Micro Final Lab class

What test is used to identify hemolysins?

Hemolysis test using Blood Agar media.

Hemolysis Test tests for

Lysis of red blood cells, partial or complete.

What indicates a positive result in the hemolysis test?

A clearing around growth (beta) and green halo around growth (alpha)

What is the reagent or indicator used in the hemolysis test?

RBC

What test is used for starch hydrolysis/amylase?

Starch Hydrolysis test using Starch Agar.

What type of media is Starch Agar?

A growth media used to detect the presence of amylase.

What enzyme is detected in the starch hydrolysis test?

Amylase.

What reagent is used in the starch hydrolysis test?

Iodine.

What indicates a positive result in the starch hydrolysis test?

Clearing in agar around growth after reagent (Iodine)

What test is used for casease/casein hydrolysis?

Casein Hydrolysis test using Skim Milk Agar.

What type of media is Skim Milk Agar?

A growth media used to detect the presence of caseinase.

What enzyme is detected in the casein hydrolysis test?

Caseinase.

What reagent is used in the casein hydrolysis test?

Milk.

What indicates a positive result in the casein hydrolysis test?

A clearing in agar around growth.

What test is used for urease/urea hydrolysis?

Urea Hydrolysis test using Urea Broth.

What type of media is Urea Broth?

A growth media used to detect the presence of urease.

What enzyme is detected in the urea hydrolysis test?

Urease.

What reagent is used in the urea hydrolysis test?

Phenol Red.

What indicates a positive result in the urea hydrolysis test?

Bright pink color in the medium.

What test is used for fermentation of sugars?

Carbohydrate Fermentation test using Carb tube with Phenol Red Broth.

What type of media is Phenol Red Broth?

A growth media used for the fermentation of specific sugars.

What indicates a positive result for fermentation in phenol red broth?

Yellow color for acid production and bubbles for gas.

What reagent is used in the phenol red carbohydrate fermentation test?

Phenol Red.

What does Carbohyrdate Fermentation test test for?

Fermentation of sugars

What test detects tryptophanase/hydrolysis of tryptophan?

Indole test using SIM Medium.

What type of media is SIM Medium?

A culture medium used to detect indole, hydrogen sulfide, and motility.

What enzyme does the indole test check for?

Tryptophanase.

What reagent is used in the indole test?

Kovac’s Reagent.

What indicates a positive result in the indole test?

A red after the addition of Kovac's Reagent.

What is the Methyl Red test used for?

It is used to assess mixed acid fermentation.

What type of broth is utilized in the Methyl Red test?

MR-VP Broth is employed as the culture medium.

What does a positive result in the Methyl Red test signify?

The appearance of a red color in the broth after adding reagent indicates a positive result.

What is the reagent for the Methyl Red test?

Methyl red.

What is the purpose of the Voges-Proskauer (VP) test?

To detect acetoin production/ non-acid byproduct

Which broth is used in the Voges-Proskauer test?

MR-VP Broth is used as the culture medium.

What reagents are added to perform the VP test?

VP A and VP B reagents are utilized.

How can a positive result be indicated in the VP test?

The development of a red color in the broth after adding VP reagents

What is the biochemical test that detects if a organism can use citrate?

Citrate test.

Which media is used in the citrate test?

Simmons Citrate Agar.

What test determines if organisms can use citrate?

Citrate test.

What indicator is used in the citrate test?

Bromthymol Blue.

What indicates a positive result in the citrate test?

A blue color change in the agar.

What is the test used to detect hydrogen sulfide (H2S) produced by organisms?

Hydrogen sulfide test.

What medium is used for the H2S test?

SIM Medium.

What reagent/indicator is present in the SIM Medium?

Iron

What indicates a positive result in the H2S test?

The formation of a black precipitate.

What is the test that measures lysine decarboxylation/lysine hydrolysis?

Lysine Decarboxylase test.

What medium is utilized for the Lysine Decarboxylase test?

LD+ and LD-

What is the reagent/indicator of Lysine Decarboxylase?

Bromcresol purple.

What does a positive result indicate in the Lysine Decarboxylase test?

