Catalase is not present in all Streptococcus species.

Catalase is not present in all Streptococcus species.

• A. True
• B. False
• C. Not sure
• D. Only in pathogenic strains

Answer: (A)

Catalase is the enzyme that breaks down hydrogen peroxide into water and oxygen, a reaction that produces noticeable bubbles if present. In clinical microbiology, this difference is used to separate Staphylococcus (catalase positive) from Streptococcus (catalase negative). Streptococcus species do not produce catalase, so the enzyme is not present in these bacteria. Because of that, the statement that catalase is not present in all Streptococcus species is accurate—the genus as a whole lacks catalase activity. In practice, a catalase test on Streptococcus cultures would show no bubbling when hydrogen peroxide is added.

Catalase is the enzyme that breaks down hydrogen peroxide into water and oxygen, a reaction that produces noticeable bubbles if present. In clinical microbiology, this difference is used to separate Staphylococcus (catalase positive) from Streptococcus (catalase negative). Streptococcus species do not produce catalase, so the enzyme is not present in these bacteria. Because of that, the statement that catalase is not present in all Streptococcus species is accurate—the genus as a whole lacks catalase activity. In practice, a catalase test on Streptococcus cultures would show no bubbling when hydrogen peroxide is added.