Elusive function of dental plaque polysaccharide produced from Kocuria rosae and it’s molecular signature

Abstract

Background Exopolysaccharides have been generally recognized as safe compounds, meaning that they do not represent a health risk when used. Owing to these properties, they have many applications in industrial areas and in healthcare. Our aim is to identify an extracellular polysaccharide (EPS)-producing strain from dental plaque bacteria and the verification of its polysaccharide’s antitumor effect. Materials and methods Isolation of 22 dental plaque bacterial isolates from plaque samples of nine patients was carried out using pour plate method. The selection of the strain for molecular identification was done according to EPS production, whereas isolate no. 4 was identified by 16S rRNA sequencing analysis. Structure characterization of the EPS was described using UV and SEM images. The cytotoxic experiment was performed to investigate the inhibitory effect of different concentrations of EPS on the growth of cell line MCF7 human White breast adenocarcinoma. Results and conclusion Oral plaque bacteria vary greatly in their occurrence, depending on age, presence of systemic diseases, and personal oral hygiene. The amount of EPS produced from oral plaque bacteria also varies, though in general Gram-negative bacteria yielded larger amounts of EPS. Results revealed that isolate no. 4 is the most producer of EPS, identified as Kocuria rosea strain Y57, having 96% similarity with Kocuria spp. The biosynthesis of EPS from K. rosea using Luria–Bertani broth medium at 37°C for 24 h gave an EPS yield of 213 μg/ml. EPS from K. rosea is a powder with white color and is water soluble. Our results of in-vitro EPS assay against MCF7 human White breast adenocarcinoma released activity with LC50 213 μg/ml.