question

Mannitol Salts Agar - Contains ____________ which inhibits growth of almost all bacteria except _______________

answer

sodium chloride, Staphylococcus

question

Mannitol Salts Agar -- Only Staph. aureus can ferment ______________

answer

mannitol

question

Mannitol Salts Agar - _______________ is the pH indicator

answer

phenol red

question

Mannitol Salts Agar - If mannitol is fermented, the phenol red turns _____________ due to the production of ____________ end products.

answer

yellow, acid

question

Mannitol Salts Agar - Only Staph. ____________ will have a ___________ zone around its growth.

answer

aureus, yellow

question

Mannitol Salts Agar - The salt selects for __________________ species.

answer

Staphylococcus

question

Mannitol Salts Agar - The mannitol helps ___________ Staph. aureus from other Staph. species.

answer

differentiate

question

Standard Plate Count - Used to estimate the number of organisms in a sample of _____________

answer

liquid

question

Standard Plate Count - Dilutions are made to reduce the number of bacteria per volume of liquid to a number that can be _______________

answer

counted

question

Standard Plate Count - Define CFU

answer

colony forming unit

question

Oxidation-Fermentation Test - Differentiates fermenters from _______________

answer

oxidizers

question

Oxidation-Fermentation Test - OF media can contain one of many ___________. We use glucose.

answer

sugars

question

Oxidation-Fermentation Test - In oxidation, glucose is oxidized to _________ and then converted to ________ in the _____________ cycle and ________ ____________ ________. _________ is the final electron acceptor. This process will produce an ____________ environment.

answer

pyruvate
CO2
Krebs
electron transport chain
Oxygen
acidic

question

Oxidation-Fermentation Test - In fermentation, glucose becomes _____________ and then is converted into an acid end product in the _____________ of oxygen.

answer

pyruvate, absence

question

Oxidation-Fermentation Test - The pH indicator _____________ blue is green at pH 7.1 and ____________ below 6.0.

answer

Bromthymol, yellow

question

Oxidation-Fermentation Test - __________ oil is used to create an ____________ environment where only ______________ can occur.

answer

mineral, anaerobic, fermentation

question

Oxidation-Fermentation Test - In the tubes without mineral oil, oxygen can diffuse into the top of the ________________ media producing an environment where ______________ can occur.

answer

semi-solid, oxidation

question

Oxidation-Fermentation Test - Fermenters, or organisms that ferment and oxidize, produce acid and turn the media _______________ in __________ tubes. The tube with oil is anaerobic throughout. Fermentation is an anaerobic process. The tube without oil is anaerobic at the bottom and fermentation will occur here. The acid will affect the ___________ tube.

answer

yellow, both, whole

question

Oxidation-Fermentation Test - Organisms that _______________ only will turn the aerobic area of the media (top) yellow only in the tube without mineral oil.

answer

oxidize

question

Oxidation-Fermentation Test - Organisms that don't ferment or oxidize glucose will not make ____________. The tubes will be ________ ;(no change). The tubes may be __________ indicating that the organism produced alkaline end products from __________ acid utilization.

answer

acid, green, blue, amino

question

MR/VP - The methyl red test (MR) is used to identify organisms that produce ____________ mixed-acid end products from _______________.

answer

stable, glucose

question

MR/VP - Methyl red is added ____________ incubation to detect acid. It will turn red ___________ pH 4.4.

answer

after, below

question

MR/VP - The Voges Proskaur test is used to detect organism that produce ___________ acids from glucose fermentation.

answer

unstable

question

MR/VP - VP test - These unstable acids are readily converted into ____________ and 2,3 butanediol which __________ the pH.

answer

acetoin, raise

question

MR/VP - VP reagents will turn _________ in the presence of these alkaline end products. An organism cannot be MR and VP positive. It is one or the other.

answer

red

question

Starch Hydrolysis - Starch is made of chains of _________________ molecules.

answer

glucose

question

Starch Hydrolysis - Starch is too big to enter ____________ cells.

