Assessment of probiotic potential and anticancer activity of newly isolated vaginal bacterium Lactobacillus plantarum 5BL

Abstract

Numerous bacteria in and on its external parts protect the human body from harmful threats. This study aimed to investigate the potential beneficial effects of the vaginal ecosystem microbiota. A type of bacteria was isolated from vaginal secretions of adolescent and young adult women, cultured on an appropriate specific culture medium, and then molecularly identified through 16S rDNA gene sequencing. Results of 16S rDNA sequencing revealed that the isolate belongs to the Lactobacillus plantarum species. The isolated strain exhibited probiotic properties such as low pH and high bile salt concentration tolerance, antibiotic susceptibility and antimicrobial activity against some pathogenic bacteria. The anticancer effects of the strain on human cancer cell lines (cervical, HeLa; gastric, AGS; colon, HT-29; breast, MCF-7) and on a human normal cell line (human umbilical vein endothelial cells [HUVEC]) were investigated. Toxic side effects were assessed by studying apoptosis in the treated cells. The strain exhibited desirable probiotic properties and remarkable anticancer activity against the tested human cancer cell lines (P 0.05) with no significant cytotoxic effects on HUVEC normal cells (P 0.05). Overall, the isolated strain showed favorable potential as a bioactive therapeutic agent. Therefore, this strain should be subjected to the other required tests to prove its suitability for clinical therapeutic application.Key words anticancer, apoptosis, microbial biotherapy.The human vagina is colonized by different microbes, over 50 microbial species promoting female health by protecting against pathogens, modulating immunity, preventing infection and maintaining the pH below 4.7 (1-3). A variety of Lactobacillus species have been identified as the predominant biota in the vagina (4): over 70% of all bacteria sampled from the vaginas of healthy women are lactobacilli (5). The ability of lactobacilli to adhere to epithelial cells and colonize the vagina is attributable to factors such as hormonal factors, vaginal pH and glycogen content (6).The protective effects of normal vaginal flora, particularly lactobacilli, are increasingly being accepted (7). Lactobacilli adjust the vaginal microbiota through various mechanisms, including auto-aggregation, coaggregation with pathogenic microorganisms, adhesion to epithelial cells, and production of various antimicrobial substances, such as lactic acid, bacteriocins,

Linoleic acid inhibits Lactobacillus activity by destroying cell membrane and affecting normal metabolism

“…Lactobacillus is an important probiotic and is generally considered to be a resident microflora in the human gastrointestinal tract . The role of Lactobacillus in maintaining human health and immune function has been widely recognized .…”

Acid lactic lactobacilli as a biotechnological toll to improve food quality and human health

“…The supernatant of L. plantarum 5BL isolated from vaginal secretions of a young adult woman presented anticancer activities against different cancer cells, including HeLa, MCF‐7, AGS, and HT‐29. The bacterial cells remained viable after 24 hr of incubation . The strains of L. paracasei M5 and X12, and L. casei X11 and K14 induce apoptosis in human colon HT‐29 cancer cells.…”

Probiotics in Inflammatory Bowel Diseases and Cancer Prevention

“…plantarum 5BL was evaluated in vitro and showed remarkable anticancer activity against different human cancer cell lines, but no cytotoxic effects were exerted on HUVEC normal cells (Nami et al, 2014a). plantarum 5BL was evaluated in vitro and showed remarkable anticancer activity against different human cancer cell lines, but no cytotoxic effects were exerted on HUVEC normal cells (Nami et al, 2014a).…”