Biochemical Test

Biochemical tests are the tests that are performed on different bacteria for their identification on the basis of their biochemical activities towards different biochemical compounds.

Biochemical tests are one of the traditional methods for the identification of microorganisms, usually performed with phenotypic identification.
For many years these methods were employed extensively, and they continue to be used nowadays, especially in some laboratory routines where a particular type of microorganism has to be identified rapidly.
The ability of microorganisms to utilize certain biomolecules, resulting in useful organic compounds for themselves forms the basis of various biochemical tests.
Biochemical tests are of different types, where the identification or distinction between different microorganisms is made on various bases.
One of the traditional methods commonly used is a simple visual detection of the growth of the organism in the presence of essential nutrients by increased turbidity in the liquid medium.
In other tests, however, the results are based on the change in color of the medium as a result of the change in the pH of the medium.
Microorganisms can be classified into different groups on the basis of their reaction to such tests. Some tests even allow the distinction of microorganisms to the species level.
Biochemical tests are thus, essential as they are inexpensive and relatively simple to perform.
The physiology of bacteria and other microorganisms differs from one another, which allows for the differentiation of such microorganisms.
Biochemical tests, however, have some disadvantages. Despite being inexpensive and allowing both quantitative and qualitative information about the diversity of microorganisms present in a sample, these methods are laborious and time-consuming, and results are only observed after several days.
In some cases, false positives are obtained, especially when considering similar microbial species.

Biochemical Test of Streptococcus mutans

August 8, 2025July 30, 2025 by Sagar Aryal, PhD

Biochemical Test of Streptococcus mutans Basic Characteristics Properties (Streptococcus mutans) Capsule Capsulated Catalase Negative (-ve) Gram Staining Positive (+ve) Hemolysis Alfa Hemolysis Motility Non-motile OF (Oxidative-Fermentative) Facultative anaerobes Oxidase Negative … Read more

Biochemical Test of Streptococcus agalactiae

August 8, 2025July 25, 2025 by Sagar Aryal, PhD

Biochemical Test of Streptococcus agalactiae Basic Characteristics Properties (Streptococcus agalactiae) CAMP Positive (+ve) Capsule Positive (+ve) Catalase Negative (-ve) Coagulase Negative (-ve) Flagella Non-flagellated Gram Staining Positive (+ve) Hemolysis Beta … Read more

Biochemical Test of Yersinia pestis

August 8, 2025July 20, 2025 by Sagar Aryal, PhD

Biochemical Test of Yersinia pestis Basic Characteristics Properties (Yersinia pestis) Capsule Positive (+ve) Catalase Positive (+ve) Citrate Negative (-ve) Flagella Non-Flagellated Gas Negative (-ve) Gelatin Hydrolysis Negative (-ve) Gram Staining … Read more

Biochemical Test of Enterobacter cloacae

August 8, 2025July 17, 2025 by Sagar Aryal, PhD

Biochemical Test of Enterobacter cloacae Basic Characteristics Properties (Enterobacter cloacae) Capsule Negative (-ve) Catalase Positive (+ve) Citrate Positive (+ve) Flagella Positive (+ve) Gas from glucose Positive (+ve) Gelatin Hydrolysis Negative … Read more

Biochemical Test of Bacillus anthracis

August 8, 2025July 15, 2025 by Sagar Aryal, PhD

Biochemical Test of Bacillus anthracis Basic Characteristics Properties (Bacillus anthracis) Capsule Capsulated Catalase Positive (+ve) Gas Negative (-ve) Gelatin Hydrolysis Positive (+ve) Gram Staining Positive (+ve) Hemolysis Negative (-ve) Indole … Read more

Biochemical Test of Bacillus cereus

May 19, 2025April 17, 2025 by Sagar Aryal, PhD

Basic Characteristics Properties (Bacillus cereus) Catalase Positive (+ve) Citrate Positive (+ve) Gelatin Hydrolysis Negative (-ve) Gram Staining Positive (+ve) Growth in KCN Positive (+ve) Hemolysis Positive (+ve) Indole Negative (-ve) … Read more

Voges-Proskauer (VP) Test: Principle, Procedure & Results

April 9, 2025April 8, 2025 by Prashant Dahal

Although most bacteria are able to ferment (metabolize) glucose, the end product of glucose metabolism by different bacteria might not always be the same. Following glycolysis, some follow the mixed … Read more

Biochemical Test of Citrobacter freundii

April 9, 2025January 12, 2025 by Sagar Aryal, PhD

Biochemical test of Citrobacter freundii Basic Characteristics Properties (Citrobacter freundii) Capsule Negative (-ve) Catalase Positive (+ve) Citrate Positive (+ve) Flagella Positive (+ve) Gas from glucose Positive (+ve) Gelatin Hydrolysis Negative (-ve) … Read more

PYR Test: Principle, Media, Steps, Results, Uses

December 19, 2024October 10, 2024 by Prashant Dahal

PYR test (L-Pyrrolidonyl-β-naphthylamide test) is a biochemical test used to detect the ability of bacteria to produce pyrrolidonyl aminopeptidase enzyme using L-Pyrrolidonyl-β-naphthylamide (PYR) as substrate. It was first reported in … Read more

Salt Tolerance Test: Principle, Procedure, Results, Uses

December 19, 2024September 4, 2024 by Prashant Dahal

Salt Tolerance Test is the biochemical test used to determine the ability of bacteria to tolerate a high salt concentration (of 6.5%). Different genera of bacteria have different requirements for … Read more