From flagellar motor behavior to bacterial swimming: defining a reference state for motility dynamics in Magnetospirillum gryphiswaldense
Year: 2026
Type: preprint
Abstract: Cell motility is powered by the bacterial flagellar motor, a rotary nanomachine whose activity is dynamically modulated by external stimuli. In Magnetospirillum gryphiswaldense , magnetic and chemical inputs are thought to converge at the level of motility control, yet the mechanisms underlying chemotactic regulation remain poorly understood. Here, we seek to establish a quantitative reference-state of a model strain of magnetotactic bacteria through bacterial flagellar motor dynamics. To achieve this goal, magnetotaxis was kept as a natural factor by keeping the earth’s magnetic field as the only source of magnetism. To avoid aerotaxis bias, oxygen gradients were removed by implementing two different constant oxygen conditions: environmental oxygen exposure, and limited oxygen exposure. Together, the tethered-cell bacterial flagellar rotational assay and the free-swimming assay in the absence of external stimuli presented in this paper establish a framework for investigating motor and cellular swimming adaptation to magnetic, aerotactic, and chemical signals. Under reference-state conditions, the bacterial flagellar motor showed a tendency to exhibit log-normal distributions for the time spent in each motor state: runs in different directions (counter-clockwise and clockwise), and pause. A semi-Markov reference-state model was developed to provide a quantitative description of bacterial flagellar motor dynamics. The model revealed that cell magnetic polarity modulates the transition pathways leading to the paused state, whereas oxygen, in the absence of a gradient, primarily regulates residence in each motility state.
Authors: Diego Roesch, Gabriel Delabre, Émilie Gachon
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7212113432