Figure 6. Difference in hemolysis and hemolytic activity of GBS strain NEM316 between incubation at 30°C and 40°C.

(A) Hemolysis zones on 5% sheep blood agar plates incubated overnight at 30°C and 40°C. The inoculum used was obtained from a stationary phase THY culture. (B) Surface of the hemolysis area was measured for 100 colonies randomly selected from blood agar plates after incubation as described above. The size of the hemolysis of the colonies after incubation at 40°C is larger than after incubation at 30°C (P<0.001). (C) Hemolytic activity measured by turbidimetry (OD₄₂₀) after 1 h incubation at 37°C with 100 µL of the bacterial suspension (10⁷ CFU) and 100 µL of 1% sheep erythrocytes in PBS-glucose. Bacterial suspension from THY broth culture incubated at 40°C has a higher hemolytic activity than bacterial suspension from THY broth culture incubated at 30°C (P<0.001). The results are based on assay of 12 independent cultures performed on 3 different days.