Raoultella planticola
Raoultella planticola was a bacterium.
History
In 2017, Agrofuel Research Operations genetically modified an sample of the bacteria using the enzyme EC 31. It was meant to break down the root system of a plant. Due to a misplaced decimal point, the bacteria became world-ending by killing life forms completely and turning it into "gunk" though in both the vision of the future and the greenhouse some dead plants were not turned into gunk.
The bacteria produced ethanol, which filled the greenhouse, as well as the lab. When the lab's vent systems cycled, it would be released into the Earth's atmosphere and destroy all life on Earth within a year as predicted by the Monks. The Twelfth Doctor destroyed the bacteria and saved the Earth by blowing up half of the lab the bacteria was created in, the fire burning the bacteria away. (TV: The Pyramid at the End of the World)
While aiding the Doctor, his companion Nardole was contaminated by the bacteria. Due to his alien physiology, he survived, but it left him too sick to do anything for six weeks. (TV: The Pyramid at the End of the World, The Lie of the Land)
Alternate Timeline
In an alternate timeline predicted by the Monks, the bacteria was released onto the Earth and wiped out all life on the planet. After seeing a vision of this timeline, the Twelfth Doctor stated that the Earth was "as dead as the Moon." The only living things that hadn't been turned to gunk appeared to be a few dead trees amongst the devastation. (TV: The Pyramid at the End of the World)
Behind the scenes
Although the complete name of the bacteria is not given on-screen, the name "R. planticola" can be seen on the screen of Agrofuel's computer.
