The control of microbial growth

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Chapter 7

• The control of microbial growth

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Principles of microbial control

• Sterilization ?????????(????)?
• ??,???????.
• ????????????????????Clostridium botulinum
  ?endospores. ?????????????????(commercial
  sterilization)?.
• Disinfection ???????????????
• ?, ???????. ?????
• ?, ?????, ???????.

disinfectant
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• Antisepsis ??antiseptic substance ????????.
• Degerming(or degermination) ???????????????.
• Sanitization ??????????????????. ???? or
  ???????.

Table 7.1
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• ?? cide(??), ex germicide, fungicide,
  virucide
• ?? (or ??) stat or stasis, ex bacteriostasis
• Sepsis decay or putrid, ????
• ???
• Asepsis ?????????????,??
• ???????.

?????? ??????, ?????????
????????????????.
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The rate of microbial death

• 106 ?????????1min. 90 ? died.
• ???1min.,???????90???.
• ??????????,?????.

Table 7.2
Fig. 7.1
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• ????????????
• 1. ?????
• 2. ?????
• 3. ?????
• 4. ????

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Actions of microbial control agents

• Alteration of membrane permeability
• ????? ????????????.
• Damage to proteins and nucleic acids
• Microbes little bags of enzymes

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Physical methods of microbial control

• Heat
• ??????????. ????media, ???? ??????????.
• Thermal death point(TDP) ???????10
  min.????????????.
• Thermal death time(TDT) ????????????????????.
• TDP TDT ??????????????????????.
• D?(decimal reduction time, DRT) ?????????.
  ?????????????90?????
• (min.) ?????????????.

Fig. 7.1a
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• Moist heat
• ?????protein???????H-bond,
• ??protein ?coagulation.
• 2. Boiling ???????????,????
• virus 10min. ??????spores.
• 3. Temp ?100oC?, ??????????. ??
• autoclave (???????)
• retorts

Fig. 7.2
Table 7.3
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• Pasteurization
• ???????, ????????????.
• ????????virus???pasteurization??
• Phosphatase test
• ???? pasteurization 63oC, 30min.
• ?? pasteurization 72oC, 15sec.
• ? high-temperature short-time(HTST)
• pasteurization

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• 5. Ultra-high-temperature treatment(UHT)
  140oC,lt 1sec.
• 6. Equivalent treatments temp ????????????.
• ex endospore -- 115oC, 70min. 125oC, 7min.

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• Dry heat sterilization
• ?????????,?????(oven)?.
• 2. ?????? ?????? (??, flaming),
  ???(incineration).
• 3. Hot-air-sterilization ?oven, 170oC, 2h.

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• Filtration
• ???????, ???media, enzymes, vaccine ????????.
• 2. ?????????filtration,????. High-efficiency
  particulate air,HEPA filter ??gt0.3 ?m????.
• 3. Filterable viruses
• 4. Membrane filters cellulose esters or
  plastic polymers

Fig. 7.3
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• Low temperature
• ?? 0-7oC, ??
• ???? ???????

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• Desiccation
• ???????
• Gonorrhea bacteria ????? 1h. tuberculosis
  bacteria ??
• ?????????????, ?????,?????????????.

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• Osmotic pressure
• ?? ????????
• ?????, ???????, ????(plasmolysis).

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• Radiation
• ?ionizing nonionizing
• Ionizing radiation gamma rays, X? or ??????,
  ?nonionizing??????,??lt1 nm,???????
• Nonionizing radiation ?? gt1 nm.
• ? UV light(260 nm)
• 4. Microwaves

Fig. 7.4
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Conditions influencing microbial control

• Type of microbe
• ??? ??? ?G()??, ?G(-)??
• G(-)?Pseudomonas ???? ??????????. ??????cell
  wall??porins.
• Mycobacteria??????????????Mycobacterium
  tuberculosis???????????????---opportunistic
  pathogen
• Environment

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Chemical methods of microbial control

• Principle of effective disinfection
• 1. ???????
• 2. ??????
• 3. ????pH?
• 4. ?????????

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• Evaluating a disinfectant
• Use-dilution tests
• ????phenol coefficient test, ????????
• ????.
• ?????use-dilution tests
• (1) ??????????, ??Salmonella choleraesuis,
• Staphylococcus aureus pseudomonas
  aeruginosa.
• (2) ?????????????????, ?37oC????
• ??, ????????????????????10
• min.(20oC?), ????????media?.
• (3) ???????????, ??????
• (mycobacteria) ??????????.
• ??????? Newcastle disease virus

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• 2. The filter paper method
• ???? ?????????(clear
• zone)

Fig. 7.5
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• Types of disinfectants
• Phenol phenolics
• Phenol(carbolic acid) Lister??, ?????, ???,
  ?????????????.
• ???throat lozenges, ?????. ?????????????. ????
  1, ??????

Fig. 7.6a
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• (3) ??????????(phenolics)?,?
• ??????, ???????????
• ???. ???? ??cell membrane,
  ?enzymes????proteins??.??????, ?????, ???????.
• (4) ???????(phenolics)???coal tar????, ????
  (cresols), (??????????)?, ? O-phenylphenol,
  ?Lysol ??????.

Fig. 7.5 7.6b
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• (5) ??????hexachlorophene,
• ???????????????
• ??????????. Cosmetic
• soaps, deodorants, ??????
• ??. ?G()?????????
• ????????????, ???
• ??, ???????.

