earticle

영어

Enterohemorrhagic (EHEC) Escherichia coli O157:H7 is a human pathogen responsible for outbreaks of hemorrhagic colitis causing bloody diarrhea that can lead to the hemolytic-uremic syndrome in many countries. Among EHEC serotype O157:H7, two strains of EDL933
(ATCC43895 Stx1+ and Stx2+) and 86-24 (Stx2+) were investigated in regards to biofilm formation on abiotic surface. Strikingly, EDL933strain forms a strong biofilm while 86-24 strain forms no
biofilm. In order to investigate the mechanisms of biofilm formation of these two EHECs, DNA microarrays were performed. In the comparison of the EDL933 strain versus 86-24 strain, genes (csgBAC and csgDEFG) involved in curli biosynthesis were distinctively induced (17- to 84-fold)
in the EDL933 strain while genes involved in tryptophan (a substrate of indole synthesis) synthesis were repressed. Our whole transcriptomic data suggest genetic mechanisms of biofilm formation since it has been reported that curli formation positively influences biofilm formation and indole reduces biofilm formation in Escherichia coli. Assay of curli formation clearly corroborates the microarray data as the EDL 933 produces a large amount of curli, while 86-24 produces no curli. Also, the production rate of indole in the EDL933 was 2-times lower than that of 86-24, which partially explains the difference of biofilm formation between two EHECs.