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  • McPherson Garrison posted an update 1 day, 11 hours ago

    Gluconobacter oxydans is well-known for its incomplete oxidizing capacity and has been widely applied in industrial production. However, genetic tools in G. oxydans are still scarce compared with model microorganisms, limiting its metabolic engineering. This study aimed to develop a clustered regularly interspaced short palindromic repeats interference (CRISPRi) system based on the typical type I-E endogenous CRISPR/CRISPR-associated proteins (Cas) system in G. oxydans WSH-003. The nuclease Cas3 in this system was inactivated naturally and hence did not need to be knocked out. Subsequently, the CRISPRi effect was verified by repressing the expression of fluorescent proteins, revealing effective multiplex gene repression. Finally, the endogenous CRISPRi system was used to study the role of the central carbon metabolism pathway, including the pentose phosphate pathway (PPP) and Entner-Doudoroff pathway (EDP), in G. oxydans WSH-003. This was done to demonstrate a metabolic engineering application. The PPP was found to be important for cell growth and the substrate conversion rate. The development of the CRISPRi system enriched the gene regulation tools in G. oxydans and promoted the metabolic engineering modification of G. oxydans to improve its performance. In addition, it might have implications for metabolic engineering modification of other genetically recalcitrant strains.Extending photoelectric response to the near-infrared (NIR) region using upconversion luminescent (UCL) materials is one promising approach to obtain high-efficiency perovskite solar cells (PSCs). However, challenges remain due to the shortage of highly efficient UCL materials and device structure. NaCsWO3 nanocrystals exhibit near-infrared absorption arising from the local surface plasmon resonance (LSPR) effect, which can be used to boost the UCL of rare-earth-doped upconversion nanoparticles (UCNPs). In this study, using NaCsWO3 as the LSPR center, NaCsWO3@NaYF4@NaYF4Yb,Er nanoparticles were synthesized and the UCL intensity could be enhanced by more than 124 times when the amount of NaCsWO3 was 2.8 mmol %. Then, such efficient UCNPs were not only doped into the hole transport layer but also used to modify the perovskite film in PSCs, resulting in the highest power conversion efficiency (PCE) reaching 18.89% (that of the control device was 16.01% and the PCE improvement was 17.99%). Possible factors for the improvement of PSCs were studied and analyzed. It is found that UCNPs can broaden the response range of PSCs to the NIR region due to the LSPR-enhanced UCL and increase the visible light reabsorption of PSCs due to the scattering and reflection effect, which generate more photocurrent in PSCs. In addition, UCNPs modify the perovskite film by effectively filling the holes and gaps at the grain boundary and eliminating the perovskite surface defects, which lead to less carrier recombination and then effectively improve the performance of PSC devices.Violacein is a naturally occurring anticancer therapeutic compound with deep purple color. In this work, we harnessed the modular and combinatorial feature of a Golden Gate assembly method to construct a library of violacein producing strains in the oleaginous yeast Yarrowia lipolytica, where each gene in the violacein pathway was controlled by three different promoters with varying transcriptional strength. After optimizing the linker sequence and the Golden Gate reaction, we achieved high transformation efficiency and obtained a panel of representative Y. lipolytica recombinant strains. By evaluating the gene expression profile of 21 yeast strains, we obtained three colorful compounds in the violacein pathway green (proviolacein), purple (violacein), and pink (deoxyviolacein). Our results indicated that strong expression of VioB, VioC, and VioD favors violacein production with minimal byproduct deoxyvioalcein in Y. lipolytica, and high deoxyviolacein production was found strongly associated with the weak expression of VioD. By further optimizing the carbon to nitrogen ratio and cultivation pH, the maximum violacein reached 70.04 mg/L with 5.28 mg/L of deoxyviolacein in shake flasks. Taken together, the development of Golden Gate cloning protocols to build combinatorial pathway libraries, and the optimization of culture conditions set a new stage for accessing the violacein pathway intermediates and engineering violacein production in Y. lipolytica. This work further expands the toolbox to engineering Y. lipolytica as an industrially relevant host for plant or marine natural product biosynthesis.An efficient cobalt-based catalytic system for protodeboronation of various aryl and vinyl boronates is described. The reaction is capable of tolerating a wide range of functional groups. The reaction is also extended to deuterodeboronation with D2O, which provides a potential protocol for the synthesis of regiospecifically deuterated arenes and olefins.Organic materials possessing solid-state emission responsive to external stimuli have significance in a variety of material, biomedical, and optoelectronic applications. check details Organic molecules having different donor-acceptor architectures integrated with aggregation-induced emission (AIE) fluorophores have been utilized in development of mechanofluorochromic (MFC) materials. In this work, we have designed and synthesized phenanthroimidazole (PI) based derivatives TPE-PI-1, TPE-PI-2, TPE-PI-3, PTZ-PI-1, PTZ-PI-2, and PTZ-PI-3 where in donors tetraphenylethylene-TPE (D) and phenothiazine-PTZ (D’) of contrasting donor abilities are attached to the N and C atom positions of PI. The position and mode of attachment of the donors have been changed, and an additional PTZ spacer has been introduced which has a direct consequence on their photophysical and electronic properties. The PI derivatives manifest AIE, solvatochromic, and mechanochromic behavior. The single crystal X-ray analysis of TPE-PI-1 and PTZ-PI-2 reveals bent structures for the PTZ unit and a twisted conformation for TPE moieties. The density functional theory calculations were used to obtain optimized ground-state structures of the PI derivatives. The work shows a comprehensive comparison of the photophysical, electronic, AIE, and MFC properties of the PI derivatives as an effect of variations in the position of donor, donor-acceptor strength, and change in molecular conformation on use of spacer.

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