Microbial phenazines: biosynthesis, structural diversity, evolution, regulation, and biological significance.

SUMMARYPhenazines are small, redox-active secondary metabolites produced by various bacterial species. These compounds participate in electron-transfer reactions, aiding microbes in surviving stressful or oxygen-limited environments. In this review, we examine the extensive structural diversity of phenazines and trace the evolutionary history of their biosynthetic pathways, which often move between distantly related species through horizontal gene transfer. We also explore how environmental factors such as nutrient levels and cell-to-cell signaling regulate phenazine production. Beyond their roles in microbial physiology, phenazines influence interactions among organisms, acting as antimicrobial agents, signaling molecules, and factors that shape microbiome dynamics in soils, plant roots, and other habitats. A better understanding of phenazine biology reveals how microbes adapt and thrive in diverse environments and emphasizes the potential applications of these compounds in agriculture and human health.