Skip to main content

Catalase test

By
    Catalase  test– this test determines bacterial production of catalase enzymes.

 Image result for catalase test
1.      Place a drop of hydrogen peroxide (3% H2O2 - reagent grade) on a microscope slide or in the concave surface of a hanging drop slide.

2.      With a sterile loop, collect a sample of 18-24 hour old pure bacterial culture.

 3.      Place the loop in the hydrogen peroxide.

 4.      If the test is positive, there will be immediate bubbling or foaming, and liberation of O2 gas.


5.      Record results.
Positive : If the mixture produces bubbles or froth, the organism is said to be 'catalase-positive

( Staphylococcus and Micrococcusare catalase-positive. Other catalase-positive organisms 

include Listeria, Corynebacterium diphtheriae, Burkholderia cepacia, Nocardia, the family 

Enterobacteriaceae 

(Citrobacter, E.coli, Enterobacter, Klebsiella, Shigella, Yersinia, Proteus, Salmonella, Serratia), Pseudom

onas, Mycobacterium tuberculosis, Aspergillus, Cryptococcus, and Rhodococcus equi).

Negative:If it is not produces bubbles, the organism is 'catalase-negative ( Streptococcus and Enterococcus spp. are catalase-negative ).

    QUALITY CONTROL:
Positive : Staphylococcus sp
Negative: Streptococcus sp 
Labels:

Comments

Post a Comment

Popular posts from this blog

Mueller Hinton Agar

By
Mueller Hinton Agar (MHA)       The major use of Mueller Hinton Agar is for antimicrobial susceptibility testing. Composition of MHA Ingredients   Beef Extract                                  2.00 gm Acid Hydrolysate of Casein         17.50 gm Starch                                           1.50 gm Agar                                             17.00 gm Distilled Water                             1000 ml Final pH 7.3 ± 0.1 at 25ºC Why Mueller Hinton agar is used for antibiotic susceptibility testing? 1.     It is a non-selective, non-differential medium. This means that almost all organisms plated on here will grow. 2.     It contains starch. Starch is known to absorb toxins released from bacteria, so that they cannot interfere with the  antibiotics . It also mediates the rate of diffusion of the antibiotics through the agar. 3.     It is a loose agar. This allows for better diffusion of the antibiotics than most other plates. A bette
Post a Comment
Read more

Urease Test

By
Urease Test The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease. Principle  Urea  is the product of decarboxylation of  amino acids . Hydrolysis of  urea  produces  ammonia  and  CO2 . The formation of  ammonia  alkalinizes the medium, and the pH shift is detected by the color change of  phenol red  from  light orange  at pH 6.8 to  magenta (pink)  at pH 8.1. Rapid urease-positive organisms turn the entire medium  pink  within 24 hours. Weakly positive organisms may take several days, and negative organisms produce  no color change  or  yellow  as a result of  acid production . Uses  1.     This test is used to differentiate organisms based on their ability to hydrolyze urea with the enzyme urease. 2.     This test can be used as part of the identification of several genera and species of Enterobacteriaceae, including  Proteus, Klebsiella ,
Post a Comment
Read more

INTRODUCTION TO MYCOLOGY

By ok learning
MYCOLOGY INTRODUCTION TO MYCOLOGY Contents 1 Objective 2 Meaning 3 Growth 4 General structures FUNGI: 1 Purpose · Types of colors and definitions · Separation of yeast and mold 2.Definition Mycology is a fossil science study. Mycosis is a fungal infection. Yeast is a large cell, with only one type of cells, most of which are non-transplantation, called budding. Mold is a multicellular cell. Most of the fertilized egg is enlarged. 3 Growth a.Yeast: routine incubation temperature is usually 25c b. Mold: routine incubation temperature is usually 25c o to 30c o , although 35c o incubation can be used to differentiate some mold based on temperature tolerance or determine whether organisms are diphasic. c. Diphasic (dimorphic fungi): These organisms differ in two forms depending on temperature. d. Frequently used media The most common use of: - spermatozoa-Sabouraud's dextrose agar (SDA) - Sabouraud's dextrose agar
Post a Comment
Read more