Abstract：Objective: To study the function of two bacteriocin immunity proteins encoded by SPI-8 of Salmonella enterica serovar Typhi. Methods: The gene deleted mutants of bacteriocin immunity proteins(△t3036, △t3038 and △t3036△t3038) were constructed by homologous recombination mediated by the suicide plasmid pGMB151. The resistance of bacteria to 8 antimicrobial agents was separately tested with the K-B method. Crystal violet staining was used to assess the formation of bacterial biofilm. Results: Based on the results of PCR verification and sequence alignment, the gene deleted mutants of bacteriocin immunity protein were successfully constructed. The results of drug sensitivity test showed that resistance of △t3038 and △t3036△t3038 to ampicillin, gentamicin, polymyxin B, ciprofloxacin, kanamycin, and imipenem were significantly attenuated(both P<0.01). However, there was no significant difference between △t3036 and the wild type strain in resistance to all of the 8 antimicrobial agents. The result of the biofilm formation test showed compared with the wild type strain, the capability of biofilm formation by △t3036 was markedly enhanced(P<0.05), but the capability of biofilm formation by △t3038 and △t3036△t3038 was significantly reduced (both P<0.01). Furthermore, the capability of biofilm formation by △t3036△t3038 was significantly reduced than that of △t3038. Conclusion: The bacteriocin immunity proteins T3036 and T3038 of S. Typhi could promote the formation of bacterial biofilm, and T3038 could also enhance the antibiotic resistance of bacteria. ［Key words］bacteriocin immunity protein; Salmonella enterica serovar Typhi; SPI-8; drug resistance; biofilm
2017, Vol. 27 
