The virulence mechanism of capsule as a bacterial structure is ANTI-PHAGOCYTIC AND ANTI-COMPLIMENTARY so that means the organism is not destroyed by the phagocytes and the complement system
Incomplete destruction of the RBCs and that will cause greenish brown discoloration to the blood agar medium brought about by the oxidation of the hemoglobin molecule or the formation of methemoglobin in the blood agar medium