LD+/LD- Purple/Yellow

What does the Lysine Decarboylase test detect?

Lysine decarboxylase/lysine hydrolysis.

Which test assesses the activity of cytochrome oxidase/electron transport?

Oxidase test.

What is the reagent used in the Oxidase test?

Oxidase swab.

What media does the oxidase test use?

TSA

What does the Oxidase test detect?

Cytochrome oxidase/electron transport

What indicates a positive result in the Oxidase test?

purple color.

What test is conducted for nitrate reduction?

Nitrate Reduction test.

Which medium is used in the Nitrate Reduction test?

Nitrate Broth.

What does the Nitrate Reduction test measure?

The reduction of nitrate to nitrite or nitrogen gas (N2).

What reagents are used in the Nitrate Reduction test?

Nitrate A and B and sometimes C/ zinc dust.

How can a positive test result be identified in the Nitrate Reduction test?

The solution turning red after adding reagents or no color change after zinc is also a positive result.

Reagent used in the catalase test

Hydrogen peroxide (H2O2) is the reagent that is added.

Positive result in the catalase test

The appearance of bubbles when hydrogen peroxide is added, indicating the presence of the catalase enzyme.

What media is used for the Catalase test?

TSA

The Catalase test tests for?

Catalase/Hydrolysis of hyrdogen peroxide.

This test utilizes PEA Agar to promote the growth of gram-positive bacteria.

PEA Test that uses PEA Agar media.

Purpose of PEA Test

To identify and isolate gram-positive organisms.

Inhibitor in PEA Test

Phenyl ethyl alcohol inhibits the growth of gram-negative bacteria.

Indicator for PEA Test

No specific indicator (NA) is used for this test.

Positive Result in PEA Test

Growth indicates a positive result for gram-positive bacteria.

Mannitol Salt Agar (MSA) Test Tests for?

Osmotolerant/ haloteoleranbt organisms that ferment mannitol.

Inhibitor in MSA Test

High concentrations of salt inhibit the growth of most gram-negative and some gram-positive bacteria. (7.5 NaCl)

Indicator in MSA Test

Phenol Red acts as the pH indicator.

Positive Result in MSA Test

A color change to yellow indicates acid production from mannitol fermentation.

MacConkey Agar Test

This test employs MacConkey Agar to assess gram-negative bacteria and lactose fermentation.

Purpose of MacConkey Test

To differentiate between lactose fermenters and non-fermenters among gram-negative bacteria.

Inhibitors in MacConkey Test

Crystal violet inhibit the growth of gram-positive bacteria.

Indicator in MacConkey Test

Neutral Red and bile salts is used as a pH indicator.

Positive Result in MacConkey Test

red colonies/ precipitated bile salts

EMB (Eosin Methylene Blue) Test

EMB(Eosin Methylene Blue) agar

Purpose of EMB Test

To identify gram-negative bacteria that can ferment lactose.

Inhibitors in EMB Test

Eosin and methylene blue

Indicator in EMB Test

Eosin and methylene blue

Positive Result in EMB Test

The presence of dark purple or a green metallic sheen on colonies indicates lactose fermentation.

What is the media used for Phenyl Ethyl Alcohol?

PEA agar.

What is the media used for Mannitol Salt test?

MSA

What is the media for MacConkey test?

MacConkey agar.

What is the media for EMB?

Eosin Methylene Blue Agar.

Phenol Red Carbohydrate Tube Interpretation

Events leading to a +/- result in a phenol red carbohydrate tube are as follows:

• Positive (+): The bacteria ferment the sugar, generating acid which causes the phenol red to change to yellow; gas production is indicated by the presence of a bubble in the Durham tube.
• Negative (-): Absence of fermentation results in the phenol red remaining red or turning slightly pink due to alkaline by-products.

Tests for Enzyme Presence/Activity

The following tests evaluate the presence or activity of specific enzymes: Catalase, Oxidase, Urea hyrolysis, Indole, Casein Hydrolysis, Starch Hydrolysis, LD (lysine decarboxylase), and nitrate reduction.