Overexpression of Capsular Polysaccharide Biosynthesis Protein in Lactobacillus plantarum P1 to Enhance Capsular Polysaccharide Production for Di-n-butyl Phthalate Adsorption

Exopolysaccharides (EPSs) are important bioactive carbohydrate compound such as Capsular polysaccharide (CPS). EPSs are often used as bioenrichment agents and bioabsorbers to remove environmental pollutants like di-n-butyl phthalate (DBP). Among the EPSs producing bacteria, lactic acid bacteria (LAB) have gained the most attention. As generally recognized as safe (GRAS) microorganisms, LAB can produce EPSs with many different structures without any health risks. However, the EPSs production of LAB is usually not enough for large-scale application in industrial production. Here, capA gene (encoding CPS biosynthesis protein) was overexpressed in Lactobacillus plantarum P1 to improve the production of EPSs and further enhance the capability of the adsorption of DBP. Compared with P1, the CPS production in capA overexpressed strain was increased by 11.3 mg/L, and the EPSs thickness was increased from 0.0786±0.0224μm in P1 to 0.1160±0.0480μm in P1-capA. These caused the adsorption ratio of DBP in P1-capA to be doubled. Overall, the findings in this study provided a safe solution for the adsorption and removing of DBP.