| Summary: | 碩士 === 國立臺灣師範大學 === 化學系 === 104 === This thesis focuses on utilizing xyl gene cluster to engineer an artificial plasmid. When engineered Escherichia coli BL21 strain senses m-xylene in environment, XylR protein binds to m-xylene and forms a complex. The complex triggers promoter of reporter protein, then reporter protein will be transcribed. We employed two signal outputs, one is red fluorescence protein (RFP), the other is Mirabilis jalapa DOPA 4,5-dioxygenase (MJDOD). RFP is a fast-folding protein and betaxanthin has brilliant color, which is synthesized from L-3,4-dihydroxyphenylalanine (L-DOPA) by MJDOD. We design various constructs in order to enhance detection performance based on the regulation mechanism of TOL network. The best performance strain was screened and examined, which was specific to m-xylene and had detection linear range: 0~1600μM. For portable application, our biosensor was coated by agarose to form bacterial beads. Bacterial beads can detect m-xylene without complex incubation procedures, which saves a lot of time. With these advantages, XylR-based biosensor can be an alternative detection option for organic solvents
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