Exercise 9: Cultural and Physiological Characteristics of Bacteria Part II

What are two tests that yield results within minutes?

-catalase

-oxidase

What are some tube media that test for other metabolic processes?

-nitrate broth

-gelatin

-urea broth

-phenylalanine

-SIM

-IMViC

In respiration, the final electron acceptor is a _____ molecule

inorganic

In aerobic respiration, the final electron acceptor is:

oxygen

In anaerobic respiration, the final electron acceptor is

any other inorganic molecule other than oxygen (nitrate, sulfate are some examples)

What is the general pathway for respiration?

Glycolysis ---> Kreb's cycle ---> ETC

What is the pathway for ETC?

Flavoprotein ---> FeS carrier ---> Ubiquinone ---> Cytochrome c ---> Cytochrome c oxidase ---> Final Electron acceptor

the transfer of electrons goes form most negative to most positive reduction potential or from most positive to most negative reduction potential?

most negative to most positive reduction potential

During aerobic metabolism, reactive oxygen species (ROS) may be produced. What are they?

-superoxide radicals

-hydrogen peroxide (H2O2)

What enzyme will breakdown superoxide radicals?

Superoxide dismutase (SOD)

SOD=

superoxide dimutase

What enzyme breaks down hydrogen peroxide?

Catalase

To test for catalase, one must add what to the edge of a colony?

hydrogen peroxide

What happens to a colony if it test positive for catalase?

bubbles will appear/form from the sample

What is the main function of cytochrome c oxidase?

to remove electrons from cytochrome c (oxidize) and transfer them to oxygen (reduce)

Cytochrome c oxidase can also reduce cytochrome c by oxidizing what?

a chromogenic reducing agent

A chromogenic reducing agent will or will not develop a color when oxidized?

will develop a color

What is dimethyl p-phenylalanine?

the indicator for an oxidase test; a aromatic amine

If the oxidase test yields positive results, what color will appear?

dark blue to black

In nitrate respiration, what is the final inorganic electron acceptor?

nitrate (NO3)

What enzyme is needed to convert nitrate to nitrite?

nitrate reductase

If a bacteria have an enzyme that can reduce nitrate all the way down to nitrogen gas (N2), what is this process called?

nitrification

If a bacteria can reduce nitrate to ammonium for incorporation, what is this process called>

assimilatory nitrate reduction

What test/media detects nitrate reductase?

Nitrate broth

Nitrate chem formula=

NO3

Nitrite chem formula=

NO2

What is added to the nitrate broth initially to test for nitrate reductase?

Nitrate I and Nitrate II

Nitrate I=

sulfanilc acid

Nitrate II=

dimethyl-alpha-naphthylamine

If the nitrate broth turns red after adding Nitrate ! and Nitrate II, what does this mean?

positive for nitrate reductase

If the nitrate broth does not turn any color after adding Nitrate I or Nitrate II, what does this mean? What must be done?

either nitrate was not used or its negative for nitrate; in order to be sure, you have to add zinc for a confirmation

What does it mean if a red result is produced after the zinc addition to the nitrate test? A no-color result?

that nitrate was not used and the organism does have the enzyme; nitrate was used and it does have the enzyme

What test/media detects urease?

Urea broth

What does urease do?

degrades urea (2 ammonia and carbon dioxide)

Urease increases or decreases pH/

increase

What is the indicator for urea broth?

phenol red (pH indicator)

As pH increase above 8.1, what color does the urea broth turn?

cerise

If the pH is neutral, what color will the urea broth turn?

red

As pH decrease, what color will the urea broth turn?

yellow

What media detects the presence of gelatinase?

Gelatin

Gelatinase breaksdown:

gelatin

Gelatin will solidify in high or low temps?

low

If gelatin stays solid after removing from ice bath, is this a positive or negative result?

negative (does not have gelatinase)

If gelatin liquifies after removing from ice bath, is this a positive or negative result?

positive (has gelatinase)

What medium detects production of phenylalanine deaminase?

