Gattaca is a surprisingly smart 1997 science fiction film dealing with genetic discrimination. Learning that the sequence GATTACA occurs 697,000 times in the human genome sparked my curiosity: What is the longest contiguous (natural) sequence of GATTACAs I can find? The answer, as it turns out, is five.
We find five consecutive occurrences of GATTACA in Botryotinia fuckeliana, the rarely observed teleomorph (i.e., sexual form) of Botrytis cinerea. (The fuckeliana name is derived, incidentally, from the mycologist Karl Wilhelm Gottlieb Leopold Fuckel.)