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 enzyme catalase converts hydrogen peroxide (H2O2) to water and O2. The evolution of O2 causes bubbling. Thus, catalase-positive organisms that are mixed into hydrogen peroxide will cause bubbling (catalase-negative organisms will not). This test is good for distinguishing between Gram-positive cocci in chains (catalase negative) versus Gram-positive cocci in clusters (catalase positive).