BIOL 351 EXAM 4
a reciprocal benefit accrues to both partners
-obligatory relationship —> partners need each
mutualism
other to grow
(e.g. Buchnera aphidicola and aphids)
gram negative bacterium (~617 kb genome),
lives in aphids
Buchnera aphidicola
-transmitted vertically from mother to daughter
-obligate mutualists
-buchnera provides aphids with tryptophan
-aphids provide buchnera with amino acids that
Mutualist relationship betweem Buchnera and
it cannot make
aphids
(around ~75% of buchnera genome has been
lost)
germ free
Gnotobiotic e.g. gnotobiotic aphids —> grow normally when
provided with a diet supplemented with amino
acids
a reciprocal benefit in both partners, but it is
NOT obligatory relationship; both partners will
Cooperation grow well without each other
e.g. Delsulfovibrio and chrmatium
One symbiont (the commensal) benefits while
Commensalism the other (host) isn’t harmed or helped
e.g. Staphylococcus epidermis
consumes human waste (oils, water, salts, dead
Staphylococcus epidermis skin cells) while normally having no impact on
human health
One organism preys on another
Predation
(e.g. Bdellovibrio)
1/15
, -gram-negative bacteria
-enters prey’s periplasmic space and feeds on
Bdellovibrio
the cytoplasmic contents
-uses synchronous septation to replicate
1. septation initiation
2. septation propagation
Synchronous septation pathway 3. filament fragmentation
4. progeny maturation
5. escape
the parasite benefits while the host is usually
Parasitism
harmed
the adverse effect that one organism has on
another
Amensalism
e.g. Streptomyces spp. produce many different
antibiotics
two organisms try to acquire the same resource
(location or nutrient)
Competition
-This concept is used in the FMT of C. diff
infections
-human body contains 10^13 human cells
-about 10 times more
How many organisms make up the human
Mouth: 0.01% total
microbiota?
Skin: 1% total
Large and small intestine: 99%
slime-encased aggregation of bacteria
biofilm -composed of polysaccharide, protein, and
extracellular DNA
1. cells attach to the surface
2. cells multiply to a confluent “lawn” of
cells on the surface
4 stages of biofilm formation 3. An “exodus” phase occurs and some
cells leave
4. biofilm matures into towers of cells
(occurs with staphylococcus aureus
2/15
a reciprocal benefit accrues to both partners
-obligatory relationship —> partners need each
mutualism
other to grow
(e.g. Buchnera aphidicola and aphids)
gram negative bacterium (~617 kb genome),
lives in aphids
Buchnera aphidicola
-transmitted vertically from mother to daughter
-obligate mutualists
-buchnera provides aphids with tryptophan
-aphids provide buchnera with amino acids that
Mutualist relationship betweem Buchnera and
it cannot make
aphids
(around ~75% of buchnera genome has been
lost)
germ free
Gnotobiotic e.g. gnotobiotic aphids —> grow normally when
provided with a diet supplemented with amino
acids
a reciprocal benefit in both partners, but it is
NOT obligatory relationship; both partners will
Cooperation grow well without each other
e.g. Delsulfovibrio and chrmatium
One symbiont (the commensal) benefits while
Commensalism the other (host) isn’t harmed or helped
e.g. Staphylococcus epidermis
consumes human waste (oils, water, salts, dead
Staphylococcus epidermis skin cells) while normally having no impact on
human health
One organism preys on another
Predation
(e.g. Bdellovibrio)
1/15
, -gram-negative bacteria
-enters prey’s periplasmic space and feeds on
Bdellovibrio
the cytoplasmic contents
-uses synchronous septation to replicate
1. septation initiation
2. septation propagation
Synchronous septation pathway 3. filament fragmentation
4. progeny maturation
5. escape
the parasite benefits while the host is usually
Parasitism
harmed
the adverse effect that one organism has on
another
Amensalism
e.g. Streptomyces spp. produce many different
antibiotics
two organisms try to acquire the same resource
(location or nutrient)
Competition
-This concept is used in the FMT of C. diff
infections
-human body contains 10^13 human cells
-about 10 times more
How many organisms make up the human
Mouth: 0.01% total
microbiota?
Skin: 1% total
Large and small intestine: 99%
slime-encased aggregation of bacteria
biofilm -composed of polysaccharide, protein, and
extracellular DNA
1. cells attach to the surface
2. cells multiply to a confluent “lawn” of
cells on the surface
4 stages of biofilm formation 3. An “exodus” phase occurs and some
cells leave
4. biofilm matures into towers of cells
(occurs with staphylococcus aureus
2/15
