Developing a mutant strain of Pseudomonas composti ODT-54 for enhanced production of Psl extracellular polysaccharide

In our previous study, a strain of Pseudomonas composti ODT-54 was isolated from the oyster digestive tissues. This strain is capable of producing Psl exopolysaccharides (EPS), which are directly involved in the specific binding to norovirus GII.6 P proteins. Here, we constructed an ODT-54 Psl EPS overexpression strain ODT-54 psl⁽⁺⁾ by substituting an exogenous arabinose-inducible promoter for the native promoter of the psl gene cluster. ODT-54 psl⁽⁺⁾ produced 50-70% more Psl EPS in FAB medium with 20 g/L arabinose induction compared to ODT-54, according to ELISA analyses. Furthermore, a 50% increase in binding to GII.6 P proteins was observed for ODT-54 psl⁽⁺⁾. These findings confirmed the success of the construction of the ODT-54 Psl EPS overexpression strain. This work provides important experimental material and helps further explore the structure of Psl EPS from P. composti.