The bioreduction capacity of Cr(VI) by Shewanella is mainly governed by its bidirectional extracellular electron transfer (EET). However, the low bidirectional EET efficiency restricts its wider applications in remediation of the environments contaminated by Cr(VI). Cyclic adenosine 3′,5′‐monophosphate (cAMP) commonly exists in Shewanella strains and cAMP–cyclic adenosine 3′,5′‐monophosphate receptor protein (CRP) system regulates multiple bidirectional EET‐related pathways. This inspires us to strengthen the bidirectional EET through elevating the intracellular cAMP level in Shewanella strains. In this study, an exogenous gene encoding adenylate cyclase from the soil bacterium Beggiatoa sp. PS is functionally expressed in Shewanella oneidensis MR‐1 (the strain MR‐1/pbPAC) and a MR‐1 mutant lacking all endogenous adenylate cyclase encoding genes (the strain Δca/pbPAC). The engineered strains exhibit the enhanced bidirectional EET capacities in microbial electrochemical systems compared with their counterparts. Meanwhile, a three times more rapid reduction rate of Cr(VI) is achieved by the strain MR‐1/pbPAC than the control in batch experiments. Furthermore, a higher Cr(VI) reduction efficiency is also achieved by the strain MR‐1/pbPAC in the Cr(VI)‐reducing biocathode experiments. Such a bidirectional enhancement is attributed to the improved production of cAMP–CRP complex, which upregulates the expression levels of the genes encoding the c‐type cytochromes and flavins synthetic pathways. Specially, this strategy could be used as a broad‐spectrum approach for the other Shewanella strains. Our results demonstrate that elevating the intracellular cAMP levels could be an efficient strategy to enhance the bidirectional EET of Shewanella strains and improve their pollutant transformation capacity.

A highly efficient tandem hydroamination and cyclization reaction of 2-trifluoromethyl-1,3-enynes with primary amines leading to 4-trifluoromethyl-3-pyrrolines was developed by using AgNO as a catalyst under mild reaction conditions. This new method is compatible with alkyl, aryl, and allyl primary amines, representing an atom-economical protocol for the construction of 4-trifluoromethyl-3-pyrrolines for the first time.

Bacteria can be genetically engineered to act as therapeutic delivery vehicles in the treatment of tumors, killing cancer cells or activating the immune system. This is known as Bacteria-Mediated Cancer Therapy (BMCT). Tumor invasion, colonization and tumor regression are major biological events, which are directly associated with antitumor effects and are uncontrollable due to the influence of tumor microenvironments during the BMCT process. Here, we developed a genetic circuit for dynamically programming bacterial lifestyles (planktonic, biofilm or lysis), to precisely manipulate the process of bacterial adhesion, colonization and drug release in BMCT process, via hierarchical modulation of the lighting power density (LPD) of near-infrared (NIR) light. The deep tissue penetration of NIR offers us a modality for spatiotemporal and noninvasive control of bacterial genetic circuits in vivo. By combining computational modeling with high throughput characterization device, we optimized the genetic circuits in engineered bacteria to program the process of bacterial lifestyle transitions by altering the illumination scheme of NIR. Our results showed that programming intratumoral bacterial lifestyle transitions allows precise control of multiple key steps throughout the BMCT process, and therapeutic efficacy can be greatly improved by controlling the localization and dosage of therapeutic agents via optimizing the illumination scheme.