Cultural Characteristics of Selected Bacteria:
Cultivation Media for Bacteria Isolation of bacteria is accomplished by growing "culturing" them on the surface of solid nutrient media.
Such a medium normally consists of a mixture of protein digests peptone, tryptone and inorganic salts, hardened by the addition of 1. Examples of standard general purpose media that will support the growth of a wide variety of bacteria include nutrient agar, tryptic soy agar, and brain heart infusion agar.
A medium may be enriched, by the addition of blood or serum. Examples of enriched media include sheep blood agar and chocolate heated blood agar.
Selective media contain ingredients that inhibit the growth of some organisms but allow others to grow. For example, mannitol salt agar contains a high concentration of sodium chloride that inhibits the growth of most organisms but permits staphylococci to grow.
Differential media contain compounds that allow groups of microorganisms to be visually distinguished by the appearance of the colony or the surrounding media, usually on the basis of some biochemical difference between the two groups.
Blood agar is one type of differential medium, allowing bacteria to be distinguished by the type of hemolysis produced. Some differential media are also selective, for example, standard enteric agars such as MacConkey and EMB agars, which are selective for gram-negative coliforms and can differentiate lactose-fermenting and non-lactose-fermenting bacteria.
Several examples of commonly used bacteriological media, as well as examples with one or more types of bacteria cultured on them are shown below. Carefully examine the plates and observe the colony morphology, colors, and patterns of growth or no growth that occurs.
This information can be valuable in the preliminary identification of pathogens in case studies.In microbiology, a colony-forming unit (CFU, cfu, Cfu) is a unit used to estimate the number of viable bacteria or fungal cells in a sample. Viable is defined as the ability to multiply via binary fission under the controlled conditions.
Counting with colony-forming units requires culturing the microbes and counts only viable cells, in contrast with microscopic examination which counts all. For much of the 20th century, prokaryotes were regarded as a single group of organisms and classified based on their biochemistry, morphology and monstermanfilm.com example, microbiologists tried to classify microorganisms based on the structures of their cell walls, their shapes, and the substances they consume.
In , Emile Zuckerkandl and Linus Pauling proposed instead using the sequences of.
Describing Bacterial Colony Morphology Although bacterial colonies can differ in the details of their appearance, a colony basically looks like a dot growing on the medium. This dot is composed of millions of bacteria that arose through binary fission from one initial bacterium, the parent.
Appearance of monstermanfilm.commidis colonies on tryptic soy agar S.
MacConkey Agar- Composition, Principle, Uses, Preparation and Colony Morphology. MacConkey agar is a selective and differential media used for the isolation and differentiation of non-fastidious gram-negative rods, particularly members of the family Enterobacteriaceae and the genus Pseudomonas. GENERAL METHODS APPEARANCE AND PHYSICAL PROPERTIES Boiling Point and Distillation Range. The following method employs ml of sample. In cases where it is necessary or would be desirable to use a smaller sample, the method of McCullough et al. [J. Chem. Ed. 47, 57 ()], which employs only 50 µl of sample, may be used. Appearance of the colony surface: Bacterial colonies are frequently shiny and smooth in appearance. Other surface descriptions might be: dull (opposite of glistening), veined, rough, .
epidermidis forms white, raised, cohesive colonies approximately millimeter in diameter after overnight incubation on tryptic soy agar. Colonies are nonhemolytic on blood monstermanfilm.com is a catalase-positive, coagulase-negative, facultative anaerobe that can grow by aerobic respiration or by fermentation.
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Different types of bacteria will produce different-looking colonies, some colonies may be coloured, some colonies are circular in shape, and others are irregular. A specific terminology is used to describe common colony types.
These are: Form - What is the basic shape of . Gram Stain Bite Sized Tutorial: This is an extremely useful tutorial that shows, step-by-step, the Gram-staining procedure and the appearance of Gram+ and Gram- bacterial cells.