Delayed onset and heterogeneous collective organization characterize twitching motility in Acinetobacter baumannii
Abstract
Type IV pili (T4P) mediate twitching motility and contribute to surface colonization, biofilm formation, and host interactions in Acinetobacter baumannii . However, the prevalence, dynamics, and diversity of twitching motility across A. baumannii populations remain poorly understood. Here, we compared twitching motility in a collection of 35 A. baumannii strains originating from clinical, environmental, and animal sources, using Pseudomonas aeruginosa PAO1 as a reference. Standardization of assay conditions revealed a strong influence of agar composition on twitching motility, with Eiken agar supporting the most robust surface translocation. Under these conditions, 14 of 35 A. baumannii isolates exhibited detectable twitching motility. Time-lapse microscopy revealed major differences between A. baumannii and P. aeruginosa . Whereas PAO1 initiated twitching within minutes after inoculation and formed characteristic multicellular rafts, motile A. baumannii strains displayed a prolonged non-motile phase before movement initiation and exhibited distinct patterns of collective organization. Two major expansion phenotypes were identified, termed Homogeneous Front (HF) and Raft-Like Front (RLF), together with Early-Onset Motility (EOM) and Delayed-Onset Motility (DOM) subgroups. Quantitative analyses further revealed substantial variation in speed, directional persistence, and migration dynamics among strains. Because a majority of isolates were non-motile, we investigated the contribution of the minor pilin FimT. Although deletion of fimT abolished twitching motility and specific substitutions modulated motility efficiency, sequence variation in FimT alone could not account for the observed phenotypic diversity. Collectively, these findings reveal extensive heterogeneity in T4P-mediated surface motility in A. baumannii and identify delayed twitching activation and distinct collective migration strategies as key features of surface colonization in this species. Highlights Population analysis reveals extensive twitching diversity in A. baumannii Delayed motility onset distinguishes A. baumannii from P. aeruginosa Homogeneous and raft-like fronts define distinct migration strategies FimT contributes to motility but not all non-motile phenotypes
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BibTeX
@misc{dessenne2026delayed,
title = {{Delayed onset and heterogeneous collective organization characterize twitching motility in Acinetobacter baumannii}},
author = {Clara Dessenne and Anaïs Henriques and Adeline Courseaux and Corentin Spriet and David Dauvillée and Olivier Vidal and Yannick Rossez},
howpublished = {HAL},
year = {2026},
month = jul,
doi = {10.64898/2026.07.01.735841},
url = {https://hal.science/hal-05794513v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Delayed onset and heterogeneous collective organization characterize twitching motility in Acinetobacter baumannii
AU - Clara Dessenne
AU - Anaïs Henriques
AU - Adeline Courseaux
AU - Corentin Spriet
AU - David Dauvillée
AU - Olivier Vidal
AU - Yannick Rossez
PY - 2026
DA - 2026/07/01
PB - HAL
DO - 10.64898/2026.07.01.735841
UR - https://hal.science/hal-05794513v1
AB - Type IV pili (T4P) mediate twitching motility and contribute to surface colonization, biofilm formation, and host interactions in Acinetobacter baumannii . However, the prevalence, dynamics, and diversity of twitching motility across A. baumannii populations remain poorly understood. Here, we compared twitching motility in a collection of 35 A. baumannii strains originating from clinical, environmental, and animal sources, using Pseudomonas aeruginosa PAO1 as a reference. Standardization of assay conditions revealed a strong influence of agar composition on twitching motility, with Eiken agar supporting the most robust surface translocation. Under these conditions, 14 of 35 A. baumannii isolates exhibited detectable twitching motility. Time-lapse microscopy revealed major differences between A. baumannii and P. aeruginosa . Whereas PAO1 initiated twitching within minutes after inoculation and formed characteristic multicellular rafts, motile A. baumannii strains displayed a prolonged non-motile phase before movement initiation and exhibited distinct patterns of collective organization. Two major expansion phenotypes were identified, termed Homogeneous Front (HF) and Raft-Like Front (RLF), together with Early-Onset Motility (EOM) and Delayed-Onset Motility (DOM) subgroups. Quantitative analyses further revealed substantial variation in speed, directional persistence, and migration dynamics among strains. Because a majority of isolates were non-motile, we investigated the contribution of the minor pilin FimT. Although deletion of fimT abolished twitching motility and specific substitutions modulated motility efficiency, sequence variation in FimT alone could not account for the observed phenotypic diversity. Collectively, these findings reveal extensive heterogeneity in T4P-mediated surface motility in A. baumannii and identify delayed twitching activation and distinct collective migration strategies as key features of surface colonization in this species. Highlights Population analysis reveals extensive twitching diversity in A. baumannii Delayed motility onset distinguishes A. baumannii from P. aeruginosa Homogeneous and raft-like fronts define distinct migration strategies FimT contributes to motility but not all non-motile phenotypes
ER -