Adhesion of Chlamydomonas microalgae to surfaces is switchable by light

Abstract

Although microbial responses to light have been widely recognized, any influence of light on cell-surface interactions remains elusive. Here, we reveal that the unspecific adhesion of microalgae to surfaces can be reversibly switched on and o by light. Using a micropipette force spectroscopy technique, we measured in vivo single-cell adhesion forces and show that the microalga's flagella provide light-switchable adhesive contacts with the surface. This light-induced adhesion to surfaces is an active and completely reversible process that occurs on a timescale of seconds. Our results suggest that light-switchable adhesiveness is a natural functionality of microalgae to regulate the transition between the planktonic and the surface-associated state, which yields an adhesive adaptation to optimize the photosynthetic e ciency in conjunction with phototaxis.

In vivoadhesion force measurements ofChlamydomonason model substrates

“…26,27 In a previous study, we report on our discovery that the flagella-mediated adhesion of Chlamydomonas to surfaces can be reversibly switched on and off by light. 28 We showed that the adhesion force of up to several nanonewton in white light is reduced to zero in red light conditions. Although we were able to identify light as a key requirement for the surface colonization, the intermolecular interactions that govern the adhesion of Chlamydomonas to surfaces remained elusive.…”

Dynamic force measurements on swimming Chlamydomonas cells using micropipette force sensors

“…A thin slab of silicon cut from a wafer (type P/Bor, orientation 100 , resistivity 120 Ωcm, unilateral polished, Si-Mat, Germany) has been glued onto a custom-made stainless steel substrate holder with PDMS. Substrate [30,33]. The micropipette cantilever, furnished with a tube and syringe filled with deionised water, was mounted onto a 3axis piezo-driven manual micromanipulator (PCS-5400, Burleigh, Thorlabs, USA) and inserted into the liquid cell.…”

“…In principle, forces can be measured simultaneously through the deflection of the micropipette. However, previous works utilizing such micropipette force sensors [30][31][32][33][34][35][36] were limited to quasistatic measurements. In this case the damping of the micropipette cantilever by hydrodynamic drag forces remains negligible, and forces can be directly recovered from the cantilever deflection and its static spring constant.…”

The Development of Biophotovoltaic Systems for Power Generation and Biological Analysis

“…[79] However, these may influence factors such as adherence of the cells to the anode, cell-cell connection in a biofilm, and phototaxis. [79,80] They may therefore have an effect on DEET without being directly involved in the electron transfer pathway.…”