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

Exopolysaccharides (EPSs) such as capsular polysaccharide (CPS) are important bioactive carbohydrate compounds and are often used as bioenrichment agents and bioabsorbers to remove environmental pollutants like di-n-butyl phthalate (DBP). Among the EPS-producing bacteria, lactic acid bacteria (LAB) have gained the most attention. As generally recognized as safe (GRAS) microorganisms, LAB can produce EPSs having many different structures and no health risks. However, EPS production by LAB does not meet the needs of large-scale application on an industrial scale. Here, the A gene (encoding CPS biosynthesis protein) was overexpressed in P1 to improve the production of EPSs and further enhance the DBP adsorption capability. Compared with P1, the CPS production in A overexpressed strain was increased by 11.3 mg/l, and the EPS thickness was increased from 0.0786 ± 0.0224 μm in P1 to 0.1160 ± 0.0480 μm in P1-A. These increases caused the DBP adsorption ratio of P1-A to be doubled. Overall, the findings in this study provide a safe method for the adsorption and removal of DBP.