1. For each box, circle the appropriate response for if the medium is rich or mi
ID: 276387 • Letter: 1
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1. For each box, circle the appropriate response for if the medium is rich or minimal complex or defined, if it is selective, and if it is differential. ( 1 pont Rich or Minimal? Complex of Defined? Selective? Differential? Rich Minimal Rich Minimal Rich Minimal Rich Minimal Complex Defined Complex Defined Complex Defined Complex Defined Yes Yes MacConkey's Agar 0 0 Yes Yes TSA at 20% NaCl 0 0 Yes es Glucose Minimal Agar 0 Yes Yes Blood Agar Carbohydrate broths start with a base of 10 g/1 Pancreatic Digest of Casein (milk proteins), S g/I NaCl, and 18mg/ phenol red. The carbohydrate of interest (glucose or lactose for us) is added at 5g/L Answer the next three questions in the space provided, keep your answers succinct. 2. For those media you marked as selective, what characteristic/type of bacteria are the selective for? (1 point) 3. For those media you marked as differential, what characteristic/type of bacteria do they differentiate for? What phenotypes can you see on the differential media and what do those phenotypes indicate? (2 points)Explanation / Answer
Mac Conkey agar: Rich, complex, media selective and differential
TSA at 20 % NaCl: Rich, complex, media
Glucose minimal agar: Minimal, defined, and selective media
Blood Agar: Rich, complex, and differential media
MacConkey agar is both selective and differential.
Selective: It contains bile salts and the dye crystal violet, which inhibit the growth of gram-positive bacteria and select for gram-negative bacteria.
Differential:
It contains the carbohydrate lactose, which allows differentiation of gram-negative bacteria based on their ability to ferment lactose. Organisms which ferment lactose produce acid end-products which react with the pH indicator neutral red, and produce a pink color.
Blood Agar (BA) is enriched medium used to culture those bacteria or microbes that do not grow easily. It is also a differential media in allowing the detection of hemolysis (destroying the RBC) by cytolytic toxins secreted by some bacteria, such as certain strains of Bacillus, Streptococcus, Enterococcus, Staphylococcus, and Aerococcus.
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