biol 2070 final

SIM stab

A microbiological test to determine motility, tryptophan degradation (indole production), and sulfur reduction (hydrogen sulfide production) of a bacterial species.

agar concentration of SIM stab

Use a lower agar concentration (1/3 of normal) to facilitate motility.

peptone

A source of amino acids, including tryptophan, in the SIM media and is necessary for bacterial metabolism.

products of tryptophan degradation

-indole (detected by a reagent) -pyruvate (pyruvic acid) -ammonia (NH3)

components of SIM stab media

-peptone -lower agar -iron -beef extract

iron in SIMS media

Used as an indicator for H2S production. H2S reacts with iron salts to form a black precipitate.

tryptophanase

The enzyme responsible for breaking down tryptophan.

what reagent is used to detect indole in SIMS stab

Kovac's reagent.

positive result for indole production

Red ring.

negative result for indole production

Golden/burnt orange ring.

positive result for hydrogen sulfide production

Black tube (iron sulfide).

negative result for hydrogen sulfide production

No change.

cysteine

An amino acid containing sulfur.

deaminase

Produces hydrogen sulfide from cysteine by removing an amino group.

What does amylase do?

Breaks down starch by inserting water between glycosidic bonds.

substrate indole tests (IMVICS)

Tryptophan.

substrate of methyl red (IMVICS)

Glucose.

Substrate in Voges-Proskauer Test (IMVICS)

Glucose.

substrate in citrate test

Sodium citrate.

which pathogens produce H2S

Salmonella and Shigella.

non-pathogenic strain typically do not produce ____

H2S.

facultative non-motile

Stays on stab line.

facultative motile

Grows through the whole tube.

obligate aerobe

On top of stab.

obligate anaerobe

Bottom of stab.

starch

A large polymer of glucose monomers.

why does starch need to be hydrolyzed

Its large size prevents it from being transported across the bacterial cell membrane so it needs to be broken down using water to break its chemical bonds.

amylase

An enzyme produced by bacteria to facilitate the hydrolysis of starch. Exoenzyme (secreted by the cell to perform its function extracellularly).

Starch Agar

A growth medium containing starch.

iodine

what is used to indicate whether or not starch is present

amylase positive

halo of clearing

amylase negative

all black plate

IMVIC stands for

-indole test

-methyl red test

-vogues-proskauer test

-citrate tests

is the imvics test specifically for gram positive or negative tests

negative

substrate of indole test

Tryptophan

enzyme in indole test

tryptophanase

products of indole test

indole, pyruvate, and ammonia

media of indole test

tryptone brother

reagent of indole test

kovac's reagent

positive result of indole test

red ring

negative result of indole test

golden or yellow ring

methyl red test

determines if bacteria can ferment glucose using mixed fermentation, producing stable acidic end-products that lower the pH

substrate in methyl red test

glucose

type of fermentation happening during the methyl red test

mixed acid fermentation

end products of mixed acid fermentation

lactic acid, acetic acid, succinic acid

pH change in methyl red test

production of acids lowers the pH in the tube

reagent in methyl red test

methyl red

positive result of methyl red

red color; indicates lower pH

negative result of methyl red

golden or yellow color; indicates higher pH

end products of methyl red test

mixed acids

Vogues-Proskauer tests

-Detects the butylene glycol pathway. -Looks for basic or neutral end products, such as 2,3-butanediol. -Detects acetoin, a precursor to 2,3-butanediol, as an indicator of the butylene glycol pathway

substrate of vogues-proskauer test

glucose

why are the methyl red and vogues-proskauer test often performed together

because bacteria typically only utilize one or the other because bacteria will perform either mixed acid fermentation, butylene glycol pathway, or neither neither.

reagents of vogues-proskauer test

a-naphthol and KOH

positive result of vogues-proskauer test

red color

negative test of vogues-proskauer

no color change or burnt oranges

End products of the vogues-proskauer test

acetoin

citrate test

determines a bacterium's ability to use citrate as its sole carbon source

media for citrate test

citrate agar slant

reagent for citrate test

citrate

reagent in citrate test

bromothymol blue

positive result of citrate test

blue color and bacteria growth

negative result of citrate test

green color and no growth

end product of citrate test

sodium bicarbonate (alkaline)

durham tube

-Small, inverted test tube inside a larger test tube

-Used to capture and measure gas production by bacteria

-Helps identify whether a bacterial strain can ferment a specific sugar and produce gas as a byproduct

oxygen

the final electron acceptor in the electron transport chain for these bacteria

catalase test

identifies the presence of the catalase enzyme, which is crucial for neutralizing toxic byproducts produced during aerobic respiration

superoxide free radicals

toxic to the cell and must be neutralized

superoxide dismutase

converts superoxide to hydrogen peroxide (H202) which is also toxic to the cell

normal oxygenic respiration

generates superoxide ____ ____ as intermediates and they are toxic to cell and muct be neutralized

catalase

enzyme responsible for breaking down hydrogen peroxide (H202) into water and oxygen

reagent for catalase test

hydrogen peroxide (H202)

positive result of catalase test

presence of bubbles

negative result of catalase test

no bubbles

cytochrome oxidase

enzyme transfers electrons to oxygen, the terminal electron acceptor in the electron transport chain, producing water

oxidase test

determines if a bacterium produces cytochrome oxidase, an enzyme involved in aerobic respiration

bacteria that produce cytochrome oxidase use a chain or _ chain

cytochrome/electron transport

importance of oxidase

if its lasks this it cannot perform aerobic respiration

procedure for oxidase test

-use a sterile cotton swab to collect a colony

-the oxidase reagent is applied to it

positive result for oxidase test

the colony turns purple, indicates the presence of cytochrome oxidase

negative result for oxidase test

doesnt change color, indicates lack of presence of cytochrome oxidase

what are both catalase and oxidase utilized for?

aerobic respiration

what process is nitrate reductase used for?

nitrate reduction

what is nitrate being reduced to in nitrate reduction

nitrite

reagents for nitrate reduction test

Nitrate reagent A&B, Zinc

Denitrification and fixation

processes where bacteria convert nitrate to nitrogen gas.

red color after adding soultion a and b

positive for nitrate reduction

no color change after adding solution a and b

negative for nitrate reduction

what do add to the tubes that are showing negatvive results after adding solution a and b

zinc

red color after adding zinc

means nothing happened is negative for everything

no color and gas in durham tube after adding zinc

positive for denitrification

How to do dilutions

made by transferring a specific volume from one dilution to the next dilution blank.

innoculation process of MPN

Row 1: 10^{-8} dilution - Add 1 mL of the 10^{-8} dilution to each tube. Row 2: 10^{-9} dilution - Add 1 mL of the 10^{-9} dilution to each tube. Row 3: 10^{-10} dilution - Add 1 mL of the 10^{-10} dilution to each tube.

what if ur missing a dilution

If a dilution is missing (e.g., 10^{-9}), it can be created from an existing dilution (e.g., 10^{-8}). To create a 10^{-9} dilution from a 10^{-8} dilution, transfer 0.1 mL (one-tenth) of the 10^{-8} dilution into the 10^{-9} dilution blank.