Redox-active antibiotics enhance phosphorus bioavailability

Microbial production of antibiotics is common, but our understanding of their roles in the environment is limited. In this study, we explore long-standing observations that microbes increase the production of redox-active antibiotics under phosphorus limitation. The availability of phosphorus, a nutrient required by all life on Earth and essential for agriculture, can be controlled by adsorption to and release from iron minerals by means of redox cycling. Using phenazine antibiotic production by pseudomonads as a case study, we show that phenazines are regulated by phosphorus, solubilize phosphorus through reductive dissolution of iron oxides in the lab and field, and increase phosphorus-limited microbial growth. Phenazines are just one of many examples of phosphorus-regulated antibiotics. Our work suggests a widespread but previously unappreciated role for redox-active antibiotics in phosphorus acquisition and cycling.