Abstract
Κefir is a rich source of potentially probiotic bacteria. In the present study, firstly, in vitro screening for probiotic characteristics of ten lactic acid bacteria (LAB) isolated from kefir grains was performed. Strain AGR 4 was selected for further studies. Molecular characterization of strain AGR 4, confirmed that AGR 4 belongs to the Lactobacillus paracasei (reclassified to Lacticaseibacillus paracasei subsp. paracasei) species. Further testing revealed that L. paracasei AGR 4 displayed adhesion capacity on human adenocarcinoma cells, HT-29, similar to that of the reference strain, L. casei ATCC 393. In addition, the novel strain exerted significant time- and dose-dependent antiproliferative activity against HT-29 cells and human melanoma cell line, A375, as demonstrated by the sulforhodamine B cytotoxicity assay. Flow cytometry analysis was employed to investigate the mechanism of cellular death; however, it was found that AGR 4 did not act by inducing cell cycle arrest and/or apoptotic cell death. Taken together, these findings promote the probiotic character of the newly isolated strain L. paracasei AGR 4, while further studies are needed for the detailed description of its biological properties.
Highlights
Probiotics are defined as viable microorganisms that can confer health benefits to the host, when consumed in appropriate amounts [1]
The aims of our study were—firstly, isolation of novel lactic acid bacteria (LAB) strains from kefir grains and in vitro screening for probiotic characteristics; secondly, molecular genotyping of the strain with the best probiotic scores; and investigation of its cellular mechanisms of action, including its adhesion properties and antiproliferative effects against two human cancer cell lines, and the potential molecular pathways involved
Kefir grains richrepresent in potentially probiotics microorganisms
Summary
Probiotics are defined as viable microorganisms that can confer health benefits to the host, when consumed in appropriate amounts [1]. Accumulating evidence suggests that probiotics may exert their effects on extraintestinal sites as well [3]. The efficacy of probiotic supplementation depends on strain- and host-specific factors. Recent studies have highlighted these aspects and introduced the need for a case-by-case approach for the study of the molecular and cellular events that are responsible for the effects induced by each individual strain [4]. The key functions of probiotics include antimicrobial and immunomodulatory activity, modulation of gut microbiota function and structure, and protection of the intestinal barrier integrity [5]
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