Engineered bacteria with synthetic gene circuits are attractive tools to detect environmental contaminants. However, their applications in realistic settings are hindered by its relatively low sensitivity, long response time, and limited portability. Here, we present a synthetic bacterial consortium-based system for detecting organophosphorus pesticides (OPs). The system consists of two Escherichia coli strains with divided tasks, including one for hydrolyzing OPs to p-nitrophenol (PNP) and the other for converting the PNP signal into β-galactosidase production for colorimetric detection. Upon optimization, the system was able to detect ethyl-paraoxon at the concentration of 1 × 10-9 M within 3.5 h of induction at 28 °C, which is approximately 200-fold more sensitive than single-cell based whole-cell sensing. In addition, it was capable of detecting several OPs, commonly used in agriculture. Furthermore, the system showed promise for on-site detection through the demonstration of a paper-based setting and real apple and soil samples. This study provides a rapid, sensitive, and portable biosensing platform for contaminant detection and also demonstrates the utility of engineered microbial ecosystems for novel environmental applications.