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The CFU/plate is read from a plate in the linear range, and then the CFU/g (or CFU/mL) of the original is deduced mathematically, factoring in the amount plated and its dilution factor. A solution of bacteria at an unknown concentration is often serially diluted in order to obtain at least one plate with a countable number of bacteria. In this ...
The following equation is used to calculate the number of colony forming units (CFU) per ml from the original aliquot / sample: CFU per ml = Average number of colonies for a dilution x 50 x dilution factor. Advantages. Faster than other methods. Produce less bacterial contamination of the working surface.
A 0.5 McFarland standard is prepared by mixing 0.05 mL of 1.175% barium chloride dihydrate (BaCl 2 •2H 2 O), with 9.95 mL of 1% sulfuric acid (H 2 SO 4). [ 1 ] Now there are McFarland standards prepared from suspensions of latex particles, which lengthens the shelf life and stability of the suspensions.
The count represents the number of colony forming units (cfu) per g (or per ml) of the sample. A TVC is achieved by plating serial tenfold dilutions of the sample until between 30 and 300 colonies can be counted on a single plate. The reported count is the number of colonies counted multiplied by the dilution used for the counted plate
Such homogeneously spread colonies are suitable for CFU enumeration. To quantify the number of cells in a culture, the cells can be simply plated on a petri dish with growth medium. If the cells are efficiently distributed on the plate, it can be generally assumed that each cell will give rise to a single colony or Colony Forming Unit (CFU ...
The colony-forming unit (CFU) is an appropriate description of the colony's origin. In plate counts, colonies are counted, but the count is usually recorded in CFU. Due to the fact that colonies growing on plates may begin as either a single cell or a cluster of cells, CFU allows for a correct description of the cell density.
To calculate the transformation efficiency, divide the number of colonies by the number of cells plated and multiply by 100. The result will be the transformation efficiency as a percentage. 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%
For a calibration curve, 1 mL of seed culture was added to 1.5 mL of PMH after the two hour incubation to generate a suspension of 10 8 CFUv/mL. A 10-fold dilution series of this suspension was made ranging from 10 7 to 10 0 CFUv/ml in 200 μl total volume of PMH, occupying eight wells of the 96-well plate. At this time, cells exposed to no ...