Selective media is often used when one is trying to isolate a specimen of interest from a mixed culture. Examples of selective exposure, attention, and perception (hint: page 292)-⢠Selective Exposure- very close minded, tendency to favor information which reinforces their pre-existing views while avoiding contradictory information.⢠Selective Attention- We hear what we want to hear, the capacity for or process of reacting to certain stimuli selectively. Samples can then be taken from the resulting colonies and a microbiological culture can be grown on a new plate so that the organism can be identified, studied, or tested.The streaking is done using a sterile tool, such as a cotton swab or commonly an inoculation loop. Differential media, unlike selective media, does not kill organisms. Very few laboratories are biosafety level 4. People will watch what they are interested in. Differential media takes advantage of biochemical properties of target organisms, often leading to a visible change when growth of target organisms are present. An undefined medium has some complex ingredients, such as yeast extract, which consists of a mixture of many, many chemical species in unknown proportions. As typified by some of the above examples, some microbes have to be grown in the lab, and some of them can infect humans. Candle jar: A candle is lit in a jar with a culture plate. Treponema pallidum belongs to the Spirochaetesphylum of bacteria. A microaerophile is a microorganism that requires oxygen to survive, but requires environments containing lower levels of oxygen than are present in the atmosphere (~20% concentration). For example, NaCl media selects for halophiles (salt lovers) versus non-halophiles. Streptococcuseosin methylene blue (EMB), which is differential for lactose and sucrose fermentation. Poor/No Growth - Organism inhibited by Bile salts and Crystal Violet - Gram Positive, EMB Agar is a selective AND differential media used to identify the presence of coliforms (Gram negative lactose fermentors), 1. A differential media will show what each species is, for example Gram + or Gram - PPLO Medium (Contains Sterol) Specialized media for Mycoplasma pneumoniae The selectivity of the medium can be achieved by employing several methods and by adding certain inhibitors to the medium. Let us say that the specimen of interest is one cell in a million. Selective media – Used for the growth of only selected microorganisms. Selective and Differential Media. Examples are: Blood agar is an enriched medium ⦠Microbial pathogen growing on blood-agar plate: Red blood cells are used to make an agar plate. For example, armadillos are often used in the study of leprosy. Animals can often be used to culture microbes. Blood agar (used in strep tests), which contains bovine heart blood that becomes transparent in the presence of hemolytic. Examples include sheep blood agar and chocolate (heated blood) agar. Normally, the presence of a specific gene or an allele of a gene confers upon the cell the ability to grow in the selective medium. Eosin methylene blue (EMB) that contains methylene blue – toxic to Gram-positive bacteria, allowing only the growth of Gram negative bacteria. Selective media allow certain types of organisms to grow, and inhibit the growth of other organisms. Undefined Media: Luria Broth as shown here is made with yeast extract, as yeast extract is not completely chemically defined Luria Broth is therefore an undefined media. Xylose lysine desoxyscholate (XLD), which is selective for Gram-negative bacteria buffered charcoal yeast extract agar, which is selective for certain gram-negative bacteria, especially Legionella pneumophila. Many human microbial pathogens also require the use of human cells or cell lysates to grow on a media. As human pathogens are often studied by microbiologists, special safety conditions know as biosafety levels are used to keep researches free of infection from the pathogens they study. Differential media – Also known as indicator media, are used to distinguish one microorganism type from another growing on the same media. Selective medium is agar based (solid) medium so that individual colonies may be isolated. The use of animals to culture animals is sometimes necessary as no simple media can be used, this presents technical and ethical issues. Selective media are used for the growth of only selected microorganisms. Streptococci grow in blood agar media. In microbiology, streaking is a technique used to isolate a pure strain from a single species of microorganism, often bacteria. When working with cultures of living organisms, it is extremely important to maintain the environments in which cells are cultured and manipulated as free of other organisms as possible. Selective media allows for the growth of specific organisms, while differential media is used to distinguish one organism from another. Biosafety Level 4: This level is reserved for work with dangerous and exotic agents that pose a high individual risk of aerosol-transmitted laboratory infections, agents that cause severe to fatal disease in humans for which vaccines or other treatments are not available, such as Bolivian and Argentine hemorrhagic fevers, Marburg virus, and the Ebola virus. Biosafety Level 1: This level is suitable for work involving well-characterized agents not known to consistently cause disease in healthy adult humans, with minimal potential hazard to laboratory personnel and the environment. Undefined media has some part of which is not entirely defined. A chemically defined medium is a growth medium suitable for the culture of microbes or animal cells (including human) of which all of the chemical components are known. Selective media contain ingredients that inhibit the growth of some organisms but allow others to grow. Usually the dilution factor at each step is constant, resulting in a geometric progression of the concentration in a logarithmic fashion. In some cases, however, adding too many distinct chemicals into a selective media mixture can create a c⦠Heat is an excellent means of killing microorganisms, and the Bunsen burner is the sterile technician’s best friend. This is an important distinction between growth media types. Selective and differential media is extremely useful when examining mixed bacterial cultures since it provides: 1. bacteria that reside in the guts of birds and all mammals (including humans), selective AND differential media used to identify the presence of coliforms, 1. 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