Abstract: Objective To construct a FYUA gene deletion mutant of uropathogenic Escherichia coli strain CFT073;To compare the different biological properties between wide-type and mutant.Methods λ Red homologous recombination technology was used to construct the FYUA gene deletion strain △FYUA. The proliferation curves of CFT073 and △FYUA in Luria-Bertani liquid medium and sterile urine were drawed by measuring the absorbance at 600nm.Colony formation abilities of CFT073 and △FYUA were evalutatd by counting the number of colonies in the plates.Crystal violet staining method was used to compare the biofilm formation abilities of CFT073 and △FYUA.Results A FYUA gene deletion strain △FYUA was constructed successfully. CFT073 and △FYUA had the similar proliferation curves in Luria-Bertani liquid medium.The proliferation rate of △FYUA in sterile urine was obviously slower than CFT073（P <0.05）.There is no difference in colony formation ability between CFT073 and △FYUA. Biofilm formation ability of △FYUA was weakened compared with CFT073（P <0.05）.Conclusion FYUA gene may plays an important role in the CFT073 proliferation and biofilm formation in sterile urine.

Key words: FYUA, gene knockout, urinary tract infection, Escherichia coli