Explain the serial dilution process - plate counts, Biology

Assignment Help:

Explain the Serial Dilution Process - Plate Counts?

Dilution factor is the reciprocal of the dilution used. As number of microorganisms in original sample is not known, the original sample is diluted several times in sterile water blanks to ensure that separate colonies are developed and some colony counts will be in the specified range. The process is called serial dilution. The procedure is shown in Figure. Usually a ten-fold serial dilution is used in the process where 1 ml of the sample is transferred to a 9 ml of the diluent to get 1:10 dilution. 1 ml of this is transferred to another tube of 9 ml of diluent to get 1:100 dilution and so on till the required dilutions are obtained.

105_Serial dilution process.png

Figure: Serial dilution process

It is important that the dilution used should produce a limited number of colonies on plate. When many cells are present, overcrowding of cells may not allow many colonies to develop and may also result in many colonies to fuse. This leads to inaccuracies in count. Similarly, too less colonies are not statistically significant. According to Food and Drug Administration, only those plates having 25-250 colonies should be considered for calculation; but most microbiologists use plates with 30-300 colonies to get the microbial numbers in the sample. Plates getting colonies less than 30 are marked too less to count (TLTC) and getting more than 300 are marked as too numerous to count (TNTC) and are discarded.


Related Discussions:- Explain the serial dilution process - plate counts

Social basis of primitive life, Social Basis of Primitive Life: In th...

Social Basis of Primitive Life: In the previous section, we gave you a glimpse of  how the primitive human beings faced the problems of day to day existence and found some so

Difference between diabetes mellitus and diabetes insipidus, Q. What is the...

Q. What is the difference between diabetes mellitus and diabetes insipidus? What are the characteristic signs of diabetes insipidus? Diabetes mellitus is the disease caused by

Do protozoans have a cellular nucleus, Q. Do protozoans have a cellular nuc...

Q. Do protozoans have a cellular nucleus? All protozoans, as eukaryotes have nucleus, some species like the paramecium have two nuclei the micronucleus and the macronucleus.

Reparative regeneration, Reparative Regeneration This type of regener...

Reparative Regeneration This type of regeneration, as the name suggests, involves repair of a wound or replacement of a body part removed intentionally or because of injury.

Medical science in ancient india, MEDICA L SCIENCE IN ANCIENT INDIA D...

MEDICA L SCIENCE IN ANCIENT INDIA Dhanvantri -"God of Medicine". Ashvini Kumar - Famous medical man of vedic times. Susruta - First Indian to study human anatomy;

Determine the central thermoreceptor neurons, Which of the following serves...

Which of the following serves as a sensor, or as part of a sensor, that functions in a negative feedback system? A. Central thermoreceptor neurons whose peripheral terminals ar

Define the post-herbal period, Define the Post-Herbal Period? It is di...

Define the Post-Herbal Period? It is difficult to draw a sharp line of demarcation between the transition period, marked by various attempts of classification, all of which we

Baby''s persistent and increasing jaundice, A mother has brought her 2-week...

A mother has brought her 2-week-old infant to the emergency department due to the baby's persistent and increasing jaundice. Blood testing reveals that the infant's unconjugated bi

Compare and contrast the effect of a deletion, Compare and contrast the eff...

Compare and contrast the effect of a deletion in the operator of the lactose operon with one in the operator of the histidine operon.

Explain about the browning reactions, Explain about the Browning Reactions?...

Explain about the Browning Reactions? The Browning Reactions are complex reactions which occur when foods are processed. In some the brown flavour is highly desirable and is in

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