Identification of enterocins and in vitro characterization of their antimicrobial and anticancer activity in Enterococcus strains isolated from traditional fermented products

Abstract

Replacing naturally occurring bioactive substances, such as microbial metabolites, with synthetic preservative compounds, and getting access to their beneficial properties, is expanding every day. Meanwhile, the focus of many researchers' attention has been on bacteriocins, which have multiple physiological functions, including antibacterial and anticancer properties. In this study, the enterocin production genes of Enterococcus isolates from two fermented dairy products (Motal cheese and Tarkhineh) were tracked using a molecular method. The kinetics of bacteriocin-like substance production, as well as its stability (at high temperatures, different pH levels, and under different enzyme influences), were investigated. The antagonistic (well diffusion method) and anticancer (with MTT colorimetric technique) characteristics of enterocins generated by these isolates were also investigated in two human cancer cell lines. The results of the PCR test showed that isolates of Enterococcus faecium AUT-7KB and Enterococcus faecalis KUMS-T48 contained all three studied enterocin production genes, and the bacteriocin-like metabolites of these strains had strong antagonistic effects on Listeria monocytogenes and Bacillus cereus. These metabolites had high stability at different pH and became ineffective under the influence of protease enzymes (trypsin and pepsin), which indicated their protein nature. Additionally, metabolites of the KUMS-T48 isolate showed strong cytotoxic effects on two cancer cell lines, AGS and HT-29. According to the findings of the current research, enterocins of the E. faecalis KUMS-T48 strain are suggested as a suitable candidate for further anti-tumor studies, such as in vivo studies, after complete investigations of safety aspects.

Keywords

• enterococcus
• bacteriocin
• antimicrobial
• antitumor