What indicates a positive result in the catalase test?

In the catalase test, a positive result is indicated by the presence of bubbles when hydrogen peroxide is added to the bacterial culture. This reaction occurs because catalase, an enzyme produced by some bacteria, breaks down hydrogen peroxide into water and oxygen gas. The formation of bubbles signifies that the bacteria can produce catalase, effectively detoxifying hydrogen peroxide, which is harmful to cells.

The other options do not indicate a positive catalase reaction. The blue color, colorless solution, and brick red coloration pertain to different biochemical tests and not to the catalase test specifically. Understanding that bubble formation is a direct visual indication of catalase activity helps in identifying catalase-positive organisms during microbiological examinations.