Media: Communion Wafer and the red pigmented bacterium Serratia marcescens.
Amongst microbiologists, the bacterium Serratia marcescens is especially noteworthy because of its production of the bright red pigment prodigiosin, and that because of this, its colonies are of a characteristically showy red colour. Very few other bacterial colonies have such a distinctive appearance making this organism very easy to identify on the basis of its colony colour alone. This characteristic, and the bacterium’s natural red aesthetic, has made it attractive to both scientists and artists alike, and it is difficult to imagine another microbe that has had a greater and more direct involvement in the arts. In fact, even before the birth of microbiology, and the discovery of bacteria, the appearance of S. marcescens was being recorded and even inspiring artists.
S. marcescens has a predilection for growing on foodstuffs, particularly those that are rich in starch, where its red-pigmented growth can be easily mistaken for blood. In this context, as long ago as the sixth century B.C., Pythagoras commented on the appearance of a red bloody material on foodstuffs. Another very similar incident was recorded in 332 B.C. at the siege of Tyre in Phoenicia (today’s Lebanon) in which the army of Alexander the Great is reported to have gained inspiration from an omen of what they perceived as drops of blood that oozed out from the bread eaten by the soldiers. Much later on, the combination of starchy Eucharist bread and damp medieval churches provided many ideal growth opportunities for S. marcescens, and many historical episodes of transubstantiation (the teaching of the Catholic Church in which the bread and the wine used in the sacrament of the Eucharist become in reality the body and blood of Christ) have been attributed to the growth of this bacterium and the production of its characteristic red pigment. In one particular episode in 1264, a priest in Bolsena, Italy, was celebrating mass when blood apparently appeared on the communion bread and dripped onto his robe. This was probably the first time that S. marcescens had directly influenced the arts, as the great master painter Raphael commemorated this apparent miracle in his fresco “The Mass of Bolsena”.
This work is a scientific recreation of Transubstantiation. To make it, a Communion Wafer was moistened with water and then inoculated with S. marcescens. From an initial pinpoint inoculation, and after overnight incubation, the red pigmented bacterium had grown and moved through the wafer to form a cross (see image below).
After another 12 hours the bacterium had moved further through the Communion Wafer (see below).
In the final work, the Communion Wafer was heat treated to kill the bacteria and then dried in order to preserve it (see image below)