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[EBOOK] Handbook of MICROBIOLOGICAL MEDIA, Ronald M. Atlas, Published by CRC PRESS

The fourth edifice. of the Handbook of Microbiological Media includes the formulations and descriptions of 7,080 media used for cultivating microorganisms—more than 1500 more than in the previous edition. These mcludc both classic and modem media used for the identification, cultivation, and maintenance of divorce bacteria, archara, and fungi. Same o: these microbiological media are produced by major suppliers of dehydrated media—including Oxoid. HiMedia, and BD Diagnostics (Dlfco. BBL. and G1BCO) These include all the media normally used m the clinical microbiology diagnostic laboratory and fertile routine examination of food and water, other media described in the fourth edition of the Handbook ofMicrơbtoiơgiccù Media are used to cultivate specific strains of bacteria, archaea. fungi, and protists, includ :ng many anaerobes and extremophiles The fourth edition of the Hand book of Microbiological Media includes tlie media needed to cultivate the numerous microorganisms cumttdy available from the world’s global bioresource centers CBRCs)

The bread of culhire media in this comprehensive resource IS enemvous and has greatly expanded n recent years with Uie explcraUcn of extreme hub itats and die use of molecular methods to identify new Inrages of bacteria and arcliara The media also represent significant advances in the ability to use chromogemc substrates to identity specific species and strains of bacteria, eg,/?, caii 0157 and melhtalltn resistant Srapin'lo-COCCU5 aureus (MRSA) These media are extremely useful for clinical diagnostics and fer the protection of the food supply from pathogenic microorganisms Additional by many culture media are now available that are tree of animal components Plant based media eliminate possible contamination with prions which is ime ortant for production of vaccines and pharmaceuticals

Organization

The media described in the Handbook of Microbiological Media are organized alphabetically Synonyms for media arc listed The description of each medium includes its name(s), composition, instructions for preparation, commercial sources, safety cautions where needed, and uses

Names of Media

Media often have numerous names For the most part the fourth edition cf the Handbook of Microbiological Media retains the original names assigned m the literature In seme cases media with identical compost lions produced by different companies have different names For example, Tryptirasc™ Soy Agar produced as a 3BL product of BD Diagnostic Systems, Tryptcnc Soy Agar produced by Oxoid Unipath, and Tryptic Soy Agar prcduced as a Dlfco product ct'BD Diagnostic Systems have identical compositions Many media also are known by acronyms 7SA. fer example. IS the common acronym for Trypticase™ Soy Agar The fourth edition of die Handbook of Microbioiogicd Media gives the various synonymous names acid directs the reader to see die entry where die information about dial medium IS given In rases -where modifications to a medium yield a new medium, such media generally are listed with the original medium name, followed by the tenr. modified—for example TSA. Modified, rather than Modified TSA Media tliat do net. have formal names are listed according to the organism grown «1 that, medium—for example. Bacúhts stearothemcphứus Brcth

Composition of Media

Media for the cultivation of microorganisms contain the substances necessary to support the growth of microorganisms Due to the diversity of microorganisms and their diverse metabolic pathways, there are numerous media. Even slight differences in the composition of a medium can result in dramatically different growth characteristics of microorganisms

When methods for culturing microorganisms were first developed m the nineteenth century, largely by Robert Kcch and his colleagues, animal and plant tissues were principally used as sources of nutrients used to support microbial growth One of the major discoveries of Fanny Hesse IR Koch’s laboratory was that agar could be used to form solidified culture media cn which microorganisms would grow Extracts of plants and animal tissues were prepared as broths or mixed with agar to form a variety of culture media Virtually any plant, animal, or animal organ was considered for use in preparing media Infusions were prepared from bee: heart, calf brains, and bee: liver, as a few examples These classic infusions still form the primary components of many media that are widely used today, such as Brain Heart Infusion Agar and Liver Broth In the last few years attempts have been made to reformulate many media containing annual tissue extracts with plan’, materials. This has added greatly to die number of media that arc commercially available.

The composition section of each medium describes the ingredients that make up the medium, their amounts, and the pH It lists those ingredients in order of decreasing amount Solids are listed first shewing the weights to be added, followed by liquids shewing the volumes to be included in the medium

The composition uses generic terms where these arc applicable. For example, pancreatic digest of casein IS marketed by various manufacturers as tryptirase, tryptone, and other commercial product names While there may well be differences between these products, such differences are undefined Variations also occur between batches of products produced as digests of animal tissues

Media for the cultivation of microorganisms have a source of carbon for incorporation into biomass For autotrophs, the carbon source most often is carbon dioxide, which may be supplied as bicarbonate within the medium Carbohydrates, such as glucose, or other organic compounds, such as acetate, various lipids, proteins, hydrocarbons, ar.d other organic compounds, are included in media as sources of carbon for heterotrophs These carbco sources may also serve as the supply of energy other compounds, such as ammemum ions, nitrite ions, ele mental sulfur, and reduced iron, may be used as the sources of energy for the cultivation of autotrophs. Nitrogen aLso is required for microbial growth. It may be supplied as inorganic nitrogen comp ounds for the cultivation of seme microorganisms but mere commonly is supplied as proteins, peptenes, cr amino acids Phosphates and metals, such as magnesium and iron, are also necessary components of microbiological media Phosphates may also serve as buffers to maintain the pH of the medium within the growth tolerance limits of the microorganism being cultivated Various additional growth factors may also be included in the media

Agars

Agar IS the most common solidifying agent used in microbiological media Agar IS a polysaccharide extract from marine algae It melts at 84®c and solidifies at 3S°C Agar concentrations of 15 Og/L typically are used to form solid media Lower concentrations of 7 5-10 Og/L are used to produce soil agars cr seuusolid media Below are some agars used as solidifyuig agents in various media Agar Bacteriological (Agar No. 1)

An agar with low calcium and magnesium Agar. Bacto

A punfied agar with reduced pigmented compounds, salts, and extraneous matter.

[EBOOK] Handbook of MICROBIOLOGICAL MEDIA, Ronald M. Atlas, Published by CRC PRESS


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