Lecture 1- oral ecology Flashcards
3 ways to detect bacterial species
microscopy
cultivation
DNA methods
by cultivation, there are … species present in the oral cavity
300+
by 16S diversity, there are around … species and perhaps more consistently detected in human mouths
700
each person harbors around … species
200
the mouth is an open system, we have … and … of the oral cavity that can grow
transient species
true residents
our microbiota includes much more … than our human genome
DNA diversity
each body site harbors a distinct …. including the oral cavity
microbial community
each of us includes slightly more …. than human cells
bacterial cells
individuals differ amongst each other although some … are shared
core species
… is the study of the interrelationships of organisms and their environment
ecology
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
niche
bacteria can adhere to … and … surfaces in the oral cavity
soft tissue and hard
some bacteria are … which mean they float in water
planktonic
most of the bacteria that cause dental problems and many medical problems are … which mean they are attached to a surface in biofilms
sessile
biofilms are made up of … and … in an .. environment
adherent organisms
ECM
aqueous
the biofilm life cycle is … then … and finally …
attachment
growth/mature
detachment (to seed new biofilm)
bacteria in biofilms sometimes cannot be treated with antibiotics because they are not always
metabolically active
3 primary mechanisms for biofilm antimicrobial resistance
slowing of diffusion
“persister cells”- alive but inactive so they survive and repopulate
close proximity and exchange of resistance genes
…. species scavange O2 and help to provide an anaerobic environment for other species– pioneers for anaerobic ecology?
fusobacterium
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
superoxide dismutase
catalase
peroxidase
The sensitivity of anaerove to oxygen is due to the genetic inability to make …
superoxide dismutase, catalase and peroxidase
2 ways ingested foods can affect pH
directly (carbonated drink is ~3)
indirectly (bacterial fermentation of sugars to lactate ~5)
2 major physical nutrient niches in the oral cavity
supragingival (saliva-endogenous, ingested foods-exogenous)
subgingival (crevicular fluid and cells- endogenous)
… in saliva prevents adhesion
sIgA
