Inhibition of quorum sensing in opportunistic pathogen, Serratia marcescens, using cyclodextrin-immobilized, multiple...

Prodigiosin production in the model opportunistic human pathogen, Serratia marcescens AS-1, depends on quorum sensing (QS), the activation of which is induced by an increase in N-hexanoyl homoserine lactone (C6HSL) concentration. When mixed with C6HSL in the broth culture of S. marcescens immobilized cyclodextrin (CD) effectively formed an inclusion complex resulting in suppression of the QS-mediated prodigiosin production. Thousands of parallel gel filament bundles could be fabricated by the dynamic flow of aqueous sodium alginate blended with α-CD or hydroxypropyl-β-CD (HP-β-CD) immobilized hydroxypropyl cellulose (HPC) inside a co-axial microfluidic device. Shear-induced fibrous domains of HPC-alginate complex assembly were immediately jacketed by calcium alginate gel formed by a sheath flow containing Ca²⁺ ions. Immobilized α-CD and HP-β-CD on the HPC/alginate gel fibers could inhibit the C6HSL-mediated prodigiosin production to approximately 10%. Furthermore, the swarming motility of S. marcescens AS-1 was effectively suppressed in the presence of free or immobilized α-CD or HP-β-CD. The CD-immobilized gel filament bundle is a novel type of preventive material against bacterial infections.