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71 Cards in this Set

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pairs that divide in one plane


chains that divide in one plane


tetrads that divide in two planes


clusters that divide in three planes irregularly


cuboidal packets that divide in three planes regularly


cocci that are slightly longer in one direction

fusiform bacilli

tapered at the ends, appearing football like

filamentous bacillary

long threads


grow in spirals

Cationic dyes

positively charged chromophore


methylene blue and crystal violet

Anionic dyes

negatively charged chromophore


Nigrosin, acid fuschin, Congo red

Fat Soluble Dyes

no charge

Sudan Black stains granules of poly-B-OH-butyric

Insoluble dyes

water insoluble

India ink, colloid suspension of carbon particles

Negative Staining

no heat fixing

good for morphology

stains background

can use Nigrosin or India Ink

Simple Staining

stains all bacteria cells

cationic dyes are used because they attract the negative cell surface

methylene blue or crystal violet

Acid Fast Stain

differentiates based on cell wall characteristics

acid fast - high wax content

Cells are steamed with carbol fuschin

decolorized with acid alcohol

counterstained with methylene blue

Acid fast will remain red

others will pick up the blue dye

what is another name for the acid fast stain?

Ziehl Neelson

Two types of acid fast microorganisms


Nocardia: less harsh decolorizer must be used

Gram stain

stains based on cell wall peptidoglycan

Crystal Violet

Grams Iodine



positive is purple

negative is pink

Spore Stain

also called the Schaeffer Fulton method

Steamed with malachite green

decolorized with water

counterstained with safranin

endospores and freespores - green

vegetative cells - pink


15-20 ml of liquid agar in a pour plate


5-7 ml of liquid media


5-7 ml solidified upright


5-7 ml of media solidified at an angle

fermentation broth

broth with durham tube added

Natural media

unknown composition

example is nutrient agar

synthetic media

known composition

designed for selection and differentiation


phenylethyl alcohol agar

selects for gram + organisms


desoxycholate agar

selects for gram - organisms

it also differentiates lactose fermenters

when lactose fermenters produce acid they precipitate bile salts and absorb the natural red dye

red = + for lactose fermentation


Eosin Methylene Blue

selects for gram -

differentiates lactose fermenters

Lactose + will show a color change

Further differentiation on EMB

Mixed Acid: produce more acid and have dark blue black centers. E coli has green sheen.

2,3 butanediol: produce less acid, colonies have pale pink to lavender centers. bulls eye colonies.

enterobacter example.

Blood Agar

Differentiates presence or absence of hemolysins.

B: complete hemolysis

A: partial hemolysis, sometimes green bc billiverdin

G: no hemolysis

Starch Agar

tests for presence of amylase which breaks down starch.

Iodine is added to the plate.

If blue appears, the result is negative and amylase is not present.

Milk Agar

tests for the presence of caseinase which hydrolyzes casein in to amino acids.

since casein gives milk its white color the presence of caseinase would cause clearing.

clearing = + for caseinase

Lipase Plate

tests for lipase which breaks down fat to form glycerol and fatty acids.

Indicator is SPIRIT BLUE DYE.

fatty acids lower the ph enough to produce a dark blue precip when lipase +.

starts blue and intensifies.

Sugar Fermentation Tubes

used to see if an organism can ferment either glucose, lactose, or mannitol.

has the sugar, indicator phenol red, and durham tube.

yellow = acid, fermented

red = negative

yellow and gas = fermented acid and gas

cerise = alkaline

Methyl Red (MR)

tests for mixed acid fermenters.

acid lowers the ph below 5.1 so when methyl red is added to the culture it remains red.

Red is a positive result.

Ex. Escherichia

Voges-Proskauer (VP)

tests for 2,3 butanediol fermenters which produce less acid.

Since AMC is easier to detect you look for that.

Add Barritts reagents.

Brick red color indicates is a 2,3 butandiol fermenter and is a positive result.

ex. Enterobacter

What are Barritt's Reagents?

1. Add VP1 (a napthol) and VP2 (KOH)

2. When o2 is present VP2 reacts with AMC and produces a brick red color

3. VP1 is used to intensify the color

Enterobacter is VP +

Catalase Test

tests for the presence of catalase which converts H2O2 to water and oxygen.

this formula is used to eliminate toxic H2O2.

1. Add 3% H2O2 to the culture.

2. Bubbles = + for catalase

Oxidase Test

tests for the presence of cytochrome c oxidase.

this is used to oxidize aromatic amines and form a colored product.

1. di methyl phenyldiamine hydrochloride will turn a dark blue black color in the presence of oxidase.

Nitrate Test

tests for nitrate reductase.

1. add n1 and n2 to the tube.

n1=sulfanilic acid n2=di methyl a napthylamine

2. if brick red color appears result is +.

3. Add zinc

4. If red color appears, the result is -.

5. if the tube stays clear, this is a + result which indicates the presence of both nitrate and nitrite reductase.

Tryptone (Indole)

tests for tryptophanase which converts tryptophan in to indole and pyruvic acid.

1. You can test for indole by adding Kovac's reagents.

2. Red ring color is a + result.

Kovac's: DMABA (dimethylaminobenzaldehyde) and HCl dissolved in amyl or butyl alcohol.

