A fluorescent, supramolecular chemosensor to follow steroid depletion in bacterial cultures

摘要

AbstractSteroids have been identified as endocrine-disrupting agents, which are thought to impact the fertility of aquatic organisms and may even have direct effects on humans. The removal of steroids from wastewater is therefore essential, and this is most efficiently achieved by microbial treatment. We report herein a simple fluorescent method to identify microorganisms that are capable of steroid degradation and to optimize the conditions for steroid removal. The method is based on the supramolecular macrocycle cucurbit8uril (CB8), which can bind either the fluorescent dye berberine or a steroid in their inner cavity. In absence of steroid, the cavity is free to bind the dye, leading to a strong increase in fluorescence. In contrast, in the presence of steroid, the dye is displaced into the bulk solution. This principle affords a stable (no thermal or photodegradation was noted), fluorescent chemosensor (excitation ca. 450?nm, maximum emission at 525?nm), which can detect testosterone at concentrations >?0.7?μM. We show that this displacement principle can be applied to follow the removal of micromolar concentrations of the steroid testosterone from a bacterial culture ofButtiauxellasp. S19-1. The reliability of the chemosensor in screening applications is demonstrated by an excellentZ-factor, which was in the range of 0.52 to 0.74 for all experiments carried out with this assay.Graphical abstractSteroid depletion by bacterial cultures can be followed by fluorescence spectroscopy using a supramolecular chemosensor based on berberine and cucurbit8uril>