- ex. testing antiobiotic resistance
- Putting bacteria on antibiotic plate. If any growth they are antibiotic resistant.
- Positive selection entails the growing the culture on a medium that will alow for the growth of only the mutant colonies
.If, for example, we want to find mutants that resistant to penicillin, we grow the culture on a medium that contains pencillin. Only those colonies that are resistant to penicillin will grow and we ca identify them directly