Urea Test

tests for the enzyme urease which converts urea in to ammonia and CO2.

Substrate is urea and indicator is phenol red.

When ammonia is released the ph increases above 8.1 and a cerise appears.

This is a + result.

Example is Proteus.

Hydrogen Sulfide Production (H2S)

tests for cysteine desulfurase which removes the sulfur side chain from cysteine to produce H2S.

H2S in the presence of iron salts forms a black precipitate.

Black color = + for enzyme

SIM Media

tests for Sulfur reduction, Indole, and Motility.

H2S + = black precipitate.

Indole + = red after Kovaks is added.

Motility + = growth away from innoculation.

Simmons Citrate

test to see if an organism can use citrate as the sole carbon source.

media has ammonia, citrate, and bromothymol blue as the indicator.

+ Result = deep prussian blue growth

Phenylalanine (PPA)

tests for phenylalanase which turns phenylalanine in to PPA and NH3.

1. Add Ferric Chloride to the media which detects the presence of PPA.

2. + result is a deep green color.

Litmus Milk

Litmus milk has the ph indicator litmus and powdered milk. starts off purple.

1. Acid Rxn: pink liquid bc lactose fermentation

2. Acid Curd Rxn: pink solid. acid production bc Lac fermentation and coagulation of proteins.

3. Reduction: litmus becomes white.

4. Alkaline Rxn: tube becomes blue when ammonia increases the ph.

5. Peptonization/Proteolysis: clearing of the medium due to caseinase. can be brown or amber.

Gelatin Test:

tests for presence of gelatinase which hydrolyzes gelatin in to amino acids.

1. Stab inoculate tube.

2. Place on ice.

3. If solidifies it is - for gelatinase.


differentiates between E Coli and EA.

Indol, MR, VP, Citrate

EC + + - -

EA - - + +

Motility Media

tests if bacteria are motile or not.

indicator is tetrazolium chloride.

red means growth.

growth away from the inoculation line indicates motility.

Russel's Double Sugar (RDS)

tests for fermentation of glucose and lactose as well as gas production.

indicator is phenol red.

media starts red and turns yellow post ferm.

yellow butt = glucose fermented

yellow slant = lactose fermented

read slant over butt

1% lactose and 0.1% glucose

24-48 hr read time

Kligler's Iron Agar

tests for ferm. of glucose and lactose, H2S, and gas production.

1% lactose and 0.1% glucose and iron salts

same fermentation results as RDS

Black precip = + H2S

Cracks or lifting = + gas

18 hr read time

KIA bacteria examples

PA: G- L- H2S-

Shigella: G+ L- H2S+

E Entero: G+ L+ H2S-

Salmonella Proteus: G+ L- H2S+

OF Glucose Test

Positive test starts purple.

Negative test starts green.

1. Two tubes are inoculated and one is covered in oil.

2. indicator is bromothymol blue

Both yellow tubes: strict fermentation

Both uninoculated color: strictly oxidative

Open yellow, Closed uninoculated: partial oxidative

Open uninoculated, closed yellow: faculative

Bismuth Sulfide Agar (BSA)

starts off dull green.

Ferrous sulfite is the H2S indicator.

Brilliant green dye and bismuth sulfite inhibit the growth of gram + and coliforms.

example: salmonella typhi produces black color

Brilliant Green Agar (BGA)

differentiates lactose and sucrose fermentation.

brilliant green dye inhibits gram + and coliforms.

phenol red is the indicator of lactose ferm.

lactose/sucrose ferm = yellow and green colonies

non lactose/sucrose ferm = opaque pink/red/white and surrounding media red

SS Agar (light pink plate)

contains bile salts, sodium citrate, and brilliant green to inhibit gram + and coliforms.

limits swarming by proteus.

natural red dye is an indicator of fermentation and + colonies appear red.

detects H2S.

Salmonella appears black.

Shigella appears colorless.

Desoxycholate Citrate (light pink)

selects for gram -

differentiates lactose fermenters

neutral red dye indicates acid production via fermentation.

+ colonies will appear red


tests for the enzyme coagulase which converts fibrinogen in to fibrin.

inoculate in a tube of rabbit plasma overnight.

clumpy = coagulase +.

only valid on gram + staph like bacteria.

Phenol Red Mannitol Salt Agar

only grows staph bc of high concentration of salt. 7.5%.

medium starts red but turns yellow if organism is mannitol positive.

Staph 110 Medium

same as PRMSA but it lacks the phenol red.

selects for staph but allows for growth of natural colony pigment.


tests for DNase which hydrolyzes DNA in to free nucleotides.

turquiose blue agar.

methyl green forms a complex with DNA in the media and if DNase is present it breaks this down and forms clearing.

clearing = + result

m-Staph broth

media containing 10% NaCl which selects for staph because of the high salt concentration.

Endo Agar

selects for gram -.

contains sodium sulfite and basic fuschin.

differentiates lactose fermenters.

lactose + = red colonies

coliforms produce golden metallic golden sheen.

Cardinal temps of psychropiles

0 - 5 - 15 to 20

cardinal temps of mesophiles

20 - 30 to 37 - 45

cardinal temps of thermophiles

45 - 55 to 65 - 70 to 90


ultraviolet resistant


ultraviolet sensitive and lethal