Bacterial filaments recover by successive and accelerated asymmetric divisions that allow rapid post‐stress cell proliferation

Abstract

Filamentation is a reversible morphological change triggered in response to various stresses that bacteria might encounter in the environment, during host infection or antibiotic treatments. Here we re‐visit the dynamics of filament formation and recovery using a consistent framework based on live‐cells microscopy. We compare the fate of filamentous Escherichia coli induced by cephalexin that inhibits cell division or by UV‐induced DNA‐damage that additionally perturbs chromosome segregation. We show that both filament types recover by successive and accelerated rounds of divisions that preferentially occur at the filaments' tip, thus resulting in the rapid production of multiple daughter cells with tightly regulated size. The DNA content, viability and further division of the daughter cells essentially depends on the coordination between chromosome segregation and division within the mother filament. Septum positioning at the filaments' tip depends on the Min system, while the nucleoid occlusion protein SlmA regulates the timing of division to prevent septum closure on unsegregated chromosomes. Our results not only recapitulate earlier conclusions but provide a higher level of detail regarding filaments division and the fate of the daughter cells. Together with previous reports, this work uncovers how filamentation recovery allows for a rapid cell proliferation after stress treatment.

Spatial mapping of mobile genetic elements and their bacterial hosts in complex microbiomes

“…While it is possible that these filamentous cells are not Veillonella and thus both the Veillonella 16S rRNA-FISH probes and the termL probes bind off-target, we suggest it is also possible that this large area termL signal reveals active phage replication and that the long filamentous morphology is a stress response of Veillonella to infection as we have observed in E. coli (for example, Fig. 1c, 20 min MOI 0.01 and 0.1) and others have demonstrated with other stressors 35 .…”

Differential requirement for RecFOR pathway components in Thermus thermophilus

“…The filamentation phenotype has been associated to RuvABC defects and other recombination function mutations (RecA, RecB, RecD, RecO, RecG, and others) in E. coli (Buljubašić et al, 2013; Ishioka et al, 1998; Zahradka et al, 1999; Zahradka et al, 2023) and in B. subtilis (Carrasco et al, 2004; Torres et al, 2017), commonly under DNA damage conditions, while in our case, important filamentation occurs in the absence of DNA damage. Filamentation has been detected so recurrently that it has even been proposed that it may be a post‐stress recovery mechanism (Cayron et al, 2023). Regarding the signalling leading to blocked cell division, it is worth noticing that in Tth there are no annotated genes equivalent to those of LexA, SulA, SlmA, Noc, YneA or SidA (Henne et al, 2004), which, in most studied bacteria, are key players for septum formation inhibition and, therefore, avoiding possible guillotine effect on the genome (Burby & Simmons, 2020; Wu & Errington, 2012).…”

The F pilus serves as a conduit for the DNA during conjugation between physically distant bacteria

“…Time lapse experiments into microfluidics chambers. Time lapse imaging in a microfluidic chamber is performed as previously described (Nolivos et al, 2019;Couturier et al, 2023;Cayron et al, 2023). Conjugation sample were obtained by mixing 50 µl of the pre-labelled donor and 50 µl of recipient into and Eppendorf tube, then 50 µl of conjugation mix was loaded into a B04A microfluidic chamber (ONIX, CellASIC®).…”