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21 Φεβ 2013 (πριν από 4 χρόνια και 3 μήνες)

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Denver School of Nursing


General Education Classes

Lecture: Friday 7:00am


11:24am

Laboratory: Friday 12:00


2:00pm

Instructor: Micah Hughes, MS Biotechnology, BA Bio / Anthro

BIO 205


Day 3 CH9 + Exam Review
Molecular Biotechnology

Microbiology

Chapter 9

Controlling Microorganisms


Sterilization


destroy all microbial
life


Disinfection


reduces number of
pathogens


pose no danger of
disease


Decontamination


renders
contaminated
surface safe to
handle


Antisepsis


kills microorganisms
on living tissue


Microbiocidal


killing of
microorganisms


Microbiostatic


inhibiting the growth
of microorganisms



Decimal reduction time


D
-
value


time required to kill 90%
of cells


Heat treatments


temperature


type of microorganism


physiological state


other substances

Figure 9.1


Thermal death point


lowest temperature


kill all microorganisms


10
minutes



Thermal death time


minimal time


kill all microorganisms


liquid suspension


at given temperature


Heat


Moist


boiling


kills most vegetative cells, not sterile


autoclave


steam under pressure: 15 lbs./in
2

at 121
o
C for 15 min.


kills endospores


Pasteurization


kills certain microorganisms


Dry


long periods


160
o
C for 2 hours


171
o
C for 1 hour



Cold


does not kill


many die slowly


useful in slowing
growth



Radiation


UV light


sterilizes by damaging DNA


Ionizing: X
-
rays and gamma rays


sterilizes by stripping electrons


Filtration


physically removes
microorganisms


heat
-
sensitive liquids


media, vitamins, antibiotics,
hormones


air filters (HEPA)


Drying


not sterilization


evaporation


lyophilization



Osmotic strength


salts and sugars


damage cells by
plasmolysis


preserving foods


Antimicrobial agents


chemotherapeutic agents


used to treat disease


germicides and
germistats


disinfectants and
antiseptics



1200 germicides


sold by 330 manufacturers in U.S
.



Selection


damage the tissue or object


control the target microorganism(s)


purpose of treatment



Paper disc method


germicide placed on paper disc


disc placed on agar seeded with microorganism


after incubation, observe zone of inhibition

Figure 9.2


Phenols and phenolics


denature proteins


act on lipids


disrupt cytoplasmic
membrane


Examples:


Paracresol


Lysol


Hexachlorophene


prescription use


Figure 9.3


Alcohols


disrupt lipids


attack cytoplasmic
membrane


denature proteins


50
-
70% solutions more
effective


increase plasmolysis
after membrane is
damaged

Figure 9.1


Oxidizing agents


inactivate proteins


oxidizes functional groups


Halogens


iodine: antiseptic


betadine, tincture of iodine


chlorine: disinfectant


Hydrogen peroxide (H
2
O
2
)


3% solution
-
weak antiseptic


broken down to water and oxygen


bubbling when applied to skin


Surfactants


hydrophobic and
hydrophilic parts


penetrate cytoplasmic
membrane


quaternary ammonium
salts


charged nitrogen with four
hydrophobic groups


Cepacol


Zephiran


Figure 9.5


Alkylating agents


inactive proteins


attach short chains of
carbons (alkyl groups)


Formalin


37% solution of
formaldehyde


Ethylene oxide


gas sterilization

Figure 9.1


Temperature


refrigeration


canning


Pasteurization


63
o
C for 30 minutes


72
o
C for 15 seconds


pH


vinegar


lactic acid
fermentation


Water


drying


evaporation


freeze
-
drying


salting


high osmotic strength


Chemicals


preservatives


And all the material covered on the
Microbiology

Exam #1


Remember to…


KEEP UP WITH YOUR:





1) Text READING




2) Homework




3) PowerPoint
Review