Test 1 Flashcards
(44 cards)
EMB (Eosin Methylene Blue)
-Selective and differential.
-Contains peptone, lactose, sucrose and dyes eosin
- grows gram - organism
-green metallic serves as indicator of lactose and sucrose fermentation typical of fecal coliforms.
PEA (Phenylethyl Alcohol Agar)
-isolates staphylococci and streptococci from specimens mixture of bacterial flora
-when prepared with 5% sheep blood used for cultivation of Gram + anaerobes
phenylethyl alcohol interferes with DNA synthesis of Gram - organisms.
- Undefine selective medium.
TSA (trypticase soy agar)
-Enriched with yeast extract
-Contains soy beans
-Complex media
-non selective
-grows bacteria and fungi
MSA (Mannitol Salt Agar)
- Selective and differential
- carbohydrate mannitol, 7.5% NaCl and Ph indicator phenol red yellow b .
-NaCl makes it selective for Staphylococci - differentiation of pathogenic - ferments mannitol which produce acid turns yellow, - nonpathogenic grow but no color change
-grow poorly no staphylococci
SAB (Sabourad’s dextrose agar)
-Selective media, acidic Ph, inhibits most bacteria.
-Preferentially grows fungi
Chemically defined media
All ingredient precisely
Complex media
Contains a least one ingredient with no precise chemical formula- soy, yeast, blood.
Selective media
Inhibits growth of some microbes
Differential media
Distinguishes between microbes (by color changes etc.)
Culture
composed of one or more kinds of organisms grown under artificial but suitable conditions
Medium
Media (plural). Medium material that contains essential resources for growth (carbon source, nitrogen source, sulfur source etc. )
Streak plate (quadrant method)
commonly used isolation technique to identify an organism.
agar
agar is added to a medium to make it solid
Colony
is the visible growth of bacteria that presumably all arose from a single bacterial cell.
broth
Does not contain agar, so it is liquid
Inoculation
process of introducing or transferring microbes into a culture media so that it reproduces there. Inoculating loop.
autoclave
high temp, high pressure machine that sterilizes.
singular of bacteria
bacterium
TSA slant advantage over TSA deep
bacteria have a greater surface area on on which to grow in a test tube.
Streak for isolation
-check for contaminants
-colony morphology
Starch Agar
-contains beef extract, soluble starch and agar
-differential media not selective
-tests for organisms that produce amylase which hydrolyzes starch into maltose
- reagent iodine reacts with starch producing a blue or dark brown color.
-therefore a clear halo around the microbial will reveal starch hydrolyzes.
Spirit Blue
- to test for production of lipase which hydrolyzes (lipolysis) fats.
-differential medium
-prepared as an emulsion with tributyrin oil (simple fats known as triglycerides) and also contains spirit blue dye as a color indicator
-hydrolyzes triglycerides to glycerol and three long chain of fatty acids.
-Lipase-positive bacteria hydrolyze the oil and produce clear halos surrounding the microorganism
Gelatin Test.
-Test tube composed of gelatin (derived from protein), peptone and beef extract.
-Differential medium
-When the tube is stab-inoculated with a gelatinase positive organism it will liquefy the medium (will become liquid)
Direct Stain
- it colors the bacteria cells, as they are colorless
-used for morphology and arrangement of bacterial cells
-one drop of water if inoculating from agar, let it air dry, heat fix it (kills bacteria and gets them to stick, so they don’t wash off during staining. - Methylene Blue (or other direct stain) added for 60 sec, then wash with water and let dry.
-oil immersion lens is necessary for viewing bacteria
