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microbiology testing

biochemical reactions, differential, etc

QuestionAnswer
what is the products formed from sugar fermentation test? Acid with or without gas
what is a positive result of sugar fermentation test? red indicator turns yellow
what is the purpose of sugar fermentation test? production of acid and/or gas in fermintation
what are possible mediums for sugar fermentation? phenol red glucose broth, phenol red lactose broth or phenol red mannitol broth
what is a negative result of sugar fermentation test? red indicator remains red
what is a negative result of Methyl Red test? Broth remains yellowish/orange or has no color
what is a negative result of Voges-Proskauer test? Broth turns a dark brown/green color
what is a negative result of Catalase test? no bubbles visible
what is a negative result of Oxidase test? no color change within 30 sec
what is a negative result of Starch Hydrolysis test? no clear zone (entire plate is dark blue)
what is a negative result of Gelatin Hydrolysis test? no liquefaction of medium
what is a negative result of Indole Production test (Tryptophen Hydrolysis)? Yellow layer on the top of the culture
what is a negative result of Urease test? no color change to medium (yellow-orange)
what is a negative result of H2S test? no black precipitate (possible red/yellow change)
what is a negative result of Citrate Utilization test? Medium is unchanged, lite green color
what is a negative result of Litmus Milk Reaction Coagulation test (Curd)? Medium is unchanged
what is a negative result of Litmus Milk Reaction Peptonization test (Casein Hydrolysis)? Medium is unchanged
what is a negative result of Litmus Milk Reaction Litmus Reduction test? Medium is unchanged
what is a negative result of Litmus Milk Reaction pH change test? Medium is unchanged
what is a positive result of Litmus Milk Reaction pH change test? acid = PINK alkaline= PURPLE
what is a positive result of Litmus Milk Reaction Litmus Reduction test? litmus changed to WHITE (changed by oxygen being used up)
what is a positive result of Litmus Milk Reaction Peptonization test (Casein Hydrolysis)? becomes Transparent (due to hydrolysis of casein)
what is a positive result of Litmus Milk Reaction Coagulation test (Curd)? Curd formation, whay liquid maybe presence on surface
what is a positive result of Citrate Utilization test? medium will turn Prussian BLUE
what is a positive result of H2S test? Black precipitate formed (iron sulfide)
what is a positive result of Urease test? medium turns HOT PINK
what is a positive result of Indole Production test (Tryptophen Hydrolysis)? red layer on the top of the culture
what is a positive result of Gelatin Hydrolysis test? liquefaction of medium
what is a positive result of starch hydrolysis test? a clear zone next to bacterial growth
what is a positive result of oxidase test ? organism turns PURPLE
what is a positive result of catalase test ? bubbles visible (immediate)
what is a positive result of Voges-Proskauer test? Broth turns RED
what is a positive result of Methyl Red Test ? Broth turns PINK/RED
2 tests can be performed on MRVP Broth, what are those tests? 1. Methyl Red (test for LOTS of ACID) 2. Voges-Proskauer (acetoin production, 2-3 Butanediol Fermentation)
The Methyl Red and Voges-Proskauer tests both use what same Medium? MRVP Broth
Methyl Red Test:Name of MEDIUM? MR-VP Broth
Methyl Red Test:Important INGREDIENTS in Medium? 1 carbohydrate (glucose, lactose, or sucrose), peptone, phenol red indicator and Durham tube (only in glucose tube)
Methyl Red Test:How to INOCULATE? Loop inoculate broth
Methyl Red Test:How to INCUBATE Medium for Test? incubate at 35°C for 48 hours
How do you perform the Methyl Red test? 1. After incubation, transfer 1 mL of broth into a NEW sterile TUBE 2. Add 4-5 drops of Methyl Red 3. Read color results
How do you interpret the Methyl Red test RESULTS? Methyl Red colors: (+) RED pH<= 4.4 (-) YELLOW pH = 6.2 (-) NO COLOR CHANGE (no mixed acid fermentation)
T/F ==CHEMICAL==If bacteria CAN do MIXED ACID FERMENTATION, acid BYPRODUCTS will OVERCOME PHOSPHATE BUFFER (LOWERS pH), ELSE pH REMAIN SAME True
T/F ==METABOLIC==Fermentation is a metabolic process in which ORGANIC MOLECULES act as ELECTRON DONOR (OXIDIZED) and 1 or more ORGANIC PRODUCTS act as FINAL ELECTRON ACCEPTOR. True
T/F Usually if (+) for Methyl Red test, then (-) for Voges-Proskauer cuz look for different acids True
1 pH CHANGE is A LOT. By what FACTOR is this? Also how many more times acidic is a change from 6 pH to 4 pH? 1 pH change = 10 times 6 to 4 pH is a 100 times more acidic
How to read results of Indole? After adding Kovac's: red layer on top -> positive for Indole -> Trytophanase hydrolyzes tryptophan Yellow layer on top-> Indole negative -> Tryptophanase absent.
Blackening of the medium?? H2S is produced.
How to read methyl red test? After adding methyl red: : MR positive= turn red (pH 4.0) MR negative= turn to any other color (pH 6.0 or higher)
How to read Voges Proskauer test? After adding Reagent A and B: : VP postitive=Turn red ->Acetoin VP negative=If no red color developed. -> no acetoin
VP test what? Acetoin.
VP reagents? VP A: Alpha Naphthol. VP B: Potassium hydroxide.
Purpose of Citrate test? Tosee if organism use citrate as its own carbon source.
How to read result of Citrate Utilization? Negative for Citrate Utilization: No growth, green color of medium. Positive: Growth on the slant, medium could be green color or blue color.
Why use Indole? used to identify if organism is capable of breaking down tryptophan to pyruvic acid, indole, ammonia by using enzyme tryptophanase.
Why use Methol red? used to see if bacteria produce acid from glucose
Why use Voges Proskauer? used to identify if org produce acetoin from 2,3-butanediol fermentation.
Why use Citrate? to see if org use citrate as it own carbon source.
What products are formed from the Methyl Red test? Mixture of acids
What is the medium for Methyl red test? MR-VP Broth
What is the medium for Voges-Proskauer test? MR-VP Broth
What is the reagent of Methyl Red test? MR red indicator
What is the reagent for Voges-Proskauer test? Barretts A and Barretts B
What is the reagent for Catalase test? Hydrogen Peroxide
What is the reagent for Oxidase test? Oxidase reagent
What is the reagent for starch hydrolysis test? Grams iodine
What is the reagent for indole production test? Kovac's reagent
what product is formed from Voges-Proskauer test? aceton
what is the product from the Methyl Red test? mixture of acids
what is the product from the catalase test? oxygen
what is the product from the oxidase test? none
Created by: jmabert
 

 



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