Skip to main content

Triple Sugar Iron Test

By
The Triple Sugar Iron (TSI) Test 

To determine the ability of an organism to ferment glucose, lactose, and sucrose, and their ability to produce hydrogen sulfide.
Principle
The Triple Sugar Iron (TSI) test is a microbiological test named for its ability to test a microorganism’s ability to ferment sugars and to produce hydrogen sulfide. An agar slant of a special medium with multiple sugars constituting a pH-sensitive dye (phenol red), 1% lactose, 1% sucrose, 0.1% glucose, as well as sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate is used for carrying out the test. 

. Due to the building of acid during fermentation, the pH falls. The acid base indicator Phenol red. is incorporated for detecting carbohydrate fermentation that is indicated by the change in color of the carbohydrate medium from orange red to yellow in the presence of acids.  In case of oxidative decarboxylation of peptone, alkaline products are built and the pH rises. This is indicated by the change in colour of the medium from orange red to deep red. Sodium thiosulfate and ferrous ammonium sulfate present in the medium detects the production of hydrogen sulfide and is indicated by the black color in the butt of the tube.
Composition of Triple Sugar Iron Test

Final pH 7.3 +/- 0.2 at 25ºC.
Method

1.    With a straight inoculation needle, touch the top of a well-isolated colony.
2.    Inoculate TSI by first stabbing through the center of the medium to the bottom of the tube and then streaking the surface of the agar slant.
3.    Leave the cap on loosely and incubate the tube at 35°-37°C in ambient air for 18 to 24 hours.
4.    Examine the reaction of medium.
Expected Results
  • An alkaline/acid (red slant/yellow butt) reaction: It is indicative of dextrose(Glucose) fermentation only.
  • An acid/acid (yellow slant/yellow butt) reaction: It indicates the fermentation of dextrose, lactose and/or sucrose.
  • An alkaline/alkaline (red slant, red butt) reaction: Absence of carbohydrate fermentation results.
  • Blackening of the medium: Occurs in the presence of H2 
  • Gas production: Bubbles or cracks in the agar indicate the production of gas ( formation of CO2and H2)
Triple sugar iron agar. A, Acid slant/acid butt with gas, no H2S (A/A). B, Alkaline slant/acid butt, no gas, H2S-positive (K/A H2S+). C, Alkaline slant/alkaline butt, no gas, no H2S (K/K). D, Uninoculated tube.
Uses
  • The test is used primarily to differentiate members of the Enterobacteriaceae family from other gram-negative rods.
  • It is also used in the differentiation among Enterobacteriaceae on the basis of their sugar fermentation patterns.
  • It is use for compare with 

    Kligler's Iron Agar (KIA) of sucrose's microbial.



References
https://www.time2026end.com/
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