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what substances do you drop onto the bacterial colony when doing the catalase production test
If both steps of nitrate reduction are complete, what is the final end product that is made.
ammonia or nitrogen
If you added drops of reagent A and reagent B in the nitrate reduction test and the medium turns red, what does that indicate about the chemical reaction?
nitrite is present in the medium, the bacteria was able to reduce nitrate to nitrite.
you are performing the nitrate reduction test. After adding reagents (A and B) to the medium, there is no change to the medium. What is the next step you take to find out if the nitrate was reduced
add zinc powder
You are performing the nitrate reduction test. If after adding zinc powder, the solution turns red. What does that tell you about the chemical reaction.
nitrate was present. therefore no nitrate reduction occurred.
In what type of medium does motility test take place.
semi solid medium with reduced amount of agar.
When performing the starch hydrolysis test, what will the medium look like if the bacteria breaks down the starch?
Clear area in the medium around the growth.
in gelatin hydrolysis the enzyme gelatinase breaks down gelatin into what.
polypeptides and amino acids.
you are performing the gelatin hydrolysis test. After inoculation, incubation and refridgeration . How can you tell if the bacteria has the enzyme gelatinase (and can breakdown gelatin).
the medium is liquid.
you are performing the urea digestion test (urea hydrolysis test). What color does the solution turn if the bacteria is able to complete urea digestion.
if a bacteria has the enzyme cysteine desulfurase it can convert cysteine into H2S(hydrogen sulfide). What will you see in the medium if this happens.
a black precipitate.
what ways do microorganisms acquire resistance
alteration, degradation, impermeability of antibiotics. or modification of metabolic pathway so inhibited enzyme is no longer needed.
antibiotics that are effect against a broad array of bacteria. including both gram(+) and gram(-) organisms?
you have the measure the zone of inhibition and look up the interpretive criteria to determine if the bacteria is susceptible(S), Intermediate(I), resistant(R). True or false?
zone size alone doesn't determine the bacterias susceptibility or resistance to the antibiotic. True or false
you should stop taking antibiotics when the symptoms go away, and you start feeling better. true or false
pathogen with that zone size will likely be killed/inhibited by the concentration of drug in the bloodstream provided by the usual dose of that agent
provides a buffer zone to prevent small differences in the test from having a major impact on the interpretation.
what is true of enteric bacteria?
they normally inhabit the digestive tract.
they are gram negative rods
they are facultative anaerobes
they ferment glucose
what is true of MacConkeys agar
Bacteria that ferment lactose look pink
it is selective for gram negative bacteria
it is differential
you inoculate MacConkeys agar medium with bacteria. the bacteria grows but does not turn pink. what do you know about this bacteria?
it is gram negative
it does not ferment lactose
how does triple sugar iron agar differentiate bacteria
some bacteria might produce gas, others won't
some bacteria might produce hydrogen sulfide, others won't
it differentiates bacteria based on the ability to ferment glucose and other sugars.
methyl red test
tests for mixed acid fermentation and the ability of an organism to produce highly acidic end products.
citrate utilization test
determines whether an organism can utilize citrate as its only source of carbon
what would you be able to learn form an organism during the citrate utilization test
whether or not the bacteria produces alkaline end products
whether or not the bacteria can utilize citrate as its only source of carbon
triple sugar iron agar positive and negative results
medium turns black if the bacteria uses iron to produce hydrogen sulfide
indole production positive and negative results
if an organism can degrade tryptophan, a red ring appears at the top of the medium
methyl red test positive and negative results
an organism that doesn't produce acid will cause this liquid medium to remain yellow.
blood agar is differential because types of bacteria lyse red blood cells similarly. true or false
Carbohydrate fermentation(broth)-what is the reaction?
(glucose,lactose,sucrose)------Fermentation/enzymes--------->acid & or gas
Carbohydrate fermentation(broth)-what is the procedure
Durham tube to detect gas formation Phenol red pH indicator is in the medium
Carbohydrate fermentation(broth)-what is the interpretation
Oxidase test(trypticase soy agar(TSA) plate-streak for isolation-reaction
Oxidase test(trypticase soy agar(TSA) plate-streak for isolation- what is the procedure?
smear bacterial colony onto drop of oxidase test reagent on filter paper
Oxidase test(trypticase soy agar(TSA) plate-streak for isolation- Interpretation
(+)-purple color within 1 mins
(-)-No purple(or delayed faint purple color)
Catalase production(trypticase soy agar(TSA) plate-streak for isolation- What is reaction
Hydrogen peroxide--->catalase--->2h2O + O2
trypticase soy agar(TSA) plate-streak for isolation- Procedure
Smear bacterial colnoy on glass slide; add drop of 3% hydrogen peroxide
Nitrate reduction(nitrate broth)-reaction
Nitrate--->nitrate reductase---nitrite---->reductase--->ammonia or nitrate
trypticase soy agar(TSA) plate-streak for isolation- Procedure
Stage 1- add 5 drops of (A sulfanilic acid) and (B napthylamine)
Stage 2- add C zinc powder
motility test(motility test broth)-interpretation
(+)organisms grow & spread away from line of innoculation
(-)Nonmotile will only grow at line of penetration
Indole production(tryptophan broth)-Interpretation
Red at top=indole present(+)
Yellow clean ring=no indole present(-)
Voges-proskauer test (MRVP medium)-procedure
Add 15 drops of VP reagent A;mix. Add 5 drops VP reagent B; Mix let set ~4hr
Citrate utilization(citrate agar slant)-interpration
blue=alkayline, citrate used(+)
green=not alkaline, citrate not used(-)
Carbohydrate fermentation(glucose,lactose,sucrose)-(triple Sugar Iron Agar(TSI))-Reaction
Carbohydrate fermentation(glucose,lactose,sucrose)-(triple Sugar Iron Agar(TSI))-Procedure
Phenol red pH indicator is in the medium
Carbohydrate fermentation(glucose,lactose,sucrose)-(triple Sugar Iron Agar(TSI))-Interpretation
Hydrogen sulfide production(triple sugar Iron agar slant)-reaction
na thisulfate--->S reduction enzymes---->H2S
Hydrogen sulfide production(triple sugar Iron agar slant)-procedure
Ferrous sulfate is in the medium
Starch hydrolysis(starch agar)-interpretation
(+) clear area in medium around growth, starch hydrolyzed
(-)Dark area around growth, staach not hydrolyzed
Casein hydrolysis(skim agar)-interpretation
(+)clear area around growth, casein hydrolyzed
(-)no change in medium around growth
Gelatin Hydrolysis(nutrient gelatin deep)-Reaction
Gelatine--->gelatinase---->Polypeptides & amino acids
Gelatin hydrolysis(nutrient gelatin deep)-interpretation
Medium is liquid, gelatin was hydrolyzed(+)
Medium remains solid, gelatin was not hydrolyzed(-)
urea Hydrolysis(urea broth)-Interpretation
(+)bright pink, urea hydrolyzed
(-)pale amber color, or no change urea not hydrolyzed
Hydrogen sulfide(H2S) production(Peptone iron agar deep)-reaction
Cysteine---> cysteine sulfurase--->H2S + alanine
Hydrogen sulfide(H2S) production(Peptone iron agar deep)-interpretation
(+)Black precipitate, H2S produced
(-)No black precipitate, no H2S produced.
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