In pursuit of their aims and conveying their message, microgeographers (explorers of the urban microbiology) should not shy away from controversy and risk taking. ProkaryPosters are a novel way of conveying microgeography’s message. The print on these posters is made entirely from living and pigmented bacteria (in this case Serratia marcescens). The posters offer great benefits over traditionally printed posters in that the print is entirely natural, biodegradable, and endlessly renewable. Further to this, the use of living biological agents adds a certain frission to the message, means that the posters must be labelled as a biohazard, and cannot be simply removed in that removal requires a specialist biohazard team!