Midterm Flashcards
(94 cards)
What methods are used to see motility and how motility is determined?
- Hanging drop technique or SIM tubes
How to determine if motile in SIM tubes
- if the bacteria turns yellow gelatin black and strays away from the stab line/spreads throughout the tube
Arm
- for carrying the microscope
- supports the lenses
What do you observe when looking at the growth of bacteria in a nutrient agar plates?
- Colony size, color, form, elevation, and margin
light intensity dial
- adjusts current to lamp
Filter Paper Disc Method Results
- a zone of inhibition (no growth around disc) is indicative microbicidal activity against the organism
- absence of a zone indicates that the chemical was not effective against the test organism
- measure from the edge of disc to the edge of growth (diameter mm)
- identify as R, I or S (resistant-lots of growth, intermediate-some growth, or sensitive-no growth)
Inoculating procedure
- sterilize the loop with the flame
- remove cap of bacteria tube and flame the tube 3x before inserting the loop
- get a loopful of culture
- heat the mouth of the tube and replace the cap
Blood Agar
- enriched and differential
- gram positive and gram negative
- gamma-hemolytic(no change red), alpha hemolytic(greenish halo around growth) and beta hemolytic (clear zone surrounding the colonies)
Concentration of Salt affect on bacterial growth (.5%, 5%, 10% and 15%) in E.coli, S.Aureus and H. salinarium
- no bacteria was able to tolerate 15% and did not grow
- as the salt concentration increased, the amount of growth did as well
- E coli- highest can tolerate is 5%
- S Aureus- highest can tolerate is 10%
- H salinarium- highest can tolerate is 10%
Starch hydrolysis Test
- ability to degrade polysaccharide starch, lipid tributryin and proteins casein and gelatin
- Starch Plate
- add several drops of grams iodine if there is a clear zone positive test result
How to make a smear using a liquid media
- place 2 loopfuls of liquid culture on the slide with a sterile loop
- spread the bacteria in a circle/target area
- allow the smear to air dry
- heat fix
How to make a smear using solid media
- get a loop of water and smear on targeted area of slide
- remove the bacterial culture and mix with water
- allow to air dry
- heat fix to kill bacteria
Nitrate Reduction Test
- ability to reduce nitrates to nitrites
- nitrate reduction broth with Durham tube
- if no gas add 5 drops of Baritts A then 5 of B, no color means negative
- to confirm negative by adding a pinch of zinc powder
- would have turned deep red if positive
Zone of Inhibition
- an effective agent will inhibit bacterial growth and measurements can be made of the size around the disc
- measure from edge of the disc to the bacterial growth (mm)
- indicate whether resistant, intermediate, or susceptible
What is the purpose of a gelatin stab and why is it important?
- the purpose is to determine the organisms ability to produce proteolytic enzymes
- a positive result will liquify the gelatin
What type of microscope do we use?
- brightfield compound microscope
Decolorizing agent affects gram positive and negative cells differently because
- the concentration of lipids
2. the thickness of the peptidoglycan layer in bacterial cell walls
Facultative anaerobes
- can grow in the presence or absence of oxygen
- particles throughout tube, but condensed at top
Micrococcus Luteus was ______
- non motile
Phases of bacterial growth in a batch culture
- Lag Phase
- Exponential Phase (Log)
- Stationary Phase
- Death Phase
Why is heat applied in an endospore stain?
- to drive the stain into the endospore because most endospores are impermeable to staining
Alkalophile
- growth from 7-14
- optimum growth at 10.5 basic
Aseptic technique
- used to exclude contaminants
Citrate Utilization Test
- ability to ferment citrate as their sole source of carbon
- Citrate agar slant
- if positive green color changes to blue