Transposable elements

Stretches of DNA able to move from one genomic site to another — within the same replicon or a different one in the same cell. They need no extensive sequence similarity with their target sites. Transposable elements are ordinary residents of chromosomes, plasmids, and phage genomes in both prokaryotes and eukaryotes; some home in on specific targets while others insert seemingly at random. In food microbiology they drive the spread of antibiotic-resistance genes and the instability of engineered strains — a starter culture’s prized trait can vanish when a transposon hops — making strain stability a selection criterion.