answer

bacterial

question

Starch Hydrolysis - In order to use the glucose, the bacteria must first break the _____________ into glucose.

answer

starch

question

Starch Hydrolysis - The enzymes bacteria use to do this are called __________________ and oligo-1,6-glucosidase.

answer

amylase

question

Starch Hydrolysis - These enzymes are _____________. That is, the cells secrete the enzymes into their environment.

answer

exoenzymes

question

Starch Hydrolysis - If the starch has been digested by the bacteria, starch will not be present in the ________ surrounding the colonies.

answer

media

question

Starch Hydrolysis - Iodine turns blue or __________ in the presence of starch.

answer

black

question

Starch Hydrolysis - If the media surrounding a colony is ______________ after the addition of iodine, the bacteria have digested the _________________.

answer

clear, starch

question

Oxidase Test - There are many types of bacterial electron transport chains. One type uses the molecule _____________ __ ___________to transfer electrons to ___________.

answer

cytochrome c oxidase, oxygen

question

Oxidase Test - Most enterobacteriaceae are oxidase _________________.

answer

negative

question

Oxidase Test - Most nonfermenters like _____________ are oxidase positive.

answer

Pseudomonas

question

Oxidase Test - Paper which is impregnated with tetramethyl-p-phenylenediamine can be ________________ by cytochrome c oxidase.

answer

oxidized

question

Oxidase Test - When tetramethyl-p-phenylenediamine is oxidized by cytochrome c oxidase, it turns dark _______. This means the organism is oxidase positive and is probably not an enterobacteriaceae.

answer

blue

question

API 20E - This system uses 20 tests simultaneously to identify bacteria. The 20E is used for enterobacteriaceae. Results are interpreted in groups of __________ to determine a code. The code is compared to a list of possible _____________.

answer

three, organisms

question

Catalase - In order to convert ADP to ATP, organisms use the _________ cycle and the _________ ________ _______.

answer

Krebs, electron transport chain

question

Catalase - One of the pathways in the electron transport chain produces hydrogen __________ (H2O2), and super oxide (O2)

answer

peroxide

question

Catalase - H2O2 and O2 are __________ to cells. So they produce the enzyme superoxide ______________ that converts O2 into H2O2 and the enzyme ___________ which converts H2O2 into water and O2. The oxygen is released as a ________.

answer

toxic
dismutase
catalase
gas

question

Catalase - When we add hydrogen peroxide to an organism that produces catalase, ________ will be produced.

answer

bubbles

question

Nitrate Reduction Test - Anaerobic respiration involves the transfer of electrons to an inorganic molecule other than ________________. Nitrate is one of those molecules.

answer

oxygen

question

Nitrate Reduction Test - Almost all enterobacteriaceae use the enzyme _________________ to reduce nitrate NO3 to ____________ NO2

answer

nitrate reductase, nitrite

question

Nitrate Reduction Test - Other bacteria further reduce nitrite to nitrogen ____________ (N2).

answer

gas

question

Thioglycollate Medium - This media has a ___________ of oxygen concentration, aerobic at the top, __________ at the bottom.

answer

gradient, anaerobic

question

Thioglycollate Medium - Sodium thioglycollate and ____________ in the media reduce oxygen to ______________.

answer

L-cystine, water

question

Thioglycollate Medium - Rezazurin in the media turns _________ when oxidized indicating that part of the media contains ____________.

answer

pink, oxygen

question

Thioglycollate Medium - A small amount of ___________ in the media _________ diffusion of oxygen.

answer

agar, slows

question

Anaerobic jar - Used to cultivate _________ and ____________.

answer

anaerobes, microaerophiles

question

Anaerobic jar -;After the jar is sealed, a packet is added to ____________ the ____________.

answer

remove, oxygen

question

Anaerobic jar -;Sodium borohydride and sodium ____________ reacted with water to form ____________ gas and ____________.

answer

bicarbonate, hydrogen, CO2

question

Anaerobic jar -;Oxygen and hydrogen form _________ in the presence of the __________ catalyst.

