microswimmer) density constant, we varied E. coli (pusher-type microswimmer) density in a high throughput manner using
an 8-well microchamber (Micro-Slide, ibidi, Germany) and recorded
time-lapse videos for 9 h. C. reinhardtii can be effectively tracked in 3D because of their intrinsic autofluorescence
properties, with live imaging to extract various quantitative information.
The 3D trajectories were generated by using a Nikon NIS 3D object
tracking module. The motions of the mixed microswimmer populations
were examined inside a custom-made microscope chamber slide harboring
8 wells (bottom thickness = 150 μm) for high-throughput analysis.
The microscopy investigation was performed with a Zeiss Axio Observer
A1 inverted microscope with an Axiocam 503 CCD camera and a 40×
(numerical aperture = 0.6) objective lens. The microalgae and bacteria
cocultures were illuminated by using a red filter with an emission
peak at 655 nm, and a bandwidth of 15 nm (655/15 BrightLine HC, AHF
Analysentechnik, Tübingen, Germany), to prevent phototactic
biased motion of the microalgae and thus to avoid false-positive results.15 (link)