Encapsulation of Autoinducer Sensing Reporter Bacteria in Reinforced Alginate-Based Microbeads

5 years ago

Encapsulation of Autoinducer Sensing Reporter Bacteria in Reinforced Alginate-Based Microbeads

Martin Frettlöh, Matthew Wook Chang, Mareike Müller, Holger Schönherr, Ping Li

Quorum sensing, in which bacteria communities use signaling molecules for inter- and intracellular communication, has been intensively studied in recent decades. In order to fabricate highly sensitive easy-to-handle point of care biosensors that detect quorum sensing molecules, we have developed, as is reported here, reporter bacteria loaded alginate–methacrylate (alginate-MA) hydrogel beads. The alginate-MA beads, which were obtained by electrostatic extrusion, were reinforced by photo-cross-linking to increase stability and thereby to reduce bacteria leaching. In these beads the genetically engineered fluorescent reporter bacterium Escherichia coli pTetR-LasR-pLuxR-GFP (E. coli pLuxR-GFP) was encapsulated, which responds to the autoinducer N-(3-oxododecanoyl)homoserine lactone secreted by Pseudomonas aeruginosa. After encapsulation in alginate-MA hydrogel beads with diameters in the range of 100–300 μm that were produced by an electrostatic extrusion method and rapid photo-cross-linking, the E. coli pLuxR-GFP were found to possess a high degree of viability and sensing activity. The encapsulated bacteria could proliferate inside the hydrogel beads, when exposed to bacteria culture medium. In media containing the autoinducer N-(3-oxododecanoyl)homoserine lactone, the encapsulated reporter bacteria responded with a strong fluorescence signal due to an increased green fluorescent protein (GFP) expression. A prototype dipstick type sensor developed here underlines the potential of encapsulation of viable and functional reporter bacteria inside reinforced alginate–methacrylate hydrogel beads for whole cell sensors for bacteria detection.

Publisher URL: http://dx.doi.org/10.1021/acsami.7b07166

DOI: 10.1021/acsami.7b07166