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

Mitral flow velotity, The normal flow pattern cross-mitral valve is a tall...

The normal flow pattern cross-mitral valve is a tall E wave where is due to early rapid filling and small A-wave which is due to atrial contraction. E/A ratio >1. Pulmonary

Explain the resorbable barriers - root perforation, Explain the Resorbable ...

Explain the Resorbable Barriers - Root Perforation It is successfully control internal bleeding through cronal access It is intended to forced in the bone, not left wi

What are the basic constituents of the cell membrane, What are the basic co...

What are the basic constituents of the cell membrane? The cell membrane is produced of lipids, proteins and carbohydrates. The membrane lipids are phospholipids, a special t

Regulatory mechanisms, Normal 0 false false false EN-IN...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Define iron - the micronutrient, Define Iron - The Micronutrient Iron, ...

Define Iron - The Micronutrient Iron, as you may be aware, is a trace element present in the body. The body contains approximately 3 - 3.5 g of iron of which about two thirds i

Theories to explain fine structure of chromosome, THEORIES TO EXPLAIN FINE ...

THEORIES TO EXPLAIN FINE STRUCTURE OF CHROMOSOME (1 ) Multistranded theory Steffenson 1959 - each chromosome composed of two chromatids (Half Chromosome) and each chromat

Explain the effect of deficiency of vitamin e, Explain the Effect of Defici...

Explain the Effect of Deficiency of Vitamin E? Fortunately, vitamin E deficiency in human is extremely rare. This may probably be due to its wide occurrence. in natural foods a

What does fungus looks like, Q. What does this fungus looks like? Ans...

Q. What does this fungus looks like? Ans. The important characteristic features of aflatoxicosis are jaundice, cirrhosis. Long term exposure to aflatoxins could lead to

Natality rate - natality, Natality Rate - Natality Natality rate or bi...

Natality Rate - Natality Natality rate or birth rate is determined by dividing the number of individuals born by unit time and is expressed as follows: Natality rate =  ΔNn

Define arterial vessels - arterioles and arteries, Q. What are arterial ves...

Q. What are arterial vessels, arterioles and arteries? Arterial vessels are every blood vessel that carries blood from the heart to the tissues, arterioles and Arteries are art

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