What is serial dilution and why is the technique used

The first step in making a serial dilution is to take a known volume usually 1ml of stock and place it into a known volume of distilled water usually 9ml. This produces 10ml of the dilute solution. Dilution is the process of decreasing the concentration of a solute in a solution, usually simply by mixing with more solvent like adding more water to a solution. To dilute a solution means to add more solvent without the addition of more solute.

If you have a small concentration , find the answer in parts per million ppm to make it easier to follow. A 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. Direct Dilution with the Echo Liquid Handler Direct dilution is the process by which Echo Liquid Handlers generates the IC 50 curve, transferring precise droplets of solution directly to individual assay wells, without tips.

Dilution Factor is the factor by which the stock solution is diluted. It may be expressed as the ratio of the volume of the final diluted solution V 2 to the initial volume removed from the stock solution V 1 , as shown in the equation above. The serial dilution agar plate procedure only accounts for living viable cells while other methods count for both living and dead cells.

Advantage : the cell count represents viable cells. Disadvantage : the method requires an incubation periods so it takes longer to get results. The direct dilution method uses far less sample than the serial dilution method. This figure shows only the first four concentrations via direct dilution. Essential to direct dilution is the ability to accurately transfer extremely small volumes of stock solution, which is generally not possible with pipets. Serial dilutions made by Andrew are more accurate than their manually performed counterparts.

A standard curve for the ideal target diluted concentration at each dilution point was calculated using the dilution factor of 2. This was compared with serial dilution curves produced either by hand or by Andrew. We use serial dilutions to create decreasing concentrations of the original sample that are then plated so that a plate will be created with a low enough number of bacteria that we can count individual colonies. From that number, we can calculate the original cell density in the broth.

What are the limitations of standard plate count? How do you calculate microbial count? What is total plate count? Is Plate Count Agar a selective medium? What is the difference between aerobic plate count and total plate count? What is pour plate method? How many cells does a visible colony consist of? Why is Plate Count agar used in this experiment?

Why must you Plate each dilution 3 times? How do you count colonies on a plate? Why is a standard plate count performed on food products? Why serial dilution is used? What are the advantages of serial dilution? What is serial dilution and its importance? Where is serial dilution used? With this method, an amount of bacteria suspended in a solution around 1 ml is placed in the center of a sterile Petri dish using a sterile pipette.

Molten cooled agar is then poured into the Petri dish containing the inoculum and mixed well. After the solidification of the agar, the plate is inverted and incubated as usual. This technique also requires a prepared sample as in the spread plate, performing serial dilutions of the mixed cultures to obtain the optimum number of colonies present in a plate to perform the count.

The drop plate method can be used to determine the number of viable suspended bacteria in a known beaker volume. The drop plate exhibits many positive characteristics. The plating and counting procedures require less labor than alternative methods, and the plating and counting steps are very convenient and manageable.

Also, less time and effort are required to dispense the drops onto an agar plate than to spread an equivalent total sample volume into the agar. This method allows dispensing the sample to be analyzed in drops, colony counting can be done faster and perhaps more accurately. Furthermore, the drops can absorb quickly into the agar on appropriately dried plates. Besides this, the drop plate method expends relatively few supplies but, despite its widespread use, the drop plate method has not been standardized yet.

Spiral plating is a two-in-one method: diluter and plater at the same time, one of the most time- and waste volume- saving methods of inoculation , which means cost savings, that is why more and more microbiological laboratories are using a Spiral Plater for bacterial determination.