The most famous of the miracles attributed to S. marcescens is the Miracle of Bolsena in the 13th century. The Holy Eucharist is a ceremony commemorating the last supper Jesus Christ shared with his disciples. During the last supper, Jesus told his disciples to eat, for this was His body, and to drink, for this was His blood. The Roman Catholic Church believes that during the sacrament of the Eucharist, the bread and wine are transformed into the body and blood of Christ. This belief is called the doctrine of transubstantiation. It was expounded in the 9th century and approved by the Council of Rome in 1079 and the Lateran Council in 1215. Nevertheless, the reality of transubstantiation was still a matter of debate in the 13th century. Among those who questioned the reality was a German priest who went on a pilgrimage to Rome in 1263. When the priest stopped at nearby Bolsena, Italy, to celebrate Mass at the church of the Santa Christina, his doubts disappeared when blood dripped from the host onto his linen robe and the altar linen. His attempts to clean his fingers and the altar only smeared the corporal, the purificators, and the marble. Repenting his doubtfulness, the priest took the bloodstained linens and sought absolution from Pope Urban IV, who was summering with his court 12 miles away, in Orvieto. The bloodied host was perceived as a miracle supporting the doctrine of transubstantiation. In 1264, Pope Urban IV issued a papal bull and instituted the feast of Corpus Christi, making the festival an obligation for the Roman Catholic Church. Pope Urban IV also ordered the construction of a new cathedral, where the host and linens are enshrined to this day.

The Miracle of Bolsena was commemorated repeatedly in works of art, the most famous of which is Raphael’s fresco in the Vatican, on the right wall as one enters from the Stanza di Eliodoro. This fresco was the last painted by Raphael for his patron, Pope Julius II, and depicts the Mass of Bolsena with Julius II rather than Urban IV.

The earliest recognition that blood on food may be a natural phenomenon occurred in the 19th century in Savonara, Italy, when Father Pietro Melo was asked to exorcise a house with bloody polenta. Although Melo was a priest, he also had a Ph.D. in botany. He believed in a natural rather than a miraculous explanation for the bloody cornmeal. For a thorough account of the transition from superstition to the evolution of scientific thought on S. marcescens and bloody food, read Gaughran (1969).

In the last decade, microbiologists have grown S. marscecens to simulate the incidents in Bolsena and Savonara. Dr. Joan Bennet and her students grew S. marcescens on Manischewitz Passover matzos and on unconsecrated wafers from the Episcopalian and Roman Catholic churches. The Protestant wafers produced growth that most resembles blood (1). Johanna Cullen cultivated S. marcescens on polenta and sacramental bread in the laboratory and produced similar bloodlike growth (2). This circumstantial evidence is consistent with the notion that the Miracle of Bolsena and other such incidents were simply a manifestation of microbial growth.

To some, the Miracle of Bolsena is no less a miracle despite its microbiological explanation. Since the German priest regained his faith, whether the blood was due to Christ or bacterial growth is deemed immaterial (5). To others, these phenomena had dire consequences. In history, the occurrence of these miracles was accompanied by the persecution or execution of Jews who were accused of desecrating the holy wafers (4). Various art works record the punishment of Jews who were "caught" defiling the sacred bread.

In Microbes, History, and Society, my microbiology course for nonscience majors, my students will be asked to simulate either the Miracle of Bolsena or the bloody polenta in Savonara and Legnaro, Italy. They will work in groups of four to design experiments to determine conditions that produce the bloodiest growth of S. marcesens on Episcopalian wafers or polenta. Some of these conditions should simulate historical accounts of the conditions in the church of the Santa Christina or the homes in Savonara. I chose Episcopalian wafers because they are what I can obtain easily from Goucher’s Episcopalian minister. Students will present their findings in a poster session and celebrate the culmination of their projects by consuming food flavored intentionally not inadvertently by microbes. Of course, we will not be sampling food products that have been altered by psychotropic microbial secondary metabolites.

In my experience, students can learn microbiology without any previous background in biology and chemistry. What better venue to educate students about microbes than a course about how microbes have influenced so many aspects of human history and how much they currently affect our daily lives? For the historical aspects, I start with the origin of life, the origin of sex, the origin of eukaryotic cells. I then fast-forward to the Miracle of Bolsena, the Eleusinian Mysteries, the death throes of the Aztec nation, the conquest of North America, and the impregnability of Africa and end by playing the majestic music composed by musicians who died from infectious diseases. For the significance of microbes in our daily lives, we discuss infectious diseases, microbes in food, microbes and the environment, and how indiscriminate use of antibiotics and the violation of civil rights can lead to emerging infectious diseases. I am working on a book and a Web site for this course; if you have any images, photographs, or references germane to this course, please contact me: leto@Goucher.edu.

References

1. Bennett, J. W. 1994. More on the Miracle of Bolsena. ASM News 60:403.
2. Cullen, J. C. 1994. The Miracle of Bolsena. ASM News 60:187-191.
3. Gaughran, E. R. L. 1969. From superstition to science: the history of a bacterium. Trans. N.Y. Acad. Sci. 31:3-24.
4. Isenberg, H. D. 1995. The other side of the Serratia "miracles." ASM News 61:155.
5. Vaclav, J. K. 1994. Any less a miracle? ASM News 60:579.

© 1999 ASM