Lecture 11 [Exam 3]

Question 1

Microbes have both __________ and ___________ growth rate.

Answer 1

fastest and slowest

Question 2

True or False: Some hot springs bacteria can double as fast as 10 minutes while some deep sea sediment bacteria can double in as long as 100 years.

Answer 2

True

Question 3

These differences are determined by ____________ and ____________.

Answer 3

Nutrition and Niche-specific physical parameters, ex. temperature and pH

Question 4

What are normal growth conditions?

Answer 4

• Sea level
• Temperature 20°C–40°C
• A near-neutral pH
• 0.9% salt
• ample nutrients

Question 5

Any habitat outside this window is called “extreme,” and organisms
inhabiting them are called ________________.

Answer 5

extremophiles

Question 6

What are extremophiles?

Answer 6

Microbes (bacteria, archaea, and a few eukaryotes) that are able
to grow in conditions very different from those for humans.

Question 7

What are polyextremophiles?

Answer 7

Microbes that can survive many extreme environments.

Question 8

True or False: The bacteria cell temperature matches its immediate environment.

Answer 8

True

Question 9

True or False: Bacteria have an optimal temperature in which they grow the quickest.

Answer 9

True

Question 10

Psychrophiles:

Answer 10

~0°C–20°C

Question 11

Mesophiles:

Answer 11

~15°C–45°C

Question 12

Thermophiles:

Answer 12

~40°C–80°C

Question 13

Hyperthermophiles:

Answer 13

~65°C–121°C

Question 14

True or False: The thermophile, Thermus aquaticus was the first source of a high temperature DNA polymerase used for PCR

Answer 14

True

Question 15

Who discovered Thermus aquaticus at Yellowstone National Park?

Answer 15

Thomas Brock

Question 16

What is sterilization?

Answer 16

process of killing of all living cells, spores, and viruses on an object

Question 17

What is disinfection?

Answer 17

killing or removal of PATHOGENS from inanimate surfaces (does not always result in sterilization)

Question 18

What is antisepsis?

Answer 18

killing or removal of pathogens from the surface of living tissues
(ex. Skin)

Question 19

What is sanitation?

Answer 19

-reducing the microbial population to safe levels which includes cleaning and disinfection

Question 20

What does bacteriostatic mean?

Answer 20

Having the ability to inhibit the growth of bacterial cells

Question 21

What does bactericidal mean?

Answer 21

Having the ability to kill bacterial cells

Question 22

What does germicidal mean?

Answer 22

Chemical substances that kill pathogens (and many nonpathogens). Does not kill some spores.

Question 23

What are the 5 physical means of killing bacteria?

Answer 23

1. High temperature and pressure
2. Pasteurization
3. Cold
4. Filtration
5. Radiation

Question 24

What temperature and pressure is used in a steam autoclave?

Answer 24

121°C (250°F) at 15 psi for 20 min

Question 25

What is pasteurization?

Answer 25

The heating of food at a temp. and time combination that will kill Coxiella burnetii

Question 26

LTLT (low temperature/long time):

Answer 26

63°C for 30 minutes

Question 27

HTST (high temperature/short time)

Answer 27

72°C for 15 seconds

Question 28

UHT (ultra-high temperature):

Answer 28

138°C for 1 to 2 seconds 20

Question 29

Low temp. have 2 basic purposes in microbiology to _________ and ___________.

Answer 29

To slow growth and preserve strains

Question 30

True or False: Gram-positive bacillus Listeria monocytogenes grows well in the cold and can cause disease when ingested.

Answer 30

True

Question 31

What happens in cryopreservation?

Answer 31

Bacteria are suspended in a glycerol solution and stored at -80°C which suspends growth and preserves the strains from dying.

Question 32

What happens during Lyophilization/freeze-drying?

Answer 32

Lyophilized bacteria (powder form) are preserved at 4°C

Question 33

What happens during filtration?

Answer 33

Micropore filters with pore sizes of 0.2 μm remove microbial cells (not viruses) from liquid solutions.

Question 34

What is the advantage of filtration?

Answer 34

It does not use heat (heat can cause damage to materials)

Question 35

What do Laminar flow biological safety cabinets do?

Answer 35

force air through high efficiency particulate air (HEPA) filters that removes >99.9% of airborne particulate material 0.3 μm in size or larger

Question 36

True or False: Newer technologies embed antimicrobial agents or enzymes into the fibers ofthe HEPA filter.

Answer 36

True

Question 37

What types of materials have the FDA approved for irradiation?

Answer 37

beef, pork, fruits, vegetables, eggs, spices, seeds

Question 38

What is ultraviolet used for?

