Labs Flashcards
What does BHIA stands for?
Brain heart infusion agar
What is the composition of a mannitol salt agar?
- Sodium Chloride
- pH indicator
- Mannitol as carbon source
how is mannitol salt agar selective?
- Because of the sodium chloride
How is mannitol salt agar differential?
- Because only organism that can ferment mannitol will grow
What is the composition of MacConkey agar?
- Lactose
- Bile salts
- pH indicator
What type of bacteria does MacConkey plate inhibit?
Inhibit growth of gram +
For what kind of test is milk agar and starch agar used&
For biochemical characterization, more specifically production of extracellular enzymes
How do we detect presence of casein degradation on the milk agar plate ?
There will be a clear zone around the bacterial growth
How do we detect presence of starch breakdown in a starch agar plate?
- First flood the SA plate with iodine
- If the starch is hydrolyzed, there will be a clear zone appearing
- If no starch hydrolyzed, the starch will stain deep blue .
What does the media of the carbon fermentation tes contain?
- glucose, lactose or sucrose as carbon source
- pH indicator
- Inverted Durham tube to trap gas
What color does the carbohydrate fermentation media turn if there is acid produced?
Yellow
What is the hydrogen sulfide production test good for?
To indentify organsim that can degrade cystein
What is the enzyme degrading cystein in the sulfide production test ?
Cystein desulfurase
What is the composition of the medium for the sulfide production test?
- cystein
- ferric ammonim citrate
What are the 2 reaction in the sulfide production test?
- Cystein degraded to hydrogen sulfide by cystein desulfurase
- reaction of hydrogen sulfide with ferric ammonim citrate to produce ferrous sulfide ( black precipitate)
