"A study in the July issue of PLoS Pathogens has shown that B.
burgdorferi metabolizes the tick's antifreeze while living in its
midgut. Many arthropods and insects produce large amounts of antifreeze
to protect themselves from freezing temperatures. The Ixodes tick's
antifreeze is glycerol, the same stuff that's often added to enzymes to
keep them from freezing in laboratory
freezers. The amount of glycerol found in other organisms is too low to
serve as antifreeze. I describe below how B. burgdorferi handles
glycerol, but the same enzymes are found in most organisms that
metabolize glycerol, including humans."