A team of investigators recently sequenced the microbiome of a mummy from the Incan capital of Cuzco. The mummy, a female between the ages of 18 and 23, was discovered in the mid 1800s. The team, consisting of researchers from the University of Pisa and California Polytechnic State University (among others) sequenced DNA fragments recovered from the mummy’s gut. They found sequences from a number of pathogens, as well as evidence of antibiotic resistance genes.
The human gut typically contains bacteria from three major groups: the Firmicutes, Bacteroidetes, and Proteobacteria. The Firmicutes are Gram-positive, and the Bacteroidetes and Proteobacteria are Gram-negative. In line with this, species of Gram-positive Streptococcus
, and Bacillus
were found in the mummy’s gut, and well as species of Gram-negative Pseudomonas
. In addition, the group found DNA sequences from Clostridium botulinum
type B, which causes food-borne illness.
The mummy also showed evidence of viral and parasitic disease. They found sequences consistent with human papillomavirus
types 21 and 49, as well as evidence that the mummy had Chagas’ disease
. Chagas’ disease is caused by the eukaryotic parasite Trypanosoma cruzi
. The parasites are transmitted by insects known as “kissing bugs
”. Chronic Chagas’ disease results in enlargement of the esophagus and colon, both of which were found in the mummy.
The researchers were most surprised to find sequences from antibiotic resistance genes. They found evidence of beta-lactamase genes (beta-lactamases provide resistance to antibiotics such as penicillin) and vancomycin resistance genes. It's not surprising that bacteria had such resistance genes, since penicillin and vancomycin are naturally-occurring antibiotics. What is surprising is that these genes appear to have been prevalent even before the modern use of antibiotics.
Sources: Discovery News
, PLOS One