Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 79: Microswimmers, Active Liquids II (joint session CPP, BP, DY)

CPP 79.7: Talk

Friday, March 20, 2015, 11:15–11:30, C 264

Low-tech, high-throughput tracking of bacteria in 3D — •Katja Taute, Sander Tans, and Tom Shimizu — FOM Institute AMOLF, Science Park 102, Amsterdam 1098XG, The Netherlands

Many bacteria swim in liquids and execute complex motility patterns. The increasingly recognized diversity of motility strategies has sparked a growing interest in their characterization via 3D tracking. The only 3D tracking techniques thus far to have passed the benchmark of resolving the model bacterium E. coli's run-tumble motility suffer from being limited to single individuals [1]; and/or are technically challenging and require specialized experimental setups [1,2,3].

Here we present a broadly applicable high-throughput 3D bacterial tracking technique which requires only a standard biological phase contrast microscope. We exploit the relationship between an object's distance to the focal plane (z) and the observed intensity pattern, and assign z positions by maximizing image cross-correlations to a reference stack. We achieve micron-scale resolution in z, <0.5 μm resolution in x and y, a range of ~350x300x200 μm (x,y,z), a throughput of tens of bacteria, and a temporal resolution that is only limited by the detector readout rate. We demonstrate the application of this technique to a range of bacterial species, verify that we recover previously observed motility patterns, and reveal that bacterial individuality, rather than stochasticity, underlies the broad population distribution observed for a key motility parameter of V. alginolyticus.

[1] Berg & Brown, Nature 239:500, 1972. [2] Vater et al., PLoS ONE 9:e87765, 2014. [3] Molaei et al., PRL 113:068103, 2014.