Abstract
A quorum sensing (QS) as one of the intercellular bacterial communication systems could be successfully suppressed by enzymatic degradation of QS signals, N-acylhomoserine lactones (AHLs), inside polymer microcapsules. It is expected to isolate novel AHL-degrading bacteria and determine their AHL-degrading activity because the QS system dominates various bacterial functions including virulence expression and biofilm formation. As the QS activation index, producing red pigment prodigiosin which depends on the AHL-mediated QS in Serratia marcescens could be conveniently determined within 1-2 s by refractive spectrometer. Co-culture system of S. marcescens and model AHL-degrading Escherichia coli DH5α (pMAL-aiiA) which is genetically engineered to produce AHL-lactonase, AiiA, could successfully determine the AHL-degrading activity by measuring color change of the culture broth. To prepare the microcapsules embedded with the AHL-producer and AHL-degrader, calcium alginate microgel beads could be rapidly fabricated by coaxial microfluidic device, followed by forming polyion complex with ε-polylysine and removing Ca2+ ions in sodium citrate solution. This microcapsule co-culture model could follow the AHL degradation by the AHL-lactonase reaction because the a* as the red chroma index kept negative value even after 18 h co-culture. This paper suggests encapsulation of the co-culture system inside hollow microcapsules which enable simultaneous evaluation of the AHL-degrading average activity for approximately 100 samples within 1-2 s.
