An updated view of metabolic handoffs in microbiomes

From the human gut to the deep ocean, diverse microbial communities underpin essential ecosystem processes. Limited understanding of the dynamics and interactions that shape these communities, however, constrains efforts to culture, investigate, and harness their potential. Further, these knowledge gaps restrict the ability to predict microbial responses to broader biodiversity declines and global change. Among the numerous types of microbial interactions, metabolite exchanges, or 'metabolic handoffs', are a well-documented phenomenon. Recent methodological advances have uncovered a broader spectrum of metabolic handoffs than previously appreciated. Varying in both mechanism and ecological role, metabolic handoffs influence diverse natural environments. In this review, we define two major types of metabolic handoffs, examine their potential drivers and benefits, and highlight emerging research that underscores their widespread occurrence and importance in complex microbial ecosystems.