Microbiology

Difference Between Cell Wall and Cell Membrane

Difference between the cell wall and the cell membrane is primarily due to the differences in three factors like composition, function and permeability. Composition: The composition of cell wall mainly comprises of proteins and carbohydrates, whereas a cell or plasma membrane comprises of lipids, proteins and some amount of carbohydrate. Function: The functional role of …

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Motility Test

Motility test can consider as the biochemical or microscopic examination of an organism to check the existence of cellular-motility. By performing this test, one can differentiate between the two major groups of bacteria, namely motile and non-motile, based on their cellular movement. Few organisms are motile, whereas few are non-motile, but all the living organisms …

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Vermicomposting

Vermicomposting is one of the types of composting technique, which turns the organic debris into a humus-like product, by the use of earthworms. The compost produced by this method refers as “Vermicompost”.  The vermicompost can merely define as earthworm’s excrement, which provides essential nutrients, aeration, porosity, structure, fertility and water-holding capacity to the soil and …

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Bile Solubility Test

Bile solubility test is a biochemical test that distinguishes bile soluble and bile resistant α-haemolytic streptococci. Streptococcus pneumoniae is the only strain that emulsifies on reaction with bile solubility reagent, while the other α-haemolytic streptococci do not undergo such reaction. The reason for the dissolution of the Streptococcus pneumoniae is due to the presence of …

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Urease Test

Urease test is an analytical method which is practised to identify the urease positive and negative organisms based on the production of cytosolic urease enzyme. It distinguishes the Proteus species from the non-lactose fermenting members belonging to the Enterobacteriaceae family. Urease test makes the use of urea base. Conventionally, Stuart formulated urea broth was used …

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Coagulase Test

Coagulase test is an analytical method that demarcates the staphylococci species into coagulase-positive and coagulase-negative species. Staphylococcus aureus, S. intermedius, S. hyicus, are the coagulase-positive organisms, whereas Staphylococcus epidermis, S. saprophyticus, S. haemolyticus, S. lugdonensis etc. are coagulase-negative organisms. Coagulase is an enzyme that can either bound to the cell surface of bacteria as “Bound …

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Oxidase Test

Oxidase test checks the production of cytochrome-c oxidases, whose presence in the test organism becomes evident by the formation of the blue-purple coloured complex (indophenols) by the oxidation of TMPD (tetramethyl phenylenediamine dihydrochloride) reagent. In the reduced form, the TMPD oxidase reagent remains colourless. Therefore, we can say that the oxidase reagent functions as both …

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Catalase Test

Catalase test in one of the biochemical analysis that generally comes into use for the identification of the organisms, whether they are catalase producers or not. It is primarily used to distinguish between the two gram-positive bacteria, namely Staphylococcus and Streptococcus species. Streptococcus bacteria are mostly facultative anaerobes (may produce catalase), while few are obligate …

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Voges Proskauer Test

Voges Proskauer test depends upon the formation of a neutral end product “Acetoin” in the MRVP media, which directly relies on the breakdown of glucose into an intermediate product “Pyruvic acid”. The pyruvic acid undergoes butylene glycol pathway and produces an end product named acetyl methyl carbinol or acetoin. It is named after the contribution …

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Methyl Red Test

Methyl red test differentiates whether the organism can undergo mixed acid fermentation or not, by the supply of glucose. Organisms that can ferment glucose will give positive MR test by producing a large amount of acid, and some organisms give negative MR test. It also helps to identify and classify between the different genera of …

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