Isolation and in vitro assessment of probiotic properties of Lactobacillus animalis isolated from puppies

HUANG Huiming; CHEN Mengyao; ZHAO Siyu; SONG Jiayi; HAN Xue; LIU Qingrong; WEN Min

doi:10.19728/j.issn1672-6634.2025100007

Abstract：The purpose of this study was to isolate probiotic lactic acid bacteria from the feces of healthy puppies.Five strains were successfully isolated from stool samples collected from puppies.Based on Gram staining and 16S rRNA gene sequencing,all five isolates were identified as Lactobacillus animalis and des-ignated as LA-1～LA-5.The results demonstrated that all five strains exhibited excellent growth charac-teristics and acid production capability.After 3 hours of exposure to pH 2.0,strains LA-1,LA-3,and LA-4 exhibited survival rates above 73%,while exposure to 0.3%bile salts resulted in a survival rate a-bove 50%for all five strains,with LA-3 exceeding 80%;Notably,strain LA-2 displayed strong auto-ag-gregation capacity,reaching 52.43%after 5 hours;Moreover,the surface hydrophobicity measured with chloroform was exceptionally high(94%)for all strains.Of particular note,LA-2 also showed a high ad-hesion rate to Caco-2 cells,at 51.82%;All five strains demonstrated DPPH radical scavenging activity,with LA-2 and LA-4 exhibiting particularly strong effects exceeding 50%.Additionally,every strain in-hibited the growth of Staphylococcus aureus,Escherichia coli,and Salmonella.Notably,LA-1 produced an inhibition zone measuring 17.67±3.33 mm against S.aureus;All isolates were also highly suscepti-ble to penicillin,chloramphenicol,and ampicillin.Furthermore,hemolysis tests confirmed that all five strains are safe for potential use.Consequently,these five L.animalis strains are strong candidate probi-otics derived from healthy puppies,with their robust in vitro functionality supporting their potential use in canine nutrition.