Isolated thunderstorms are when there are either thunderstorms present at the current time or there is a change for them to form, but they are scattered. These usually occur in the afternoon and the evening when the sun is out at its peak and heats up the atmoshpere.
For example, bacteria from the genus Salmonella are mostly facultative anaerobes, oxidase-negative, catalase-positive and gramnegative rods. Most strains are motile and ferment glucose with production of both acid and gas.
The presence of catalase enzyme in the test isolate is detected using hydrogen peroxide. If the bacteria possess catalase (i.e., are catalase-positive), when a small amount of bacterial isolate is added to hydrogen peroxide, bubbles of oxygen are observed. The catalase test is done by placing a drop of hydrogen peroxide on a microscope slide. Using an applicator stick, a scientist touches the colony, and then smears a sample into the hydrogen peroxide drop. If the mixture produces bubbles or froth, the organism is said to be 'catalase-positive'.