短双歧杆菌对鼠伤寒沙门氏菌的抑制

Inhibition of Salmonella typhimurium by Bifidobacterium breve

摘要:

【背景】鼠伤寒沙门氏菌是主要的肠道病原菌之一，利用益生菌治疗肠道病原菌感染已成为一种新型、绿色的微生态疗法。【目的】研究筛选出的短双歧杆菌无细胞发酵上清液(Cell-free supernatant，CFS)对鼠伤寒沙门氏菌的体外抑制作用及机制。【方法】采用微量稀释法测定短双歧杆菌YH68 CFS对鼠伤寒沙门氏菌的最小抑菌浓度(Minimum inhibitory concentration，MIC)和亚抑制浓度(Sub-inhibitory concentrations，SIC)，并从鼠伤寒沙门氏菌的细胞形态、细胞膜通透性、膜完整性以及毒力基因表达的变化探讨YH68 CFS对鼠伤寒沙门氏菌的抑菌机理，同时检测YH68 CFS对鼠伤寒沙门氏菌粘附和侵袭肠上皮细胞HT29的影响。【结果】YH68 CFS (3×109 CFU/mL)对鼠伤寒沙门氏菌具有较好的抑制效果，抑菌圈直径为22.27±0.44 mm，最小抑菌浓度为250 μL/mL，对鼠伤寒沙门氏菌的抑制机制是通过增加其细胞膜通透性破坏其完整性，形成难以修复的孔洞，最终达到抑菌的目的；亚抑制浓度为62.5 μL/mL时YH68 CFS并不能影响鼠伤寒沙门氏菌的生长，但仍然能通过下调毒力基因表达的方式抑制其对肠上皮细胞的粘附和入侵。【结论】短双歧杆菌YH68对鼠伤寒沙门氏菌具有良好的抑菌作用，可作为治疗沙门氏菌感染的潜在益生菌。

Abstract:

[Background] Salmonella typhimurium is one of the major intestinal pathogens. The use of probiotics to treat intestinal pathogen infection has becoming a new, green micro-ecological method. [Objective] Investigate the antibacterial activity and mechanism of the cell-free supernatant (CFS) of Bifidobacterium breve on S. typhimurium in vitro. [Methods] The microdilution method was used to detect the minimum inhibitory concentration (MIC) and sub-inhibitory concentration (SIC) of YH68 CFS against S. typhimurium. The antibacterial mechanism of YH68 CFS against S. typhimurium was investigated from the changes of cell morphology, cell membrane permeability, membrane integrity and virulence gene expression of S. typhimurium. The adhesion and invasion of S. typhimurium to HT29 cells were also studied. [Results] YH68 CFS (3×109 CFU/mL) has a good inhibitory effect on S. typhimurium, and the diameter of the inhibition zone is 22.27±0.44 mm. When YH68 CFS was at MIC concentration (250 μL/mL), its mechanism of action against S. typhimurium was to increase the membrane permeability, destroy its integrity, form the cell membrane pores, and ultimately achieve antibacterial purposes. However, YH68 CFS did not affect the growth of S. typhimurium at the concentration of SIC (62.5 μL/mL), but it could still inhibit the adhesion and invasion of intestinal epithelial cells by down-regulating the expression of its virulence genes. [Conclusion] Bifidobacterium breve YH68 has a good antibacterial effect against S. typhimurium and could be used as a potential probiotic for clinical treatment of Salmonella infection.