Culture media are substances used to grow and maintain microorganisms in the laboratory. They typically consist of a mixture of nutrients and other substances that support the growth and metabolism of microorganisms. Culture media can be liquid, semisolid, or solid, and they can be tailored to the specific requirements of different types of microorganisms.
Culture media are an important tool in microbiology, as they allow scientists to isolate, identify, and study microorganisms in the laboratory. They are used in a wide range of applications, including the identification of pathogens, the production of biotechnology products, and the study of the biology and behavior of microorganisms.
There are many different types of culture media, including:
Culture media are an essential tool in microbiology and are used in a wide range of research and applied settings. They allow scientists to study the biology, behavior, and ecology of microorganisms and to identify and characterize new species. They also play a crucial role in the production of biotechnology products and in the diagnosis and treatment of diseases caused by microorganisms.
Ashdown’s medium can be described as a selective culture medium that allows for the identification and characterisation of Burkholderia pseudomallei (the bacteria which causes the disease melioidosis). The Ashdown’s Medium was initially identified by LR Ashdown in 1979.
Coliforms are all facultative and aerobic rod-shaped, gram-negative, non-spore-forming bacteria that produce lactose by fermentation with gas and acid production within 48 hours, at temperatures of 35 degrees Celsius. Methods to identify, enumerate and presumedly identify coliforms are utilized in the testing of dairy and food products. One method of performing the presumptive test to identify coliforms employs the Violet Red Bile Agar (VRBA). The Violet Red Bile Aggar (VRBA) is an selec-tive medium that can be used to detect and quantify lactose-fermenting coliform microorganisms.
Baird Parker Agar was created by Baird Parker using the Tellurite–glycine formulation of Zebovitz et al. It allows for a good differentiation between coagulase positive strains.
Tryptic Soy Agar can be used to grow microorganisms. These media are non-selective and general-purpose. They provide enough nutrients to support a variety of microorganisms. This medium can also be used to grow, store, maintain, and transport pure microorganism cultures.
Thioglycolate broth, an enrichment broth that is multipurpose and can be used to determine the oxygen needs of microorganisms, is called a differential medium. It is used most often in diagnostic bacteriology as an enrichment broth. This broth is supportive of the growth and development of microorganisms fastidious, anaerophilic, microaerophilic and aerobes.
Amies Transport Medium, which contains charcoal to increase the viability and longevity of pathogenic organisms, is an improved transport medium. It is semisolid media that can be used in qualitative procedures to transport clinical swab specimens from the hospital to the laboratory. This modified Stuart’s Transport Medium is made by adding charcoal to the medium and replacing the glycerophosphate. This modified medium produced a higher percentage positive results than Stuart’s transport medium.
In 1984, Bolton et al. Bolton et al. (1984) suggested that charcoal could be used to replace blood in a medium for the isolation of Campylobacter species. Endtz et al. Later, it was confirmed that Campylobacter isolates at a higher rate when using charcoal selective media.
Selenite Broth was invented by Leifson who proved that selenite is inhibitory to bacteria, coliforms, and other species, like streptococci from feces, which are found in fecal samples and, consequently, beneficial in the recuperation from Salmonella species. Selenite-F Broth is utilized to enrich the environment that is buffered by Lactose Peptone Broth to which Sodium Biselenite is added to act as the agent that is selective for elimination of Salmonella from urine, feces and water, as well as food items and other substances that are of sanitary significance.
The majority of bacteria are able to ferment carbohydrates, especially sugars. Within them, every bacteria is able to ferment just a few of the sugars, whereas it is unable to ferment all the other sugars. So, the sugars that a bacterium is able to ferment, as well as the sugars that it can’t, is the signature of the bacterium and is an important factor in its determination. It is the Triple Sugar Iron (TSI) Agar is a type of culture medium known for its capacity to determine a microorganism’s capacity to produce sugars and generate hydrogen sulfur.
Lysine iron Agar (LIA), a differential medium, is used to test organisms’ ability to deaminate or decarboxylate Lysine. Lysine deamination, an aerobic process, occurs in the media. Lysine decarboxylation, an anaerobic process occurring in the media’s butt, is also known as Lysine decarboxylation. Edwards and Fife created LIA in 1961 in order to presumptively determine Salmonella species. This includes Salmonella arizonae that is lactose fermenting, which has been linked to foodborne gastroenteritis outbreaks.
