Cross-check data

It is time to compare data from BactoBox® and CFU methods. To do so, we will export the data and do the cross-check in a spreadsheet tool.

Example of data export from Access to CSV file. The CSV file is opened in a spreadsheet tool such as Excel.

We provide a data example for download. Note that the example features both end-of-fermentation cross-check and the full growth curve.

pseudomonas-pq-summary.xlsx

22KB

Open

Step by step data analysis

1

Export CSV file

Use EXPORT CSV in Access to download a file of comma-separated values.

Open the CSV file in a spreadsheet tool like Excel. Save the file as .xlsx.

2

Calculate arithmetic mean

Use a spreadsheet to calculate the arithmetic mean of the three time points for a given growth medium. In excel the formula would be =AVERAGE(number1:number3).

3

Calculate standard deviation

Use a spreadsheet to calculate the standard deviation of the three time points for a given growth medium. In excel the formula would be =STDEV.S(number1:number3).

4

Plot data

Make a column chart of the arithmetic mean.

Add error bars for standard deviation

Example of harvesting too early

The below column chart is an example of potential premature harvest after 13.5 hours.

The ratio is 1.02 and the error bars are overlapping. This means that BactoBox® and CFU results are practically identical. This corresponds to the cyan region from the introduction Cross-check at end of fermentation.

In theory this could mean that you have harvested at the perfect time. But maybe the cell concentration has yet to peak? We will investigate this in a moment in the Summary.

Example of end-of-fermentation cross-check after 13.5 hours where BactoBox ~ CFU . Mean of BactoBox® (lavender) and CFU (yellow) results.

Example of harvesting too late

In the below column chart, the BactoBox/CFU ratio is 6.40 and there is a clear distinction between the error bars. This means that BactoBox® is higher than CFU. This corresponds to the grey region from the introduction Cross-check at end of fermentation. It would likely be beneficial to harvest earlier, but let's explore in more detail in the Summary .

Example of end-of-fermentation cross-check after 35.8 hours where BactoBox > CFU . Mean of BactoBox® (lavender) and CFU (yellow) results.

Summary

The CFU and BactoBox® data is now cross-checked. We will wrap up the findings and recommendations for next steps in the Summary.