Abstract: DNA damage response (SOS response) refers to an important protective mechanism for bacteria to cope with genomic DNA damage. The RecA protein plays a key regulatory role in the induction of SOS responses in many bacteria, and its homologous proteins are widely present in various organisms. The purpose of this study was to explore whether RecA protein regulates the SOS response of Riemerella anatipestifer. We constructed the recA deletion mutant and complemented strain. The growth abilities of the parental strain, deletion mutant and complemented strain, the transcriptional levels of recA gene and SOS response of the above strains with ultraviolet treatment were detected. The results showed that the recA deletion mutant ΔrecA and complemented strain cΔrecA were successfully constructed. Inactivation of recA gene had no significant effect on the growth rate of RA-GD strain. Under ultraviolet radiation irradiation, the transcription level of recA gene of parental strain increased significantly. Compared with the parent strain and the complemented strain, the survival ability and the genomic integrity of the deletion strain reduced significantly. This study confirmed for the first time that the RecA protein is involved in the SOS response of Riemerella anatipestifer.

Key words: Riemerella anatipestifer, recA gene, growth, SOS response