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Object-adapted optical trapping and shape-tracking of energy-switching helical bacteria


Optical tweezers are a flexible manipulation tool used to grab micro-objects at a specific point, but a controlled manipulation of objects with more complex or changing shapes is hardly possible. Here, we demonstrate, by time-sharing optical forces, that it is possible to adapt the shape of the trapping potential to the shape of an elongated helical bacterium. In contrast to most other trapped objects, this structure can continuously change its helical shape (and therefore its mechanical energy), making trapping it much more difficult than trapping tiny non-living objects. The shape deformations of the only 200-nm-thin bacterium (Spiroplasma) are measured space-resolved at 800 Hz by exploiting local phase differences in coherently scattered trapping light. By localizing each slope of the bacterium we generate high-contrast, super-resolution movies in three dimensions, without any object staining. This approach will help in investigating the nanomechanics of single wall-less bacteria while reacting to external stimuli on a broad temporal bandwidth.

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Figure 1: Principles of space-variant trapping and tracking of a complex three-dimensional structure.
Figure 2: Interferometric tracking signals varying with time.
Figure 3: Three-dimensional representation of measured and simulated shape deformations.
Figure 4: Time-dependent transitions between ground and excited levels of mechanical energy.
Figure 5: Local phase changes induced by the bacterium.


  1. Dholakia, K. & Reece, P. Optical micromanipulation takes hold. Nano Today 1, 18–27 (2006).

    Article  Google Scholar 

  2. Hell, S. W. Far-field optical nanoscopy. Science 316, 1153–1158 (2007).

    Article  ADS  Google Scholar 

  3. Gustafsson, M. G. L. Surpassing the lateral resolution limit by a factor of two using structured illumination microscopy. J. Microsc. 198, 82–87 (2000).

    Article  Google Scholar 

  4. Xu, W. B., Jericho, M. H., Meinertzhagen, I. A. & Kreuzer, H. J. Digital in-line holography for biological applications. Proc. Natl Acad. Sci. USA 98, 11301–11305 (2001).

    Article  ADS  Google Scholar 

  5. Lee, S.-H. & Grier, D. G. Holographic microscopy of holographically trapped three-dimensional structures. Opt. Express 15, 1505–1512 (2007).

    Article  ADS  Google Scholar 

  6. Pralle, A., Prummer, M., Florin, E.-L., Stelzer, E. H. K. & Hörber, J. K. H. Three-dimensional position tracking for optical tweezers by forward scattered light. Microsc. Res. Tech. 44, 378–386 (1999).

    Article  Google Scholar 

  7. Rohrbach, A. & Stelzer, E. H. K. Three-dimensional position detection of optically trapped dielectric particles. J. Appl. Phys. 91, 5474–5488 (2002).

    Article  ADS  Google Scholar 

  8. Dreyer, J. K., Berg-Sorensen, K. & Oddershede, L. Improved axial position detection in optical tweezers measurements. Appl. Opt. 43, 1991–1995 (2004).

    Article  ADS  Google Scholar 

  9. Speidel, M., Friedrich, L. & Rohrbach, A. Interferometric 3D tracking of several particles in a scanning laser focus. Opt. Express 17, 1003–1015 (2009).

    Article  ADS  Google Scholar 

  10. Friedrich, L. & Rohrbach, A. Improved interferometric tracking of trapped particles using two frequency detuned beams. Opt. Lett. 35, 1920–1922 (2010).

    Article  ADS  Google Scholar 

  11. Kress, H., Stelzer, E. H. K. & Rohrbach, A. Tilt angle dependent three-dimensional-position detection of a trapped cylindrical particle in a focused laser beam. Appl. Phys. Lett. 84, 4271–4273 (2004).

    Article  ADS  Google Scholar 

  12. Irrera, A. et al. Size-scaling in optical trapping of silicon nanowires. Nano Lett. 11, 4879–4884 (2011).

    Article  ADS  Google Scholar 

  13. Min, T. L. et al. High-resolution, long-term characterization of bacterial motility using optical tweezers. Nature Methods 6, 831–U871 (2009).

    Article  Google Scholar 

  14. Rowe, A. D., Leake, M. C., Morgan, H. & Berry, R. M. Rapid rotation of micron and submicron dielectric particles measured using optical tweezers. J. Mod. Opt. 50, 1539–1554 (2003).

    Article  ADS  Google Scholar 

  15. Chattopadhyay, S., Moldovan, R., Yeung, C. & Wu, X. L. Swimming efficiency of bacterium Escherichia coli. Proc. Natl Acad. Sci. USA 103, 13712–13717 (2006).

