Microbiology

Exocytosis

Exocytosis is a means of membrane transportation that expels the intracellular material out of the cell. The transport of the substance is mediated by the vesicles that eliminate the cell debris and release specific proteins, enzymes, hormones etc., outside the cell. It is a type of active transport mechanism that makes the use of ATP. …

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Difference Between Cell Wall and Cell Membrane

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

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Motility Test

A motility test refers to the biochemical or microscopic examination of an organism that checks the existence of cellular motility. By performing this test, we could differentiate the two major groups of bacteria, namely motile and non-motile, based on their cellular movement. Few organisms are motile, and some are non-motile. Still, all living organisms tend …

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Vermicomposting

Vermicomposting is a composting technique, which turns the organic debris into a humus-like product by employing earthworms. “Vermicompost” is the compost produced by the vermicomposting unit. The vermicompost merely refers to the earthworm’s excrement, which provides essential nutrients, aeration, porosity, structure, fertility and water-holding capacity to the soil and plant body. The vermicomposting method requires …

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Bile Solubility Test

The 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 by reacting with the bile solubility reagent, whereas the other α-haemolytic Streptococci do not undergo such reaction. The reason for the dissolution of the Streptococcus pneumoniae is due to the …

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Urease Test

Urease test is an analytical method 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 to identify …

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Coagulase Test

The coagulase test is an analytical method that demarcates the staphylococci species into coagulase-positive and coagulase-negative species. Coagulase is an enzyme, which can either bound to the cell surface of bacteria as “Bound coagulase” or reside within the extracellular space as “Free coagulase”. Staphylococcus aureus, S. intermedius, S. hyicus are coagulase-positive organisms. Staphylococcus epidermis, S. saprophyticus, …

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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). It uses TMPD (tetramethyl phenylenediamine dihydrochloride) reagent. In an oxidized state, TMPD develops a blue-purple coloured complex while remains colourless in a reduced state. Therefore, we can say that the …

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Catalase Test

Catalase test is one of the biochemical analysis that generally comes into use in identifying the organisms (whether they are catalase producers or not). It is primarily used to distinguish between the two classes of 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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