Abstract:[Background] Bacteria exist in the form of complex microbial communities in the environment, and the competition among bacteria is an important way for bacteria to survive. Salmonella typhimurium is an important zoonotic pathogen that causes gastrointestinal diseases. It needs to interact with other bacteria in water, food or host intestine to gain survival advantage. [Objective] This study intends to construct a transposon insertion mutant library of Salmonella typhimurium by transposon technology, and to screen the mutant library according to the bacterial competitiveness, thus to explore the relevant mechanism of bacterial competition. [Methods] The EZ-Tn5?Tnp Transposome? kit was used to obtain a mutant library of Salmonella typhimurium containing 1 323 mutants. The competition of the mutants and wild type strain with Escherichia coli JM109 and MG1655 were screened. Then the flanking sequences were identified by reverse PCR, the insertion sites were determined. [Results] This study screened out 13 mutant strains with significant differences in bacterial competition. Among them, 2 mutant strains showed enhanced competitiveness. The inserted mutation genes were polB and flhd. Eleven bacterial mutants with decreased competitiveness were inserted in fstJ, rfbG, recC, rfaI, rfaG, rfbC, udha, plsc, mdh, res and ackA. [Conclusion] Virulence factors, the integrity of bacterial membrane, the normal bacterial metabolic capacity and their natural immunity and the appropriate modification of DNA are all closely related to the ability of bacteria to participate in competition. This study laid the foundation to further explore the specific factors affecting the ability of bacterial competition.
