This study aims to investigate the biological function of the Clumping factor B(clfB)gene in Staphylococcus aureus.The recombinant plasmid pBT2-△clfB was constructed and elec-troporated into Staphylococcus aureus J57 to delete clfB by homologous recombination.The ex-pression plasmid pLI50-clfB was constructed,modified,and electroporated into clfB gene deletion strain △clfB and constructed a complementation strain(C△clfB).J57,△clfB,and C△clfB were cultured at 37℃ for 12 h,and the growth curves of each strain were plotted.The hemolytic properties of each strain were analyzed by contact method,the motility of each strain on TSA plates was determined,and the autolysis rate of each strain under the action of TritonX-100 was determined.Crystal violet staining was used to detect each strain's biofilm formation ability,and biofilm components formed by each strain were quantitatively analyzed.The K-B method was used to determine the sensitivity of each strain to commonly used antibiotics.ClfB gene deletion strain△clfB and the complemented strain C△clfB were successfully constructed.The growth curves of the deletion strain were almost consistent with those of the wild and complemented strains,and there was no significant difference.Compared with J57 and C△clfB,the hemoly ability and the athletic of △clfB decreased.In the condition of TritonX-100,the autolysis rate of △clfB was significantly lower than that of J57 and C△clfB(P＜0.01).Compared with J57 and C△clfB,the ability of △clfB to form biofilm was significantly lower than that of J57 and C△clfB(P＜0.05),and the content of extracellular DNA and protein in the biofilm was significantly decreased.In con-trast,the content of soluble polysaccharides was significantly increased(P＜0.05).Compared with J57 and C△clfB,△clfB was more sensitive to chloramphenicol,gentamicin,and kanamycin while more resistant to linezolid.ClfB gene is closely related to the autolysis,hemolytic activity,athlet-ic,and biofilm formation ability of Staphylococcus aureus,affecting the sensitivity of bacteria to certain antibiotics.

This study aims to investigate the biological function of the Clumping factor B(clfB)gene in Staphylococcus aureus.The recombinant plasmid pBT2-△clfB was constructed and elec-troporated into Staphylococcus aureus J57 to delete clfB by homologous recombination.The ex-pression plasmid pLI50-clfB was constructed,modified,and electroporated into clfB gene deletion strain △clfB and constructed a complementation strain(C△clfB).J57,△clfB,and C△clfB were cultured at 37℃ for 12 h,and the growth curves of each strain were plotted.The hemolytic properties of each strain were analyzed by contact method,the motility of each strain on TSA plates was determined,and the autolysis rate of each strain under the action of TritonX-100 was determined.Crystal violet staining was used to detect each strain's biofilm formation ability,and biofilm components formed by each strain were quantitatively analyzed.The K-B method was used to determine the sensitivity of each strain to commonly used antibiotics.ClfB gene deletion strain△clfB and the complemented strain C△clfB were successfully constructed.The growth curves of the deletion strain were almost consistent with those of the wild and complemented strains,and there was no significant difference.Compared with J57 and C△clfB,the hemoly ability and the athletic of △clfB decreased.In the condition of TritonX-100,the autolysis rate of △clfB was significantly lower than that of J57 and C△clfB(P＜0.01).Compared with J57 and C△clfB,the ability of △clfB to form biofilm was significantly lower than that of J57 and C△clfB(P＜0.05),and the content of extracellular DNA and protein in the biofilm was significantly decreased.In con-trast,the content of soluble polysaccharides was significantly increased(P＜0.05).Compared with J57 and C△clfB,△clfB was more sensitive to chloramphenicol,gentamicin,and kanamycin while more resistant to linezolid.ClfB gene is closely related to the autolysis,hemolytic activity,athlet-ic,and biofilm formation ability of Staphylococcus aureus,affecting the sensitivity of bacteria to certain antibiotics.