What key feature differentiates a natural antibiotic from a synthetic one?

A key feature that distinguishes natural antibiotics from synthetic ones is that natural antibiotics are derived from living organisms. These substances are typically produced by fungi, bacteria, or other microorganisms as part of their natural processes to inhibit the growth of competing species or to establish niches in their environment. This natural origin is crucial because it reflects an evolved interaction within ecosystems, where these organisms have developed compounds to enhance their survival.

In contrast, synthetic antibiotics are chemically manufactured and may be designed to mimic natural compounds or to enhance certain properties, but they do not come directly from living microorganisms. The effectiveness of natural antibiotics can vary and is not inherently superior to synthetic ones. Additionally, while some synthetic antibiotics may be inspired by natural substances, it is not accurate to state that they have no natural counterparts, as many are based on naturally occurring molecules. Finally, synthetic antibiotics can be derived from other sources and are not limited to those derived from bacteria alone. Thus, the focus on the origin of natural antibiotics highlights their unique relationship with living organisms.