Lipid Hydrolysis Test

Lipid hydrolysis test one of the such tests which helps us to detect the ability of the bacterium to hydrolyze the lipids that are present in the medium. Lipids are the compounds which are high in the molecular weight compounds that posses the large amount of energy. When these molecules get accumulated into the cell, they start metabolizing through the process of aerobic respiration and thus produces cellular energy known as ATP (Adenosine Triphosphate). These components enters into the other metabolic pathways for synthesing the other protoplasmic cellular components.

However, before the bacteria starts the process of assimilation and gets degraded. The degradation of the lipids which are known as triglycerides is usually accomplished but the extracellular hydrolyzing enzymes that are commonly known as lipases or esterase’s, which plays an important role in cleaving the ester bonds in the molecule by adding the water and thus results in the formation of the building blocks generally called as glycerol and also in fatty acids.

Lipid Hydrolysis Test Objective

 The main aim of the Lipid Hydrolysis Test is to determine the ability of the organism that whether it has a capability to hydrolyze a lipid.

 To identify the species of the bacteria that are capable producing an exoenzyme lipase.

Lipid Hydrolysis Test Principle

Lipids are generally known as non-polar molecules which to do not dissolve in water. Fats are one type of the lipids which contains a large polymer of fatty acids and glycerol in it which makes the cell to large to absorb those compounds into its membranes. In order to utilize the facts, bacterial cells play an important role in secreting the enzymes known as exoenzymes which are most commonly known as lipases that are present outside the cell and helps in hydrolyzing the lipids that are present into fatty acids and glycerol.

These lipids then result in a formation of an emulsion when they are dispensed with agar and thus produces an opacity when it is further hydrolyzed with the end products such as fatty acids and glycerol which neither forms an emulsion with the agar instead of forming a transparency. In lipid hydrolysis test, the test bacteria that are grown on the agar plate that contains tributyrin as the lipid substrate, which plays a role in forming an opaque suspension in an agar medium.

Incase, if the bacteria have its ability to hydrolyze lipids, the bacterial colonies hydrolysis the tributyrin that is present in the medium in the areas that is surrounded but the, into the soluble glycerol and the butyric acid, where as the rest of the areas on the plate contains the unhydrolyzed tributyrin. Thus, hydrolysis results in demonstration of a transparent clear zone around the colonist and the remaining areas of the plate remain opaque which results as an indicative of the unhydrolyzed tributyrin region.

Lipid Hydrolysis Test Media

Tributyrin agar is very important for performing this test, this medium is prepared using about 5 grams of peptic digest of animal tissue and a yeast extract of about 3 gram and the agar 15.0 gram.

Lipid Hydrolysis Test Procedure

 Initially the tributyrin agar medium is inoculated in the medium of the agar using a single line of streaking of organism.

 Then the inoculated medium is incubated aerobically in a gas pack jar immediately after streaking.

 Then the medium is incubated at a temperature of about 35 to 37ºC for about 24 to 48 hours.

 After incubation, if the result is positive then the formation of clear zone around the growth of the colony can be noted.

Lipid Hydrolysis Test Results

Positive Lipid Hydrolysis Test Results: If the results are positive then the clear zone can be seen around the bacterial growth.

Negative Lipid Hydrolysis Test Results: If the results are negative then there will be no formation of clear zone around the growth of the bacteria.

Lipid Hydrolysis Test Uses

 This test is helpful in identifying the species of the bacteria which secretes the enzyme lipase. The species mostly include Enterobacteriaceae, fusobacterium, Propionibacterium, Clostridium, Pseudomonas, Corynebacterium, Staphylococcus.

 This test also helps us to detect and enumerate the species of the lipolytic organisms which is usually present in the food and other materials.

Lipid Hydrolysis Test Limitations

It is usually suggested that the biochemical, molecular, immunological, or mass spectrometry tests are performed only in colonies that are taken from the pure culture for complete identification of the species.