First platereading

Two centrifuge tubes (50 ml) where filled with media and algaecells (Nannochloropsis CCMP 1779) that had been growing for 3 days. The tubes where then centrifuged at 6000 rpm for 5 minutes, and some of the supernatant was taken away. This was done to concentrate the cells approximately 8-folds. The solution was then transferred to a 24-well plate to make a dilution series.

The dilution series where as follows:
1:1, (1000 µl of cell solution)
8:10, (800 µl of cell solution, +200 µl of sterile media)
6:10,  (600 µl cells, +400 µl sterile media)
4:10, (400 µl cells, +600 µl sterile media)
and 2:10 (200 µl cells, +800µl sterile media).

In addition to the dilution series, several wells where filled with BLANK (sterile media).
The cell solution where diluted with sterile media.

There was not enough cell solution to add 200 µl to the last well in the A-row, and therefore the chart for the A-wells will not be analyzed any further.
The plate was then analyzed with a pectrophotometer (infinite M200PRO) at 750 nm and 730 nm.

Figure 1: The graph shows absorbance at 750 nm plotted against a concentration gradient.

Figure 2: Absorbance at 750 nm plotted against a concentration gradient.

The well numbers that figure 1 and 2 shows to, correlates with the concentration gradient, i.e well #1=1000 µl of cells.

Table 1: Data for absorbance/concentration graphs.

The values in table 1 have been corrected by subtracting the mean BLANK value. The graphs however, where made by using the raw data. The slope remains unchanged whether one uses the raw data or the corrected values.

The plate was then analyzed one more time at the spectrophotometer at 730 nm.

A basic cell counting using a Bükkner chamber was also done to figure out the concentrations. The concentration was found to be approximately 170 million cells per mL.