Probiotic potential and anticancer properties of Pediococcus sp. isolated from traditional dairy products

Abstract

Herein, 18 lactic acid bacteria isolated from 30 samples of traditional dairy products were identified, and their probiotic potential was evaluated. According to the results, almost all strains showed the probiotic properties sufficiently, though M1 had better characterise. 16S rRNA gene sequencing revealed that this strain belongs to the Pediococcus sp. (<95 % similarity). This strain had substantial antipathogenic activity and did not show any worrying antibiotic resistance. Also, the strain was resistant to high concentrations of bile salt (1 %), NaCl (6.5 %), and low pH (2). Furthermore, it was revealed that cell-free supernatant (CFS), heat-killed cells and live cells derived from M1 significantly decreased the viability of MCF-7 cells so that the CFS resulted in 85 % cell death. Flow cytometry and western blot analysis determined that this compound induced apoptosis in the cancerous cells through increasing the BAX protein expression and decreasing the Bcl-2 protein expression.

Keywords: Anti-cancer; Apoptosis; Bacterial derivatives; Breast cancer; Pediococcus; Probiotics.

Fig. 1

The biofilm formation status of the strains. M2 and CH6 are two strains weakly produce biofilm. S. aureus was used as a well-known biofilm producer strain. The data presented are the mean numbers ± standard deviations.

Fig. 2

(A) shows the effects of bacterial derivatives on MCF-7 cells evaluated via Trypan blue assay, and (B) shows the control MCF-7 cells treated with the cell culture medium (Ba) in comparison with the cells treated with the medium containing CFS (Bb).

Fig. 3

Cytotoxicity effects of isolated strains on MCF-7 after 24 h of treatment with bacterial derivatives. The data presented are the mean numbers ± standard deviations. All treatments are significantly different from control (p < 0.05).

Fig. 4

(A) Flow cytometry analysis of apoptosis in MCF-7 cells treated with the CFS, NCFS, and HK cells of M1 strain. The control was untreated MCF-7 cells. (B) Protein expression of Bax and Bcl-2 genes of MCF-7 cells in the control group and the group treated with CFS of M1 strain. **P < 0.05 and ***p < 0.001 significantly different from control.

Fig. 5

Phylogenetic analysis of the 16S rRNA sequence obtained from the amplified product of M1 strain. The analysis was constructed using the neighbor-joining method in MEGA6.