What is a carbohydrate utilization profile?

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A carbohydrate utilization profile measures what sugars a microbe can use for energy, producing a characteristic pattern of substrate metabolism that helps identify the organism. In practice, many different carbohydrates are tested separately on the same platform, each with a readout such as a pH indicator. When a microbe metabolizes a sugar, it often produces acid (and sometimes gas), causing a color change in that well. The overall pattern of positive and negative results across all tested sugars becomes the utilization profile.

This is a metabolic test, not a genetic sequencing assay, not a test of antibiotic susceptibility, and not simply a measure of how fast a species grows on standard medium. Different organisms have distinct capabilities for fermenting or oxidizing certain sugars, so their profiles can distinguish them—even among closely related species. For example, a microbe that ferments glucose and lactose but not sucrose will show positives and negatives in a specific combination that helps identify it.