answer

water, palladium

question

Anaerobic jar -;The indicator contains ____________ blue which is colorless when _______________ (anaerobic) and blue when in the presence of ______________.

answer

methylene, reduced, oxygen

question

The nitrate reduction test is based on the detection of ____________________ in the medium after incubation with an organism

answer

nitrite (NO2)

question

Nitrate reduction test - After adding nitrate A ; B reagent, red indicates:

answer

Nitrate positive

question

Nitrate reduction test - After adding nitrate A ; B reagent, yellow indicates:

answer

that nitrite is not present in the medium and that zinc dust must be added to determine if the organism is nitrate negative or if the organism has reduced the nitrate to nitrite and then reduced to nitric oxide, nitrous oxide or nitrogen (will not react to nitrate reagents)

question

Nitrate reduction test - After adding zinc dust, red indicates:

answer

organism is nitrate negative

question

Nitrate reduction test - After adding zinc dust, yellow indicates:

answer

organism is nitrate positive and produced nitrite which was further reduced to NO, N2O, or N2.

question

serial dilution

answer

a series of controlled transfers down a line of dilution blanks (tubes containing a known volume of sterile dilutent). The series begins with a sample containing an unknown concentration of cells (density) and ends with a very diulte mixture containing only a few cells.;

question

countable plate

answer

one that contains between 30 and 300 colonies. A count lower than 30 is considered statistically unreliable (TFTC - too few to count) and greater than 300 is typically too many to be viewed as individual colonies (TMTC - too many to count).

question

formula for Original Cell Density (OCD)

answer

CFU
OCD=----------------
D X V

question

If you innoculate a plate with 0.1 mL of a 10^-5dilution and counted 37 CFUs, what is the original density count?

answer

OCD = CFU/D x V
OCD = 37 CFU/ 10^-5 x 0.1 mL
OCD = 37 CFU/10^-6 mL
OCD = 37 x 10⁶ CFU/mL
OCD = 3.7 x 10⁷ CFU/mL

question

If you innoculate a plate with 0.1 mL of a 10^-7dilution and counted 33 CFUs, what is the original density count?

answer

OCD = CFU/D x V
OCD = 33 CFU/ 10^-7 x 0.1 mL
OCD = 33 CFU/10^-8 mL
OCD = 33 x 10⁸ CFU/mL
OCD = 3.3 x 10⁹ CFU/mL

question

formula for dilution

answer

mL of sample
dilution = --------------------------------------
total volume

question

What would be the dilution if 96 mL of dilutent is added to 4 mL of a bacterial suspension?

answer

dilution=mL of sample/total volume
dilution= 4 mL/96 mL + 4 mL
dilution = 4 mL/100 mL
dilution = 4/10²
dilution = 4 x 10^-2

question

If you add 1.0 mL of an undiluted sample to 99 mL of sterile dilutent, what is the dilution?

answer

dilution=mL of sample/total volume
dilution= 1 mL/99 mL + 1 mL
dilution = 1 mL/100 mL
dilution = 1/10²
dilution = 1 x 10^-2

question

If you add 5.0 mL of an undiluted sample to 99 mL of sterile dilutent, what is the dilution?

answer

dilution=mL of sample/total volume
dilution= 5 mL/99 mL + 5 mL
dilution = 5 mL/104 mL
dilution = 0.048
dilution = 4.8 x 10^-2

question

The plate has 72 colonies, with a sample volume of 10^-7 mL. What was the original concentration in the sample?

answer

OCD = CFU/sample volume
OCD = 72 CFU/10^-7 mL
OCD = 72 x 10⁷CFU/mL
OCD = 7.2 x 10⁸ CFU/mL

question

The plate has 259 colonies, with a sample volume of 10^-6 mL. What was the original concentration in the sample?

answer

OCD = CFU/sample volume
OCD = 259 CFU/10^-6 mL
OCD = 259 x 10⁶ CFU/mL
OCD = 2.59 x 10⁸ CFU/mL

question

How many colonies should be on the plate innoculated with a sample volume of 10^-7 with an OCD of 2.59 x 10⁸?

