Answer :
Final answer:
Serotyping differentiates bacterial strains based on their cell surface antigens, while phage typing uses the susceptibility of strains to specific viruses (bacteriophages) to distinguish them.
Explanation:
Serotyping and Phage Typing:
While agarose gel electrophoresis is a technique used to separate DNA fragments based on size for genomic typing, there are other methods such as serotyping and phage typing used for bacterial strain characterization. Serotyping differentiates bacterial strains based on their cell surface antigens, typically proteins or carbohydrates, which elicit an immune response. Different strains having distinct surface antigens are grouped into different serotypes. Phage typing, on the other hand, utilizes bacteriophages, which are viruses that infect bacteria. This method identifies bacterial strains based on their susceptibility to different phages. Each phage will only infect specific bacterial strains, so the pattern of susceptibility can be used to differentiate between strains.