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micro review exam 3

Hemolysis: to see what type of lysis a bacteria can conduct, alpha, beta, or gamma

Positive will

Simmon’s citrate: to see if the bacteria can use corrate as a carbon source

bromothymol blue is a ph indicator in the tube and has citrate to see if it uses citrate as a source
If acidic turns yellow(negative), if basic blue(positive), if neutral, stays green(negative)
Makes enzyme citrate permease(will use citrate as source, turns blue)

Gram stain: To see cell shape and find out if its gram positive or negative

Crystal violet
Iodine
Ethanol
Safranin

Catalase: to see if a bacteria has a catalase enzyme

reagents: TSA plate & hydrogen peroxide

white blood cells produce hydrogen peroxide, oxidative burst kills bacteria
2H2O2+ catalase→ 2H2O + O2 (gas)
positive will have bubbles, negative will not

Spirit blue plate(lipase): can see if bacteria can produce lipase, breaks lipids(fats) apart

PH indicators: if it is positive dark blue around bacteria is basic(positive), cloudy/grey is (negative), neutral(no change, negative)
Checks to see if it breaks oil tributin oil
What does a positive mean? It produces the enzyme Lipase

Capsule stains: checks to see if bacteria have capsules

characteristic: will have a halo around bacteria
Reagents: congo red and manevals
Positive: will have halo around bacteria
Negative: will not have halo around bacteria

SIM: Sulfur Indo Motility

Sulfur: checks to see if it uses cysteine to make a gas, reduce sulfur

positive: will look black, uses cystine
Negative: will be yellow/no color change
Makes Enzyme: cystine desulferase (SIM)
What does a positive mean? A black precipitate means there was sulfur reduction

Indole: checks to see if enzyme tryptophanase can be turned into indole

enzyme: tryptophanase makes indole
Reagent: kovac’s, tryptophan
Positive: it turns red on top of tub
Negative: yellow/no color change
Procedure: stab
What does a positive mean? red color is indole present

Voges proskauer: checks to see if bacteria makes fermentative product acetoin which turns into butanediol

reagents: alpha-naphthol(VPA) then KOH( VPB)*postassium hydroxide

inauculate bacteria, add bacteria, add aphanaphol first then hydrogen peroxide second
Positive: will look like red
negative: will be yellow
MR-VP detects presence of 2,3 butendiol
What does a positive mean? Red means there is acetoin present, becomes butanediol

Pages 86-87

DNAse: to see id bacteria produces DNAse which breaks down DNA

Reagents: methyl green & dna with green attached to it
Positive: will have halo around bacteria
Negative: no halo around bacteria
Not a PH INDICATOR
procedure: line down middle of plate
What does a positive mean? Halo means bacteria makes DNAse which destroys bacteria

Pages 91

Casein/milk plate: check to see if bacteria makes caseinase, which breaks casein a milk protein

caseinase makes milk white
Positive: will leave a white halo around bacteria
negative: no halo around bacteria
What does a positive mean? Halo means caseinase is present which gives bacteria ability to break down casein in milk

Page 90

Starch plate: to see if bacteria makes amylase, which breaks down starch into glucose

Reagents: iodine& starch

amylase takes starch and breaks it down to glucose
Positive will have a halo around bacteria
negative will not have halo
Procedure: Add iodine to plate
Starch+ broken down sugars is clear, black is not
What does a positive mean? Halo around bacteria makes amylase, which destroys starch into glucose(iodine only binds to starch not glucose)

Page 89

Phenylalanine slant: to see if bacteria makes phenylalanine deaminase which releases NH3

Reagents: slant has phenylalanine but add 10% ferric chloride
positive: makes phenyl pyruvic acid, makes it green
Positive: green, makes enzyme
negative: is copper color/ no color change
What does a positive mean?green means it turns phenylalanine into ammonia NH3

OF glucose: checks if bacteria oxidize or ferment a specific carbohydrate

Reagents: bromothymol blue, mineral oil, glucose
Checks for fermentation and oxidation
Positive will look like: 3 categories
1. Both green = negative
2. Both yellow= fermentation
3. One green & one yellow = oxidation
Negative: both green
What does a positive mean? Both yellows mean your bacteria ferments glucose, one green one yellow means it oxidizes glucose

Gelatin stab: checks to see if bacteria makes gelatinase, breaks gelatin down

reagents: semi-solid agar made with gelatin
Positive will look: liquid if it stays that way after 15 minutes in the refrigerator
Negative: solid

procedure: stab agar with gelatin, must be in fridge for 15 minutes, quick
What does a positive mean? Turned Liquid agar means it had gelatinase that breaks down gelatin

Page 92

Methyl red: to see if bacteria makes mixed acids via fermentation

Reagents: methyl red after incubation
Ph indicator
Positive: red
negative: yellow/no color change
What does a positive mean? Red means bacteria makes mixed acids through fermentation

Page 86

Nitrate test: to see if bacteria makes nitrate reductase enzyme which turns NO3(nitrate) into NO2(Nitrite)

Reagents: dimethyl alpha napthalamine(reagent A), then sulfanilic acid (reagent B); maybe zinc (reagent C)
Positive: A+B red = positive
A+B+C = clear positive
Negative: A+B+C= red negative

Fermentation test: to see if bacteria can ferment different types od sugar

reagents: sucrose, lactose, maltose, glucose, trehalose, phenol red, peptone
positive : Yellow+gas
Negative - red basic/pink
what does a positive mean? Yellow(and maybe gas) means it can ferment in that sugar
Note: must have more than 20% gas to count as a gas

Acid + gas * big bubble

5 tubes

Urease: assesses bacteria production into urease, makes ammonia

Positive: If it does makes it basic, turns pink,
negative: would be orange/yellow
Reagents: urea and phenyl red
procedure is add bacteria and inauculate

Decarboxylation:checks to see if bacteria can produce decarboxylases , removes carboxyl group from amino acids