Study Of Lactobacillus Salivarius XP132 Against Salmonella Pullorum Infection In Chickens

Probiotics can antagonize pathogenic microorganisms through a variety of mechanisms,stimulate host immune cells,and enhance host resistance.With the global trend of banning antibiotics,the application of anti-probiotics has become a new trend to fight pathogenic bacteria and enhance host immunity.This study evaluated the probiotic properties of a strain of Lactobacillus salivarius with broad-spectrum antibacterial activity,and carried out in vitro and vitro research on the infection and spread of Salmonella Pullorum in chicken,which provided a new tool for the control of Salmonella infection and purification of Salmonella Pullorum in chicken.In this study,the safety and probiotic properties of XP132 strain were first tested,and the Lactobacillus salivarius XP132 strain was applied to HT29 and HD11 cells,and cultured in MRS medium at p H 5,4 and 3 and MRS liquid medium with bile salt concentrations of 0.2%and 0.6%(w/v),respectively,and the results showed that XP132 strain had no obvious toxicity to HT29 and HD11 cells and showed good acid and bile salt resistance.The auto-agglutination characteristics of XP132 strain and co-agglutination characteristics with Salmonella Pullorum C79-1 were detected,and the auto-agglutination rate was about 88.9%and the co-agglutination rate was about51%after 12 h.The antibacterial activity was detected by agar diffusion,and the results showed that Lactobacillus salivarius XP132 had strong broad-spectrum antibacterial activity.In the inflammatory model,Lactobacillus salivarius XP132 could downregulate the inflammatory factors IL-1β,IL-6 and IL-8,showing anti-inflammatory properties.In the cell model of Salmonella pullorum infection,Lactobacillus salivarius XP132 could downregulate inflammatory factors TNF-αand IL-6.Upregulated anti-infective cytokines IFN-γand anti-inflammatory factor IL-10,exhibiting anti-inflammatory and anti-infective properties.Lactobacillus salivarius XP132 showed strong broad-spectrum antibacterial activity against gram-positive pathogens and gram-negative pathogens,especially against gram-negative salmonella,with an average antibacterial ring diameter greater than 22 mm and a maximum inhibitory ring diameter close to 30 mm.The sterile fermentation supernatant of Lactobacillus salivarius XP132 was treated with Na OH and Proteinase K,and its antibacterial components were analyzed,and the results showed that Lactobacillus salivarius XP132 mainly exerted antibacterial effects through acidic substances and protein substances.Further treatment of Salmonella Pullorum with Lactobacillus salivarius XP132 sterile supernatant showed that Lactobacillus salivarius XP132 could destroy the bacterial structure of Salmonella Pullorum by releasing antibacterial components into the culture supernatant,which could lead to bacterial cytoplasmic leakage and exert bacteriostatic or bactericidal effects.The results of animal experiments exploring the transmission of oral Lactobacillus salivarius to Salmonella Pullorum in chickens showed that daily oral administration of Lactobacillus salivarius XP132(1×10~9 CFU/pc)could significantly increase the weight of broiler breeders,induce the production of high levels of CD4~+T cells,significantly downregulate the expression levels of inflammatory factors such as IL-1β,and upregulate the levels of anti-inflammatory factors IL-10 and anti-infection cytokine IFN-γ.100%block the conversion rate of Salmonella Pullorum antibodies in cohabiting chickens,and significantly inhibit the growth of Salmonella Pullorum in liver,spleen,intestinal contents and eggs,and effectively block the horizontal transmission of Salmonella Pullorum.At the same time,it can reduce the content of salmonella in eggs and prevent the vertical spread of Salmonella Pullorum.In summary,Lactobacillus salivarius XP132 is a probiotic with broad-spectrum antibacterial activity,which can effectively inhibit the growth of Salmonella Pullorum,improve the immunity of poultry,reduce inflammation,and prevent the horizontal and vertical spread of Salmonella Pullorum.This study provides an important reference for the development and application of new anti-antibiotic preparations,especially for the prevention and control of salmonella and purification of Salmonella Pullorum in chicken.