Answer 38

Since it has poor penetrating power, it is mainly used on surface sterilization

Question 39

What type of radiation has high penetrating power and can be use to irradiate foods and other heat-sensitive items?

Answer 39

Gamma rays, electron beams, and X-rays

Question 40

How does radiation kill bacteria?

Answer 40

forms very short-lived reactive chemicals (reactive oxygen species) that damage DNA and proteins

Question 41

Sensitivity to irradiation, depends on multiple factors including:

Answer 41

* the size of the genome of the bacteria * the rate at which bacteria can repair damaged DNA * condition of the food - takes a higher dose of radiation to kill microbes in frozen foods 28

Question 42

True or False: Deinococcus radiodurans has the greatest ability to survive radiation of any known organism.

Answer 42

True

Question 43

What properties account for Deinococcus radiodurans amazing resistance to radiation?

Answer 43

* highly efficient double-strand- break DNA repair system requiring homologous recombination * 4-6 copies of its two chromosomes and two plasmids * aggressively protect its proteins

Question 44

A number of factors influence the efficacy of a given chemical agent including:

Answer 44

*The presence of organic matter – lowers the agent’s effectiveness against microbes * The kind of organisms present – should be effective against broad range of pathogen * Corrosiveness - should not corrode the surface or, in the case of an antiseptic, damage skin * Stability, odor, and surface tension 31

Question 45

____________ uses the high potency of phenol as the benchmark against other disinfectants to be measured.

Answer 45

The phenol coefficient test

Question 46

_________ is a toxic liquid that is no longer used as a routine disinfectant.

Answer 46

Phenol

Question 47

Derivatives, cresols and orthophenylphenol are still in use because they are:

Answer 47

*Very effective *Denature protein * Effective in the presence of organic matter * Remain active on the surface long after application

Question 48

Examples of derivatives, cresols, and orthophenylphrenol that damage DNA and proteins:

Answer 48

* Ethanol * Iodine * Chlorine * Detergents

Question 49

Altering the fatty acid synthesis protein (normally targeted by triclosan) can ________________.

Answer 49

Enable bacteria to develop a resistance to certain disinfectants

Question 50

True or False: Pseudomonas can pump several biocides, detergents out of the cell, reduce efficacy. This is an example of bacteria being able to reduce efficacy by producing membrane-spanning, multidrug efflux pumps.

Answer 50

True

Question 51

True or False: Forming multispecies biofilms offer collaborative protection against certain disinfectants.

Answer 51

True

Question 52

__________ binds disinfectants, slowing their penetration.

Answer 52

Extracellular matrix

Question 53

_________________have time to activate protective stress response system.

Answer 53

Cells in the deeper biofilm area

Question 54

__________ are chemical compounds synthesized by one microbe to either kill (bactericidal) or stop the growth of (bacteriostatic) other competing microbial species.

Answer 54

Antibiotics

Question 55

True or False: Antibiotics are classified according to their modes of action.

Answer 55

True

Question 56

The four functions/structures that antibiotics target:

Answer 56

*cell wall synthesis * b. protein synthesis * c. DNA replication * d. cell membrane structure

Question 57

_______________ is bactericidal because it prevents peptidoglycan synthesis and cell wall formation (bacteria cant live without support of the cell wall).

Answer 57

Penicillin

Question 58

How do antibiotic-producing microbes avoid suicide?

Answer 58

a. lacks the target molecule (Penicillium mold lacks peptidoglycan) b. modify its own receptors (some bacterial colicins). c. modify the antibiotic if it renters the cell (streptomycin produced by Streptomyces griseus).

Question 59

______________ is the use of one microbe to control the growth of another

Answer 59

Biocontrol

Question 60

True or False: Presence of harmless microbes retard the growth of pathogenic strains.

Answer 60

True

Question 61

______________ are food or supplements that contain live microbes. When ingested, they can restore balance to intestinal flora.

Answer 61

Probiotics (ex. Lactobacillus and Bifidobacterium)

Question 62

True or False: Every bacterial species is susceptible to a limited number of specific phages.

Answer 62

True

Question 63

_______________ are viruses that prey on bacteria. Can cause bacterial lysis and serve as a possible way to treat infectious diseases.

Answer 63

Bacteriophages

Question 64

Commercial phage products target a __________ food-borne pathogens.

Answer 64

few

Question 65

A ________________ contains several phages.

Answer 65

Phase product

Question 66

True or False: Phase products are sprayed onto the hides of cattle 1-4 hrs before slaughter.

Answer 66

True

Question 67

Using ___________ phages in each preparation eliminates the risk that phage resistance will develop in the pathogen.

Answer 67

multiple