Question

Evaluate the significance of TSI slants. Provide a brief overview of the process and the meaning of the results.

Answer 1

Ans) Tsi stands for triple sugar ion which is used to test the ability of microorganisms to ferment sugar and give rise to hydrogen sulphide. It is also used to distinguish Salmonella as well as Shigella bacteria. It is based on the principle that different Organism shows different carbohydrate fermentation pattern as well as different hydrogen sulphide production. As agar slant is a special type medium which contains pH sensitive dye also known as phenol red , 1% sucrose , 1% lactose , 0.1% glucose , ferrous ammonium sulphate. All these ingredients mix together and solidifies at an angle in a test tune which is known as slanted angle which provides an saray of surface so that it is either expose to air which is oxygen rich in varies degrees.

RESULTS :

• Red slant / yellow butt which is KA shows dextrose fermentation.

• Yellow slant / yellow butt (AA) , it shows fermentation of dextrose , sucrose and lactose.

(Where K represent alkaline media and A represents acidic media).

INTERPRETATIONS :

• The black colour ferrous sulphide shows the presence of H_{​​​​​​2}​​​​​S gas produced.

• If there is no fermentation of lactose or glucose then both the slant as well as butt will become wet.

• If there is no fermentation of lactose but glucose is ferment then butt will be yellow in colour.

• If lactose is ferement , it turns phenol red indicate into yellow in the butt as well as in the slant.

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