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In a groundbreaking study, scientists have successfully extracted and analyzed DNA from ancient cheese samples found alongside mummies in the Tarim Basin, China, dating back approximately 3,600 years. This remarkable research, published on September 25 in the journal Cell, not only suggests a new origin for kefir cheese but also provides insights into the evolution of probiotic bacteria.

Dr. Qiaomei Fu, the lead author and researcher at the Institute of Vertebrate Paleontology and Paleoanthropology, emphasizes the significance of this discovery: "This is the oldest known cheese sample ever discovered in the world. Studying ancient cheese can help us better understand our ancestors' diet and culture."

The cheese was originally found on the mummies at the Xiaohe cemetery, prompting speculation about its identity. After more than a decade of advances in DNA analysis, Fu's team extracted mitochondrial DNA from samples across three tombs, identifying cow and goat DNA. Notably, the ancient Xiaohe people utilized different animal milks separately, contrasting with the mixing practices common in Middle Eastern and Greek cheesemaking.

The researchers confirmed that the white substances were kefir cheese, identifying bacteria and fungi, including Lactobacillus kefiranofaciens and Pichia kudriavzevii, both present in modern kefir grains. This discovery provides a direct link to the fermentation techniques of the past, akin to how sourdough starters function today.

Through genetic sequencing, the team compared ancient and modern strains of Lactobacillus kefiranofaciens. They found that the ancient strain was more closely related to Tibetan varieties, challenging the notion that kefir originated solely in Russia's North Caucasus region. Fu notes, "Our observation suggests kefir culture has been maintained in Northwestern China's Xinjiang region since the Bronze Age."

The study also revealed how Lactobacillus kefiranofaciens exchanged genetic material over time, enhancing its stability and fermentation capabilities. Remarkably, modern strains are less likely to trigger immune responses in humans, indicating adaptation through centuries of interaction.

"This unprecedented study allows us to observe how a bacterium evolved over the past 3,600 years," Fu concludes. "We hope to explore other unknown artifacts with this technology." This discovery not only illuminates the past but also highlights the intricate relationship between humans and their food.

The ancient cheese from the Tarim Basin not only represents a culinary relic but also serves as a pivotal point for understanding the evolution of probiotics and ancient human diets. As researchers delve deeper into this fascinating field, the ultimate revelations about our ancestors' lives and their food practices are just beginning to unfold.