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Raising the Dead: New Species of Life Resurrected from Ancient Andean Tomb

Ecuadorian scientists have revived a new species of yeast from pre-Incan tomb, illuminating prehistoric life



R. Douglas Fields

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QUITO, ECUADOR—Long before the Spanish conquered the Incas in 1533, and centuries before the Incas inhabited this area, the present-day site of Quito International Airport was a marshy lake surrounded by Indian settlements—the Quitus on one shore and the Ipias on the other. Between A.D. 200 and 800 these cultures prospered here, fishing the lake, growing corn, beans and potatoes in the fertile soil, and fermenting an alcoholic drink—chicha—made of a watery corn broth.

In 1980, while clearing land for new construction in a warren of graffiti-covered cinderblock shanties bristling with barbwire and defended by concrete walls tipped with broken glass, workers scraped open a tomb that had been hidden for over a millennium beneath the ramshackle neighborhood. Then, nine more deep-welled tombs were uncovered in the volcanic rock, each containing about 20 bodies. The walls of the shafts were lined with Quitus remains, each one crouched in the fetal position, clothed in the finest textile, adorned with gold jewelry, and surrounded by pottery containing offerings of food and chicha for the afterlife.

Yeast biologist Javier Carvajal Barriga, of the Pontificia Universidad Católica del Ecuador in Quito, collected scrapings from inside large, torpedo-shaped clay fermentation vessels taken from one of the tombs in an attempt to recover microbes that had fermented the ancient chicha and, if possible, revive them.

» View a Slide Show of Tombs in Ecuador Where Ancient Yeast Was Found

Under the sterile conditions of his laboratory, he scratched away the surface layers from inside the fermentation vessels hoping to collect yeast trapped deep in the pottery's pores. Using a special method that he devised to humidify the desiccated cells, repair their damaged membranes, and jump-start their arrested metabolisms, he coaxed a community of yeasts, which had lain dormant in the entombed vessels since A.D. 680, back to life. Carvajal says he resurrected "a consortium of yeasts" from the containers, but none of the yeasts were  Saccharomyces cerevisiae—the type used in modern fermentation. They were primarily strains of the genus Candida, closely related to the well-known yeast that causes skin and vaginal infections. But careful genetic analysis showed that two strains of yeast were a new species of Candida, which he named C. theae, meaning "tea."

These findings confirm 16th-century reports of how indigenous people in the Ecuadorian Andes fermented their chicha. According to Spanish chroniclers, Inca Indians initiated fermentation using animal bones, human saliva and even human feces.

"The most closely related species to C. theae are C. orthopsilosis, C. metapsilosis and C. parapsilosis, all of which are found in human saliva and feces," Carvajal says.  Indeed he found human-associated C. parapsilosis, along with C. tropicalis, among the community of yeast in the ancient fermentation vessels. C. parapsilosis is the second-most commonly isolated pathogenic species of Candida infecting people. "Also [there are] the Crytococcus saitoi and C. laurentii that are related to respiratory diseases. They [the Quitus] were chewing and spitting the corn [into the fermentation vessels], so we can assume this population probably had some respiratory problems caused by pathogenic yeasts."

These species of yeast can produce alcohol up to 4 percent in strength but, unlike S. cerevisiae, Candida dies when alcohol levels reach higher concentrations. S. cerevisiae is not common in the South American environment because it is most widely associated with oak trees, which are not indigenous to the region, so the Indians utilized Candida. "It is much better to have 3 to 4 percent alcohol than nothing," Carvajal says.

Caravajal fermented his own chicha from C. tropicalis that he resurrected from fermentation vessels taken from the tomb to relive the experience of these prehistoric Indians. "The flavor was very good. The aroma was very good. The alcohol was relatively good, but the effect was horrible. Just two drinks of this chicha and I had this bad headache typical of aldehydes and esters."

He also recovered Rhodotorula mucilaginosa from the ancient fermentation vessels. Although one of the most abundant yeast species, it does not produce alcohol, rather it is associated with flowering plants, evidence that the Quitus folded flowers into the brew for flavor enhancement—and most likely to increase the kick of their low-alcohol drink: Adding plants such as Datura produces psychotropic effects.

