Final answer:
Beta-hemolysis in a blood agar test signifies the complete lysis of red blood cells and release of hemoglobin, resulting in a clear zone around bacterial colonies such as hemolytic Streptococcus.
Step-by-step explanation:
Complete destruction of red blood cells (RBCs) and hemoglobin (Hb) in a blood agar test is known as beta-hemolysis. This result is characterized by a transparent zone in the agar surrounding the bacterial colonies, indicating that the RBCs have been fully lysed and Hb has been released. An example of bacteria capable of beta-hemolysis is hemolytic Streptococcus, which is commonly used to diagnose Streptococcal infections. Other forms of hemolysis include alpha-hemolysis, which is a partial lysis causing a greenish discoloration in the agar due to the conversion of Hb to methemoglobin, and gamma-hemolysis (y-hemolysis), which shows no change in the agar indicating no lysis of RBCs.