microbial control of growth supplemental instruction designed by pyeongsug kim ©2010...
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Microbial Control of Microbial Control of GrowthGrowth
Supplemental instruction
Designed by Pyeongsug Kim ©2010 [email protected]
Fall 2010
For Dr. Wright’s Bio 7/27 Class
Updated: 04/21/23 02:00 AM
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-Kill the bacteria-eg. Disinfectant, sterilization…-Biocides : Kill the microbes: bacteria, funcgi, viruses
BactericidalBactericidal
BacteriostaticBacteriostatic-Prevent(inhibit) growth of the bacteria or reduce the microbes-but does not kill the bacteriaRemoval or dilution of the antimicrobial can result in a resurgence of bacterial growth
-eg. Handwashing with soap food in refrigerator
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____________________ - Bateriocides or germercides *Kill microbes
-Disinfectants(Chemicals) -Toxic or non-toxic to skin -Objects or skin -Water treatment Facilities -Bacteria(including endospores), fungi, and viruses. -eg. Antiseptics (for skin)
____________________ - Bateriocides -Free of microbes -Bacteria(including endospores), fungi, and viruses. -Not for prion(protein)! -Bio7/27 Lab. Hospital,… -eg. filtration, using heat (flaming loop), certain certain chemicals, or irradiation
Disinfection
Sterilization
*Biocides – Kill microbes Biostatics – Prevent microbes
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____________________ -Bacteriostatic -Chemicals (Disinfectants) -Non-toxic to skin -Surgery, handwashing - Bio7/27Lab. Hospitals,…
Antiseptics
____________________ -Bateriocides or Bacteriostatics -Brief heat -Food or objects
Pasteurizationhttp://z.about.com/d/thyroid/1/0/K/X/surgery-clipart.jpg
http://altmed.creighton.edu/MilkPasteurization/Page1.htm
____________________ - Bacteriostatics -Surface area including skin.
Degerming
____________________ -Biostatics
-Objects -Health standards; clean in appearance *no specific level of control
Sanitization
____________________ -Biostatics
-ingredients or conditions(temp. pH, dry….) -Food or products -Delay spoilage - Jam, Pickling food, Dry food…
Preservation
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____________________ -Biostatics -heat, disinfectants, washing -safe to handle
Decontamination
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______________-The use of specific methods to exclude contaminating microorganisms from an environment.- Microbiology laboratory, medical procedure….etc
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Aseptic technique
____________________ -Resistant forms -Much harder to destroy than vegetative cells. -may destroy EXTREME heat or chemicals
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Endospores
What types of organisms or other things are resistant to disinfectants? Endospores, Mycobacterium(waxy cell wall), Naked viruses, Protozoan cysts & oocysts, Pseudomonas
____________________ -Waxy cell walls -detected by acid fast stains -Resistant to chemicals -May be required strong toxic to destroy -TB
Mycobacterium
http://diverge.hunter.cuny.edu/~weigang/Images/04-21_sporulation_1.jpg
____________________ -Lack of a lipid envelop -More resistant to disinfectants than enveloped -Poliovirus. -However, viruses are NOT organisms or microbes. but, viruses are pathogens.
Naked viruses
_____________-can metabolize many chemicals-Grow in disinfectants!-Hospital-acquired infection (nosocomial)
Pseudomonas
*Prion are new concern in Hospital, but rare.
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_________ - the amount of timerequired to kill 90% of organisms. (Or 10% remained.) *Assumption: death occurs at a constant rate
D-Value = 10 minutes100,000,000 are present.
100,000,000 ----(10min) 10,000,000 10,000,000 ----(10min) 1,000,000 1,000,000 ----(10min) 100,000 100,000 ----(10min) 10,000 10,000 ----(10min) 1,000 1,000 ----(10min) 100 100 ----(10min) 10 10 ----(10min) 1 Therefore, it takes 80 minutes (8D-values) to kill all.
