Micro lab Flashcards
Culture
A liquid or solid medium with microorganisms growing in or on it
Mixed Culture
contains a mixture of different species of bacteria or other organisms
Pure culture
contains only one species or strain
Bacterial colony
A visible mass of cells that arises from a single original cell
Steps for streak plating
1) label plate (on bottom!!)
2) fire inoculation loop
3) fire top of test tube
4) dip inoculation loop in bacteria
5) fire and close lid
6) streak plate
7) streak across agar plate and inoculate plate
8) store upside down into incubator
Colony morphology traits (7)
size
shape
margin
surface
elevation
texture
optical properties
Size
measurement of the colony’s dimensions- the diameter if circular of length and width if shaped otherwise
Shape
round(circular), irregular, punctiform(tiny, pinpoint)
Margin
entire (smooth with no irregularities), undulate (wavy), lobate (lobed), filamentous (unbranched strands) or rhizoid (branched like roots)
surface
smooth, rough, wrinkled (rugose) shiny, or dull
texture
moist, mucoid (sticky), butyrous (buttery) or dry
elevations
flat, raised, convex, pulvinate (very convex) and umbonate (raised in center)
other descriptive features
color, opaque (can’t see through it) and translucent (can see through it)
Colony description slant
filiform growth (dense and opaque with smooth growth)
texture (moist/friable)
optical (opaque/translucent)
margin (same as bacteria)
pigment/color
Colony description broth
Pellicle (surface membrane)
Sediment (sink to bottom)
Uniform fine turbidity (foggy all over)
Flocculant (clumps)
Steps to using light microscope
1) set up & clean with ethanol
2)place on slide at lowest power (4x)
3) focus first with coarse-focus adjustment knob
4) focus then with fine-focus adjustment knob
5) find desired area and advance to next objective
6) once focused at 40x rotate nose piece position to midway between high-dry and oil immersion lenses
7) add drop of immersion oil
8) rotate tip into oil, pass through it, and then return into oil
9) clean and put away when done
Simple stain
uses one stain (generally basic), basic stain will be attracted to negative charges on surface of bacterial cell, can determine cell morphology, size, and arrangement
Negative stain
negatively charged chromogen dye, bacteria repels and remains unstained, can determine morphology and cell arrangement, allows for accurate size measurements, used for bacteria that can’t withstand heat fixation
Gram stain
Differential stain, based on differences in cell wall construction
Differential stain
detects differences between organisms or differences between parts of same organism
Acid fast stain
differential stan based on presence of mycolic acid in cell wall, important for ID of Mycobacterium, Nocardia, and Cryptosporidium
mycolic acid increases affinity for primary stain and resists decolorization
reagents in acid fast stain
carbolfuschin (penetrates waxy cell wall)
acid alcohol (decolorize non acid fast cells)
counter stain with methylene blue
Capsule Stain
differential stain used to detect cells with extracellular capsule, capsules increase virulence and are less vulnerable to phagocytosis, composed of mucoid polysaccharide or polypeptide (repel most stains) capsule stain will stain around cell with acidic stain and use basic stain to colorize cell. Capsule does not take up an stain
not heat fixed
Capsule stain reagents
congo red and maneval’s stain
