Optimization of Lacticaseibacillus paracasei AS20(1)-Derived Exopolysaccharide and its Potential as an Anti-Biofilm and Anticancer Agent

Bioactive exopolysaccharides (EPSs) synthesized by lactic acid bacteria are therapeutic polysaccharides. EPSs are safe, so they can be used to make functional foods. Consumption of these foods can be a promising approach to prevent life-threatening and hard-to-treat diseases such as cancer and biofilm-associated infections. However, the low efficiency of synthesis makes their industrial implementation much more difficult. The aim of this study was to evaluate the anticancer and anti-biofilm activities of Lacticaseibacillus paracasei AS20(1) EPS and to optimize its production.

In the present study, the EPS synthesis by Lacticaseibacillus paracasei AS20(1) was optimized by Central Composite Design. Also, the effects of this EPS on inhibition of biofilm formation of Staphylococcus aureus (0.78-25 mg/ml), the viability of human colon cancer cell line, HT-29 (0.005-2 mg/ml), and the induction of apoptosis (2 mg/ml) in them were evaluated. Finally, the toxicity of this microbial EPS (50 and 100 mg/ml) was evaluated through a hemolysis assay of human red blood cells.

According to the predicted model, the maximal EPS production was achieved at pH 7.2, yeast extract, and sucrose concentrations of 2.3%(w/v) and 33.3 g/L, respectively. This EPS showed promising anti-biofilm (11-70%) and anticancer activity against HT-29 (IC50=1451.42 µg/ml). EPS treatment increased the percentage of cells in the early apoptotic state (28.8%). This microbial EPS showed negligible toxicity (<5%) on red blood cells.

Collectively, the ideal optimized conditions can be useful in large-scale production of EPS by Lacticaseibacillus paracasei AS20(1) which possesses valuable bioactivities.