•SA-Pt/g-C3N4-K as a SAzyme with high peroxidase activity was reported.•This SAzyme was firstly applied in biosensor and antibacterial application.•A colorimetric assay based on a SAzyme for ...oxytetracycline detection is reported.•This SAzyme with good biocompatibility exhibits killing efficiency > 99.99 %.
Nanozymes currently face challenges in respect to their structure, properties, and mechanism compared to natural enzymes. Single-atom nanozymes (SAzymes) can realize the maximum metal atom utilization and the possibility of overcoming inherent limitations. Herein, a SAzyme based on Pt single atoms modified carbon nitride nanorod (SA-Pt/g-C3N4-K) was synthesized, and exhibits peroxidase-mimicking activity for antibiotic detection and antibacterial applications. Both experimental results and density functional theory calculations reveal that the Pt-N-C structure of SA-Pt/g-C3N4-K significantly enhances OH generation via reducing the desorption energy of the intermediate state of OH* from the active site during H2O2 activation. Notably, the peroxidase-like activity of SA-Pt/g-C3N4-K can be regulated by the aptamer, and guarantees the SAzyme with high sensitivity to antibiotic. Moreover, SA-Pt/g-C3N4-K nanozyme shows remarkable hydroxyl radical-mediated in vitro gram-negative bacteria inactivation performance with killing efficiency > 99.99 % in the presence of 1 mM H2O2 and enabled healing of gram-negative bacteria-infected wounds. This work provides new insights into designing highly efficient multifunctional SAzymes for environmental and biological applications.
Despite recent advances in genome editing capabilities for the model organism Saccharomyces cerevisiae, the chromosomal integration of large biochemical pathways for stable industrial production ...remains challenging. In this work, we developed a simple platform for high-efficiency, single-step, markerless, multi-copy chromosomal integration of full biochemical pathways in Saccharomyces cerevisiae. In this Di-CRISPR (delta integration CRISPR-Cas) platform based on the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated systems (Cas), we specifically designed guide RNA sequences to target multiple delta sites in the yeast genome. The generation of double stranded breaks at the delta sites allowed simultaneous integration of multiple copies of linearized donor DNA containing large biochemical pathways. With our newly developed Di-CRISPR platform, we were able to attain highly efficient and markerless integration of large biochemical pathways and achieve an unprecedented 18-copy genomic integration of a 24kb combined xylose utilization and (R,R)-2,3-butanediol (BDO) production pathway in a single step, thus generating a strain that was able to produce BDO directly from xylose. The simplicity and high efficiency of the Di-CRISPR platform could provide a superior alternative to high copy plasmids and would render this platform an invaluable tool for genome editing and metabolic engineering in S. cerevisiae.
Display omitted
•Created a novel approach for integration of DNA at delta sites of yeast genome.•Enabled efficient multi-copy, one-step, markerless integration of large DNA.•Achieved an unprecedented 18-copy genomic integration of a 24 kb pathway in one step.•The platform surpassed current strategies and will be a useful genome editing tool.
By combining cellulase production, cellulose hydrolysis, and sugar fermentation into a single step, consolidated bioprocessing (CBP) represents a promising technology for biofuel production. Here we ...report engineering of Saccharomyces cerevisiae strains displaying a series of uni-, bi-, and trifunctional minicellulosomes. These minicellulosomes consist of (i) a miniscaffoldin containing a cellulose-binding domain and three cohesin modules, which was tethered to the cell surface through the yeast a-agglutinin adhesion receptor, and (ii) up to three types of cellulases, an endoglucanase, a cellobiohydrolase, and a β-glucosidase, each bearing a C-terminal dockerin. Cell surface assembly of the minicellulosomes was dependent on expression of the miniscaffoldin, indicating that formation of the complex was dictated by the high-affinity interactions between cohesins and dockerins. Compared to the unifunctional and bifunctional minicellulosomes, the quaternary trifunctional complexes showed enhanced enzyme-enzyme synergy and enzyme proximity synergy. More importantly, surface display of the trifunctional minicellulosomes gave yeast cells the ability to simultaneously break down and ferment phosphoric acid-swollen cellulose to ethanol with a titer of ~1.8 g/liter. To our knowledge, this is the first report of a recombinant yeast strain capable of producing cell-associated trifunctional minicellulosomes. The strain reported here represents a useful engineering platform for developing CBP-enabling microorganisms and elucidating principles of cellulosome construction and mode of action.
Here we report a transcription factor decoy strategy for targeted activation of eight large silent polyketide synthase and non-ribosomal peptide synthetase gene clusters, ranging from 50 to 134 ...kilobases (kb) in multiple streptomycetes, and characterization of a novel oxazole family compound produced by a 98-kb biosynthetic gene cluster. Owing to its simplicity and ease of use, this strategy can be scaled up readily for discovery of natural products in streptomycetes.
