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Serial Dilution Formula:
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Serial dilution CFU calculation is a method used in microbiology to determine the concentration of microorganisms in a sample after performing a series of dilutions. It helps in obtaining countable colony-forming units (CFUs) from highly concentrated samples.
The calculator uses the serial dilution formula:
Where:
Explanation: The formula calculates the final concentration of microorganisms after applying a known dilution factor to the initial concentrated sample.
Details: Accurate CFU calculation is essential for determining microbial concentrations in various applications, including water testing, food safety, pharmaceutical quality control, and clinical microbiology.
Tips: Enter the initial CFU value in CFU/mL and the total dilution factor. Both values must be positive numbers greater than zero for accurate calculation.
Q1: What is a colony-forming unit (CFU)?
A: A CFU is a unit used to estimate the number of viable bacteria or fungal cells in a sample. One CFU represents one or more cells that form a single visible colony.
Q2: How is the total dilution factor calculated?
A: The total dilution factor is the product of individual dilution factors in a serial dilution series. For example, three 1:10 dilutions would give a total dilution factor of 10 × 10 × 10 = 1000.
Q3: Why is serial dilution necessary?
A: Serial dilution is necessary to reduce the concentration of microorganisms to a countable range, typically between 30-300 colonies per plate for accurate enumeration.
Q4: What are common sources of error in CFU calculations?
A: Common errors include inaccurate pipetting, improper mixing, colony counting errors, and incorrect dilution factor calculations.
Q5: Can this calculator be used for any microorganism?
A: Yes, the calculation applies to all microorganisms that form countable colonies, including bacteria, yeast, and mold, though specific protocols may vary.