2 - BACTERIOWEB

Chromosomal genes
Efflux systems in E. coli
– 37 putative drug transporters: 19 MFS, 3 SMR, 7 RND, 7 ABC,
1 MATE
– 20 pumps are able to transport toxic/antibiotic molecules
– 15-17 pumps may provide with some resistance to antibiotics when
overproduced from cloned genes (Nishino K et al. J. Bacteriol. 2001)
– Most of these intrinsic systems are not expressed in standard
laboratory growth conditions
– Spontaneous mutations may result in stable overproduction of a
single pump and resistance
Foreign genes
– Genes carried by mobile elements (plasmids, transposons)
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