"Chicha must be drunk young, while it is still fermenting, because it quickly develops a rancid taste with time," Carvajal says. "But if you drink it too early in the fermentation process, you will experience food poisoning because the bacteria, amoeba and harmful yeasts have not yet been killed off by the alcohol."

After much searching, I was able to sample a modern version of chicha in Mama Clorinda Ecuadorian Food, a Quito restaurant. It was made from cooked corn, cinnamon, orange leaves, coriander and several other ingredients, including rotten pineapple skin added to initiate fermentation in the mix, which was contained in a plastic gallon-size jug. The cloudy yellow brew looked like a drink from an organic juice bar. It smelled of spicy cardamom and cinnamon, and fruity papya and fermented pineapple. It tasted delightful: lightly carbonated, with a sweet pineapple and papaya flavor, and a thick body and a clean finish.

"This is only about 2 to 3 percent alcohol," I was told by the restaurant manager, Roberto Guoma, "because we made it today. By tomorrow it will be 4 to 5 percent." The chef, Nelson Cardenas, who makes the chicha daily, generously provided his recipe for readers interested in brewing their own chicha, which uses rotten pineapple rind to initiate fermentation:

Recipe: Morocho Chicha

  1. 0.45 kilograms of morocho corn flour
  2. 500 grams of brown sugar (panela)
  3. Aromatic herbs (lemon verbena, cedron (quassia family, Simaroubaceae, native to Colombia and Central American), leaves of the orange tree
  4. 10 grams whole cloves
  5. Five grams cinnamon sticks
  6. Five grams allspice
  7. 250 grams white sugar
  8. Skin of one pineapple

1.    Boil two liters of water
2.    Mix the morocho corn flour in one half liter of water and mix with the two liters of boiling water. Boil for 10 minutes.
3.    Boil two liters of water and add the herbs, orange tree leaves, cloves, cinnamon and allspice. Cook for 10 minutes and strain out liquid.
4.    Combine the water–corn mix with the water–herb mix. Strain and add the pineapple skin.
5.    Ferment for one day.
6.    Check the consistency of the drink and add more water as needed. Add the brown sugar and white sugar until sweetened to taste. Add ice and serve.

(Translated by Claudia Alderman)

Global yeast?
Recalling of the movie Jurassic Park, one wonders about the potential dangers of reviving an ancient pathological microbe that could produce a modern plague. "There exists the possibility," he says, but Carvajal thinks that these species have been living with man for thousands of years." Indeed, that suspicion proved to be true.

Simultaneously, on the other side of the globe two cases of bottled tea were found clouded with contamination in 2010. The manufacturer sent the bottles to Ching-Fu Lee at the National Hsinchu University of Education, one of the few yeast taxonomists in Taiwan. He identified the contaminant as a new species of Candida and began to write a paper describing his discovery. During the peer review process, the anonymous reviewer suggested that Lee check the National Institutes of Health GenBank database. There he found the genetic sequence of the new species of Candida that Carvajal had recovered from the ancient fermentation vessel. Lee immediately contacted Carvajal, along with the latter's collaborator Stephen James, a yeast taxonomist at the Institute of Food Research in England, and the three teams of scientists jointly published their paper in the February issue of the International Journal of Food Microbiology.

But how did the identical yeast turn up simultaneously in Taiwan and Quito? "I don't think this is a beverage-related yeast, I think it is a human-related yeast," Carvajal says. "We know now that there were contacts between Polynesians and South American peoples. [Polynesians] departed from Taiwan 6,000 years ago."

Carvajal cites the example of another new yeast he has discovered, C. fodens, to buttress his argument. The yeast was collected in Australia, Costa Rica and Ecuador's Galápagos Islands. Genetic analysis shows that the yeast from all three Pacific locations are identical. "It is very hard to imagine that such a distance was covered by one single strain," he says. "This yeast is tightly associated with the flowers of the sweet potatoes. This probably has some relation with human migration, because we know that sweet potatoes come from the Andes. We are using yeasts to track human migration and contacts. That is part of what we call 'microbiological archaeology.'"

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