What are two possible errors associated with serial dilution?
There are many potential sources of error. Examples include: incorrect measuring of the sample or diluent; insufficient mixing; not switching pipettes between each step of the serial dilution; contamination because of poor sterile technique; or inadequate mixing of sample and molten agar in the Petri dish.
How do you calculate serial dilutions in microbiology?
Serial dilutions are the culmination of a number of diluted tubes used in order to get smaller dilutions. When a sample diluted 1/100 is added to a sample diluted 1/10, the final dilution would be: (1/100) x (1/10) = 1/1000.
How do you solve serial dilution problems?
In serial dilutions, you multiply the dilution factors for each step. The dilution factor or the dilution is the initial volume divided by the final volume. For example, if you add a 1 mL sample to 9 mL of diluent to get 10 mL of solution, DF=ViVf = 1mL10mL=110 .
What is the main disadvantage of the serial dilution technique?
The advantage of the serial dilution-agar plat-ing procedure is that the cell count represents only viable cells. The disadvantage of this method is that it requires an incubation period that precludes the ability to obtain immediate results.
What are some sources of error in the serial dilution method?
What are some sources of error in the serial dilution/direct plate counting method? Some sources of error include inaccurate transferring will cause less accurate dispensing. Also the higher the dilution is when doing variable counts, the more common it is for an error to be made when estimating the count.
What is serial dilution in microbiology PDF?
It is a method of diluting a stock solution where concentration decreases by the same quantity in each successive step.
Why are serial dilutions more accurate?
The more evenly spaced the calibration standards are over this range, makes the results of the analysis more reliable. Each successive standard uses a small portion of the previous standard, which is diluted by solvent to generate the next calibration standard in the series.
Why serial dilution is important in microbiology?
Serial dilution is used in microbiology to estimate the concentration or number of cells/organisms in a sample to obtain an incubated plate with an easily countable number of colonies. It is believed than dilution increases the potency of the diluted substance by activating its vital energy.
What is serial dilution in microbiology?
In microbiology, serial dilutions (log dilutions) are used to decrease a bacterial concentration to a required concentration for a specific test method, or to a concentration which is easier to count when plated to an agar plate.
What is dilution factor in microbiology?
The dilution factor (or dilution ratio) is used to express how much of the original stock solution is present in the total solution, after dilution. Or dilution factor is the ratio between the final volume and the initial volume of the solution.
What are the advantages and disadvantages of serial dilution?
The advantage of the serial dilution-agar plat-ing procedure is that the cell count represents only viable cells. The disadvantage of this method is that it requires an incubation period that precludes the ability to obtain immediate results. There are 5.6 × 10^8 cells per ml of culture.
How is a serial dilution of a sample created?
A serial dilutionis the dilution of a sample, in 10-fold dilutions. As shown in the illustration below, it begins when 1 mL of the bacterial sample is added to 9 mL, and it is mixed together (creating a 10-1 dilution). Then, 1 mL from that mixture is added to 9 mL, and it is mixed together (a 10-2dilution).
How are serial dilutions used to reduce the concentration of bacteria?
Each dilution will reduce the concentration of bacteria by a specific amount. So, by calculating the total dilution over the entire series, it is possible to know how many bacteria you started with. The best way to fully grasp serial dilutions is to try out the procedure yourself.
How many liquid blanks do you need for serial dilution?
Your liquid could be growth media, saline, sterile water, or any other appropriate liquid. For this example, we need 5 dilution blanks, numbered 1-5. In each tube, we need exactly 9 ml of liquid media.