The Study Of Lactobacillus Strains With Antagonistic Activities Against Campylobacter Jejuni

Campylobacter jejuni as anthropozoonosis is one of the main pathogenic bacteria ofinfectious diarrhea. At present, the treatment of C. jejuni infections with antibiotics has somedisadvantages, such as antibiotic resistance and residues in the animal or human body. Severalstudies reported that probiotics have inhibition effects on enteric pathogens. Therefore, thepurpose of this study was to screen Lactobacillus isolated from difference sources forantimicrobial activities against C. jejuni, investigate the effects of simulated gastric juices andsmall intestinal juices on the viability of Lactobacillus, study the viable cell counts of C.jejuni in a co-culture study of C. jejuni and Lactobacillus, investigate the capacity of theseisolates to intervene with the infection of C. jejuni in intestinal epithelium cells, build themodel of C. jejuni infections in mice.The effects of simulated gastric juices and small intestinal juices on the viability of15Lactobacillus were investigated. The results showed that the viable cell counts still retained ahigh level of viability when these strains were exposed to simulated gastric juices after2h.There was no remarkable difference in viability when the four strains were exposed for2h tosimulated small intestinal juices.In a co-culture study of C. jejuni and Lactobacillus, the results show that trained after48h, most of the experimental group the viable cell counts of C. jejuni dropped by about1.0logCFU/mL. However, the viable cell counts of C. jejuni of L.salivarius ZX5group fell by about2.0log CFU/mL. Its bacteriostatic effect is much larger than other experimental strains. SoL.salivarius ZX5had the strongest anti-C. jejuni activity.The inhibitory substance of CFS was studied by using well diffusion agar assays, theresults showed that the antibacterial activity was heat stable. An obvious reduction ofinhibition was found when the supernatant was at pH6.5. But L.salivarius ZX5wassusceptive to catalase, proteinase K and trypsin. It suggested that the antibacterial activity ofL.salivarius ZX5CFS depended on the pH and the production of metabolites, such as acticacid and bacteriocin.The L.salivarius ZX5strains were further evaluated for intervening with the infection ofC. jejuni in the HT-29cells model. The results showed that L.salivarius ZX5had significantpotential for reducing adhesion and invasion of C. jejuni to HT-29cells in exclusion,competition and displacement assays.The model of C. jejuni infections in mice was built by combining clinical grading,examining the viable cell counts of C. jejuni in mice intestinal tract, and testing cytokines.Thestudy set up a model which pregavaged the mice with E.coli ATCC43893and lavage C. jejuni followed. The model of C. jejuni can colonize effectively in the intestinal tract of mice.In the future, the study of L. salivarius ZX5which could have antagonistic activity of C.jejuni in mice can use this model.Through the research, it suggested that the L. salivarius ZX5showed antagonisticactivity against C. jejuni and could be used as potential probiotics for prevention of C. jejuniinfections.