Example 1. The following spreadsheet uses the Excel Char function to return the character associated with different supplied character set numbers. Note that these results are from the Ansi character set (used on the Windows operating system).
Potassium tellurite agar is selective for the growth of Staphylococci and is somewhat selective for the growth of Corynebacteria. Staphylococci and Corynebacteria reduce the potassium tellurite in the agar, which makes the colonies grow black.
Starch agar is a differential medium that tests the ability of an organism to produce certain exoenzymes, including a-amylase and oligo-1,6-glucosidase, that hydrolyze starch.tarch agar is a simple nutritive medium with starch added. Since no color change occurs in the medium when organisms hydrolyze starch, we add iodine to the plate after incubation. Iodine turns blue, purple, or black (depending on the concentration of iodine) in the presence of starch.