A microbial sensor platform based on bacterial bioluminescence (luxAB) and green fluorescent protein (gfp) reporters for in situ monitoring of toxicity of wastewater nitrification process dynamics.

To avoid the upset of nitrification process in wastewater treatment plants, monitoring of influent toxic chemicals is essential for stable operation. Toxic chemical compounds can interfere with the biological nitrogen removal, thus affecting plant efficiency and effluent water quality. Here we report the development of fluorescence and bioluminescence bioassays, based on E. coli engineered to contain the promoter region of ammonia oxidation pathway (AmoA1) of Nitrosomonas europaea and a reporter gene (lux or gfp). The fluorescence or bioluminescence signal was measured with newly designed optical devices. The microbial sensors were tested and validated at different concentrations of nitrification-inhibiting compounds such as allylthiourea, phenol, and mercury. The signal decrease was immediate and proportional to inhibitor concentration. The developed bacterial bioassays could detect the inhibition of the nitrification process in wastewater for allylthiourea concentrations of 1 μg/L for E.coli pMosaico-Pamo-gfp and 0.5 μg/L for E.coli pMosaico-Pamo-luxAB. The results were confirmed using water from a wastewater plant, containing nitrification-inhibiting compounds.