Nitrate reductase

Gelatin Hydrolysis

or

Gelatin hydrolase

or 

Gelatinase

The product of breakdown of starch (amylose) by amylase yields what?

Starch negative

(The organism did not break down the starch into glucose)

Starch positive

(The organism has the amylase enzyme which broke down the starch into glucose)

Cysteine positive +

An anaerobe

(The organism contains the enzyme cysteine desulfhydrase which breaks down cysteine to yield Hydrogen Sulfide (H₂S) which reacts with the iron in the agar to form a black precipitate.)

Cysteine is an amino acid that contains sulfur.

(Think CySteine) S = Sulfur

Urea positive

(The organism contains urease which breaks down the Urea into ammonia (NH₃OH).  Since ammonia is alkaline/basic, it turns the phenol red within the broth hot pink.)

Urea negative -

(Phenol red in the broth turns yellow in acidic conditions, meaning the organism lacks the ability (enzyme: urease) into ammonia.)

1. Innoculated nitrate broth turns red with the addition of reagents sulfanilic acid and dimethylalphanaphthylamine.  The organism is _______?

2. What product caused the red color?

1. Nitrate positive

2. Nitrite (NO₂)

1. Innoculated nitrate broth is treated with Nesslers' reagent (aka HCl) and a yellow/brown precipitate forms.  The organism is ______?

2. What is the product that forms the precipitate?

1. Nitrite (NO₂) positive

2. Ammonia (NH₃ or N₂)

(Nitrite reductase within the organism broke down Nitrite to Ammonia which combined with Nesslers to form Ammonium, the brown precipitate)

The same organism is innoculated into two tubes, A and B, containing Nitrate Broth.  Sulfanilic acid and Dimethylalphanaphthylamine reagents are added to Tube A which yields a red color.  Nesslers' reagent is added to Tube B and yields a yellow color.

This organism is nitrate ___ and nitrite ____?

Nitrate positive

Nitrite negative

Nitrate reductase

and 

Nitrite reductase

Gelatin hydrolase

(Gelatin hydrolase breaks down the gelatin so the conents of the tube can no longer solidify and so they remain liquid)

Carbohydrate Fermentation

(Carbohydrase) Test

Lactase

Acid and Gas

(The organism is lactose positive + for acid and gas)

Lactase

Acid only

(Organism is Lactose positive for acid)

Dextrase

Acid and Gas

(Organism is dextrose positive +)

Trick question:

The organism is Sucrose negative - it does not contain sucrase and thefore could not break down the sucrose into acids nor gas.

• Indole (Tryptophanase)
• Methyl Red 
• Voges-Proskauer (Butanediol Dehydrogenase)
• Citrate Utilization (Citrase)

Innoculated 1% tryptone broth is treated with Kovacs' reagent.  A red layer forms. 

1) What is this red layer?

2) What enzyme formed this product?

1. Indole

2. Tryptophanase

IMViC

Methyl Red (MR)

and 

Voges-Proskauer (VP)

Dextrose positive +

Acid

Barritt's solutions include what?

In what test is it used?

1. alphanaphthol

2. potassium hydroxide (KOH)

Voges-Proskauer (VP)

Butanediol positive +

Acetyl methyl carbionl (Acetoin)

MR test identifies organisims that make strong acids

VP test identifies organisims that make weak acids

(The weak acids are more neutral, but still acidic)

"MR. Strong, meet VP weak"

pH < 7.6

"pH is less than 7.6"

Products range from neutral to acidic

pH > 7.6

"pH is greater than 7.6"

The products range from neutral to basic/alkaline

Innoculated Simmons Citrate Agar slant turned blue.  

1) The organisim is citrate _____.

2) The organism contains what enzyme?

1) Citrate positive

2) Citrase

(Lots of coliforms (bacteria that grow in the colon) produce a lot of alkaline products.  Bromthymol indicator turns blue in presence of alkaline products.)

"Dehydrogenperoxidease"

It breaks down hydrogen peroxide (de-) and is an enzyme (-ase)

Hydrogen peroxide or Catalase positive +

Bubbles are Oxygen (O₂₎

Hydrogen peroxide or catalase negative -

1. Gram's Crystal Violet (Primary Stain)
2. Gram's Iodine (Mordant)
3. Ethyl Alcohol (Decolorizer)
4. Gram's Safranin (Counterstain)

Retain the primary

Lose the secondary

(Gram + bacteria are blue/violet due to Gram's crystal violet

Lose the primary stain

Retain the counter/secondary stain

(Gram - bacteria are red because they retain the Safranin counter stain)

Litmus is red in _____

Litmus is blue in ____

Litmus is red in acids

Litmus is blue in bases

The organism contains lactase which broke down (fermented) the lactose and made acids.

The organism is lactose positive +

The organism does not contain lactase so the lactose was not fermented

The organism is lactose negative -

The organism contains casein hydrolase which broke down the casein protein in the milk.

The organism is casein +

The organism has reduced the litmus.  The white is the milk.

Organism is Casein negative -

Hemolysin

exo-enzyme

Hemolytic +

Beta Hemolytic

 the Zone of inhibition

Sensitive

Nessler's reagent is used in what test?

What is Nessler's reagen?

Nitrite Reductase

HCl

Sulfanilic acid 

and

Dimethylalphanaphthylamine