Sezmis, A. | Search bioRxiv

bioRxiv2025

De Novo Genome Assembly and Characterization of Plant Growth-Promoting Rhizobacteria isolated from field grown Canola Plants

Plant growth-promoting rhizobacteria have the potential to reduce reliance on synthetic fertilizers. Yet the rhizosphere microbiome of canola (Brassica napus) remains understudied despite the crops global significance. In this study, we isolated and characterized 12 bacterial strains from canola roots, to better understand the diversity and potential agricultural benefits of the canola microbiome. Using a combination of long- and short-read whole-genome sequencing, we generated high-quality genome assemblies of all 12 bacterial species. Genomic analysis revealed genes linked to nitrogen fixation, phosphorus solubilization and phytohormone production, suggesting these bacterial strains may play beneficial roles in plant growth and resilience. Growth assays showed that most isolates proliferated in the presence of canola root exudates, indicating their adaptation to the rhizosphere. Several strains also exhibited nitrogen fixation traits, including growth in nitrogen-deficient media and ammonium production, yet bacterial inoculation did not significantly enhance early seedling development under nitrogen-limited conditions. Our findings expand the current knowledge of the diversity and functional potential of the canola microbiome and highlight promising bacterial candidates for development as biofertilizers or biocontrol agents, with implications for improving soil health and canola productivity.

microbiology↗

bioRxiv2021

Long-term experimental evolution decouples size and production costs in Escherichia coli

Body size covaries with population dynamics across lifes domains. Theory holds that metabolism imposes fundamental constraints on the coevolution of size and demography. However, studies of interspecific patterns are confounded by other factors that covary with size and demography, and experimental tests of the causal links remain elusive. Here we leverage a 60,000-generation experiment in which Escherichia coli populations evolved larger cells to examine intraspecific metabolic scaling and correlations with demographic parameters. Metabolic theory successfully predicted the relations among size, metabolism, and maximum population density, with strong support for Damuths law of energy equivalence in this experiment. In contrast, populations of larger cells grew faster than those of smaller cells, contradicting the fundamental assumption that costs of production should increase proportionately with size. The finding that the costs of production are substantially decoupled from size requires re-examining the evolutionary drivers and ecological consequences of biological size more generally.

evolutionary biology↗