Bacterial nanotubes are membranous structures that have been reported to function as conduits between cells to exchange DNA, proteins, and nutrients. Here, we investigate the morphology and formation of bacterial nanotubes using Bacillus subtilis. We show that nanotube formation is associated with stress conditions, and is highly sensitive to the cells' genetic background, growth phase, and sample preparation methods. Remarkably, nanotubes appear to be extruded exclusively from dying cells, likely as a result of biophysical forces. Their emergence is extremely fast, occurring within seconds by cannibalizing the cell membrane. Subsequent experiments reveal that cell-to-cell transfer of non-conjugative plasmids depends strictly on the competence system of the cell, and not on nanotube formation. Our study thus supports the notion that bacterial nanotubes are a post mortem phenomenon involved in cell disintegration, and are unlikely to be involved in cytoplasmic content exchange between live cells.

Department of Microbial Genetics Institute of Molecular Biology Slovak Academy of Sciences 845 51 Bratislava Slovakia

Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences 160 00 Prague 6 Czech Republic

Laboratory of Bioinformatics Core Facility Institute of Microbiology of the Czech Academy of Sciences 142 20 Prague 4 Czech Republic

Laboratory of Microbial Genetics and Gene Expression Institute of Microbiology of the Czech Academy of Sciences 142 20 Prague 4 Czech Republic

Laboratory of Molecular Structure Characterization Institute of Microbiology of the Czech Academy of Sciences 142 20 Prague 4 Czech Republic

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Nat Commun. 2020 Nov 3;11(1):5672. doi: 10.1038/s41467-020-19618-8. PubMed

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