Kligler Iron Agar Test- Principle, Media, Procedure, Results, Uses

Kligler Iron Agar Test

Objective To differentiate the enteric gram-negative bacilli based on the production of hydrogen sulfide and fermentation of dextrose and lactose. Principle of Kligler Iron Agar Test Kligler Iron Agar (KIA) test is used in differentiating certain members of the Enterobacteriaceae by demonstrating hydrogen sulfide production and the fermentation of dextrose and lactose. Kligler agar used for the test comprises casein and meat peptones that supply nitrogenous compounds and amino acids, vitamins necessary for bacterial growth. The medium comprises two sources … Read more

Triple Sugar Iron Agar (TSIA) Test- Principle, Media, Procedure, Results, Uses

Result Interpretation of TSIA Test

Objectives of TSIA Test To determine whether a gram negative bacilli ferments glucose and lactose or sucrose and forms hydrogen sulfide (H2S). To differentiate members of the Enterobacteriaceae family from other gram-negative rods. Principle of TSIA Test The Triple Sugar Iron agar (TSIA) test is designed to differentiate among the different groups or genera of the Enterobacteriaceae, which are all gram-negative bacilli capable of fermenting glucose with the production of acid and to distinguish them from other gram-negative intestinal bacilli. … Read more

Lysine Iron Agar Test- Principle, Media, Procedure, Results, Uses

Result Interpretation of Lysine Iron Agar Test

Objective of Lysine Iron Agar Test To differentiate gram-negative bacilli based on decarboxylation or deamination of lysine and the formation of hydrogen sulfide (H2S). Principle of Lysine Iron Agar Test Lysine iron agar (LIA) contains lysine, peptones, a small amount of glucose, ferric ammonium citrate, and sodium thiosulfate. The medium has an aerobic slant and an anaerobic butt. Lysine deamination is an aerobic process that occurs on the slant of the media. Lysine decarboxylation is an anaerobic process that occurs in the butt of the media. The indicator in LIA is bromcresol purple. Bromocresol … Read more

Biuret Test for Protein- Definition, Principle, Procedure, Results, Uses

Biuret Test for Protein

What is Biuret Test? Proteins are complex compounds formed by thousands of amino acids. Amino acids are amphoteric electrolytes having carboxyl and amino groups that act like acid and base. It has one positive charge and one negative charge, hence these ions are electrically neutral and do not migrate in the electric field. The two amino acids are linked together with the help of a bond called peptide bond and it yields dipeptide. The bond is formed between the α … Read more

Bile Esculin Test- Principle, procedure, results, uses, limitations

Bile Esculin Test

What is the Bile Esculin Test? The bile-esculin test is a biochemical test performed to differentiate Enterococci and group D Streptococci from non-group D viridans group Streptococci on the basis of their ability to hydrolyze esculin. Many organisms are capable of hydrolyzing esculin, but only a few of them can do so in the presence of bile (4% bile salts or 40% bile.). Thus, this property is utilized to identify organisms of a particular group. The Bile-esculin test is performed … Read more

Casein Hydrolysis Test- Objectives, Principle, Media, Procedure, Results

Result of Casein Hydrolysis Test

Objectives of Casein Hydrolysis Test To determine the ability of the organism to degrade the casein protein. To differentiate the organism on the basis of production of exoenzyme proteinase (caseinase) Principle of Casein Hydrolysis Test Casein is a macromolecule composed of amino acids linked together by peptide bonds, CO-NH. Some microorganisms have the ability to degrade the casein protein by producing proteolytic exoenzyme, called proteinase (caseinase) which breaks the peptide bond CO-NH by introducing water into the molecule, liberating smaller chains of … Read more

Carbohydrate Fermentation Test | Sugar Fermentation Test

Carbohydrate fermentation test

Introduction Carbohydrates are organic molecules that comprise carbon, hydrogen, and oxygen in the ratio (CH2O)n. There are three types of carbohydrates based on their structure and number of carbon atoms present, they are monosaccharides (simple sugar containing 3-7 carbon atoms), disaccharides (comprising of two monosaccharides linked together by the glycosidic bond), polysaccharides (containing eight or more monosaccharide molecules). The energy is released by the process of catabolism referring to the breakdown of the complex organic molecules. The power of chemical … Read more

Oxidase Test- Principle, Procedure and Results

Oxidase Test

Objective of Oxidase Test To determine the ability of the organism to produce the cytochrome oxidase enzyme. Principle of Oxidase Test The oxidase test is designed for specifically detecting the presence of the terminal enzyme system in aerobic respiration called cytochrome C oxidase or cytochrome a3. Cytochrome C oxidase is the terminal or last H2 electron acceptor in an aerobic respiratory mechanism which is composed of a number of enzymes that alternatively oxidize and reduce each other by donating or accepting … Read more

Urease Test- Principle, Media, Procedure, Result, Uses

Urease Test- Principle, Procedure and Result

Urease Test Definition Urease test is a biochemical test that detects the alkaline fermentation of urine (urea) with the resultant production of ammonia by microorganisms. The fermentation of urea occurs in the presence of the enzyme ‘urease’, resulting in two molecules of ammonia and carbon dioxide. Urease activity is one of the important characteristics for the identification of Proteus species and allows for Proteus to be distinguished from non-lactose-fermenting members of the Enterobacteriaceae. Christensen developed the test in 1946 for … Read more

Indole Test- Principle, Media, Procedure, Types, Results, Uses

Indole Test

Indole Test Definition Indole test is a biochemical test conducted on bacterial species to detect their ability to produce indole from tryptophan in the presence of a group of enzymes called ‘tryptophanase’. It is a qualitative test that tests the conversion of tryptophan into indole. The test is performed as a part of the IMViC test that is used to differentiate the members of the Enterobacteriaceae family. It is important in the identification of different bacteria like Escherichia coli, Proteus, … Read more