    Article  ADS  Google Scholar 

  16. Dombrowski, C. et al. The elastic basis for the shape of Borrelia burgdorferi. Biophys. J. 96, 4409–4417 (2009).

    Article  ADS  Google Scholar 

  17. Wang, S. Y., Arellano-Santoyo, H., Combs, P. A. & Shaevitz, J. W. Actin-like cytoskeleton filaments contribute to cell mechanics in bacteria. Proc. Natl Acad. Sci. USA 107, 9182–9185 (2010).

    Article  ADS  Google Scholar 

  18. Ashkin, A. & Dziedzic, J. M. Optical trapping and manipulation of viruses and bacteria. Science 235, 1517–1520 (1987).

    Article  ADS  Google Scholar 

  19. Gilad, R., Porat, A. & Trachtenberg, S. Motility modes of Spiroplasma melliferum BC3: a helical, wall-less bacterium driven by a linear motor. Mol. Microbiol. 47, 657–669 (2003).

    Article  Google Scholar 

  20. Wolgemuth, C. W., Igoshin, O. & Oster, G. The motility of mollicutes. Biophys. J. 85, 828–842 (2003).

    Article  Google Scholar 

  21. Shaevitz, J. W., Lee, J. Y. & Fletcher, D. A. Spiroplasma swim by a processive change in body helicity. Cell 122, 941–945 (2005).

    Article  Google Scholar 

  22. Bastian, F. O. et al. Spiroplasma spp. from transmissible spongiform encephalopathy brains or ticks induce spongiform encephalopathy in ruminants. J. Med. Microbiol. 56, 1235–1242 (2007).

    Article  Google Scholar 

  23. Trachtenberg, S. & Gilad, R. A bacterial linear motor: cellular and molecular organization of the contractile cytoskeleton of the helical bacterium Spiroplasma melliferum BC3. Mol. Microbiol. 41, 827–848 (2001).

    Article  Google Scholar 

  24. Trachtenberg, S. The cytoskeleton of Spiroplasma: a complex linear motor. J. Mol. Microbiol. Biotechnol. 11, 265–283 (2006).

    Article  Google Scholar 

  25. Kurner, J., Frangakis, A. S. & Baumeister, W. Cryo-electron tomography reveals the cytoskeletal structure of Spiroplasma melliferum. Science 307, 436–438 (2005).

    Article  ADS  Google Scholar 

  26. Rohrbach, A. Stiffness of optical traps: quantitative agreement between experiment and electromagnetic theory. Phys. Rev. Lett. 95, 168102 (2005).

    Article  ADS  Google Scholar 

  27. Faucheux, L. P., Stolovitzky, G. & Libchaber, A. Periodic forcing of a Brownian particle. Phys. Rev. E 51, 5239–5250 (1995).

    Article  ADS  Google Scholar 

  28. Nambiar, R. & Meiners, J. C. Fast position measurements with scanning line optical tweezers. Opt. Lett. 27, 836–838 (2002).

    Article  ADS  Google Scholar 

  29. Neuman, K. C., Chadd, E. H., Liou, G. F., Bergman, K. & Block, S. M. Characterization of photodamage to Escherichia coli in optical traps. Biophys. J. 77, 2856–2863 (1999).

    Article  Google Scholar 

  30. Seitz, P. C., Stelzer, E. H. K. & Rohrbach, A. Interferometric tracking of optically trapped probes behind structured surfaces: a phase correction method. Appl. Opt. 45, 7903–7915 (2006).

    Article  Google Scholar 

  31. Born, M. & Wolf, E. Principles of Optics 5th edn (Cambridge Univ. Press, 1975).

    Google Scholar 

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The authors thank S. Trachtenberg, F. Hamprecht, J. Huisken and L. Friedrich for stimulating discussions, as well as J. Korvink, B. Tränkle, F. Fahrbach, F. Kohler, B. Landenberger and B. Bosworth for a careful reading of the manuscript. This study was supported by the Excellence Initiative of the German Federal and State Governments (EXC 294) and by the Deutsche Forschungsgemeinschaft (DFG) (grant nos RO 3615/1 and RO 3615/2).

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Authors and Affiliations



M.K. performed experiments and simulations, analysed data and prepared all graphs. A.R. initiated and supervised the project, designed the system, developed the theory and wrote the manuscript.

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Correspondence to Alexander Rohrbach.

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The authors declare no competing financial interests.

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Koch, M., Rohrbach, A. Object-adapted optical trapping and shape-tracking of energy-switching helical bacteria. Nature Photon 6, 680–686 (2012).

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