[RmlA gene deletion affects biofilm formation by avian pathogenic Escherichia coli]

To characterize rmlA gene inavian pathogenic Escherichia coli (APEC).

We constructed the rmlA mutant of APEC by the Red recombination system. Then we analyzed the differences of growth, movement and biofilm formation between mutant strain and wild strain. We compared the differences of virulence gene transcription between mutant strain and wild strain by real-time PCR.

The rmlA mutant did not affect the growth and motility of APEC, but enhanced the biofilm formation significantly. In addition, the transcription level of some virulence genes in rmlA mutant showed that the luxS , irp2 were raised 2 and 1.6 times respectively, but decreased the iucD and fyuA by 25 times compared to the wild strain.

These data indicate that the rmlA gene could strengthen the ability of APEC biofilm formation, and affect the transcription level of some virulence genes, but not the growth and motility.