SummaryRecently, we showed that the MarR-type repressor YkvE (MhqR) regulates multiple dioxygenases/ glyoxalases, oxidoreductases and the azoreductase encoding yvaB (azoR2) gene in response to thiolspecific stress conditions, such as diamide, catechol and 2-methylhydroquinone (MHQ). Here we report on the regulation of the yocJ (azoR1) gene encoding another azoreductase by the novel DUF24/MarR-type repressor, YodB after exposure to thiol-reactive compounds. DNA binding activity of YodB is directly inhibited by thiol-reactive compounds in vitro. Mass spectrometry identified YodB-Cys-S-adducts that are formed upon exposure of YodB to MHQ and catechol in vitro. This confirms that catechol and MHQ are auto-oxidized to toxic ortho-and para-benzoquinones which act like diamide as thiol-reactive electrophiles. Mutational analyses further showed that the conserved Cys6 residue of YodB is required for optimal repression in vivo and in vitro while substitution of all three Cys residues of YodB affects induction of azoR1 transcription. Finally, phenotype analyses revealed that both azoreductases, AzoR1 and AzoR2 confer resistance to catechol, MHQ, 1,4-benzoquinone and diamide. Thus, both azoreductases that are controlled by different regulatory mechanisms have common functions in quinone and azo-compound reduction to protect cells against the thiol reactivity of electrophiles.

The facilitation of redox-neutral reactions by electrochemical injection of holes and electrons, also known as “electrochemical catalysis”, is a little explored approach that has the potential to expand the scope of electrosynthesis immensely. To systematically improve existing protocols and to pave the way toward new developments, a better understanding of the underlying principles is crucial. In this context, we have studied the Newman–Kwart rearrangement of O-arylthiocarbamates to the corresponding S-aryl derivatives, the key step in the synthesis of thiophenols from the corresponding phenols. This transformation is a particularly useful example because the conventional method requires temperatures up to 300 °C, whereas electrochemical catalysis facilitates the reaction at room temperature. A combined experimental–quantum chemical approach revealed several reaction channels and rendered an explanation for the relationship between the structure and reactivity. Furthermore, it is shown how rapid cyclic voltammetry measurements can serve as a tool to predict the feasibility for specific substrates. The study also revealed distinct parallels to photoredox-catalyzed reactions, in which back-electron transfer and chain propagation are competing pathways.

The feasibility of recovering copper from electronic industrial waste mud (galvanic sludge) using a combination of leaching and electrowinning has been examined. Leaching with sulfuric acid was found to be the most efficient and cost-effective way of extracting the copper from the sludge, and the optimum acid concentration and time were determined. The copper was then extracted by electrowinning in a batch recirculation electrochemical reactor (Porocell™) employing a three-dimensional carbon felt cathode. The influence of applied current, flow rate and the presence of other metal ion contaminates on the rate and current efficiency of copper electrowinning was investigated. An analysis of the experimental data showed that the current efficiency was lower than unity even though the limiting current for copper deposition was not exceeded. This low current efficiency was attributed to the occurrence of a side reaction, most likely the reduction of dissolved oxygen or oxygen-induced corrosion. The influence of this side reaction can be minimized by operating at relatively high currents and low flow rates

The Cat Ba Biosphere Reserve is internationally renowned for its spectacular karst landscape. It covers a large area with hundreds of limestone islands and various ecosystems including caves, tropical forests, and mangroves. However, previous surveys were only conducted in terrestrial ecosystems on Cat Ba Island. Therefore, bats inhabiting mangroves and the remaining islands did not receive attention from scientists up to 2014. To initially fill in the gaps, we conducted ten bat surveys between 2015 and 2020 with an emphasis on mangroves and previously unsurveyed islands. Bats were captured using mist nets and harp traps. Twenty-three species belonging to 13 genera of six families were recorded during the surveys. Of these, four species (Macroglossus minimus, Myotis hasselti, Phoniscus jagorii, Tylonycteris fulvida) are new to the reserve. Remarkably, 15 species belonging to seven genera of five families were captured in mangrove, which is the highest species diversity for bats reported from any mangrove area in mainland Southeast Asia. Based on results from the surveys and literature review, we here provide the most updated bat diversity of the reserve with confirmed records of 32 bat species belonging to 16 genera of six families. Historical records of each species in the literature were reviewed. Two species, Scotophilus heathi and Scotophilus kuhlii, are unconfirmed because of unclear evidence in previous publications. Results of this study indicated that the mangrove ecosystem is important for bats but still poorly studied in Cat Ba Biosphere Reserve and Vietnam as a whole. In addition, morphological measurements, echolocation data, distributional records, and conservation status of each species are also given in this paper for potential research and conservation campaigns in the future.