Microbial extracellular electron transfer (EET) is the basis for many microbial processes involved in element geochemical recycling, bioenergy harvesting, and bioremediation, including the technique for remediating U(VI)contaminated environments. However, the low EET rate hinders its full potential from being fulfilled. The main challenge for engineering microbial EET is the difficulty in optimizing cell resource allocation for EET investment and basic metabolism and the optimal coordination of the different EET pathways. Here, we report a novel combinatorial optimization strategy with a physiologically adapted regulatory platform. Through exploring the physiologically adapted regulatory elements, a 271.97-fold strength range, autonomous, and dynamic regulatory platform was established for Shewanella oneidensis, a prominent electrochemically active bacterium. Both direct and mediated EET pathways are modularly reconfigured and tuned at various intensities with the regulatory platform, which were further assembled combinatorically. The optimal combinations exhibit up to 16.12-, 4.51-, and 8.40fold improvements over the control in the maximum current density (1009.2 mA/m 2 ) of microbial electrolysis cells and the voltage output (413.8 mV) and power density (229.1 mW/m 2 ) of microbial fuel cells. In addition, the optimal strains exhibited up to 6.53fold improvement in the radionuclide U(VI) removal efficiency. This work provides an effective and feasible approach to boost microbial EET performance for environmental applications.

Conveniently and cost-effectively obtained Fe(III) can be utilized for peracetic acid (PAA) activation in the presence of natural polyphenols. However, the effect of polyphenols on the fate of generated reactive oxygen species (ROS) remains unclear. In this study, it was demonstrated that Fe(III) can efficiently trigger PAA oxidation of pollutants with the assistance of gallic acid (GA), a widely distributed natural polyphenol. The GA/Fe(III)/PAA system efficiently removed bisphenol A (BPA) over a wide initial pH range of 4.0−7.0, with a removal rate of >90% over 20 min. Further, •OH played a dominant role in BPA degradation, and O 2 •− functioned as an intermediate contributing to the partial generation of •OH. The generated organic radicals (R-O•) did not considerably contribute to BPA removal. Apart from GA itself, both the reaction intermediates (phenoxy radicals) of GA with ROS and BPA degradation intermediates were crucial for the regeneration of Fe(II) from Fe(III) and the subsequent enhanced activation of PAA. Notably, further comprehensive analysis revealed an increase in •OH yield, but a decrease in R-O• production as the dosage of GA was increased from 10 to 100 μM. This finding emphasized the importance of properly utilizing GA, considering the reactivity of varied ROS toward different contaminants. R-O• (CH 3 CO 2 • and CH 3 CO 3 •) was quickly consumed by the GA-Fe(II) complex through single-electron transfer (SET) and/or by GA via H-abstraction (HAA). This study proposes a promising strategy for improving the Fe(III)/PAA process and advances the understanding of the trade-off between radical generation and elimination by polyphenols in PAA-based advanced oxidation processes (AOPs).