Explain the presumptive test - most probable number test, Biology

Assignment Help:

Explain the Presumptive Test - Most Probable Number Test?

The Presumptive test is used to detect and estimate coliform population of a water sample. This test is carried out by inoculating a series of lactose broth medium with three different sample volumes (10 ml, 1 ml and 0.1 ml). The series consists of 3 groups, each composed of 5 tubes and each group is inoculated with the designated volume of the water sample. The greater the number of tubes per group, the greater the sensitivity of the test. Lactose medium contains the lactose, bile salt and pH indicator.

Lactose and bile salts are selective for coliforms as lactose is used only by coliforms and not by other enteric bacteria while bile salts are depressent for enteric bacteria other than coliforms. A pH indicator such as bromocresol purple is added to the medium to detect acid fermentation from lactose. Production of acid changes the colour of the medium to yellow. Gas production during fermentation is detected by inverted Durham tube in lactose medium. Positive test for coliforms is indicated by the production of acid and gas from lactose fermentation after 24-48 hours of incubation. Number of tubes showing positive test is counted and the result is expressed as most probable number (MPN) of coliforms by matching the results

 


Related Discussions:- Explain the presumptive test - most probable number test

Explain major limiting factors of photosynthesis, Q. What are the three maj...

Q. What are the three major limiting factors of photosynthesis? The three major limiting factors of photosynthesis process are light intensity, carbon dioxide temperature and c

Aortic allograft -biological valves, Aortic Allograft (Homograft) :  ...

Aortic Allograft (Homograft) :  In the earlier years fresh antibiotic preserved aortic allografts were tried. As the shelf life is limited, availability of all sizes at all t

Pre-requisites of counselling, In diabetes mellitus counsellor help the dia...

In diabetes mellitus counsellor help the diabetic patient to cope up with the stress and take own decision for their treatment and life style changes. Decision making  capacity of

What are venous vessels and veins, What are venous vessels, veins and venul...

What are venous vessels, veins and venules? Venous vessels are each blood vessel that carries blood from the tissues to the heart. Veins and venules are venous vessels. Venules

Explain gastro-intestinal system, Explain G.I. (Gastro-Intestinal) system? ...

Explain G.I. (Gastro-Intestinal) system? A. Skeletal muscles directly control the movement of substances at the entrance of the G.I. system. B. Smooth muscles control the mo

Spoilage by fungi and bacteria, Q. Explain Spoilage by fungi and bacteria? ...

Q. Explain Spoilage by fungi and bacteria? The dominant spoilage organisms in fruits are fungi, as their pH is low (normally 5),whereas the pH of vegetables is fiom 5.0 to 7

List the tissues of pancreas, Q. List the tissues of pancreas? The panc...

Q. List the tissues of pancreas? The pancreas is made up of two types of tissue: The exocrine tissue secretes digestive enzymes. These enzymes are secreted into a network of

What do you understand by the term controlled vocabulary, Question 1: E...

Question 1: Enlist the applications of programming and encoding in Pharmaceutical industries Explanation on what is programming and encoding in Pharmaceutical industries

Mitosis and meiosis, briefly desribe the eggs and follicles in rabbit

briefly desribe the eggs and follicles in rabbit

Represents two things that are identical, Which of the following represents...

Which of the following represents two things that are identical? a.Two alleles for the same gene in a homologous chromosome pair. b.The sequences of DNA in the two sister chr

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd