Engineered Fungal Biofilms in a Novel Biosensor for the Real-time Monitoring of Estrogenic Endocrine Disrupting Chemicals

The presence of emerging contaminants such as endocrine-disrupting chemicals (EDCs) in water resources is a global concern, with reported persistent and rising concentrations in surface- and groundwaters. Endocrine-disrupting chemicals (EDCs) are known to be bioactive and interfere with the vertebrate endocrine system which regulates hormone synthesis, transport and degradation. Although analytical chemistry can detect for single chemical contaminants, it does not address the possible biological activity of the chemical cocktail of hazardous chemicals potentially present in environmental samples. Effect-based methods (EBMs) address this shortcoming by accounting for chemical-chemical interactions and assessing acute or chronic exposure risks to ecosystem and human health. Both analytical chemistry and EBM techniques, however, require an advanced skill level to conduct with other added financial costs. Deployable automated biosensors functioning as EBMs could provide a solution to EDC screening, bridging the resource and human capacity gaps. Within this study, we developed a fluorescent yeast estrogen screen (fYES) strain, Saccharomyces cerevisiae SC-ERCIT, to respond in a dose-dependent manner to the presence of estrogenic EDCs. A low-cost, deployable biosensor device was subsequently designed to allow for inline exposure to and monitoring of environmental samples. By exploiting the biofilm growth mode of this organism, the designed reactor sensor system was applied to detect the presence of estrogenic EDCs under continuous flow conditions, allowing real-time and online monitoring of water source quality. The sensitivity, specificity, response time and limits of detection (LoD) and quantification (LoQ) of the constructed yeast strain showed promise under static and continuous flow conditions for future in situ applications. This will include assessing not only the quality of groundwater directly as part of Managed Aquifer Recharge (MAR), but also the sources like treated wastewater that could possibly feed MAR resources.