Archeology meets clinical microbiology: Analysis of the microbial content of soil from archeological sites in Italy and Belize

Background: Soil was obtained from pottery near Lecce, Italy, and from Lubaantun, Belize. We compared the microbial contents of the 2 soil specimens. Methods: Soil from each site, mixed thoroughly, was solubilized with phosphate buffer and used for culture and microscopy by standard methods. Cultures for aerobic and anaerobic bacteria, acid-fast bacilli, fungi, and actinomycetes were done at 22°C and 35°C. Stains included Gram, methylene blue, calcofluor white, Ziehl-Neelsen, trichrome, iodine, Grocott-Gomori methenamine-silver, and modified acid-fast. Results: Soil from Lecce: Only grampositive bacilli were seen microscopically. Many spp. of Bacillus were recovered. Aeromonas caviae complex, Aspergillus niger, A. versicolor, Clostridium bifermentans, C. butyricum, Mycobacterium avium, and several unidentified fungi were recovered. Soil from Lubaantun: Rare gram-positive bacilli were seen microscopically. Clostridium bifermentans, C. innocuum, C. tetani, Bacillus cereus group, Pantoea agglomerans, Aspergillus flavus, Penicillium sp., Chaetomium sp., Chrysosporium sp., Acremonium sp., Streptomyces sp., and Gordonia sp. were recovered in culture. Conclusion: While we noted that cultures and microscopy of the microbial flora of soil from these 2 archeological sites revealed somewhat similar findings, the flora from the Lubaantun site was more complex.