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Efficient and long-term photoelectrochemical (PEC) hydrogen liberation from hydrazine hydrate was achieved using CdS nanorod arrays (CdS NRs) as the photoelectrode. Under light irradiation, the CdS photoelectrode exhibited high efficiency and stability for the anodic oxidation of N2H4·H2O with high selectivity for hydrogen production at the counter cathode. The yield and Faradic efficiencies (FE) of hydrogen from N2H4·H2O solution under mild conditions were determined to be 658 μmol/cm2 and 90%, respectively, after 5 h of operation. The photocurrent density of the CdS electrode in electrolyte with N2H4·H2O reached 7.6 mA/cm2 at 1.23 V versus RHE, five times higher than that in N2H4·H2O free electrolyte. And the persistence of CdS electrodes in electrolytes with N2H4·H2O was more than 100 h, while in N2H4·H2O free electrolytes, it was less than 100 s. An obvious cathodic shift of the photocurrent onset potential of about 300 mV was also observed. Furthermore, the kinetics of PEC oxidation of N2H4·H2O were further tested. In addition, it is expected that this work may provide a strategy to stabilize other unstable photoelectrodes for a wide range of applications and supply a way to produce hydrogen by photoelectrochemical decomposition of N2H4·H2O. [ABSTRACT FROM AUTHOR]

Bacterial metabolosomes are a family of protein organelles in bacteria. Elucidating how thousands of proteins self-assemble to form functional metabolosomes is essential for understanding their significance in cellular metabolism and pathogenesis. Here we investigate the de novo biogenesis of propanediol-utilization (Pdu) metabolosomes and characterize the roles of the key constituents in generation and intracellular positioning of functional metabolosomes. Our results demonstrate that the Pdu metabolosome undertakes both "Shell first" and "Cargo first" assembly pathways, unlike the β-carboxysome structural analog which only involves the "Cargo first" strategy. Shell and cargo assemblies occur independently at the cell poles. The internal cargo core is formed through the ordered assembly of multiple enzyme complexes, and exhibits liquid-like properties within the metabolosome architecture. Our findings provide mechanistic insight into the molecular principles driving bacterial metabolosome assembly and expand our understanding of liquid-like organelle biogenesis. Bacteria have evolved proteinaceous microcompartments (BMCs) to control the passage of metabolites and facilitate catabolism in a micro-environment. Here, Yang et al. apply fluorescence microscopy to characterize the protein-protein interaction and assembly involved in the de novo biogenesis of propanediol-utilization (Pdu) metabolosomes and show that Pdu BMCs undergo a combination of 'Shell first' and 'Cargo first' assembly. [ABSTRACT FROM AUTHOR]

Some enteric bacteria including Salmonella have evolved the propanediol-utilising microcompartment (Pdu MCP), a specialised proteinaceous organelle that is essential for 1,2-propanediol degradation and enteric pathogenesis. Pdu MCPs are a family of bacterial microcompartments that are self-assembled from hundreds of proteins within the bacterial cytosol. Here, we seek a comprehensive understanding of the stoichiometric composition and organisation of Pdu MCPs. We obtain accurate stoichiometry of shell proteins and internal enzymes of the natural Pdu MCP by QconCAT-driven quantitative mass spectrometry. Genetic deletion of the major shell protein and absolute quantification reveal the stoichiometric and structural remodelling of metabolically functional Pdu MCPs. Decoding the precise protein stoichiometry allows us to develop an organisational model of the Pdu metabolosome. The structural insights into the Pdu MCP are critical for both delineating the general principles underlying bacterial organelle formation, structural robustness and function, and repurposing natural microcompartments using synthetic biology for biotechnological applications. Enteric pathogens such as Salmonella depend on propanediol-utilising microcompartments (Pdu MCP), which self-assemble from cytosolic proteins. Using mass spectrometry-based absolute quantification, the authors here define the protein stoichiometry and propose an organizational model of a Salmonella Pdu MCP. [ABSTRACT FROM AUTHOR]