Phenylalanine slant

Phenylalanine deaminase breaksdown phenylalaline into:

phenylpyruvic acid (PPA) and ammonia (NH3)

What is the reagent added to phenylalanine slant to detects the presence of PPA?

5-10 drops of 10% ferric chloride (FeCl3)

What color will the slant turn it is positive for phenylalanine deaminase?

green

SIM stands for:

Sulfide, Indole, and Motility

To test for indole in SIM, what needs to be added?

3-5 drops of Kovac's reagent

What color is a positive result for indole in SIM?

pink/red

Fermentation produces as much energy as respiration does, T or F?

false; does not produce as much energy as respiration

What are the end products when pyruvate under goes fermentation?

organic acids and gases

What are the two main pathways for fermentation?

-mixed-acid fermentation

-2,3-butanediol fermentation

What bacteria is known to use the mixed acid pathway?

E. coli

What bacteria is known to use the 2,3-butanediol pathway?

E. aerogenes

What tes/media can be used to test whether or not a bacteria is E.coli or E. aerogenes?

MR-VP broth

MR=

Methyl red

VP=

Vogues-Proskauer

MR and VP can be ran at the same time, T or F?

false; need to be run separately

MR in MR-VP media will test for:

mixed acid fermenters

What reagent is used to test MR in MR-VP broth? What is it indicatijng?

methyl red reagent; pH indicator

Methyl red reagent in MR-VP broth is detecting for? Lowers or raises pH to?

high acid production; lowers pH to 4.4 or less

If there is low acid concentration when adding methyl red reagent to MR in MR-VP broth, what will happen to the color?

Will not retain the red color

If pH is above 4.4, is that a positive or negative result for mixed acid fermentation in MR for MR-VP broth?

negative

E. coli will show what result for MR in MR-VP?

positive; will retain red color

VP in MR-VP media will test for:

2,3-butanedoil fermenters

What intermediate is formed in the 2,3-butanediol pathway?

acetoin

What reagents are used to test for VP in MR-VP broth?

VP I and VP II

VP I=

alpha naphthol

VP II=

KOH

VP 1 and VP II are also know as:

Barritt's reagents

Acetoin will interact with:

Barritt's reagents

How many drops of VP I is added to MR-VP broth? What will it do?

10 drops; will intensify the red color

How many drops of VP II is added to MR-VP broth after the addition of VP I? What does this addition do? What is made?

10 drops; will produce an alkaline condition that favors acetoin oxidation; diacetal and O2 is made

A positive result for VP in MR-VP broth produces what color?

a red color

E aerogenes will show what result for VP in MR-VP broth?

positive; will produce red color

What test/media tests for tryptohanase?

Tryptone broth

Tryptophanase ____ tryptophan

hydrolyzes

What reagent is added to tryptone broth?

3-5 drops of Kovac's reagent

What does the reagent that is added to tryptone broth do? Is it polar and nonpolar?

nonpolar; extracts indole to top

A positive results in tryptone broth will produce what color?

Cerise (Indole + Kovac's reagent)

What is Kovac's reagent made of?

paradimethyl-aminobenzaldehyde + HCl + amyl alcohol

What medium detects the utilization of citrate as the sole carbon source for growth?

Simmons Citrate Slant

What is the indicator for Simmons Citrate Slant?

bromothymol blue

What indicates a positive result for the Simmons Citrate Slant? What color MAY accompany a positive result?

growth; blue

Is a blue color on a Simmons Citrate Slant the sole indicator for a positive result?

NO; growth is; if a blue color does show, that means it did grow. But if you see growth and no color change, it is still positive

What four set of tests can be used to differentiate E. coli and E. aerogenes?

IMViC

What are the four tests for IMViC?

-indole

-methyl red

-Voges-Proskauer

-Citrate

E. coli will produce what results for IMViC?

positive for indole and MR; negative for VP and citrate

E. aerogenes will produce what results for IMViC?

negative for indole and MR; positive for VP and citrate