Question

The following test is used to differentiate the faecal coliforms from non faecal counterparts in dairy industry.

• A. Presumptive coliform test
• B. Confirmatory coliform test
• C. Most Probable Number method
• D. Eijkman’s test

Hint:

Incubation at $45^{\circ}\text{C}$ is the standard method for selective growth of fecal coliforms, as non-fecal strains are inhibited at this temperature.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
In dairy hygiene, coliforms are used as indicators of sanitation.
It is necessary to differentiate between general environmental coliforms and those of direct fecal origin, such as Escherichia coli.

Step 2: Detailed Explanation:
Eijkman's test differentiates fecal coliforms from non-fecal environmental coliforms (like Enterobacter aerogenes).
The test relies on the physiological ability of fecal coliforms to ferment lactose with gas production at an elevated incubation temperature ($44^{\circ}\text{C}$ to $45^{\circ}\text{C}$).
Most environmental coliforms cannot grow or produce gas at this temperature.
Regarding the other options:
Presumptive and Confirmatory coliform tests on MacConkey or Brilliant Green Bile Lactose (BGBL) broth detect general coliforms at $37^{\circ}\text{C}$ but do not differentiate fecal strains.
The Most Probable Number (MPN) method is a statistical technique used to estimate microbial concentration rather than differentiate specific biological groups.

Step 3: Final Answer:
Therefore, Eijkman's test is used to differentiate fecal coliforms from non-fecal counterparts.