Biochemical tests are laboratory procedures that use specific chemical reactions to identify and characterize microorganisms, such as bacteria. These tests are often used to identify the presence of specific enzymes or metabolic pathways in a microorganism, which can help to distinguish it from other microorganisms.
Some common biochemical tests used in bacteriology include:
Oxidase test: This test is used to detect the presence of the enzyme cytochrome oxidase, which is involved in the metabolism of oxygen.
Catalase test: This test is used to detect the presence of the enzyme catalase, which helps to break down hydrogen peroxide.
Indole test: This test is used to detect the presence of the enzyme tryptophanase, which breaks down the amino acid tryptophan.
Nitrate reduction test: This test is used to detect the ability of a microorganism to reduce nitrate to nitrite.
Gelatinase test: This test is used to detect the ability of a microorganism to produce the enzyme gelatinase, which breaks down gelatin.
These are just a few examples of the many different biochemical tests that are used in bacteriology. Biochemical tests can be useful for identifying and classifying bacteria, and for understanding their metabolism and ecological role.
30 min read 
What is Bile Solubility Test? Definition of Bile Solubility Test The bile solubility test is a biochemical assay used to differentiate Streptococcus pneumoniae from other alpha-hemolytic Streptococci based on the lysis of bacterial cells in the presence of specific bile salts. Objectives of Bile Solubility Test In essence, the bile solubility test is a pivotal … Read more
6 min read 
Test Name Growth at 42 Test Purpose This test distinguishes pyocyanogenic pseudomonas from other Pseudomonas species.Determine an organism’s capacity to live at a temperature of 42°C.To distinguish fermentative bacteria from non-fermentative bacteria. Uses The test is used to determine an organism’s capacity to grow at 42°C.This test distinguishes pyocyanogenic pseudomonas from other Pseudomonas species. Result … Read more
26 min read 
What is Sulfur Reduction Test? Definition of Sulfur Reduction Test The Sulfur Reduction Test is a biochemical assay used to determine the ability of microorganisms to metabolize sulfur-containing compounds, resulting in the production of hydrogen sulfide (H2S) gas. This test aids in differentiating and identifying bacterial species based on their sulfur-reducing capabilities. Objective of Sulfur … Read more
6 min read 
The ability to develop in the presence of varying concentrations of sodium chloride (NaCl) has been used to distinguish between various bacteria.
3 min read 
Pyruvate Broth Test Purpose Pyruvate Broth Test Principle Requirement Pyruvate Broth Composition Pancreatic digest of casein (10 gm/L) sodium pyruvate (10 gm/L) yeast extract (5 gm/L) NaCl (5 gm/L) dipotassium Phosphate K2HPO4 (5 gm/L) bromothymol blue (0.04 gm/L) pH 7.3 +/- 0.2 at 25ºC. Pyruvate Broth Test Procedure Expected Results of Pyruvate Broth Test Quality … Read more
6 min read 
o-Nitrophenyl-b-D-Galactopyranoside (ONPG) Test Overview ONPG Test Purpose ONPG Test Principle Requirements for ONPG Test ONPG broth Composition Ingredients Gms / Litre Casitose (Equivalent to Casein Peptone) 7.500 O-Nitrophenyl-β-D-galactopyranoside 1.500 Disodium hydrogen phosphate 0.350 Sodium chloride 3.750 Final pH ( at 25°C) 7.5±0.2 ONPG Test Procedure ONPG broth method ONPG disk method Discs made of ONPG-impregnated … Read more
8 min read 
Purpose of OF Test Principle of OF Test Hugh and Leifson’s OF basal medium Composition of Hugh and Leifson’s OF basal medium Ingredients g/l Peptone (tryptone) 2.0 g Sodium chloride 5.0 g Glucose (or other carbohydrate) 10.0 g Bromthymol blue 0.03 g Agar 3.0 g Dipotassium phosphate 0.30 g Preparation Procedure of OF (Oxidation-Fermentation) Test … Read more
6 min read 
The novobiocin (antibiotic) differentiation disc can be used in the Novobiocin Susceptibility Test to help make a preliminary distinction between Staphylococcus saprophyticus and other coagulase-negative staphylococci (CoNS) in clinical (urinary) specimens.
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Purpose Principle of MUG Test Requirements Quality control of MUG Test Using the following quality control organisms, all lot numbers of MUG Disk have been tested and found to be good. Control organisms should be tested using quality control methods that have already been set up in the lab. If there are problems with quality … Read more
6 min read 
Some bacteria make substances that other bacteria need to grow. The X factor and the V factor are two such substances. The heat-stable X-factor can be protoporphyrin IX, hemin, or other iron-containing porphyrins. It can be found in red blood cells and outside of them in the blood. The heat-sensitive V-factor may be nicotinamide adenine dinucleotide (NAD) or nicotinamide adenine dinucleotide phosphate (NADP), and it is mostly found inside red blood cells. The X and V factor test or a disc test can be used to find out if a bacterium depends on its X factor or its V factor. The results can help identify the bacteria.