Microbe species can be chosen for their natural colours to form a palette for the artwork. Suitable species of bacteria (with their colours) include Bacillus subtilis (cream to brown), Chromobacterium violaceum (violet), Escherichia coli (colourless), Micrococcus luteus (yellow), Micrococcus roseus (pink), Proteus mirabilis, Pseudomonas aeruginosa (brown), Pseudomonas fluorescens (naturally blue-green fluorescent with pyoverdine), Serratia marcescens (pink or orange), Staphylococcus aureus (yellow), and Vibrio fischeri (bioluminescent).[5]