RESUMO
Background: Breast milk is always the best choice for infant's nutrition due to its useful compounds such as immune cells and molecules, oligosaccharides, as well as bacteria and their metabolites. We identified and characterized the isolated strain from human breast milk in this study. Materials and Methods: A total of 20 lactating mothers aged 25 to 34 years were enrolled in our study. We collected the breast milk samples in sterile microtubes. 100 µl of each sample was spread on de Man-Rogosa-Sharpe (MRS) agar plates and incubated aerobically at 37°C for 48 hr. After identifying the isolated strain, initial tests (hemolysis inactivity and L-arginine hydrolysis, catalase), the acid tolerance, bile tolerance, and antibiotics susceptibility of the isolated strain were estimated. Furthermore, the antiproliferative and proapoptotic activities of heat-killed cells) HKC) and cell-free supernatant (CFS) of the strain on the HT-29 cell line were evaluated using MTT assay and flow cytometry analysis, respectively. Results: The isolated strain was Gram-positive, bacilli in shape, catalase-negative, non-hemolytic, and negative for L-arginine hydrolysis. By 16S rRNA gene sequencing, the isolated strain was Lactobacillus fermentum. According to MTT assay and flow cytometry results, the HKC and CFS of the isolated strain reduced the viability of the HT-29 cells. The total apoptosis induced in HT-29 cells by HKC and CFS was 65.98% and 70.1%, respectively. Conclusion: Our findings suggest that this strain, despite the properties of probiotic bacteria, has potential antiproliferative and proapoptotic capabilities.