Structural and functional properties of bacterial communities associated with rootless duckweed (Wolffia globosa) and their effect on the Wolffia growth.

Background: Rootless duckweed, Wolffia globosa, is emerging as a high-protein and starch biomass resource for various applications. However, the microbiomes and functional properties associated with Wolffia across a wide range of microbial sources remain largely unexamined. This study investigates the structure and functioning of the Wolffia microbiome and its impact on plant growth.

Results: A co-cultivation experiment with axenic W. globosa and bacterial communities derived from various sources revealed varied effects, that municipal wastewater-derived bacterial communities had a more pronounced positive effect on growth of W. globosa compared to those from pond water. 16S rRNA amplicon sequencing found that Beijerinckiaceae, Caulobacteraceae, Comamonadaceae, Methylophilaceae, Rhizobiaceae, and Sphingomonadaceae were consistently conserved and identified as core taxa in the Wolffia microbiome. Functional profiling indicated that genes related to bacterial colonization and adaptation to the rootless morphology contribute to selective microbiome recruitment, with enriched functions in motility, chemotaxis, flagella assembly, quorum sensing, and ABC transporters. In addition, it was found that Bdellovibrionaceae, Beijerinckiaceae, and Sphingomonadaceae may act as "hub microorganisms" and "keystone taxa," shaping community structure and directly or indirectly influencing Wolffia growth.

Conclusion: Collectively, the results of this study unveiled the robust core taxa and functional profiles of the Wolffia microbiome across diverse microbial sources, with certain taxa differing from those in rooted duckweed. This study comprehensively characterizes the Wolffia microbiome and enhances understanding of it, providing insights for developing efficient biomass production systems.