Pestalozzi, C. | Search bioRxiv

bioRxiv2026

ZeaMiC: a Publicly Available Culture Collection of Maize Root-Associated Bacteria

Plant-associated microbiota are composed of hundreds of microbial species. For many of them, little is known about their individual functions and even less is known about their emergent community-level traits. While culture-independent methods provide valuable insights into the composition, diversity, and functional potential of plant-associated microbiota, culture-dependent methods are essential for reductionist lines of inquiry into the roles of individual species and their interactions within a community. Here, we present ZeaMiC, a publicly available culture collection of root-associated bacteria from Zea mays (maize). This resource comprises 88 isolates obtained from diverse soils and several maize genotypes, with live cultures available through DSMZ (German Collection of Microorganisms and Cell Cultures) both as single stocks and as cost-effective bundles (https://www.dsmz.de/collection/catalogue/microorganisms/microbiota/zeamic). To maximize relevance, isolates were selected to be representative of maize root-associated microbiomes in the Corn Belt of the United States, based on abundance-occupancy patterns from previously published root microbiome data, phylogenetic diversity, and literature-based evidence of functional importance. Whole-genome sequencing and annotation revealed genes associated with root colonization, plant growth promotion, and nutrient cycling, including functions such as chemotaxis, biofilm formation, secretion systems, hormone modulation, and phosphate solubilization. This collection serves as a community resource for future mechanistic studies of plant-microbe and microbe-microbe interactions, filling the gap in our understanding of the ecological interactions in plant microbiomes.

microbiology↗

bioRxiv2025

Synthetic communities of maize root bacteria interact and redirect benzoxazinoid metabolization

Plant roots are colonised by diverse microbial communities. These communities are shaped by root exudates including plant specialized metabolites. Benzoxazinoids are such secreted compounds of maize. Individual microbes differ in their ability to tolerate and metabolize antimicrobial benzoxazinoids. To investigate how these traits combine in a community, we designed two synthetic communities of maize root bacteria that share six common strains and differ in their ability to metabolize benzoxazinoids based on the seventh strain. We exposed both communities to the benzoxazinoid MBOA (6-methoxybenzoxazolin-2(3H)-one) and found that the metabolizing community did not degrade MBOA to its aminophenoxazinone, as observed for individual strains, but as a community they formed the corresponding acetamide. MBOA shaped differential compositions of both communities and increased the fraction of MBOA-tolerant strains. The benzoxazinoid metabolizing community showed a higher tolerance to MBOA and was able to utilize MBOA as their sole carbon source for growth. Hence, bacterial interaction results in alternative benzoxazinoid metabolization and increases community performance in presence of these antimicrobial compounds. Future work is needed to uncover the genetics of this metabolic interaction and ecological consequences for the bacterial community and the host plant. ImportanceWe investigated how maize root bacteria - alone or in community - tolerate and metabolize antimicrobial compounds of their host plant. We found the capacity to metabolize such a compound to impact bacterial community size and structure and most importantly, to beneeit community eitness. We also found that interacting bacteria redirected the metabolisation of the antimicrobial compound to an alternative degradation product. Our work highlights the need to study the team work of microbes to uncover their community traits to ultimately understand the ecological consequences for the bacterial community and eventually the host plant.

microbiology↗