answer

OCD = CFU/sample volume
2.59 x 10⁸ = x CFU/10^-7 mL
(2.59 x 10⁸⁾(10^-7mL) = (x CFU/10^-7 mL)(10^-7 mL)
2.59 x 10¹ CFU = x

question

How many colonies should be on the plate innoculated with a sample volume of 10^-5 with an OCD of 2.59 x 10⁸?

answer

OCD = CFU/sample volume
2.59 x 10⁸ = x CFU/10^-5 mL
(2.59 x 10⁸⁾(10^-5mL) = (x CFU/10^-5 mL)(10^-5 mL)
2.59 x 10³ CFU = x

question

A plate inoculated with a sample volume of 10^-7 mL produced 170 colonies. What was the orignial concentration?

answer

OCD = CFU/sample volume
OCD = 170 CFU/10^-7 mL
OCD = 170 x 10⁷CFU/mL
OCD = 1.7 x 10⁹ CFU/mL

question

After incubation, how many colonies should be on the 10^-8 mL plate from the dilution series with an OCD of 1.7 x 10⁹?

answer

OCD = CFU/sample volume
1.7 x 10⁹ = x CFU/10^-8 mL
(1.7 x 10⁹)(10^-8mL) = (x CFU/10^-8 mL)(10^-8 mL)
1.7 x 10¹ CFU = x

question

After incubation, how many colonies should be on the 10^-6 mL plate from the dilution series with an OCD of 1.7 x 10⁹?

answer

OCD = CFU/sample volume
1.7 x 10⁹ = x CFU/10^-6 mL
(1.7 x 10⁹)(10^-6mL) = (x CFU/10^-6mL)(10^-6 mL)
1.7 x 10³ CFU = x

question

You have inoculated 100 μL of a sample diluted by a factor of 10^-3 on a plate. After incubation, you count 58 colonies. What was the original cell density?

answer

100 μL = 0.1 mL

OCD = CFU/D x V
OCD = 58 CFU/ 10^-3 x 0.1 mL
OCD = 58 CFU/10^-4 mL
OCD = 58 x 10⁴ CFU/mL
OCD = 5.8 x 10⁵ CFU/mL

question

Results of E. coli on mannitol salt agar

answer

no growth on MSA, can't grow in salt

question

Results of Staph. aureus on mannitol salt agar

answer

growth with yellow, tolerates salt

question

Results of Staph. epi on mannitol salt agar

answer

growth on MSA, but remains red, tolerates salt

question

Mannitol Salts Agar Lab - What purpose does the Nutrient Agar plate serve? In what way does it increase the validity of the test result?

answer

The Nutrient Agar plate acts as a control to see if each organism grows without the presence of salt.

question

What would be the likely consequences of omitting the NaCl in Mannitol Salt Agar? Why?

answer

The E. coli would grow and you could not select for the Staphylococcus.

question

Would omitting the NaCl alter the Mannitol Salts Agar's specificity or sensitivity?

answer

It would alter the medium's specificity because you could not select for the Staphylococcus.

question

[image]

answer

mannitol salts agar

question

O-F test - What is the purpose of the uninoculated control tubes used in this test?

answer

Two uninoculated control tubes are needed to show the results of the medium in both aerobic and anaerobic environments. It is used to show that the medium remains green under both conditions, showing it is sterile and also as a color comparison.

question

O-F test - What color results would you expect for organisms in O-F glucose media inoculated with an enteric?

answer

Since enterics can both oxidize and ferment, both the unsealed (aerobic) tube and the sealed (anaerobic) tube will turn yellow.

