Proteolysis and hemolysis of sessile and planktonic bacteria. Proteolytic and hemolytic activity was determined qualitatively by agar diffusion assay on skim milk, respectively sheep blood agar. Hemolytic activity was measured in diluted sheep blood. (A) Skim milk agar and (B) sheep blood agar with sessile bacteria. (C) Sheep blood agar with sterile-filtered supernatants of stationary phase planktonic bacteria. (D) Release of hemoglobin by stationary phase supernatants of planktonic bacteria. Representative data of three independent experiments are shown with standard deviations of technical triplicates.