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D value
How about…D-Value = 7 minutes234,123,000 are present. Looks complicated to you? But, very simple!
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234,123,000 cells are killed, in other word, 2 cells are remained. 234,123,000 One! 234,123,000 Two! 234,123,000 Three! 234,123,000 Four! 234,123,000 Five! 234,123,000 Six! 234,123,000 Seven! 234,123,000 Eight! Stop!
7 min.(D-value) X 8 = 56 minutes. Or 8D values Believe it or not… It is the answer.
AutoclavingAutoclaving
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-high temperature, high pressure, steam (121oC) (15 psi)
-can kill endospores; may destroyprions-Chemical indicators Turn black indicates if the objects are exposed heat.
-Biological indicators Change color growth of endospores. Wrongfully work! -Bacteriocidal-surgical instruments, microbial media for culture
Picture from http://www.surgipro.com/ http://www.novamed.co.il/NovaMed/Templates/showpage.asp?DBID=1&LNGID=1&TMID=842&FID=534
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PasteurizationPasteurization-reduces numbers of microbes to tolerable levels (bacteriostatics)-HTST(High-temperature-short-time) method brief heat (72 oC )
-UHT(Ultra-high-temperature) method-Ice cream, Milk or juices, rubber, cloth,… -Anesthesia masks in hospitals
Picture from http://altmed.creighton.edu/MilkPasteurization/Page1.htm http://www.outtakes.com/work/taster.html
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Commercial canning processCommercial canning process-Industrial-sized autoclave-designed to kill spore formers(C.botulinum) but, destroy almost all organisms. -12 D process (kill 1012 organisms)-Bacteriocidal
Dry heatDry heat-flaming, baking, hot air oven-sterilize certain items-less effective than wet heat-oxidizes cell components; denature proteins.-Bacteriocidal-Glass Petri dishes and glass pipets powders, oils, and other anhydrous materials
Picture from http://www.directindustry.com/prod/memmert/laboratory-oven-28305-257562.html
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Chemicals Chemicals -disrupt tissue cell membrane, proteins, DNA-Disinfectants :chemicals kill microbes-antiseptics non-toxic to skin eg. Alcohol (weakly bacteriocidal)
Picture from http://www.ahptechnology.com/products/disinfectants
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Filtration Filtration can sterilize but do not kill microbes.
-membrane-sterilizes heat-sensitive liquids (drinking water)liquids (drinking water)-HEPA (high-efficiency particular air) air filtration- filters remove particles. Hospitals-Laminar flow hoods :protect workers and materials from contamination. Laboratory
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RadiationRadiation- can be used foods. control E.coli (0157:H7), Salmonella in beef, poultry…
- surgical supplies, drugs, Petri dishes - Not for skin - Bacteriocides - Endospores resistant to radiation
•Gamma radiationGamma radiation - penetrating - damage DNA and cell membrane
•UV radiationUV radiation - poor pemnetrating not effective for solid surfaces and turbid liquids
- damage DNA - air, dringking water, surfaces… -Caution! in human tissue (skin and eyes) skin cancers
PreservativesPreservatives
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Food preservation -nontoxic for food -Benzoic, sorbicBenzoic, sorbic acids lower pH; bread, cheese, juice prevent growth bacteriostatics by altering cell membrane function and energy transformation -NitrateNitrate inhibit spore formersspore formers bacteriostatics prcessed meats, bacon, ham but, potential carcinogens -Preservation for non-food items sampoo, deodorants, soaps, mouth wash….
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Cold storageCold storage-low-temperature; freezing-inhibit growth bacteriostatic
-enzymatic inactive-PsychrophilesPsychrophiles can grow spoil the food in refrigerator
DryingDrying-draw water out of cells; dehydration-inhibit growth bacteriostatic
-Drying food Desiccation (removing water) Lyophilization(freeze-drying) ~ coffee, milk, meats, vegetables
-Adding salt, sugar S.aureus can grow in high salt conditions meat jerkies