Fig. 7.6c
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• 2. Biguanides
• ?Chlorhexidine, Str. ?phenol, ????. ????????,
  ???????mix, ?????????????.
• ?? ???????????, ?????. ??????.
• ???? ??cell membrane, ?????????cell fungi ??,
  ??????(sporicidal). ??????virus?????????(envelope)
  ???.

Fig. 7.6d
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• 3. Halogens
• I2 or Cl2 ?????
• I2 ????, ?????, ????, ??, ??, ??virus??. ????
  ?tyrosine binding, ????enzymes??, ????A.A.?-SH
  gr., ??????cell protein ?Str.
• I2???(tincture)??, ???????.?????(iodophor)???????
  ?complex, ? I2 ????, ????????????. ?????
  Betadine? Isodine?. ?????? povidine ??????,
  ?????. I2 ?????????????.

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• (4) Cl2 ?????????????HOCl.
• (i) Cl2 H2O H Cl- HOCl
• (ii) HOCl H OCl-
• HOCl?????, ??cell enzyme??.
• ??????????cell wall, ????
• ?. OCl-???, ??????cell membrane.
• (5) Cl2 ?????, ??????????.
• Ca(OCl)2??????, ?????.
• NaOCl ?????, ???(?Clorox?)
• Chlor-Floc? ?sodium dichloroisocyanurate.

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• (6) Cloramine ?????????, ????, ???????????.
• ??, ??????, ???????.?? ???, ????????.

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• 4. Alcohols
• ???, ??????, ??endospore ???
• ??(envelope)?virus??.
• ?? ??protein??, ????cell membrane ??lipid,
  ?virus???lipid.
• (2) ?? ???????, ?????, ??????protein?coagulation
  , ????, ??????.
• (3) ??(ethanol), ???(isopropanol)???, 70 or
  60-95.
• ??????, ???????isopropanol.
• (4) ZephiranTM 2 min.???40??, ???????80??.

Table 7.6
Fig. 7.10
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• 5. Heavy metals their compounds
• (1) ?Ag, Hg, Cu. Ag Cu ????????oligodynamic
  action. ????protein??-SH gr. binding, ?protein
  ??.

Fig. 7.8
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• (2) 1 AgNO3 ??????? gonorrheal ophthalmia
  neonatorum, ??? antibiotics??.
• (3) Ag ???????,???????.
• (4) HgCl ????????, ???????, ????, ?????,
  ??????????, ????.????????????.
• (5) CuSO4 ????, ?????????, ??copper
  8-hydroxyquinoline??????.
• (6) Zn, ??, ZnCl2 ??????, ZnO??????, ??????????.

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• 6. Surface-active agents
• (1) ?????????????, ???????, ???????, ??????????,
  ???????, ????????????, ????????, ?????.
• (2) ?????triclocarbon triclosan, ???G()??.
• (3) Acid-anionic surface-active sanitizers
  ??????????, ???????cell membrane??.

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• 7. Quaternary ammonium compounds
• (Quats)
• ?????????, ?????, ???
• NH4??. ??G()????, ??G(-)??.
• (2) ???, ??????????virus????, ??endospore??????.
  ???????cell membrane??.(??cell membrane???, ?
• K??)
• (3) Zephiran?(benzalkonium chloride) Cepacol?
• (cetylpyridinium chloride) ?????, ??, ??,
  ??, ???, ??????.
• (4) ???Pseudomonas?????.

Fig. 7.9
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• 8. Chemical food preservatives
• (1) ?? sodium benzoate, sorbic acid calcium
  propionate. Sorbic acid potassium sorbate,
  sodium benzoate ??? cheese ????????. Calcium
  propionate ???????bacillus.
• (2) ?? ?pH?, ??????????cell membrane.
• (3) Sodium nitrate, sodium nitrite ?????.
• ???????nitrate???????????.
• Nitrite???? ????????????????.
• (4) Nitrite ?amino acids ???nitrosamines ? ??

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• 9. Antibiotics
• (1) ??????(Nisin) ??cheese????,
  ???????????????????protein.
• (2) Natamycin(pimaricin) ???, ??cheese.

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• 10. Aldehydes
• (1) Formaldehyde glutaraldehyde ? protein
  ?-NH2, -OH, -COOH -SH gr. Binding ???.
• (2) 37 Formaldehyde formalin
• (3) 2 glutaraldehyde(CidexTM) ?????. 10
  min.????, ????virus 3-10h ??

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• 11. Gaseous chemosterilizers
• Ethylene oxide ???protein??. Protein??H, ?-SH,
  -COOH -OH?alkyl gr.
• (-CH2CH2OH)???.
• ????, ???? ???, ?? CO2 N2 mix. ??????.
• (2) ???propyl oxide ?-propiolactone, ?? ??.

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• 12. Peroxygens, oxidizing agents
• (1) O3, H2O2, peracetic acid
• (2) Benzoyl peroxide ????????????, ?acne??????.
• (3) peracetic acid ????.

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• Microbes relatively resistant to chemical
  antimicrobials
• 1. G()?chemical antimicrobials?????G(-)?,
  G(-)?Pseudomonas??chemical antimicrobials.
• 2. ??????? hexachlorophene?G(-)?????.
• 3. Endospore, ????????. ????????cell wall.

Table 7.7
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The end !!