolution
- Must be 70-90% concentration, or it will not be taken in by cell
- Bactericidal and Fungicidal
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Isopropanol
- Alcohol
- Rubbing alcohol
- Bactericidal and Fungicidal
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Ethanol
- Alcohol
- Bactericidal and Fungicidal
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Heavy Metals
- Kills by oligodynamic action
- Denatures proteins and enzymes
- Biocidal
- Silver nitrate, copper sulfate, mercurichrome
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Copper Sulfate
Heavy Metal
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Mercurichrome
Heavy Metal
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Soaps and Detergents
Do not kill microbes, but physically remove them
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Acid-Anionic Sanitizers
- Santiize food and dairy industry
- Probably denatures enzymes?
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QUATS (what it stands for)
Quatenary Ammonium Compounds
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QUATS (what it is)
- Very effective at killing bacteria
- Denatures proteins
- Disrupts plasma membrane
- Enzyme inhibition
- Controls mold and bacteria in food and cosmetics
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Organic Acids
- Sorbic acid
- Benzoic Acid
- Citric Acid
- Lactic Acid
Food Preservatives
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Nitrates and Nitrites
Prevents botulism in cured meats and keeps pink color of meat
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Antibiotics
- kill bacteria
- produced by fungii or streptomyces bacteria
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Aldehydes
Denature proteins
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Gas Sterilants
Inhibits cellular functions
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Ethylene Oxide
- Gas
- Used by dentists to sterilize tool s
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Most Resistant to lease resistant microbes
- Prions
- Bacterial Endospores
- Mycobacteria
- Cysts of protozoa
- Vegatiative Protozoa
- Gram - bacteria
- Fungi
- Viruses without envelopes
- Gram + bacteria
- Viruses with lipid envelopes
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Use-Dillution
- Way to evalutate chemical agents
- Dry bacteria and put it in disinfectants and put in plate to see how many bacteria remain
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Danger Zone
60-130 degrees
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Safe Temperature for cooked meats
160-165 degrees
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Disc Diffusion
- put disinfectant in center of culture
- the bigger the ring of no growth the better it works
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Thermal Death Point (TDP)
lowest temperature in which all microrganisms will be killed in a particular medium in 10 minutes
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Thermal Death Rate (TDR)
Minimal length of time for bacteria to be killed at a given temperature
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Decimal Reduction Time (DRT)
Amount of time to reduce # of spores by 90% at a given temperature
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Pasteurization
Enough heat to kill all pathogens and extend shelf life
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Dry Heat
- Kills by oxidation Effects
- Direct Flaming
- Incineration
- Hot Air (Ovens)
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Time and Temp to Sterilize in an Oven
170 degrees C for 2 hours
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High Efficiency Particulate Air Filters (HEPA)
Removes microbes lager than .3um in diameter
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Membrane Filters
- In liquids
- removes bacteria larger than .22 or .45 um
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Refridgeration
- 32-40 degrees
- Slows down enzymes=stops growth
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Freezing
Eliminating water
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High Pressure
- (ie Hummus)
- If you dont care about texture
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Osmotic Pressure
5% salt or 65% sugar will casue all H20 to leave cell causing it to shrink (hypertonic)
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Dessication
- Drying
- Microorganism cannot grown or reproduce without water
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Ionizing Radiation
- Gamma, X-rays, High Energy Electron Beams
- Shorter Wavelength = more energy
- Messes with bacteria's DNA
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Non-Ionizing Radiation
- UV Light
- Kills bacteria but doesnt penetrate surface
- Longer wavelength= less energy
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Psychrophiles
- Cold Loving Microbes
- OT: 15 degrees
- Range: 0-20 degrees
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Psychotrophs
- Cold Loving
- OT: 25 degrees
- Range 0-30 degrees
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Mesophiles
- Moderate temp loving Microbes
- OT: 37 degrees
- Range: 10-50 degrees
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Thermophiles
- Heat loving microbes
- OT: 50-60 degrees
- Range: 40-70 degrees
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Hyperthermophiles
- Extreme heat loving microbes
- OT:95 degrees
- Range: 65-110 degrees
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Obligate Aerobes
Need O 2 to survive
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Obligate Anaerobes
O2 Kills them
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Faculative AnaerobeS
- Can live with (aerobic) or without oxygen (fermentation)
- Survive better with
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Aerotolerant Anaerobes
Dont use O2 but can detoxify
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Microaerophilic
Use less O2 (usually 20%)
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Extrinsic Factors for Microbes to Grow
- Temperature
- Atmosphere
- Pressure
- Radiation
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Intrinsic Factors for Microbes to Grow
- Nutrients
- Water Activity
- pH
- Osmotic Pressure
- Bilogical Structure
- Presence of antimicrobials
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Pressure
- Factor that affects growth
- some organisms live in high or low pressure situations (bottom of sea vs. top of mountain)
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Necessiary Nutrients
- Carbon
- Nitrogen
- Oxygen
- Hydrogen
- Sulfur
- Phosphates
- Minor Elements
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pH
- Most organisms grow best at pH 6.5-7.5
- Some can grow at much lower pH (Acidophiles)
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Osmotic Pressure
5% salt or 65% sugar will kill most bacteria by shrinkage (hypertonic)
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Biological
Nuts, skins, shells etc will not allow microbes in
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Presence of Natural Antimicrobials
- Garlic=antifungal
- Cranberries= natural benzoic acid
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Chemically Defined Media
A medium whose exact chemical composition is known
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Complex media
- medium made of various nutrients and proteins that most heterotrophic would be able to hgrow in
- nutrient agar or nutrient broth
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Reducing Media
To grow anaerobes
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Selective Media
Excludes unwanted microbes (gram + vs. gram -)
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Differential Media
Differentiates between closely related species
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Enrichment Culture
Favors particular microbes to grow
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Deep Freezing
microbes are placed in liquid and frozen to preserve microbes
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Lyophilization (freeze-drying)
Water is removed from frozen microbes and they are sealed in glass to preserve
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Generation Time
1-3 hours for most bacteria
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Lag
Prepping for reproduction and growth but none yet
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Log
Rapid growth of population
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Stationary
- Births = deaths
- Equilibrium
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Death
Population decreases at rapid rate
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