Today our group carried out a serial dilution using a 96-well plate. Starting with a saturated yeast culture, the objective was to make a 1/100000th concentration dilution. We placed 200μL of saturated yeast in well 1A. In well 1B, we took 180μL from 1A and added 20μL of water. This created a 1/10th concentration of yeast (9 parts saturated yeast to 1 part water). In well 1C, we took 180μL from 1B and added 20μL of water. This created a 1/100th concentration of yeast (9 parts 1/10th yeast to 1 part water). This process was repeated three more times to end with 200μL of 1/100000th concentration in well 1F.

 

We ran our 96-well plate through a spectrophotometer, which measured the optical density (OD), or absorbance of light, of the liquid yeast cultures in each well. The values returned were plotted on a graph (which is pictured below), and the concentration of yeast was logarithmically transformed.