For the cultivation of Haemophilus, Levinthal’s Medium can be used. Although there are many species in the genus Haemophilus that can cause infections, they all share a common morphology. They also require blood-derived factors for growth. This is what gave the genus its name. The Haemophilus Genus is a large grouping of gram-negative rods, which can grow on agar-containing human blood. Two factors are required for Haemophilus species to grow: factor-X, and factor-V.
Eosin Methylene Blue (EMB), a microbiological media, is a differentiating medium that slightly inhibits the growth and color of Gram-positive bacteria. It also provides a color indicator to distinguish between organisms that ferment lactose (e.g. E.coli) and those who do not (e.g. Salmonella, Shigella). Holt-Harris, Teague, and Levine first created EMB agar.
Yeasts, unicellular eukaryotes, are a well-studied model organism in molecular genomics. They are chemoorganotrophs because they use organic compounds for energy. Yeast extract peptone, or YEPD), Growth Agar is used to maintain and propagate yeasts. YPD is a complete medium that allows for yeast growth.
In 1978, Feeley et al developed a medium for isolating Legionella species. They later modified it by replacing casein hydrolysate with beef extract and starch with activated carbon and naming it Charcoal Yeast extract (CYE) Agar. A further modification was made by Pasculle et al in 1980 by the addition of ACES (N-2-acetamido-2-aminoethane sulfonic acid) buffer in order to maintain the proper pH for optimal growth designated as BCYE for Buffered Charcoal Yeast Extract. Edelstein et al modified the medium in 1981 by adding potassium salt to alpha-ketoglutaric acids, which increased the medium’s sensitivity. It is used in primary isolation and cultivation of Legionella species. It is recommended to be used in the cultivation and primary isolation of Legionella spp.
Egg Yolk Agar modified is based upon the original Egg Yolk Agar formula developed by McClung & Toabe to isolate and differentiate organisms based in Lecithinase, lipase production, and proteolytic activities.
Salmonellae are the most complex taxonomically diverse group of bacteria in Enterobacteriaceae. Salmonella infections in humans are usually caused by the consumption of food, milk, and water contaminated with animal or human excreta. S. Typhi is only found in humans.
Endo created Endo Agar to distinguish gram-negative bacteria based on lactose fermentation and inhibit gram-positive bacteria. The latter were not inhibited by bile salts, as was traditional. Endo was able to inhibit gram-positive bacteria using sodium sulfite, basic fuchsin.
Over the years, many media have been developed for mycobacteria cultivation. Early ones included egg-based formulations such as Lowenstein-Jensen Medium or Petragnani Medium. Later, Dubos, Middlebrook and Middlebrook created a variety of formulations that contained oleic and albumin as key components. These ingredients protect Mycobacterium against toxic agents and allow for the growth and development of tubercle bacteriailli. Cohn and Middlebrook improved the formulations of oleic acids-albumin agar to achieve a faster and more luxurious growth of Mycobacterium strains.
Cetrimide, a quaternary salt of ammonium, acts as a detergent that lowers the surface tension at the point-of-contact. It also has precipitant, complexing, and denaturing effects upon bacterial membrane proteins. It has inhibitory properties on many microorganisms, including Pseudomonas species that are not Pseudomonas. Lowburry was the first to develop cetrimide agar. It is a modified version of Tech Agar (developed in King et al. For the selective inhibition other than Pseudomonas, aeruginosa, 0.1% cetrimide (cetyltrimethyl ammonium bromide), was added. Cetrimide agar can be used to presumptive identify and selectively isolate Pseudomonas.aeruginosa species from both clinical and nonclinical specimens.
As a primary plating medium, Brilliant Green Agar medium should be used to isolate Salmonella species. Kristensen and colleagues first described it as a selective isolation medium to Salmonella species. Kristensen et al. first described it as a selective isolation medium for Salmonella species. Kauffmann modified the formula to make it a highly selective plating media for the isolation and identification from salmonellae in feces, other pathological material, food and dairy products. Brilliant Green Agar should always be used in conjunction with other selective plating media like Deoxycholate Citrate Agar and Hektoen Enteric Agar. Salmonella Typhi is treated with Bismuth Sulphite.
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