A Whole-Cell Biosensor Panel for Agriculture Endocrine Disruptors

Abstract: Chemical agents, such as pesticides applied at inappropriate~ levels, may compromise water quality or contaminate soils and hence threaten human populations. Global demographics assure that threats to agriculture will continue to grow. An emerging threat is posed by endocrine disrupting compounds (EDCs), a class of compounds compromising both human and ecosystems' reproductive health; many pesticides have been implicated as EDCs. EDCs pose a threat in proportion to their bioavailability, since that which is biounavailable or can be rendered so is a priori not a threat; bioavailabiiity, in turn, is mediated by complex matrices such as soils. Genetically engineered biosensor bacteria hold great promise for sensing bioavailability because the sensor is a live soil- and water-compatible organism with biological response dynamics, and because its response can be genetically "tailored" to report on general toxicity, on bioavailability, and on the presence of specific classes of toxicants. We propose the development of a sensor panel incorporating multiple strains of genetically engineered biosensors for the purpose of detecting different types of biological effects in tandem. Some of the biosensors used will have specific or "lights on" response - i.e., wherein response results from formation of a luminescent reporter molecule in direct proportion to the amount of exposure the biosensor has to its target analytes (e.g. pesticides or EDCs). Others will be "lights off' type biosensors wherein the organisms are engineered to be luminescent in the absence of exposure, this luminescence decreasing as a function of group-effect exposure (our panel will target endocrine disruption capacity as well as overall toxicity). The panel will consist of a matrix of spots, each spot containing a different strain of bacterial biosensor that will yield individual response information for evaluation of the biological effects of the target analytes. Additionally, algorithms suitable for small sensor arrays will be borrowed from the area of electronic nose sensing to discriminate biological effects from the cumulative panel response, constituting a type of biological multiplexing. The ultimate goal of the project is to demonstrate applicability of the sensor panel with real samples such as soil solutions, runoff, material leaching into aquifers, sewage from secondary treatment, etc., and the project will culminate in a field trial. This work relates directly to issues of water quality and soil health, but is extensible to risk-based assessment and homeland security issues as well.