The Effects of Commercial Probiotics on Biological Properties of Enterococci in Colon Carcinoma Cell Culture

The interactions between dysbiosis of gut microbiota and development of colorectal cancers are well known. The effects of three different commercial probiotics, purchased from pharmacies, on several biological properties of enterococci (vancomycin resistant “VRE” and vancomycin susceptible “VSE”) in colon adenocarcinoma cell culture (HT-29) were investigated. Cell-free supernatants (CFSs) were prepared after the isolation of probiotic strains (Bifidobacterium lactis, Saccharomyces boulardii and Bacillus clausii). Bacterial growth was detected spectrophotometrically after three, six and 24 hours incubation. Adhesion and invasion assays were performed via colony counting method. Biofilm formation was performed using microtiter plate assay. After 24 hours incubation in culture medium, all three probiotics increased the growth of VRE and VSE. Bacterial growth was also increased in cell culture in the presence of probiotics. Adhesion of both enterococci was shown to be reduced by all probiotics. The invasion and biofilm formation were shown to be varied according to strains and probiotics tested. As conclusion, all of these findings indicate the potential risk of enhanced pathogenicity under certain circumstances, especially in immune suppression.