Online Microbiology and Biology Study Notes
Introduction NYC Agar Base medium was originally developed by Fauer, Weisburd and Wilson at the New York City Department of Health for selective isolation of pathogenic Neisseria species from clinical specimens. NYC medium, primarily designed for isolation of pathogenic Neisseria, also readily supports the growth of large-colony mycoplasmas and T-mycoplasmas (Ureaplasma). It is a transparent medium, highly-selective which permits direct, microscopic …
Introduction Thayer-Martin Agar was developed in 1964 for the isolation of N. gonorrhoeae and N. meningitidis. A further modification of these early formulations was developed to improve the isolation of pathogenic Neisseria sp. from specimens, which contained large amounts of mixed microbial flora. Martin-Lewis Agar is the formulation made after modification which contains an increased level of vancomycin for greater …
Thayer and Martin reported an improvement of the Chocolate Agar formulation that contained antimicrobics vancomycin, colistin and nystatin have been added to minimize overgrowth by contaminants, suppress the growth of saprophytic Neisseria sp., and enhance the growth of pathogenic Neisseria. Martin and Lester later added antibiotic trimethoprim to make the medium further selective and shown to be of value in …
Yeasts are unicellular eukaryotes and extensively studied model organism in molecular genetics. They are chemoorganotrophs as they utilize organic compounds as a source of energy. Yeast extract peptone dextrose (YPD or YEPD) Growth Agar is used for the maintenance and propagation of yeasts including S. cerevisiae in various molecular microbiology procedures. YPD functions as a complete medium for yeast growth. …
Fastidious organisms having exacting nutritional requirement can be cultivated on infusion media. Meat infusions were included in the first media used for the cultivation of bacteria. Huntoon prepared a medium using fresh beef heart and peptone which became known as Heart Infusion Agar. He demonstrated it could be used to support the growth of nutritionally fastidious microorganisms without the addition …
Egg Yolk Agar, modified is based on the original formula for Egg Yolk Agar developed by McClung and Toabe for the isolation and differentiation of organisms based on Lecithinase and lipase production and proteolytic activity. Image Source: Noura El-Ahmady El-Naggar, DOI: 10.5897/AJMR11.346 Composition of Egg Yolk Agar Ingredients Gms/litre Casein enzymic hydrolysate 15.000 Papaic digest of soyabean meal 5.000 Yeast extract …
The first chromogenic culture medium for detection of E. coli was invented and patented by Dr. A. Rambach in 1979. This technology is color-based differentiation method. It is based on soluble colorless molecules (called chromogens), composed of a substrate (targeting a specific enzymatic activity) and a chromophore. When the target organism’s enzyme cleaves the colorless chromogenic conjugate, the chromophore is …
Endo Agar was developed by Endo to differentiate gram-negative bacteria on the basis of lactose fermentation while inhibiting gram-positive bacteria. Inhibition of the later was achieved without the use of bile salts as was traditionally used. Endo was successful in inhibiting gram-positive bacteria on his medium by the incorporation of sodium sulfite and basic fuchsin. The resulting Endo Agar, also …
Hektoen Enteric Agar is a selective and differential medium designed to isolate and differentiate members of the species Salmonella and Shigella from other Enterobacteriaceae. The medium was introduced in 1968 by Sylvia King and William I. Metzger. They formulated HE Agar medium while working at the Hektoen Institute in Chicago, to increase the recovery Salmonella and Shigella from clinical specimens. Composition of Hektoen Enteric …
Eosin Methylene Blue (EMB) agar is a differential microbiological medium, which slightly inhibits the growth of Gram-positive bacteria and provides a color indicator distinguishing between organisms that ferment lactose (e.g., E. coli) and those that do not (e.g., Salmonella, Shigella). EMB agar was originally devised by Holt-Harris and Teague and further modified by Levine. It is thus a combination of the Levine and Holt-Harris and Teague formulae …