Dependence of swarming in Escherichia coli K-12 on spermidine and the spermidine importer


  • Editor: Robert Burne

Correspondence: Shin Kurihara, Japan Collection of Microorganisms, Microbe Division, RIKEN BioResource Center, Wako, Saitama 351-0198, Japan. Tel.: +81 48 462 111; fax: +81 48 462 4618; e-mail:


In a previous work, it was observed that the swarming of polyamine-deficient Proteus mirabilis (speB::sm) was severely inhibited on Luria–Bertani (LB) swarming plates (LBSw) (LB, 0.5% glucose, 0.5% agar), and it was clarified that extracellular putrescine was important as a signaling molecule for the induction of swarming in P. mirabilis. However, a polyamine-deficient strain (delta-speAB delta-speC) of Escherichia coli swarmed as well as the parental strain on LBSw plates. We report that the swarming phenotype of a polyamine-deficient E. coli strain is dependent on spermidine and PotABCD, a spermidine importer.