Colony Morphology

Question 1

Colonies

Answer 1

aggregates of microorganisms grown on media
-reproduce by binary fission
-all cells in a colony are genetically identically and originate from a single parent cell

Question 2

Colony morphology

Answer 2

many features of colonies that help identify a particular species
-determined by genetics but can be influenced by environmental conditions

Question 3

Agar plates

Answer 3

Petri dish that contains a growth medium solidified with agar, used to culture microorganisms

Question 4

What causes urinary trach infections in humans

Answer 4

Proteus Mirabilis
-colonies are often smooth, grey, and large, and contain circular rings
-has a rotten fish smell

Question 5

The physical appearance of a bacterial colony is determined by?

Answer 5

1. pigment production
2. cell wall type
3. motility
4. metabolism

Question 6

Growth in liquid media (broth)

Answer 6

-some bacteria may grow and produce uniform clouding, or settle at the bottom of the tube
-others may have layering of growth at top, middle, layer depending on organisms oxygen requirement
-can even tell cell pigmentation

Question 7

what are the 6 general categories to describe colony morphology?

Answer 7

1. size
2. elevation
3. edge
4. color
   5.surface/texture
   6.odor

Question 8

Size

Answer 8

this can only be used when comparing two different species grown in identical environmental conditions
-generally not used can be influenced by environment

Question 9

Elevation

Answer 9

the profile or height of the colony
-flat, raised, and convex are the most common

Question 10

color

Answer 10

while many colonies are a white or cream color, some have very unique coloration due to the production of pigmentation molecules
-serratia marcescens produces a red pigment called prodigiosin
-micrococcus was yellow color
-pseudomonas is a green

Question 11

what microorganism did we use in this class

Answer 11

sserratia marcescens and micrococcus

Question 12

surface

Answer 12

colony surface is often related to the glycocalyx of the bacterial cell
-cells that lack a capsule often have a dry powdery look
-capsule or slime layer causes the shiny appearance

Question 13

Edge

Answer 13

the outline or border of the colony
-spreading out indicates bacteria are motile
undulate = wavy
erose = serrated
spreading and rhizoid = root like

Question 14

odor

Answer 14

some colonies will have a distinct odor
-pseudomonas have a fruity like smell

Question 15

general purpose media

Answer 15

has all the essential nutrients needed to support the growth of most bacterial species
-we use trypticase soy broth (TSB) and agar (TSA) to culture and characterize their colony morphology
-they contain pancreatic digest of casein, papain digest of soybean, and sodium chloride