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

Instances of human diseases caused by bacteria, Q What are instances of hum...

Q What are instances of human diseases caused by bacteria? Some human diseases caused by bacteria are tuberculosis, pertussis, diphtheria, gonorrhea, bacterial meningitis, bubo

Fats, what are fats

what are fats

Plants of the open water zone, Plants of the open water zone In this z...

Plants of the open water zone In this zone plants are restricted to the limnetic one and generally consist of phytoplankton such as dinoflagellates, blue green algae and green

Methods to overcome incompatibility, Methods to Overcome Incompatibility ...

Methods to Overcome Incompatibility It has been possible to facilitate the germination of incompatible pollen by extracting pollen wall proteins from compatible pollen and su

Human biology, can i get a complete note to conceptualise human biology for...

can i get a complete note to conceptualise human biology for medical entrance preparation?

Zoology, Write briefly on neural mechanism of learning?

Write briefly on neural mechanism of learning?

Explain an important strategy of group meetings, Explain An important strat...

Explain An important strategy of group meetings An important strategy could be to conduct small group meetings for behavioural change encouraging full participation. The group

Respiration in scorpion or spider, RESPIR A TIO N IN SCORPION OR SPIDER ...

RESPIR A TIO N IN SCORPION OR SPIDER - Respiratory organs are book lungs. A book lung is a chamber containing a series of thin, vascular, parallel lamellae arranged li

Hmp shunt in erythrocytes, HMP shunt in erythrocytes HMP shunt in eryth...

HMP shunt in erythrocytes HMP shunt in erythrocytes is of importance due to the generation of NADPH, which maintains the glutathione (G-SH)  in  the reduced  state by  glutathi

Explain common concerns during pregnancy, Explain Common Concerns during Pr...

Explain Common Concerns during Pregnancy? Many of the physiological changes that occur during pregnancy affect the digestive tract and may cause discomfort to the mother. Most

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