Clostridioides difficile Single Cell Swimming Strategy: A Novel Motility Pattern Regulated by Viscoelastic Properties of the Environment

Abstract

Flagellar motility is important for the pathogenesis of many intestinal pathogens, allowing bacteria to move to their preferred ecological niche. Clostridioides difficile is currently the major cause for bacterial health care-associated intestinal infections in the western world. Most clinical strains produce peritrichous flagella and are motile in soft-agar. However, little knowledge exists on the C. difficile swimming behaviour and its regulation at the level of individual cells. We report here on the swimming strategy of C. difficile at the single cell level and its dependency on environmental parameters. A comprehensive analysis of motility parameters from several thousand bacteria was achieved with the aid of a recently developed bacterial tracking programme. C. difficile motility was found to be strongly dependent on the matrix elasticity of the medium. Long run phases of all four motile C. difficile clades were only observed in the presence of high molecular weight molecules such as polyvinylpyrrolidone (PVP) and mucin, which suggests an adaptation of the motility apparatus to the mucin-rich intestinal environment. Increasing mucin or PVP concentrations lead to longer and straighter runs with increased travelled distance per run and fewer turnarounds that result in a higher net displacement of the bacteria. The observed C. difficile swimming pattern under these conditions is characterised by bidirectional, alternating back and forth run phases, interrupted by a short stop without an apparent reorientation or tumbling phase. This motility type was not described before for peritrichous bacteria and is more similar to some previously described polar monotrichous bacteria.

Bacterial Motility and Its Role in Skin and Wound Infections

“…Chemical gradients are sensed by chemoreceptors, which trigger the autophosphorylation of the cytoplasmic CheA, which forms a complex with the receptor through the coupling protein CheW [ 33 , 41 ]. In response to these changes, CheA transfers its phosphate group to CheY, a diffusible cytoplasmic response regulator that interacts with the flagellar motor and leads to a modulation of motility characteristics [ 33 , 41 ]. This signalling core is highly conserved among all chemotaxis pathways [ 42 ].…”

“…Although only a fraction of bacteria associated with animal hosts are motile, flagellar motility and chemotaxis are important for the successful colonisation and virulence of many pathogens, for example, gastrointestinal Campylobacter jejuni , Salmonella enterica serovar Typhimurium, Helicobacter pylori , and Vibrio cholerae [ 41 ]. In several cases, it has also been shown that the same flagellin, the protein subunit comprising the bacterial flagellum, can be a major driver of inflammation [ 35 ].…”

“…Although the term twitching refers to fast incoherent movements, there are studies that show that single cells moving with T4P can move in one direction for over an hour, and individual T4P compounds generate a force of approximately 100–150 pN [ 31 , 65 , 66 , 67 ]. Moreover, the cell speed during twitching may vary from approximately 0.02 µm/s to 0.16 µm/s, which depends on environmental conditions, for example, the number of pili involved, the surface, oxygen conditions, and the chemotactic factor [ 33 , 40 , 41 , 43 ]. Studies indicated that twitching can be induced chemotactically and/or mechanotactically; in P. aeruginosa , this signalling is suggested in both cases to be attributed to the Chp operon [ 66 , 68 ].…”

Clostridioides difficile minimal nutrient requirements for flagellar motility

“…We recently investigated single cell motility and swimming behavior of C. difficile with the aid of a bacterial tracking program (YSMR), which generates quantitative data on motility parameter such as speed, turning points and run lengths, simultaneously from several hundred bacteria ( Schwanbeck et al, 2020 ). We could demonstrate that every motile C. difficile clade requires specific visco-elastic properties of the medium in order to display flagellar driven swimming motility ( Schwanbeck et al, 2021 ). A motility pattern with long run phases only occurred when the matrix elasticity was increased by high molecular weight molecules, as for example, polyvinylpyrrolidones (PVP) or mucins.…”

“…A motility pattern with long run phases only occurred when the matrix elasticity was increased by high molecular weight molecules, as for example, polyvinylpyrrolidones (PVP) or mucins. The motility behavior of C. difficile appears thus to be well adapted to the mucin-rich mucosal layer of the gastrointestinal tract ( Schwanbeck et al, 2021 ).…”