Dataset of phototactic response kinetics of Chlamydomonas reinhardtii

The directed movement of microorganisms towards light is called
phototaxis-a fundamental process shown by many uni- and multi-cellular
photosynthetic microorganisms for their survival and growth. Here, we
determine the time-dependent response of a population of model phototactic
single-celled algae Chlamydomonas reinhardtii to changing light
conditions. When the condition changes from dark to light, we show that
the response of a dark-adapted isotropic population depends on not just
the light intensity but also on the cell number density. On the other
hand, when conditions change from light to dark, the time dependence of
the recovery from an aligned state to an isotropic state is independent of
cell density and light intensity. We find that such kinetics emerge from
the coupling between flagellar dynamics, cell speed, and incident photon
flux. We further show that existing minimal non-interacting models, that
robustly describe the steady state properties of populations of
Chlamydomonas under given light conditions, capture this time-dependent
phenomenon only for dilute suspensions.