Block B 3

Question 1

what is isolation in pure culture important for

Answer 1

detailed studies in controlled (lab) environment
biotechnology applications

Question 2

what are biofilms

Answer 2

assemblages of bacterial cells adhered to a surface and enclosed in an adhesive matrix excreted by the cells

Question 3

what is the matrix typically composed of in biofilms

Answer 3

polysaccharides

Question 4

what is the microbial hormone that controls biofilm formation

Answer 4

c-di-GMP

Question 5

why do bacteria form biofilms

Answer 5

-self defense
-allows cells to remain in favourable niche
-allows bacterial cells to live in close associated with one another

Question 6

what are the 2 ways of microbial isolation from the environment

Answer 6

direct isolation
enrichment culture

Question 7

what is direct isolation used for

Answer 7

enumeration
detailed studies in controlled environments

Question 8

what is enrichment culture used for

Answer 8

isolation (biotechnology)
risk assessment

Question 9

what are the established medium and incubation conditions for

Answer 9

selective for desired organism
de selective for undesired organisms

Question 10

3 ways that pure cultures can be obtained

Answer 10

streak plate
agar plate
liquid dilution

Question 11

how can anaerobic bacteria grow method

Answer 11

agar shake up method
dilutions of mixed cultures in tubes of molten agar

Question 12

how can aerobic bacteria grow method

Answer 12

plates

Question 13

problems with direct counting

Answer 13

cannot distinguish between live and dead cells without special stains
small cells overlooked
phase contrast microscope req if stain not used

Question 14

2 main ways to perform plate counts

Answer 14

spread plate method
pour plate method

Question 15

to obtain the appropriate colony number the sample counted should always be …

Answer 15

diluted

Question 16

what does MPN stand for

Answer 16

most probable numbers

Question 17

how to obtain MPN

Answer 17

-serial dilution of inoculum in liquid until final tube shows no growth
-repeat until pure culture obtained
-estimation of microbial numbers for routine sampling

Question 18

how to check for purity when finding MPN

Answer 18

-microscopy
-colony characteristics on plate
-test for growth in other media
-check for contamination

Question 19

what must organisms balance

Answer 19

growth and death rates

Question 20

what 2 methods are there for organisms to balance growth and death rates

Answer 20

oligotrophs
copiotrophs

Question 21

what other names are there for oligotrophs

Answer 21

k strategists
autochthonous microbes

Question 22

what other names are there for copiotrophs

Answer 22

r strategists
zymogenous microbes

Question 23

what can be said about nutrient uptake with oligotrophs

Answer 23

nutrient uptake enzymes with low specificity but high affinity

Question 24

what can be said about nutrient uptake with copiotrophs

Answer 24

nutrient uptake enzymes with high specificity but low affinity

Question 25

what undergoes cell rounding and reduction in growth

Answer 25

arthrobacter (oligotroph)

Question 26

what spores are metabolically active

Answer 26

streptomyces (copiotroph)

Question 27

what does VBNC stand for

Answer 27

viable but nonculturable

Question 28

metabolic activity of VBNC bacteria

Answer 28

very low

Question 29

what is reduced in VBNC bacteria

Answer 29

nutrient transport respiration synthesis of macromolecules

Question 30

what does VBNC have the ability to

Answer 30

become culturable once resuscitated

Question 31

sources of novel targets

Answer 31

synthetic non synthetic natural products (fungi, plants, bacteria)

Question 32

3 steps to see zone of inhibition

Answer 32

lawn of indicator organism agar plug of producing organism filter paper disk soaked in test compound

Question 33

what does MIC stand for

Answer 33

minimum inhibitory concentration