Applying high-throughput rRNA gene sequencing to assess microbial contamination of a 40-year old exposed archaeological profile

We used 16S rRNA gene sequencing to evaluate microbial contamination of exposed archeological profiles at Crvena Stijena, a rock shelter in the Dinaric alps in Montenegro that contains archaeological deposits spanning 80,000+ years. Excavations in the early 1960s exposed profiles that have been cleaned several times to permit sampling for archaeological, geological, and biomolecular analyses. The growth of green biofilms on the exposed profiles after cleaning has prompted the question of whether this surface contamination penetrates into the profile. We examined microbial communities from five different geological layers by sampling sediments from the exposed surface and at 1 cm intervals horizontally into the profile.