After the incubation of plates, the number of cell can be counted. Once organism is diluted out by certain dilution factor, it is allowed to inoculate on suitable nutrient media in Petri dished.
IMPORTANCE OF SERIAL DILUTION RESEARCH SERIES
Serial dilution is a series of dilutions used to determine the concentration or titer of a substance. However, serial dilution-agar plate technique is used in order to count only the viable cells. Almost all of the above listed methods are limited in distinguishing between viable and dead cells. However, they are limited by high cost of chemicals and low sensitivity to microbial suspension respectively. The chemical methods and spectrophotometric analysis are also used for counting the number of cells. The structure and principle of Coulter counter is shown below:įigure 3.Coulter counter and its principle Thus, the resistance is recorded enumerating the number of cell flowing through the orifice. After passing ofįluid containing cells via each microchannel, some particles causes change to the electrical resistance of liquid. A Coulter counter is an example of electronic cell counters, and has one or more micro channels in order to separate two chambers containing electrolyte solutions. This method also does not discriminate between viable and dead cells as in Petroff-Hausser method. Breed method is mainly used to assess the quality of milk by giving the number of bacteria and leucocytes in milk.
IMPORTANCE OF SERIAL DILUTION RESEARCH FREE
Also, the sample needs to be free from debris and food extraction.
Moreover, the cells that own too small size is difficult to count. However, there is no different cells calculation for live and dead cells. There advantages of this method are quick and easy count of cells and cheap cost.
Petroff-Hausser method is performed to calculate the total cell of microorganism in small sample by using the glass slides in square form with fixed volume as shown in figure 1 and 2.įigure 1.Petroff-Hausser counting chamberįigure 2.Petroff-Hausser counting chamber grid Generally, there are two types of direct microscopic counts such as Petroff-Hausser method and breed method. Direct microscopic counts are performed by placing a bacterial suspension in a counting chamber, and require the use of specialized slide called the Petroff-Hausser counting chamber. Because of above reasons, variety of methods had been developed for quantitative enumeration of microorganisms such as direct microscopic counts, electronic cell counters, chemical methods, spectrophotometric analysis and serial-dilution agar plate analysis. In addition, worldwide the numbers of microorganisms in a given sample are required to know in certain aspects such as dairy industries, water treatment, food manufactures, and importantly in investigation and study of diseases.
Moreover, it is often important to know not only what kinds of microorganism are present in a given or obtained sample but also to know the number of microorganism in sample which is difficult to count under the naked eyes because of their small size. The size of microorganisms is about 1/10th the size of a typical human cell, and measured in the scale of one millionth of a meter known as micrometer. When performing a dilution there is a equation that can be used to determine the final concentration.Introduction It is difficult to know and imagine the size of microorganisms, since they are too small to be seen under the naked eyes. By performing a dilution on a sample it may reduce the interfering substance to a point where it no longer interferes with the test. If the Mn+6 is present in the sample it will add to the value of the chlorine test due to the way the it reacts to the chlorine test reagents. For example, oxidized manganese (Mn+6) acts as an interference to the chlorine test. An example is if performing a chlorine test, chlorine would be the analyte.Īn interference is a compound that can add to, or subtract from the result of the analysis. Dilutions can be important when dealing with an unknown substance.Ī dilution can be performed not only to lower the concentration of the analyte that is being tested, so that it is in range, but also to help eliminate interferences from other substances that may be present in the sample that can artificially alter the analysis.Īn analyte is the compound in the sample that is desired to be tested.
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