Midichloria mitochondrii is a species of bacteria which infects the ovaries of the tick species Ixodes ricinus. Unusually, it specifically infects the mitochondria, structures found within individual cells which release energy from organic compounds. The infection seems to have no effect on the ticks.
Australian researcher Nate Lo, then working at the University of Milan, was the first researcher to discover and describe the organisms. In May 2006, now at the University of Sydney, he and his colleagues submitted a paper to International Journal of Systematic and Evolutionary Microbiology, describing the bacteria and suggesting the name Midichloria mitochondrii. The paper was accepted and published in December 2006.
The name was a reference to the midi-chlorians, organisms described in the Star Wars prequel trilogy as being present inside all living cells, and being responsible for communicating the Force's will. While their paper was being reviewed, Lo's team submitted the suggested name to George Lucas, and received a reply from Lucas's assistant which gave permission for them to name the bacterium for the midi-chlorians.
Since midi-chlorians are believed to have been modeled after real-world mitochondria, and mitochondria are thought to have evolved from free-living bacteria which were incorporated into more complex cells, naming a bacterium which infects mitochondria after midi-chlorians is doubly appropriate.