https://phys.org/news/2018-10-scientists-great-diversity-molecules-microbiome.html

Microbes use natural products primarily as signals to communicate with other microbes or with the host plant. These molecules can trigger bacteria to grow, change, or slow their development. As competition for key resources can be fierce, microbes also secrete natural products as antibiotics to eliminate competitors.

The specific nature of these antibiotics, which often target select bacteria, makes them attractive candidates for use as targeted medicines that could kill the harmful species rather than a broad swath of microbes in a particular community, such as the human gut. The findings provide a starting point for exploring natural products and lay the groundwork for further investigation into the role these molecules play in plant-microbe interactions.