TSI and KIA are complex media with many ingredients What wou

TSI and KIA are complex media with many ingredients. What would be the consequences of the following mistakes in preparing this medium? Consider each independently.

a. 1% glucose is added rather than the amount specified.

b. Ferrous ammonium sulfate (or ferric ammonium citrate in KIA) is omitted.

c. Casien and animal tissue are omiited

d. Sodium thiosulfate is omitted.

e. Phenol red is omitted

f. The initial pH is 8.2

g. The agar butt is shallow rather than deep.

Solution

a. The amount of glucose to be added in TSI agar is 0,1%. Since this is a small amount, Bacteria like Salmonella and Shigella will utilize this glucose in the aerobic areas during initial hours of incubation and turns the slant and but into yellow, but later turns into red slant and yellow bottom. If we are adding more glucose, it will give a false result.

b. If ferrous ammonium sulphate is not includesd in the medium , we cannot identify the H2S productio by the organism. Because along with sodium thiosulphate it reacts with H2S and gives a black colour .

c. Caesin

d. Sodium thiosulfate also helps in identifiying H2S production. Along with ferrous ammonium sul[phate it reascts with H2S and give a black colour.

e.Phenol red is the pH indicator. Which turns yellow in acid production and remains red if the medium is alkaline.

f. If the initial phH is 8,2 it is alkaline and the medium will remain red in colour.

g. if the butt is shallow the anaerobic condition will not be there. some organisms reduces thiosulphate and produces hydrogen gas and it will produce bubble below the butt. if butt is very shallow this wont occur.