Ch 7 Control of Microbial Growth

Question 1

removal of all forms of microbial growth

Answer 1

sterilization

Question 2

destroys Clostridium botulinum spores (criteria for food industry)

Answer 2

commercial sterilization

Question 3

destruction of vegetative forms of bacteria

Answer 3

disinfection

Question 4

destruction of vegetative pathogens on living tissue

Answer 4

antisepsis

Question 5

mechanical removal from surface w alcohol swab

Answer 5

de-germing

Question 6

washing to lower microbial count that is generally safe

Answer 6

sanitization

Question 7

putrefaction from microbial contamination

Answer 7

sepsis

Question 8

2 basic ways a microbe can be killed

Answer 8

alter membrane permiability (easier for things to get in, easier for components of cell to leak out)
or
damage proteins or nucleic acids inside cell (disrupts metabolism, prevents reproduction)

Question 9

what is the thermal death point

Answer 9

lowest temp in which 10 min exposure will kill bacteria

Question 10

what is thermal death time

Answer 10

minimum time for all microbes to die at a given temp

Question 11

what is decimal reduction time

Answer 11

time for 90% of microbes to die at a given temp

Question 12

what are equivalent treatments

Answer 12

same result of # of microbes killed, different temp or time

Question 13

a higher temp means (more/less) time needed to kill

Answer 13

less

Question 14

define moist heat sterilization

Answer 14

denatures proteins by breaking H bonds (boiling/steaming)

Question 15

how long endospores can survive boiling

Answer 15

20 hours

Question 16

what is the max temp of boiling water

Answer 16

212 F

Question 17

define pastuerization

Answer 17

brief but high temp (HTST)

72 C for 15 sec or 140C for 4sec

Question 18

which is more effective and why; dry heat sterilization or moist

Answer 18

moist; water conducts heat most efficiently than air

Question 19

define dry heat sterilization

Answer 19

170C for 2 hr

Question 20

HEPA filters v membrane filters

Answer 20

HEPA- filter down to ab .3um

membrane filters- down to ab .01 um

Question 21

which filter would be used to capture viruses (HEPA or membrane filters)

Answer 21

membrane

Question 22

a refrigerator is bacteria___

Answer 22

bacteriastatic

Question 23

freezing (<0C, -44F) is bacteria___ for many species

Answer 23

bacteriacidal

Question 24

how an increase of pressure affects bacteria

Answer 24

denatures proteins

Question 25

why it takes repeated cycles of pressure to eliminate endospores

Answer 25

pressure may germinate them, repeated cycles to kill

Question 26

define dessication

Answer 26

drying to kill microbes

Question 27

how osmotic pressure is used to kill microbes

Answer 27

create a hypertonic environment causing water to move out of cell (desiccating it)

Question 28

canning w sugar or salt is an example of

Answer 28

using osmotic pressure to kill microbes

Question 29

____ can tolerate high osmotic pressure

Answer 29

molds

Question 30

the shorter the wavelength the (higher/lower) the energy

Answer 30

higher

Question 31

how long are ionizing wavelengths, how they affect microbes, examples?

Answer 31

<1 nanometer, creates ions and hydroxyl radicals that can cause mutations in DNA and kill microbes; xrays, gammarays

Question 32

how long are non-ionizing wavelengths, examples? | how they affect microbes

Answer 32

>1 nanometer ; UV light | kills microbes by creating thymine dimers causing a bump in DNA and mutations

Question 33

what are thymine dimers

Answer 33

section of DNA w 2 thymines next to eachother, absorb UV light bonds break between adenines and a covalent bond forms between the two T's

Question 34

wavelength bactericidal range

Answer 34

200-295

Question 35

how phenols affect microbes

Answer 35

damage PM

Question 36

what biphenols (O-phenylphenol) do

Answer 36

inhibit biosynthesis of fatty acids

Question 37

what biguanide does | example

Answer 37

disrupts PM, antiseptic | chlorhexidine

Question 38

what halogen phenols do | examples

Answer 38

disrupts enzyme function (iodine and chloride) | impairs protein synthesis, alters PM (chlorine)

Question 39

iodine + alcohol is called

Answer 39

an iodine tincture

Question 40

how alcohol affects microbes

Answer 40

denatures proteins, disrupts membranes, dissolves lipids

Question 41

why 100% alcohol is less effective than alcohol w water

Answer 41

alcohol + water helps it to penetrate lipid membrane (alcohol is non-polar)

Question 42

at what conc does alcohol begin reducing in effectivness

Answer 42

less than 50%

Question 43

how heavy metals affect microbes

Answer 43

metal ions bind to sulfur, disrupts bonds and makes proteins ineffective

Question 44

heavy metals in use for killing microbes

Answer 44

silver, copper, zinc

Question 45

what are surface acting agents and how they affect bacteria

Answer 45

soaps/detergents, emulsify/ degerm bacteria on skin

Question 46

example of surface acting agent and how it works

Answer 46

Quat compounds (benzalconium chloride)- ammonium ions replace each H w/ different organic mlcl, inhibit enzyme function, denatures protiens, disrupts PM

Question 47

most resistant to biocides

Answer 47

prions

Question 48

least resistant to biocides

Answer 48

viruses w/ lipid envelopes

Question 49

An autoclave is an example of moist or dry heat sterilization

Answer 49

Moist