In Gram staining, Bacillus subtilis and Staphylococcus aureus are Gram-positive bacteria that are stained purple (or purple-red). E. coli is a Gram-negative bacterium that is stained red.

In addition, bacteria can be divided into: bacilli, cocci and spiral bacteria according to their morphology. Bacillus subtilis and Escherichia coli are rod-shaped, and Staphylococcus aureus is spherical.

So the experimental phenomena are: Bacillus subtilis - purple rod shape; Staphylococcus aureus - purple ball shape; Escherichia coli - red rod shape.