The aim of this study was to identify the Lactobacillus strains that are resistant to Salmonella and provide antibiotic alternatives for the chicken industry. Lactobacillus were isolated from chicken jejunal contents using MRS medium, candidate strains were screened by in vitro bacterial inhibition, acid resistance, enzyme production and adhesion, selected strains were orally administered to one-day-old AA chickens for 28 days to evaluate their effects on growth performance. At 42 days, a Salmonella challenge test was conducted to validate the inhibitory effect against salmonellosis, finally the Lactobacillus strain resistant to Salmonella was identified. Results A total of 27 Lactobacillus strains (including 13 strains of Ligilactobacillus salivarius, 11 strains of Limosilactobacillus reuteri, 2 strains of Lactobacillus johnsonii, and 1 strain of Lactobacillus gasseri) were isolated and identified, among which L. salivarius S31 could significantly inhibit Salmonella Typhimurium and Salmonella Gallinarum, with survival rate of more than 50% at pH 3.0, and produce protease and lipase. This suggests that S31 strain not only has a strong ability to inhibit Salmonella, but also has gastrointestinal adaptability and potential probiotic function. The results of animal experiments showed that the transplantation of L. salivarius S31 strain for 28 d significantly increased the body weight (P<0.000 1), leg muscle weight (P<0.001), breast muscle weight (P<0.01), jejunum length (P<0.01), intestinal villi length (P<0.05), goblet cell counts (P<0.05), and abundance of Lactobacillus in jejunum of the chickens (P<0.05), which suggests that S31 strain can promote the growth of chickens. The Salmonella attacking was carried out at 42 days, and bacterial load of the spleen (P<0.05), the transcription levels of TLR-4, MyD88 and AP-1 signaling pathways in the ileum (P<0.01), and the transcription levels of pro-inflammatory factors IL-1β, IL-6 and IL-12 (P<0.05) in L. salivarius S31 transplantation group were significantly lower than those in the control group, and the jejunum and ileum structures were intact. L. salivarius S31 strain exhibits robust Salmonella-inhibitory capacity, favorable gastrointestinal adaptability, and superior growth-promoting properties, demonstrating significant potential for practical applications.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |