Lecture 7a- Microbial Diversity

Question 1

what is the first way to describe microbial diversity?

Answer 1

phylogenetic diversity

Question 2

how are phylogenetic trees organized?

Answer 2

microbes are grouped into phyla based on evolutionary relationships
based on 16S rRNA gene sequence

Question 3

what does the phylogenetic tree divide into?

Answer 3

92 named bacterial phyla
26 archaeal phyla
5 eukaryotic supergroups

Question 4

what is the second way to describe microbial diversity?

Answer 4

functional diversity

Question 5

how is functional diversity characterized?

Answer 5

groups of microbes based on the activities they carry out

Question 6

what does the bacterial phyla tenericutes consist of?

Answer 6

gram positive but without a cell wall therefore gram stain negative
often pleomorphic (many different shapes)

Question 7

what is an example of a bacterium in the phyla tenericutes?

Answer 7

mycoplasma genitalium
causes urethritis and pelvic inflammatory disease
first free living bacterium to have its genome sequenced
one of the smallest genomes known

Question 8

what does the bacterial phyla actinobacteria consist of?

Answer 8

gram positive
layer of mycolic acids outside the peptidoglycan layer (makes them acid fast)
includes coryneform bacteria (club shaped morphology) swiss cheese originates from this phyla (bacteria is propionic acid bacteria)

Question 9

what is an example of actinobacteria?

Answer 9

corynebacterium diphtheriae

Question 10

what does corynebacterium diphtheriae do?

Answer 10

produces an exotoxin that inhibits protein synthesis
causes tissue death in the respiratory tract
can lead to death by suffocation

Question 11

what is the filamentous actinobacteria? what do they consist of?

Answer 11

gram positive
most produce obligate aerobes (love oxygen)
form branching hyphae and mycelia

Question 12

what are hyphae?

Answer 12

produce reproductive spores for dispersal but are NOT endospores, just act like them

Question 13

where do filamentous actinobacteria live?

Answer 13

aerated soils
gives soil its earthy smell (geosmins)

Question 14

what do filamentous actinobacteria produce?

Answer 14

substances that kill or inhibit the growth of other microbes (antibiotics)

Question 15

what is an example of a filamentous actinobacteria?

Answer 15

streptomyces griseus

Question 16

what does streptomyces griseus do?

Answer 16

produces streptomycin: broad spectrum protein synthesis inhibitor active against gram negative bacteria

Question 17

what does the bacterial phyla bacteroidetes consist of?

Answer 17

gram negative bacteria
large
heterogeneous phylum
aerobes and anaerobes
few unifying characteristics

Question 18

what is an example of the bacterial phyla bacteroidetes?

Answer 18

bacteroides thetaiotaomicron

Question 19

what do bacteroides thetaiotaomicron do?

Answer 19

strict anaerobe
numerically dominant microbe in the human large intestine
produces enzymes to degrade polysaccharides, greatly increasing the variety of plant polymers that can be digested in the human gut

Question 20

what does the bacterial phylum acidobacteria consist of?

Answer 20

very little is known about acidobacteria
only recognized within the last 20 years
difficult to cultivate
first sequenced genome in 2009
makes up between 20-50% of soil microbial community

Question 21

what does the phyla chlamydiae consist of? cell wall type? what type of parasites are they?

Answer 21

gram negative cell wall type but lack peptidoglycan
obligate intracellular parasites

Question 22

what are the two types of cells of the life cycle within the phyla chlamydiae?

Answer 22

elementary body
reticulate body

Question 23

what does the elementary body life cycle consist of?

Answer 23

small dense cell
resists drying
allows infection of new host cells

Question 24

what does the reticulate body life cycle consist of?

Answer 24

larger vegetative cells
multiply inside an existing host
are not infective

Question 25

what is an example of the reticulate body life cycle?

Answer 25

trachoma/ chlamydia trachomatis
causes infection of the eye, if left untreated, causes scarring and blindness

Question 26

how does the bacterial phyla planctomycetes reproduce? what is the protein stalk used for? what does the cell wall consist of?

Answer 26

budding and appendaged bacteria
protein stalk used for attachment
lack peptidoglycan in the cell wall and have some membrane bound compartments inside the cell

Question 27

what is an example of a planctomycete that has membrane bound compartments inside the cell?

Answer 27

gemmata obscuriglobus (nucleoid is surrounded by a true unit membrane)

Question 28

what makes the bacterial phyla cyanobacteria morphologically diverse?

Answer 28

unicellular
filamentous
branching filamentous

Question 29

what can some cyanobacteria form?

Answer 29

heterocysts which are specialized for nitrogen fixation

Question 30

all cyanobacteria carry out oxygenic photosynthesis, what does that entail?

Answer 30

harvests energy from light and produces oxygen

Question 31

all cyanobacteria are autotrophs, what does that entail?

Answer 31

fixes CO2 to build cell material (calvin cycle)

Question 32

where is the photosynthesis carried out in cyanobacteria? what does the structure contain?

Answer 32

thylakoids contains cell walls with peptidoglycan, thus gram negative cell wall type

Question 33

where are cyanobacteria found?

Answer 33

terrestrial freshwater and marine habitats

Question 34

why do cyanobacteria have the lowest nutritional requirements of any organisms?

Answer 34

because they are primary producers and can fix nitrogen and carbon dioxide

Question 35

what is an example of a bacteria within cyanobacteria?

Answer 35

prochlorococcus (accounts for around half of photosynthesis in the worlds oceans)

Question 36

when do cyanobacteria bloom in lakes?

Answer 36

addition of phosphate