question

O-F test - results of Enterobacteriaceae, Pseudomonas, and Alcaligenes

answer

Enterobacteriaceae - sealed:yellow, unsealed:yellow - oxidation and fermentation
Pseudomonas - sealed:green, unsealed:yellow - oxidation
Alcaligenes - sealed:green, unsealed:green - non-reactive

question

O-F Medium Results and Interpretation
[image]

answer

sealed:green or blue, unsealed:any yellow - oxidation
sealed:yellow, unsealed:yellow - oxidation and fermentation (or fermentation only)
sealed:green or blue, unsealed:green or blue - no sugar metabolism
blue indicates organism used peptone and produced alkaline end products

question

MR-VP test - Detects organisms capable of performing _____________________ and produce _________ acids.

answer

mixed acid fermentation
stable

question

MR-VP test - for MR test, a positive result is ______ and indicates a ______ pH.

answer

red
low (acidic)

question

MR-VP test - VP test detects organisms that are able to ferment glucose, but convert their products to _____________

answer

acetoin

question

MR-VP test - VP test - a positive result is _________ and indicates a _________ pH

answer

red
high (alkaline)

question

MR-VP test - Which of the two tests would likely produce more false negatives with a shorter incubation time and why?

answer

The VP test because VP positive organisms need time for the unstable acids to convert to acetoin

question

[image]

answer

MRVP test

question

[image]

answer

MRVP test

question

Starch Hyrdolysis - Organisms that can break down starch contain the enzyme ___________

answer

amylase

question

Starch Hydrolysis - A positive result is:

answer

a clearing around growth, indicating amylase is present

question

Starch hydrolysis - a negative result is:

answer

no clearing around growth, no amylase present

question

starch hydrolysis - in many tests it is acceptable to read a positive result before the incubation time is completed. why is this not the case with starch agar?

answer

because if the enzyme amylase is present, it needs time to break the starch down to glucose

question

[image]

answer

starch hydrolysis - left negative result, right positive result

question

catalse test - catalase test converts hydrogen peroxide into ____________

answer

water and gaseous oxygen

question

catalase test - positive result is:

answer

bubbles, catalase is present

question

catalase test - negative result

answer

no bubbles, no catalase is present

question

catalase test - why is it advisable to perform this test on a known catalase-positive organism along with the organism you are testing?

answer

to make sure the hydrogen peroxide has not broken down and is still working

question

[image]

answer

catalase test

question

oxidase test - positive result is:

answer

dark blue withing 20 seconds, cytochrome c oxidase is present

question

oxidase test - negative result is:

answer

no color change to blue within 20 seconds, cytochrome c oxidase is NOT present

question

[image]

answer

oxidase slide test

question

API 20 E - why is it important to perform the reagent test last?

answer

Because you need to look for spontaneous reactions first. Also, if you splash reagents into adjacent cups you could change their color

question

[image]

answer

how to read an API 20 E test

question

Nitrate Reduction Test - after adding A & B reagents, a red result means:

answer

nitrate-positive, nitrate reduction to nitrite (NO₃ -> NO₂)

question

Nitrate reduction test - yellow result after adding A & B reagents indicates:

answer

incomplete test, zinc must be added
may be nitrate-negative
or may have further reduced nitrite to nitric oxide, nitrous oxide or nitrogen

question

nitrate reduction test - after adding zinc dust, no color change indicates:

answer

nitrate positive - nitrate reduction to NO, N₂O, or N₂

question

nitrate reduction test - after adding zinc dust, red color change indicates:

answer

no nitrate reduction, nitrate-negative

question

[image]

answer

nitrate reduction test

question

fluid thioglycollate medium - good for cultivation of _____________ and ______________

answer

strict anaerobes, microaerophiles

question

fluid thioglycollate medium - is ________ at the top and _____________ at the bottom

answer

aerobic, anaerobic

question

fluid thioglycollate medium - the aerobic zone is _________ in color

answer

pink

question

fluid thioglycollate medium growth
[image]

answer

1 - aerobe - growth only at top
2 - faculative anaerobe - growth throughout, but more growth at top
3 - aerotolerant anaerobe - growth throughout tube
4 - anaerobe - no growth at top

question

[image]

answer

Brewer anaerobic jar, used to culture anaerobes

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