Transposon insertion elements have been reported to increase the fitness of gram-negative "E. coli" strains through either major transpositions or genome rearrangements, and increasing mutation rates. In a study on the effects of long-term exposure of simulated microgravity on non-pathogenic "E. coli", the results showed transposon insertions occur at loci, linked to SOS stress response. When the same "E. coli" strain was exposed to a combination of simulated microgravity and trace (background) levels of (the broad spectrum) antibiotic (chloramphenicol), the results showed transposon-mediated rearrangements (TMRs), disrupting genes involved in bacterial adhesion, and deleting an entire segment of several genes involved with motility and chemotaxis. Both these studies have implications for microbial growth, adaptation to and antibiotic resistance in real time space conditions.