To tax or not to tax? Parallels between chemotaxis and phoretic responses of bacterial spores

Chemotaxis is the phenomenon that a cell's locomotion direction is determined by a gradient of one or more chemicals.[1] Understanding chemotaxis is relevant for many processes that control our well-being: inflammation, neuronal patterning, wound healing, tumor dissemination in cancer, and even embryogenesis.
It is assumed that the molecular mechanisms that control fundamental aspects of chemotaxis appear to be evolutionarily conserved.[2] For this reason studies in lower eukaryotic models have helped massively to understand working principles, uncover molecular attractants and signalling substances and test a variety of chemotactic models and strategies.
A recently developed setup allows the study of physical principles that lead to chemotaxis in simple artificial active matter[3] revealing phoretic principles that underly this phenomenon. How these principles might have affected early bacteria, giving some a slight evolutionary advantage which could have paved the way towards the development of most simple detection principles, has been rarely in the focus of research.
Now, we aim at closing the loop by studying the behaviour of both, motile bacteria and their spores[4] in chemical gradients.