Isolation and Identification of Lactic Acid Bacteria from Calves and Their Probiotic Properties in Vitro
The purpose of this study was to screen Lactobacillus reuteri and Lactobacillus johnsonii with excel-lent probiotic properties,and to lay a theoretical basis for the development and utilization of probiotics in the later stage.In this experiment,the rectal feces of weaned Chinese Holstein calves after fecal microbiota trans-plantation were used as the source of strain isolation.Lactic acid bacteria were isolated and purified by MRS solid medium containing calcium carbonate,and 14 strains of Lactobacillus reuteri and 1 strain of Lactobacillus johnsonii were isolated and identified by physiological and biochemical and 16S rDNA sequencing.The probi-otic properties were evaluated by acid production,acid and bile salt resistance,hydrophobicity,antibacterial a-bility and antibiotic sensitivity tests.The results showed that each strain had good acid production ability.After 24 h of culture,the pH in the bacterial solution was concentrated between 4.0 and 4.5.When pH was 4,the survival rate of each strain was more than 80％.In 0.3％bile salt environment,the survival rate of each strain was more than 75％,and the survival rates of L81 and L29 were higher,which were 88.40％and 86.87％,re-spectively.In terms of hydrophobicity,the hydrophobic rates of L29,L39,L65,L74,L81,L102,L107,L1 16 and L120 were all above 55％,showing good hydrophobicity.All the 15 strains showed certain antibacte-rial effects,among which L10 and L81 had better antibacterial effects on Staphylococcus aureus,Escherichia coli and Salmonella.L29,L35 and L81 showed higher sensitivity to at least three of the five antibiotics than the other strains.In summary,the 14 strains of Lactobacillus reuteri and 1 strain of Lactobacillus johnsonii screened in this experiment have good probiotic properties,especially Lactobacillus re uteri L81 and Lactobacil-lus johnsonii L29,which can be used as backup strains for subsequent development of bovine lactic acid bacte-ria probiotics.[Chinese Journal of Animal Nutrition,2024,36(1):626-636]
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维普
