A colleague of yours has produced a set of meda that was noc
Solution
1. K/A
slant- when lactose is not fermented,but glucose is,the less acd produced will be oxidized to carbon dioxide and water
butt- lactose is not fermented but glucose is,the acis produced turns phenol red indicator yellow, the oxygen deficient butt will be yellow
this test eliminates Ec
2. MR test -positive VP test- negative
reagent for MR test - methl red(p- dimethylaminoaeobenxene-O- carboxylic acid)
reagent for VP test- alha naphthol and potassium hydroxide
interpretation- the MR test is used to determine whether the organism does mixed acid fermentation.The large amount of acid decreases the pH of the medium,which is detected by methyl red indicator which is red at pH 4.4.
VP test-This test is used to detect the presence of acetoin in bacteria.On addition of VP reagent ,a cherry red colour ring indicates a positive test.
MR test eliminates Ec
VP test eliminates Kp
4. pH indicator of macconkey media- neutral red
interpretation- clear colonies are formed by nonlactose fermenting bacteria,which do not utilize lactose instead use peptone.This forms ammonia,raises the pH and leads to formation of colourless colonies.
this test eliminates -Ec,Kp
5.interpretation
sulphur- no blackening indiactes no H2S production.
indole- negative indole test .It means that the organism does not produce the enzyme tryptophanase that degrades tryptophan to produce indole
Motility- no motility,because there is no cloudiness along the stab line.
This test eliminates Kp
6. indicator-phenol red
interpretation- yellow colour with growth indicates that the organism does not produce the enzyme urease that splits urea into ammonia and carbon dioxide.
This test eliminates Ec

