Microbiology Lab Final Exam

Heat reaction to 95 C to denature DNA

Cool rxn to 55 C to allow primers to anneal

Heat rxn to 72 C to allow Taq polymerase to bind

Give the steps of a PCR

thermocycler

What machine is used to carry out a PCR reaction?

30

How many cycles does a PCR rxn usually go?

Bacillus subtillis

Enterobacter aerogenes

Entero cloacae

Escherichia coli

Klebsiella pneumoniae

Pseudomonas aeruginosa

Salmonella typhimurium

Staphylococcus aureus

Staphylococcus epidermidis

Name the 9 organisms used in the unknown lab

E. coli

E. cloacae

E. aerogenes

K. pneumonia

Which organisms can ferment lactose?

rod-shaped, Gram-negative, non-spore forming, and motile or non-motile bacteria which can ferment lactose with the production of acid and gas

Define caliform bacteria

Blood Agar

Bile Esculin

Mannitol Salt Agar (MSA)

MacConkey Agar (MaC)

Eosin Methylene Blue (EMB)

Hektoen Enteric Agar (HEA)

Xylose Lysine Desoxiolate (XLD)

Name the selective medias used in class

O/F Glucose

MRVP

Catalase

Oxidase

Citrate

Starch

Indole

TSI

Name the differential medias used in class

indole

methyl red

vogues proskaver

in

citrate

What does the acronym IMViC stand for?

used to differentiate gram negative rods

What is the IMViC series of tests used for?

Enterobacter

Which specific orgnaisms are the IMViC tests good at differentiating?

designed to grow only specific bacteria but not others

Define selective media

designed to show the difference between different organisms grown on

Define differential media

shows the types of hemolysis (ability to break down RBCs) of organisms

What does blood agar show?

alpha

beta

gamma

What are the 3 types of hemolysis?

partial growth, green

Describe alpha growth on blood agar

total growth, clear

Describe beta growth on blood agar

nothing, still red

Describe gamma growth on blood agar

ability of organisms to tolerate bile and hydrolyze esculin

Bile esculin shows what?

enterococci and streptococci

What two types of organisms is bile esculin good at differentiating?

ferric citrate

What reagant is added to bile esculin?

black is +

What could be the results of a bile esculin test?

enterococci

streptococci

What two types of organisms usually grow on bile esculin?

Mannitol Salt Agar

MSA stands for

If the organisms produces acid products

MSA shows what?

S. aureus

MSA is used to identify which organism?

phenol red

What is the indicator in MSA whether the fermentation takes place or not?

yellow is +

What is the result of a positive MSA test?

MacConkey Agar

MaC stands for

If the organism is a lactose fermenter

MaC shows what?

good growth indicates a gram negative bacterium that is not inhibited by crystal violet or bile.

pink to red growth without bile indicates that the organism produces acid from lactose fermentation and is a probable coliform.

colorless growth is a non lactose fermenting organism and noncoliform.

What are the possible outcomes of a MaC test?

No

Can gram positive organisms grow on MaC?

Eosin Methylene Blue

EMB stands for

tests if an organism is caliform

EMB shows what?

dark growth indicates a lactose fermenter and acid production

pink growth indicates lactose fermenter

What are the possible results of an EMB test?

Hektoen Enteric Agar

HEA stands for

indicates lactose fermentation and hydrogen sulfide production

HEA shows what?

isolates salmonella & shigella bacteria

HEA is used for?

pink growth indicates lactose fermenter and sulfur reducer

What are the possible results of a HEA test?

xylose lysine desoxiolate

XLD stands for

if an organism can ferment the sugar xylose to produce acid

XLD shows what?

isolates salmonella & shigella bacteria

XLD is used for?

yellow indicates acid production

red with some black growth indicates sulfur reduction

What are the possible results of XLD test?

oxidative/fermentation

O/F in O/F glucose stands for

does the organism oxidize and/or ferment glucose

O/F glucose tests show what?

2 tubes, one with oil (anaerobic) and one not:

yellow in anaerobic means fermenting glucose but if yellow only in aerobic, then oxidizing glucose

What could be the results of an O/F glucose test?

methyl red vouges proskaur

MRVP stands for what?

MR- tests for acid fermentation

VP- can it ferment glucose

MRVP shows what?

red is +

yellow is -

What could the results of the methyl red look like?

red is +

nothing is -

What could the results of vouges proskauer look like?

does the organism have catalase

Catalase tests for what?

bubbles indicates catalase is present

no bubles is -

What could be the results of a catalase test?

catalyzes the decomposition of hydrogen peroxide to water and oxygen (H₂O² → H₂O + O₂)

Define catalase enzyme

does the organism have cytochrom c oxidase

Oxidase tests for what?

if the organism becomes blue after 20 secs then cytochrome c oxidase is present

What could be the results of oxidase test?

an enzyme that promotes the transfer of a hydrogen atom from a particular substrate to an oxygen molecule, forming water or hydrogen peroxide.

Define oxidase enzyme

can the organism use citrate as its sole source of carbon

Citrate tests for what?

any amount of blue is +

growth but no blue means citrate is utilized

nothing is -

What could the results of a citrate test be?

can the organism break down starch

Starch tests for what?

plate appeared white and cloudy where hydrolysis occurred, black is original color

What would a positive starch hydrolysis test look like?

does the organism have tryptophan

Indole tests for what?

red ring

What will a positive indole test look like?

kovac's reagant

What reagant is added to an indole test?

triple sugar iron

TSI stands for

used to differentiate bacteria on the basis of glucose fermentation, lactose fermentation, sucrose, and sulfur reduction

TSI test for what?

cracks indicate gas production

black precipitate indicates sulfur production

red slant with yellow butt indicates glucose fermentation

yellow slant indicates glucose and lactose fermentation

What could be the results of a TSI test?

aids in the protection of foreign DNA, restriction enzymes function by binding to the DNA and cutting out damaged portions. sites are short, usually 4-8 nucleotides

Define restriction digest

negative

What is the charge of DNA?

its molecular weight

What determines how far a molecule will move in gel electrophoresis?

binds to DNA and will fluoresce under a UV light

Describe the role ethydium bromide gel electrophoresis

an enzyme produced chiefly by certain bacteria, having the property of cleaving DNA molecules at or near a specific sequence of bases (restriction sites)

Define restriction enzymes

a genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium

Define plasmid

Vouges Proskauer

Which test tests for acetoin?

E. coli can be

Give an example of a motile bacteria