Comparative Probiotic Properties Of Two Lactobacillus Salivarius Strains Isolated From Different Sources

The slow growth rate and the invasion of pathogens have received a lot of attention in the animal production,improving the ability of animals to against pathogens and the growth efficiency is of great importance to the animal production.The gut of animals is rich in microbial resources,and as a unique fish species in Yunnan Dianchi,Sinocylochulus grahami may have a large number of strains with antibacterial effect in its gut.Lactobacillus salivarius is a representative probiotic of the Lactobacillus.L.salivarius metabolically produces antibacterial active substances such as organic acid and bacteriocins that can effectively inhibit or kill pathogens in food,it can also improve the flavor and taste of feed,so that it has a very wide range of applications in the treatment of animal bacterial diseases and food enticement.In this study,we propose to isolate and screen L.salivarius with high antibacterial activity from the gut of S.grahami.Biochemical tests and whole genome analysis to evaluate the probiotic potential,safety,and antibacterial effect of the strain in vitro.The safety and beneficial potential for animal production was evaluated by feeding S.grahami(fish)and Nandan-Yao Chicken(black).L.salivarius L.S.05(isolated from Wuliangshan Silky Chicken)was also introduced to compare the effect of feeding L.salifarius from different isolated sources on the same animal and the effect of feeding L.salifrius S01 on different animals during the rearing of Nandan-Yao Chicken.(1)The results showed that the bacteriocin(protein or peptide)produced by L.salivarius S01 isolated from the gut of S.grahami exhibited excellent antibacterial activity against several pathogens.The bacteriocin LSP01 exhibited excellent acid-base tolerance and temperature stability.XTT,Cell-Check? Viability XTT,and SEM measurements revealed that bacteriocin LSP01 can contribute to the death of pathogens by forming pores on the cell membrane surface and reducing metabolic activity.(2)Also,three clusters of antibacterial substances related genes were identified using anti SMASH and BAGEL4 database predictions.Furthermore,whole-genome analysis confirmed the presence of functional genes related to stress resistance,adhesion,immunity,and other genes responsible for probiotic potential in the genome of L.salivarius S01.Resistance genotypes and phenotypes analysis showed sensitivity to multiple antibiotics and excellent tolerance to simulated gastric and intestinal juices environments.Moreover,the activity of hepatic main antioxidant enzymes was enhanced,the possible pathogenic microorganisms decreased and potential beneficial microorganism increased after S.grahami was fed with L.salivarius S01.(3)The effects of feeding L.salivarius S01 and L.salivarius L.S.05 on growth performance,antioxidant enzyme activity,Blood serum-specific factors,and gut microbiota of1-day-old Nandan-Yao Chicken were determined.The results showed that both S01 and L.S.05 could improve the growth performance of Nandan-Yao Chicken.L.S.05 was able to better improve the growth performance of Nandan-Yao Chicken compared to S01,probably because L.S.05 is a host-associated strain.Moreover,both L.salivarius strains increased the main hepatic antioxidant enzyme activity and reduced hepatic malondialdehyde(MDA)levels to some extent,which indicated that both S01 and L.S.05 could improve the host tolerance and reduce oxidative damage.Blood serum-specific factors showed that S01 and L.S.05 could alter the levels of pro-inflammatory and anti-inflammatory factors to some extent.Gut microbiome data showed that both strains increased Romboutsia,which previous studies have shown to be positively associated with obesity.L.salivarius S01 significantly increased OIsenella(hardly observed in other groups),which may be induced by its use as a fish-derived bacteria in order to adapt to the chicken gut environment.Moreover,microbiome data analysis of S.grahami and Nandan-Yao Chicken after feeding L.salivarius S01 showed that S01 could reduce possible pathogenic microorganisms and enhance potential beneficial microorganisms in the gut of both animals.Bifidobacterium showed an increasing trend in S.grahami,and yet the opposite in the Nandan-Yao Chicken,which suggests that the effect of L.salivarius S01 is species-specific.Overall,in this study,L.salivarius S01 with good antibacterial activity was isolated from the gut of S.grahami,which showed good safety and probiotic effects at the genomic level and in the feeding experiment of S.grahami.The feeding experiment with Nandan-Yao Chicken showed that L.salivarius S01 from fish source and L.salivarius L.S.05 from chicken source showed different probiotic effects,which indicated that the host-associated probiotics might have better probiotic effects.The results of the study may provide a valuable research basis and theoretical basis for the application of L.salivarius species from different sources in different animals.