뉴스&공지 KAIST Graduate School of Engineering Biology

Root exudate “super-consumers” for next-generation agricultural biologicals

Across agriculture, bacterial inoculants protect against stress, improve plant growth, deliver nutrients, fight pathogens, and repel insects. These bacterial survive in the rhizosphere by consuming carbon compounds secreted by the roots (exudates). Different exudates are produced at different times in the season and under different environmental stresses. Because not all bacteria consume all exudates, this variability leads to farm-to-farm inconsistency and lower total function in the field. Here, we engineer the root-colonizing bacterium Klebsiella variicola into a catabolic “super-consumer” that can utilize a broader set of root-derived carbon sources. Guided by phenotypic characterization, we introduced catabolic pathways for six root-associated metabolites (25 recombinant genes total), enabling robust growth on each substrate. By expanding the catabolic repertoire of a nitrogen-fixing bacterium, this work aims to improve rhizosphere persistence and nutrient exchange, ultimately increasing microbially supplied nitrogen to crops. This approach provides a path to more reliable microbial inoculants and reduced dependence on synthetic nitrogen fertilizers.