This paper presents a study on the degradation of Poly (lactic acid) (PLA), Poly (butylene abdicate—terephthalate) (PBAT) and their blends with different proportions in the environment of digested sludge. The degradation rates of PLA and PBAT were obtained through anaerobic reaction device. The samples obtained at regular intervals were measured and analyzed by differential scanning calorimeter (DSC), infrared spectrometer (FTIR) and scanning electron microscope (SEM) respectively. The results showed that the degradation rate of PLA was higher than that of PBAT under the same degradation environment and degradation time. DSC results showed that the degradation rate of PLA in the amorphous phase was slowed by the influence of PBAT. The characteristic peaks of the materials on the infrared spectrum shifted after degradation which implicit the degradation occurs. At the microscopic level, numerous protruding ribs in the material can be seen in the electron micrograph. Obviously, the samples can be degraded under the environment of digested sludge. [ABSTRACT FROM AUTHOR]

2D Bi2S3/CdS nanosheet arrays have been constructed by a simple three-step method. Firstly, BiOI nanosheet arrays have been electrochemically grown on the surface of conductive FTO substrate and then converted into Bi2S3 nanosheet arrays by ion exchange. Finally, CdS was hydrothermally deposited onto the surface of Bi2S3 nanosheet arrays to form hybrid Bi2S3/CdS nanosheet arrays. The obtained hybrid heterojunction arrays have been used as photoanodes for photoelectrochemical hydrogen evolution and showed enhanced performance and prolonged stability. The photocurrent density of the elegant Bi2S3/CdS nanosheet arrays reaches 9.48 mA/cm2 at 1.23 VRHE under an illumination of 100 mW/cm2 from AM 1.5G sun simulator, which is more than ten times higher than that of the pure Bi2S3 nanosheet arrays and the photocurrent density does not decline obviously after 4 h of continuous operation. Ultimately, a rational mechanism is proposed to elucidate the high performance and excellent stability of Bi2S3/CdS nanosheet arrays for photoelectrochemical cells. To obtain nanosheet arrays: Arrays of Bi2S3/CdS nanosheets on a FTO substrate are synthesized by electrodeposition, ion exchange and hydrothermal process. The Bi2S3/CdS nanosheet photoanodes show better photoactive and photostability compared to bare Bi2S3 (CdS) nanosheets for photoelectrochemical splitting of water. [ABSTRACT FROM AUTHOR]

Compartmentalization is a ubiquitous building principle in cells, which permits segregation of biological elements and reactions. The carboxysome is a specialized bacterial organelle that encapsulates enzymes into a virus-like protein shell and plays essential roles in photosynthetic carbon fixation. The naturally designed architecture, semi-permeability, and catalytic improvement of carboxysomes have inspired rational design and engineering of new nanomaterials to incorporate desired enzymes into the protein shell for enhanced catalytic performance. Here, we build large, intact carboxysome shells (over 90 nm in diameter) in the industrial microorganism Escherichia coli by expressing a set of carboxysome protein-encoding genes. We develop strategies for enzyme activation, shell self-assembly, and cargo encapsulation to construct a robust nanoreactor that incorporates catalytically active [FeFe]-hydrogenases and functional partners within the empty shell for the production of hydrogen. We show that shell encapsulation and the internal microenvironment of the new catalyst facilitate hydrogen production of the encapsulated oxygen-sensitive hydrogenases. The study provides insights into the assembly and formation of carboxysomes and paves the way for engineering carboxysome shell-based nanoreactors to recruit specific enzymes for diverse catalytic reactions. The extreme oxygen sensitive character of hydrogenases is a longstanding issue for hydrogen production in bacteria. Here, the authors build carboxysome shells in E. coli and incorporate catalytically active hydrogenases and functional partners within the empty shell for the production of hydrogen. [ABSTRACT FROM AUTHOR]