Which method can be used to differentiate pathogenic bacteria based on metabolic characteristics?

The method that can be used to differentiate pathogenic bacteria based on metabolic characteristics is biochemical tests. Biochemical tests involve assessing the metabolic activities of bacteria, such as their ability to ferment sugars, produce gas, hydrolyze starch, or utilize specific substrates. This information is crucial because different bacterial species exhibit unique metabolic profiles, which can be used for identification and differentiation.

For instance, certain bacteria may ferment lactose while others may not, which helps in distinguishing between species, like Escherichia coli and Salmonella. The metabolic pathways and reactions can be measured using various media and biochemical indicators that reveal the presence of enzymes specific to certain bacteria.

In contrast, antibiotic susceptibility testing evaluates the effectiveness of antibiotics against bacteria, which does not primarily focus on their metabolic characteristics. Serological tests rely on antibody-antigen interactions and are useful in identifying specific pathogens but do not directly measure metabolic activities. Visual inspection under a microscope provides morphological characteristics but lacks the specificity required to differentiate based on metabolic processes.