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 …
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 …
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 …
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 …
Citrate utilization test distinguishes different genera of enteric bacteria based on citrate utilization by an enzyme catalyst (Citrase) produced by the test organism. During citrate utilization, many by-products form. By the complete hydrolysis of citrate, an alkaline product forms, namely sodium carbonate that cause alkalinity in the medium and change the colour of media from …
Indole test is a biochemical test that helps in the identification and classification of bacteria based on their tendency to decompose amino acid (Tryptophan) into a compound refers as “Indole”. It is a part of a biochemical method popularly known as IMViC test, where ‘I’ stands for indole test. Indole is one of the end …
Bacterial conjugation is a gene transfer mechanism, first introduced by the scientists named Lederberg and Tatum in the year 1946. The conjugation method was first studied in Escherichia coli. The formation of a conjugation tube is the characteristic feature in a conjugation mechanism. Instead of transduction and transformation, some bacteria passes the genetic information from …
Centrifugation method is a process of separating different components or the suspended particles from the homogenous solution, by the practice of centrifugal force. It separates particles based on their physical properties like size, shape, density etc. and chemical properties like molecular weight and viscosity. A natural gravitational force can also concentrate particles but in an …
SOS repair is one of the DNA repair mechanisms, which commonly refers to as “bypass” or “Emergency” repair. This system was first introduced in the year 1975, by a scientist named Miroslav Radman. It is a regulatory system which comprises of many complex inducer proteins that helps to repair the damaged DNA, caused due to …
Oxidation pond is a type of wastewater treatment which also refers as lagoons or water stabilization pond. It is a secondary treatment of wastewater coming from industries, residential areas etc. It makes the use of microorganisms like bacteria, algae and light energy (sunlight) to stabilize the wastewater. Oxidation pond is constructed 1-1.5m deep inside the …