Why do alpha streptococci produce a green color on blood agar?
All of the different streptococci are organized into three groups based on how they break down red blood cells, a process called hemolysis. The group of streptococci that perform alpha hemolysis are called alpha streptococci. In alpha hemolysis, the hydrogen peroxide produced by the streptococci oxidizes the blood's hemoglobin, turning it into methemoglobin, which is green in color.