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For example, if you plate 1x 10 7 cells and count 1000 colonies, the transformation efficiency is: (1000/1x 10 7) x 100 = 0.1% Alternatively, CFUs can be reported per microgram of DNA used for the transformation. This can be calculated by multiplying the number of colonies by the volume of the culture plated and dividing by the amount of DNA used.
In each sector, 1 x 20 μl of the appropriate dilution is dropped onto the surface of the agar and the drop allowed to spread naturally. In the original description of the method a drop from a height of 2.5 cm spread over an area of 1.5-2.0 cm. It is important to avoid touching the surface of the agar with the pipette.
The "dilution factor" is an expression which describes the ratio of the aliquot volume to the final volume. Dilution factor is a notation often used in commercial assays. For example, in solution with a 1/5 dilution factor (which may be abbreviated as x5 dilution ), entails combining 1 unit volume of solute (the material to be diluted) with ...
Determining the viable cell count is important for calculating dilutions required for the passaging of cells, as well as determining the size and number of flasks needed during growth time. It is also vital when seeding plates for assays, such as the plaque assay , [ 2 ] because the plates need a known number of live replicating cells for the ...
One of the most important features of chemostats is that microorganisms can be grown in a physiological steady state under constant environmental conditions. In this steady state, growth occurs at a constant specific growth rate and all culture parameters remain constant (culture volume, dissolved oxygen concentration, nutrient and product concentrations, pH, cell density, etc.).
Theoretically, one viable cell can give rise to a colony through replication. However, solitary cells are the exception in nature, and in most cases the progenitor of a colony is a mass of cells deposited together. [1] [2] In addition, many bacteria grow in chains (e.g. Streptococcus) or clumps (e.g., Staphylococcus). Estimation of microbial ...
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Conversely, in an indirect dilution assay the dose levels are administered at fixed dose levels, so that the response is a stochastic variable. In some assays, there may be strong reasons for believing that all the constituents of the test preparation except one, are without any effect on the studied response of the subjects.