Physarum polycephalum, also known as the many headed slime mould, is a single celled Eukaryotic microorganism that grows in damp and dark places where it consumes other microbes, such as fungal spores and bacteria.
Here this yellow pigmented slime mould was given a choice of four naturally pigmented bacteria as its sole source of food, Serratia marcescens (red), Micrococcus luteus (yellow), Arthrobacter polychromogenes (blue) and Chromobacterium violaceum (purple.
After overnight incubation, it had moved towards and begun to assimilate the yellow and blue pigmented bacteria but seemed to be avoiding the red, and to a lesser extent the purple pigmented bacteria
After further incubation, the slime mould continues to assimilate the blue and yellow pigmented bacteria whilst avoiding red.
After further incubation, and having assimilated the yellow and blue pigmented bacteria, the slime mould now begins to feed on the purple pigmented bacterium having avoided it at first.
Eventually it approaches the red pigmented bacterium
Eventually, the slime mould has consumed the yellow, blue and purple pigmented bacteria leaving some pigmented residue but still has not consumed red and sporulates rather than doing so.