Cell-Based Biosensor with Dual Signal Outputs for Simultaneous Quantification of Phenylacetic Acid and Phenylethylamine

Abstract

Despite the importance of 2-phenylacetic acid, a plant hormone in the endogenous auxin family, its biosynthesis pathway has yet to be elucidated. In this study, we developed a novel whole-cell biosensor for the simultaneous quantification of 2-phenylacetic acid (PA) and 2-phenylethylamine (PEA) through the regulation of bacterial catabolism of aromatic compounds. We used the PA regulon to enable the recognition of PA and PEA. Differentiation of PEA from PA involves the incorporation of the FeaR regulon within the same whole-cell biosensor to report the presence of aromatic amines. The proposed system is highly sensitive to PA as well as PEA.

Simultaneous Determination of l-Phenylalanine, Phenylethylamine, and Phenylacetic Acid Using Three-Color Whole-Cell Biosensors within a Microchannel Device

“…This result is consistent with our previous work that the activation of PpaaA remains at the basal level of PaaK. 15 3.2. Selection of Ribosome-Binding Sites and Fluorescent Proteins for Phe, PEA, and PA Biosensors.…”

“…The PA biosensor also produced the largest quantity of GFP in the absence of IPTG (Figure C). This result is consistent with our previous work that the activation of PpaaA remains at the basal level of PaaK …”

“…Many methods have been reported for the detection of Phe and PA, such as capillary electrophoresis, mass spectrometric methods, and high-performance liquid chromatography. − However, these analysis methods require tedious sample preparation as well as expensive equipment and may not be suitable for immediate diagnosis. In previous work, our laboratory has developed a whole-cell biosensor to simultaneously detect Phe and Tyr. − However, the measurements were acquired from 24 h postinduction, which is not suitable for real-time monitoring. In addition, multiplexed detection of a panel of metabolites is crucial for making clinical decisions for real applications.…”

Genetic Circuit Design in Rhizobacteria

“…PAA similarly affects plant growth and rhizobacterial activities [ 182 , 183 ], albeit at higher concentrations than IAA. Bacterial circuits were optimized to output the fluorescent reporters, GFP and RFP, in response to PAA and its related compounds, 4-hydroxyphenylacetic acid, and 2-phenylethylamine [ 184 , 185 ]. Future developments in hormone sensing circuitry might enable design of rhizobacterial strains that rewire plant signaling to influence plant growth and immunity [ 186 ].…”