Distribution of the insertion sequence IS1 in Gram-negative bacteria

Abstract
The distribution of the insertion sequence IS1 in various bacteria, particularly members of the family Enterobacteriaceae is reported. Comparision of the results with the phylogenetic relationship of these bacteria suggests that IS1 was transferred from one bacterium to another after their divergence and in some bacteria the copy number of IS1 increased by translocation. The increase in the number of copies of IS1 in bacteria may increase the probability of the genetic rearrangement responsible for the generation of resistance and enterotoxin plasmids, the existence of which is a serious problem in medical microbiology. [Bacteria studied included the gram-negative bacteria Escherichia coli, Serratia marcescens, Salmonella typhimurium, Edwardsiella tarda (E. anguillimortifera), Enterobacter aerogenes, Klebsiella aerogenes (K. pneumoniae), Proteus mirabilis, P. morganii, Shigella dysenteriae, S. sonnei, S. boydii, S. flexneri, Pseudomonas aeruginosa, Acinetobacter sp., Myxococcus xanthus, Erwinia amylovora, Caulobacter crescentus and the gram-positive bacterium Bacillus subtilis.].