The Rhizosphere Microbiome: A Playground for Natural Product Chemists

The threat of antibiotic-resistant bacteria is an ongoing battle that continues to confound scientists and doctors alike. Reinvestigation of past methods has led to the interrogation of natural microbiomes with the goal of identifying the survival mechanisms employed by its local inhabitants. One such example is that of the rhizosphere; home to many microorganisms capable of producing a variety of essential compounds, such as cyclic lipopeptides, siderophores, quorum sensing molecules, and antibiotics. The intricacies of this ongoing battle inspired our synthetic efforts toward a species-specific natural product, promysalin, isolated from the rhizosphere of a rice plant in Sri Lanka. Recently, our group completed the total synthesis, absolute structural assignment, and identified unique bioactivity. These efforts have informed our insights toward its mechanism of action and role within the rhizosphere.