Electrochemical reduction of CO2 to ethanol, a clean and renewable liquid fuel with high heating value, is an attractive strategy for global warming mitigation and resource utilization. However, ...converting CO2 to ethanol remains great challenge due to the low activity, poor product selectivity and stability of electrocatalysts. Here, the B‐ and N‐co‐doped nanodiamond (BND) was reported as an efficient and stable electrode for selective reduction of CO2 to ethanol. Good ethanol selectivity was achieved on the BND with high Faradaic efficiency of 93.2 % (−1.0 V vs. RHE), which overcame the limitation of low selectivity for multicarbon or high heating value fuels. Its superior performance was mainly originated from the synergistic effect of B and N co‐doping, high N content and overpotential for hydrogen evolution. The possible pathway for CO2 reduction revealed by DFT computation was CO2→*COOH→*CO→*COCO→*COCH2OH→*CH2OCH2OH→CH3CH2OH.
Efficient and selective electrochemical reduction of CO2 to ethanol was achieved on a nonmetallic B‐ and N‐co‐doped nanodiamond used as an electrocatalyst. The synergistic effect of co‐doping, N content, and H2 evolution potential were used as key factors for tailoring ethanol selectivity.
Genetic sensors capable of converting key metabolite levels to fluorescence signals enable the monitoring of intracellular compound concentrations in living cells, and emerge as an efficient tool in ...high-throughput genetic screening. However, the development of genetic sensors in yeasts lags far behind their development in bacteria. Here we report the design of a malonyl-CoA sensor in Saccharomyces cerevisiae using an adapted bacterial transcription factor FapR and its corresponding operator fapO to gauge intracellular malonyl-CoA levels. By combining this sensor with a genome-wide overexpression library, we identified two novel gene targets that improved intracellular malonyl-CoA concentration. We further utilized the resulting recombinant yeast strain to produce a valuable compound, 3-hydroxypropionic acid, from malonyl-CoA and enhanced its titer by 120%. Such a genetic sensor provides a powerful approach for genome-wide screening and could further improve the synthesis of a large range of chemicals derived from malonyl-CoA in yeast.
The Broad Learning System (BLS) has demonstrated strong performance across a variety of problems. However, BLS based on the Minimum Mean Square Error (MMSE) criterion is highly sensitive to label ...noise. To enhance the robustness of BLS in environments with label noise, a function called Logarithm Kernel (LK) is designed to reweight the samples for outputting weights during the training of BLS in order to construct a Logarithm Kernel-based BLS (L-BLS) in this paper. Additionally, for image databases with numerous features, a Mixture Autoencoder (MAE) is designed to construct more representative feature nodes of BLS in complex label noise environments. For the MAE, two corresponding versions of BLS, MAEBLS, and L-MAEBLS were also developed. The extensive experiments validate the robustness and effectiveness of the proposed L-BLS, and MAE can provide more representative feature nodes for the corresponding version of BLS.
The current deep learning methods for copy–move forgery detection (CMFD) are mostly based on deep convolutional neural networks, which frequently discard a large amount of detail information ...throughout convolutional feature extraction and have poor long-range information extraction capabilities. The Transformer structure is adept at modeling global context information, but the patch-wise self-attention calculation still neglects the extraction of details in local regions that have been tampered with. A local-information-refined dual-branch network, LBRT (Local Branch Refinement Transformer), is designed in this study. It performs Transformer encoding on the global patches segmented from the image and local patches re-segmented from the global patches using a global modeling branch and a local refinement branch, respectively. The self-attention features from both branches are precisely fused, and the fused feature map is then up-sampled and decoded. Therefore, LBRT considers both global semantic information modeling and local detail information refinement. The experimental results show that LBRT outperforms several state-of-the-art CMFD methods on the USCISI dataset, CASIA CMFD dataset, and DEFACTO CMFD dataset.
Microorganisms have become an increasingly important platform for the production of drugs, chemicals, and biofuels from renewable resources. Advances in protein engineering, metabolic engineering, ...and synthetic biology enable redesigning microbial cellular networks and fine-tuning physiological capabilities, thus generating industrially viable strains for the production of natural and unnatural value-added compounds. In this review, we describe the recent progress on engineering microbial factories for synthesis of valued-added products including alkaloids, terpenoids, flavonoids, polyketides, non-ribosomal peptides, biofuels, and chemicals. Related topics on lignocellulose degradation, sugar utilization, and microbial tolerance improvement will also be discussed.
Celotno besedilo
Dostopno za:
CEKLJ, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
