Bacteria use type IV pili to walk upright and detach from surfaces
ABSTRACT Bacterial biofilms are structured multicellular communities involved in a broad range of infections. Knowing how free-swimming bacteria adapt their motility mechanisms near surfaces is crucial for understanding the transition between planktonic and biofilm phenotypes. By translating microscopy movies into searchable databases of bacterial behavior, we identified fundamental type IV pili-driven mechanisms for Pseudomonas aeruginosa surface motility involved in distinct foraging strategies. Bacteria stood upright and "walked" with trajectories optimized for two-dimensional surface exploration. Vertical orientation facilitated surface detachment and could influence biofilm morphology.
Full-textDOI: · Available from: Maxsim L Gibiansky, Aug 10, 2015
- SourceAvailable from: Jacinta C Conrad
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- "As wild-type bacteria detach at a higher rate from the surface than either appendage-deficient mutant, the launch sequence and other mechanisms of appendage cooperation may enhance the ability of bacteria to redistribute on surfaces and thereby affect the morphology of biofilms as they form. Some support for this idea is found in flow-cell experiments: TfP-deficient bacteria, which lack the launch sequence and cannot easily detach, form large clusters at the surface sites at which they originally attach, whereas wild-type bacteria that can freely detach and redistribute form a uniform and thin layer of cells (Gibiansky et al., 2010). In addition, P. aeruginosa bacteria that have flagella and TfP exhibit a higher probability of detaching from surfaces at short times when exposed to shear flow than appendage-deficient mutants (Lecuyer et al., 2011). "
ABSTRACT: We review physically-motivated studies of bacterial near-surface motility driven by flagella and type IV pili (TfP) in the context of biofilm formation. We describe the motility mechanisms that individual bacteria deploying flagella and TfP use to move on and near surfaces, and discuss how the interactions of motility appendages with fluid and surfaces promote motility, attachment and dispersal of bacteria on surfaces prior to biofilm formation. (C) 2012 Published by Elsevier Masson SAS on behalf of Institut Pasteur.Research in Microbiology 10/2012; 163(9-10). DOI:10.1016/j.resmic.2012.10.016 · 2.83 Impact Factor
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- "These studies illustrate that outer membrane proteins and surface appendages play an important role in bacterial motility. However, there have been no previous reports on how fimbriae affect bacterial motility (Gibiansky et al 2010). Since motility is crucial to bacterial invasion (Betts and Finlay 1992 ) , antiphagocytosis ( Amiel et al 2010) and virulence ( Meng et al 2011 ), studying the the first step of infection ( Baker et al 2009, Evans et al 1975 ). "
ABSTRACT: Enterotoxigenic Escherichia coli CFA/I is a protective antigen and has been overexpressed in bacterial vectors, such as Salmonella Typhimurium H683, to generate vaccines. Effects that overexpressed CFA/I may engender on the bacterial host remain largely unexplored. To investigate, we constructed a high CFA/I expression strain, H683-pC2, and compared it to a low CFA/I expression strain, H683-pC, and to a non-CFA/I expression strain, H683-pY. The results showed that H683-pC2 was less able to migrate into semisolid agar (0.35%) than either H683-pC or H683-pY. Bacteria that migrated showed motility halo sizes of H683-pC2 < H683-pC < H683-pY. In the liquid culture media, H683-pC2 cells precipitated to the bottom of the tube, while those of H683-pY did not. In situ imaging revealed that H683-pC2 bacilli tended to auto-agglutinate within the semisolid agar, while H683-pY bacilli did not. When the cfaBE fimbrial fiber encoding genes were deleted from pC2, the new plasmid, pC2(-), significantly recovered bacterial swimming capability. Our study highlights the negative impact of overexpressed CFA/I fimbriae on bacterial swimming motility.Physical Biology 05/2012; 9(3):036005. DOI:10.1088/1478-3975/9/3/036005 · 3.14 Impact Factor
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ABSTRACT: Bradyrhizobium japonicum bacteroids in soybean nodules expressed fibrillar appendages during senescence. In both scanning and transmission electron microscopy (SEM and TEM), these structures were observed to connect adjacent bacteroids, and bacteroids to symbiotic membranes. They were 20–25 nm in diameter, 100–2,500 nm in length and were linear, branched, or part of a web-like matrix. Bacteroids expressing appendages were not uniformly distributed, but were abundant within localized regions in the senescing nodule. The root systems of nodulated greenhouse-grown plants flushed with argon induced the appendages at earlier plant ages, and they were more prolific and wide spread than those in untreated nodules. Bradyrhizobium japonicum symbiotic appendages appear to be a response to an environmental niche within senescing nodules.Symbiosis 06/2011; 54(2). DOI:10.1007/s13199-011-0132-4 · 0.94 Impact Factor