Improvement of daptomycin yield by overexpression of the accessory genes of daptomycin gene cluster

The effects of the accessory genes flanking the non-ribosomal peptide synthetase (NRPS) genes on daptomycin production were investigated by overexpression under the control of ermE* promoter via the integrative Escherichia coli–Streptomyces vector pIB139. The yield of daptomycin was promoted significantly when either of the upstream accessory genes of dptE and dptF or downstream accessory genes of dptG, dptH, dptI and dptJ was overexpressed individually or by a combined manner. The yield of daptomycin further increased to 869 ± 25 mg/L, approximately 42.6% higher than the parental strain of LC-54-16, when all of the six upstream and downstream accessory genes were overexpressed simultaneously. The results above suggested that the upstream and downstream accessory genes of NRPS had positive cooperativity in the biosynthesis of daptomycin. The transcriptional levels of both the upstream and the downstream accessory genes of NRPS in HP-EJ were approximately 2.5-fold as high as that in the parental strain of LC-54-16.Key words: Daptomycin production, accessory genes of NRPS, overexpression, Streptomyces roseosporus

Synthesis of Silicate-Bridged Heterojunctional SnO2/BiVO4 Nanoplates as Efficient Photocatalysts to Convert CO2 and Degrade 2,4-Dichlorophenol

Bismuth vanadate (BiVO4) is a promising visible‐light responsive photocatalyst, whose photocatalytic activity can be significantly improved by increasing its surface area and utilizing its high‐energy‐level photogenerated electrons effectively. In this work, 2D BiVO4 nanoplates with large specific surface area are successfully fabricated by hydrothermal conversion with the pre‐prepared BiOCl nanosheets as precursors. To improve the photogenerated charge separation, resulted BiVO4 nanoplates are further coupled with nanocrystalline SnO2 to construct heterojunctions, then silicate bridges are introduced between the interfaces of BiVO4 and SnO2. The amount‐optimized silicate‐bridged SnO2/BiVO4 nanocomposite exhibit exceptional visible‐light photocatalytic activities, by ≈7‐time and 4‐time enhancements for CO2 conversion to CH4 and for 2,4‐dichlorophenol degradation, respectively, compared to bare BiVO4 nanoparticles. The significantly enhanced charge separation is verified by steady‐state and time‐resolved surface photovoltage responses and produced hydroxyl radical amounts. Moreover, it is deduced through designed photo‐electrochemical experiments that the introduced SnO2 acts as a proper‐energy platform capable of accepting the photogenerated electrons of BiVO4 nanoplates, and the constructed silicate bridges further facilitate the electron transfer between BiVO4 and SnO2. This work opens up a feasible route to synthesize visible‐light‐driven 2D bismuth‐based nano‐photocatalysts with high photocatalytic activities for efficient fuel production and environmental remediation

Source analysis of P3a and P3b components to investigate interaction of depression and anxiety in attentional systems

published_or_final_versio

Interface-modulated nanojunction and microfluidic platform for photoelectrocatalytic chemicals upgrading

Photoelectrocatalytic oxidation provides a technically applicable way for solar-chemical synthesis, but its efficiency and selectivity are moderate. Herein, a microfluidic photoelectrochemical architecture with 3-D microflow channels is constructed by interfacial engineering of defective WO3/TiO2 heterostructures on porous carbon fibers. Kelvin probe force microscopy and photoluminescence imaging visually evidence the charge accumulation sites on the nanojunction. This efficient charge separation contributes to a 3-fold enhancement in the yield of glyceraldehyde and 1,3-dihydroxyacetone during glycerol upgrading, together with nearly doubled production of high value-added KA oil and S2O82− oxidant through cyclohexane and HSO4− oxidization, respectively. More importantly, the microfluidic platform with enhanced mass transfer exhibits a typical reaction selectivity of 85 %, which is much higher than the conventional planar protocol. Integrating this microfluidic photoanode with an oxygen reduction cathode leads to a self-sustained photocatalytic fuel cell with remarkably high open-circuit voltage (0.9 V) and short-circuit current (1.2 mA cm−2)

Universal and tunable liquid–liquid separation by nanoparticle-embedded gating membranes based on a self-defined interfacial parameter

Superwetting porous membranes with tunable liquid repellency are highly desirable in broad domains including scientific research, chemical industry, and environmental protection. Such membranes should allow for controllable droplet bouncing or spreading, which is difficult to achieve for low surface energy organic liquids (OLs). Here we develop an interfacial physical parameter to regulate the OL wettability of nanoparticle-embedded membranes by structuring synergistic layers with reconfigurable surface energy components. Under the tunable solid-liquid interaction in the aggregation-induced process, the membranes demonstrate positive/negative liquid gating regularity for polar protic liquids, polar aprotic liquids, and nonpolar liquids. Such a membrane can be employed as self-adaptive gating for various immiscible liquid mixtures with superior separation efficiency and permeation flux, even afford successive achievement of high-performance in situ extraction-back extraction coupling. This study should provide distinctive insights into intrinsic wetting behaviors and have pioneered a rational strategy to design high-performance separation materials for diverse applications

Digital photoprogramming of liquid-crystal superstructures featuring intrinsic chiral photoswitches

Dynamic patterning of soft materials in a fully reversible and programmable manner with light enables applications in anti-counterfeiting, displays and labelling technology. However, this is a formidable challenge due to the lack of suitable chiral molecular photoswitches. Here, we report the development of a unique intrinsic chiral photoswitch with broad chirality modulation to achieve digitally controllable, selectable and extractable multiple stable reflection states. An anti-counterfeiting technique, embedded with diverse microstructures, featuring colour-tunability, erasability, reversibility, multi-stability and viewing-angle dependency of pre-recorded patterns, is established with these photoresponsive superstructures. This strategy allows dynamic helical transformation from the molecular and supramolecular to the macroscopic level using light-activated intrinsic chirality, demonstrating the practicality of photoprogramming photonics

Tiling genomes of pathogenic viruses identifies potent antiviral shRNAs and reveals a role for secondary structure in shRNA efficacy

shRNAs can trigger effective silencing of gene expression in mammalian cells, thereby providing powerful tools for genetic studies, as well as potential therapeutic strategies. Specific shRNAs can interfere with the replication of pathogenic viruses and are currently being tested as antiviral therapies in clinical trials. However, this effort is hindered by our inability to systematically and accurately identify potent shRNAs for viral genomes. Here we apply a recently developed highly parallel sensor assay to identify potent shRNAs for HIV, hepatitis C virus (HCV), and influenza. We observe known and previously unknown sequence features that dictate shRNAs efficiency. Validation using HIV and HCV cell culture models demonstrates very high potency of the top-scoring shRNAs. Comparing our data with the secondary structure of HIV shows that shRNA efficacy is strongly affected by the secondary structure at the target RNA site. Artificially introducing secondary structure to the target site markedly reduces shRNA silencing. In addition, we observe that HCV has distinct sequence features that bias HCV-targeting shRNAs toward lower efficacy. Our results facilitate further development of shRNA based antiviral therapies and improve our understanding and ability to predict efficient shRNAs