Lecture 1- oral ecology

Question 1

3 ways to detect bacterial species

Answer 1

microscopy
cultivation
DNA methods

Question 2

by cultivation, there are … species present in the oral cavity

Answer 2

300+

Question 3

by 16S diversity, there are around … species and perhaps more consistently detected in human mouths

Answer 3

700

Question 4

each person harbors around … species

Answer 4

200

Question 5

the mouth is an open system, we have … and … of the oral cavity that can grow

Answer 5

transient species

true residents

Question 6

our microbiota includes much more … than our human genome

Answer 6

DNA diversity

Question 7

each body site harbors a distinct …. including the oral cavity

Answer 7

microbial community

Question 8

each of us includes slightly more …. than human cells

Answer 8

bacterial cells

Question 9

individuals differ amongst each other although some … are shared

Answer 9

core species

Question 10

… is the study of the interrelationships of organisms and their environment

Answer 10

ecology

Question 11

a … is the specific combination of conditions that are necessary for the survival of a particular organism. the parameters may be physical, chemical and biological

Answer 11

niche

Question 12

bacteria can adhere to … and … surfaces in the oral cavity

Answer 12

soft tissue and hard

Question 13

some bacteria are … which mean they float in water

Answer 13

planktonic

Question 14

most of the bacteria that cause dental problems and many medical problems are … which mean they are attached to a surface in biofilms

Answer 14

sessile

Question 15

biofilms are made up of … and … in an .. environment

Answer 15

adherent organisms
ECM
aqueous

Question 16

the biofilm life cycle is … then … and finally …

Answer 16

attachment

growth/mature

detachment (to seed new biofilm)

Question 17

bacteria in biofilms sometimes cannot be treated with antibiotics because they are not always

Answer 17

metabolically active

Question 18

3 primary mechanisms for biofilm antimicrobial resistance

Answer 18

slowing of diffusion

“persister cells”- alive but inactive so they survive and repopulate

close proximity and exchange of resistance genes

Question 19

…. species scavange O2 and help to provide an anaerobic environment for other species– pioneers for anaerobic ecology?

Answer 19

fusobacterium

Question 20

The action of these 3 enzymes is to detoxify oxygen radicals that are generated by living systems in the presence of O2. So the distribution of these enzymes in cells determines their ability to exist in the presence of O2

Answer 20

superoxide dismutase

catalase

peroxidase

Question 21

The sensitivity of anaerove to oxygen is due to the genetic inability to make …

Answer 21

superoxide dismutase, catalase and peroxidase

Question 22

2 ways ingested foods can affect pH

Answer 22

directly (carbonated drink is ~3)

indirectly (bacterial fermentation of sugars to lactate ~5)

Question 23

2 major physical nutrient niches in the oral cavity

Answer 23

supragingival (saliva-endogenous, ingested foods-exogenous)

subgingival (crevicular fluid and cells- endogenous)

Question 24

… in saliva prevents adhesion

Answer 24

sIgA

Question 25

… in crevicular fluid directed against periodontally important organisms

Answer 25

IgG

Question 26

both sIgA and IgG are systematically and locally produces and they inhibit … , act as … and activate ..

Answer 26

colonization

opsonins

complement system

Question 27

major salivary proteins are … which digests starches and binds bacteria and …

Answer 27

a-amylase

mucins (lubricants)

Question 28

… is a minor salivary protein that digests peptidoglycan in bacterial cell wall leading to osmotic disruption and cell death

Answer 28

salivary lysozyme

Question 29

… and … are minor salivary proteins that bind iron so that it is not bioavailable to bacteria

Answer 29

salivary lactoferrin and serum transferrin

Question 30

the … system in saliva generates superoxide radicals which inactivate bacterial enzymes leading to bacterial death

Answer 30

sialoperoxidase

Question 31

… in saliva have activity against bacteria and yeast

Answer 31

antimicrobial peptides

Question 32

…. proteins and …. modulate salivary calcium and phosphate chemistry

Answer 32

acidic proline-rich

statherin

Question 33

carbon dioxide generated by a # of organisms including … and …. enhances the growth of … and …

Answer 33

peptostreptococci
eubacteria

capnocytophaga
A.a.

Question 34

removal of oxygen by …. causes more fastidious anaerobes such as … to survive

Answer 34

fusobacterium nucleatum

tanerella forsythia

Question 35

6 ecologic determinants

Answer 35

surface receptors for adherence

oxygen tension (Eh)

pH

nutrients

host inhibitory factors

bacterial community interactions