Inhibitory mechanism of Lactobacillus plantarum culture supernatant on Salmonella of different serotypes

Abstract:

[Objective] Our study investigated the inhibitory effect and pathogenicity of Lactobacillus plantarum culture supernatant (LPC) on Salmonella cholerae (SC), Salmonella enteritidis (SC) and Salmonella pullorum (SP). [Methods] Three serotypes of Salmonella enterica were co-cultured with 2% LPC. Salmonella growth and antibacterial compounds were identified using turbidimetry and the Oxford cup antimicrobial zone. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression levels of pathogenicity-related genes in Salmonella, and crystal violet staining was used to identify the biofilm of Salmonella. [Results] 2% LPC reduced the development of three Salmonella strains considerably, with an efficacy comparable to gentamicin (GM) and even better than SE. Additionally, the main antibacterial substance was organic acids. 2% LPC markedly suppressed the expressions of the main virulence genes encoded by SPI-1 (InvA, InvF, SopE, SopB, SipB, HilA and SipA), SPI-2 (SopD2), pili related genes (FliF, LpfA, SefA and FimF) and flagellum related genes (FlhD, FlIC and FliD) and the inhibitory effect was similar to GM. 2% LPC had significant inhibitory effect on biofilm formation of the three Salmonella strains, the inhibition rate was 40%–50% at 12 h and 60%–80% at 24 h. Compared with SC and SP, 2% LPC was superior to inhibit SE. [Conclusion] 2% LPC has significant inhibitory effects on the growth and pathogenicity of Salmonella serotypes, particlarly SE.