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 Bacillus cereus

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Biochemical Test of Bacillus cereus

ยญBasic 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

Biochemical Test ofย Citrobacter freundii

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Biochemical test ofย Citrobacter freundii

Biochemical test of Citrobacter freundii ยญBasic 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

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PYR Test

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