Division of labour among genetically identical bacterial subpopulations as an organisational rule driving root microbiota Establishment

• Applicant: Stephane Hacquard, Ph.D.
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems ; Microbial Ecology and Applied Microbiology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 530004127

Unlike multicellular eukaryotic hosts that evolved diverse cell-types to achieve distinct biological functions and promote tasks division, unicellular organisms rely on metabolic exchange with their surrounding biotic environment. Metabolic interdependencies and cross feeding exchanges can occur and explain co-existence within complex bacterial communities. However, a key question is whether populations of genetically identical bacteria can minimize energetically costly processes by executing different metabolic tasks at the subpopulation level. DIVIDE will explore the division of labour between bacterial subpopulations of a core member of A. thaliana root microbiota – Pseudomonas brassicacearum R401 (PsR401) – a robust root colonizer that also modulates microbiota composition at the root interface. Three complementary guiding principles regarding the division of labour in PsR401 population will be explored in the DIVIDE project (1) a transcriptional differentiation among bacterial cells rising from genetic changes within the population to promote population growth (2) a 'noisy regulation' of metabolism mediated by heterogeneous transcriptional reprogramming in bacterial cells within a clonal population (3) a division of labour in the context of three energetically costly metabolic compounds (iron chelators, antimicrobials, and phytotoxins) as a key mechanism to promote PsR401 persistence and competitiveness at roots. By combining a library of transposon mutants, transcriptional reporter lines, novel single cell transcriptomic approaches and microbiota reconstitution experiments in gnotobiotic plant systems, DIVIDE aims to provide a novel understanding of whether metabolic ‘coordination’ within a bacterial population is key for bacterial establishment in the root environment.

• DFG Programme: Research Grants
• International Connection: France
• Cooperation Partners: Professor Philippe Vandenkoornhuyse, Ph.D.; Dr. Nathan Vannier