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What are the different qualities we look at for bacterial colony morphology?
- form or shape
- margins
- elevation
- texture
- color
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How do we grow bacteria?
bacteria can be isolated and grown on or in either solid media or liquid media
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What are the two different types of media?
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How to we place bacteria on agar plate?
"streak out" the bacteria onto the agar
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What is a pure culture?
agar plate or broth tube contains only one type of bacteria all descending from a common ancestor
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What is a mixed culture?
agar plate or broth tube contains more than one type of bacteria
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Can a mixed culture become a pure culture?
yes, you can transfer cells from a single pure colony to begin a pure culture on another agar plate or in a broth tube
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How do we classify form or shape of bacterial colonies?
- punctiform
- circular
- filamentous
- irregular
- rhizoid
- spindle
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How do we classify elevation of bacterial colonies?
- flat
- raised
- convex
- pulvinate
- umbonate
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How do we classify margins of bacterial colonies?
- entire
- undulate
- lobate
- erose
- filamentous
- curled
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Define rhizoid.
root-like, branched like roots
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Define pulvinate.
very convex
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Define umbonate.
raised in the center (like a belly button)
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Define erose.
irregularly indented
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What influences bacterial colony color?
- temperature
- nutrient supply
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What can we combine colony color with when we are describing it?
optical properties - opaque, translucent, shiny, or dull
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What growth patterns do we look for in broth?
- cloudiness (uniform fine turbidity)
- flocculent (clumps)
- sediment
- broth surface growth
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What do we have to do with the tube of broth to see the surface growth?
gently tilt the tube
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What characteristics do we note about the broth surface growth?
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How do we test for aerotolerance?
stab inoculation of bacteria into the bottom of an agar tube and see where the bacteria grows
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What is obligate (strict) aerobes?
growth only on the surface
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What is obligate anaerobes?
growth only in lower tube, away from the surface
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What is facultative anaerobes?
grows everywhere
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What is microaerophiles?
growth just below the surface
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Once we have identified size, shape, arrangement, structure, and gross appearance of the bacterial colony, what are the next steps?
- gram stain
- enriched media
- differential media
- selective media
- biochemical testing
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