Long-dormant bacteria and viruses trapped in ice and permafrost, which are trapped under a layer of frozen soil, for centuries are recovering as Earth's climate is warming up.
Climate change is melting permafrost territories that have been frozen for thousands of years and as the earth melts, ancient viruses and bacteria that have been dormant are releasing and launching back to life.
A group of scientists discovered ancient viruses frozen in two ice samples taken from the Tibetan Plateau in China, and most of them are unlike anything they have ever seen before. Scientists said that the findings began to freeze at least 15,000 years ago.
“These glaciers were formed gradually, and along with dust and gases, many, many viruses were also deposited in that ice," Zhi-Ping Zhong, a lead author, and researcher at the Ohio State University Byrd Polar and Climate Research Center, said in a statement. "The glaciers in western China are not well-studied, and our goal is to use this information to reflect past environments. And viruses are a part of those environments."
As researchers analyzed the ice, they found genetic codes for 33 viruses. Of the 33, genetic codes for four of them showed they are part of virus families that typically infect bacteria. Up to 28 were novel, meaning they had never before been identified.
It is believed that the viruses did not originate from animals or humans but came from the soil or plants. The scientists said roughly half of them survived because of the ice.
Matthew Sullivan, the co-author of the study and director of Ohio State’s Microbiome Science Center, said that these viruses would have thrived in extreme environments. He also added that these viruses have signatures of genes that help them infect cells in cold environments – just surreal genetic signatures for how a virus can survive in extreme conditions.
Some bacteria grow at 4ºC. These bacteria never die at 4ºC. But some bacteria grow at 37ºC. These bacteria never grow at 4ºC. Refrigeration slows down their metabolism. When bacterial metabolism slows down, it never grows and divides. It becomes dormant. But when optimal conditions arrive, bacteria grow and start the division.
Freezing may kill bacteria. When bacteria grow at 0ºC or below this temperature, it freezes the bacterial cell. The water content of the cell converts into crystals. Crystallization of water content produces spikes that can rupture the cell membrane and whole-cell content move outside from the cell. It causes the death of bacterial cells.