Enzymatic functionalization of decellularized tilapia skin scaffolds with enhanced skin regeneration.

The decellularized tilapia skin (dTS) has gained significant attention as a promising material for tissue regeneration due to its ability to provide unique structural and functional components that support cell growth, adhesion, and proliferation. However, the clinical application of dTS is limited by its low mechanical strength and rapid biodegradability. Herein, we prepare a novel RGD (arginine-glycine-aspartic acid) functionalized dTS scaffold (dTS/RGD) by using transglutaminase (TGase) crosslinking. The developed dTS/RGD scaffold possesses excellent properties, including a medium porosity of ∼59.2%, a suitable degradation rate of approximately 80% over a period of two weeks, and appropriate mechanical strength with a maximum tensile stress of ∼46.36 MPa which is much higher than that of dTS (∼32.23 MPa). These properties make the dTS/RGD scaffold ideal for promoting cell adhesion and proliferation, thereby accelerating skin wound healing in a full-thickness skin defect model. Such an enzymatic cross-linking strategy provides a favorable microenvironment for wound healing and holds great potential for application in skin regeneration engineering.

Kai-Xin-San ameliorates Alzheimer's disease-related neuropathology and cognitive impairment in APP/PS1 mice via the mitochondrial autophagy-NLRP3 inflammasome pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Kai-Xin-San (KXS) is a classic famous prescription that has been utilized for centuries to address dementia. New investigations have shown that the anti-dementia effect of KXS is connected with improved neuroinflammation. Nevertheless, the underlying mechanism is not well elucidated. AIM OF THE STUDY: We propose to discover the ameliorative impact of KXS on Alzheimer's disease (AD) and its regulatory role on the mitochondrial autophagy-nod-like receptor protein 3 (NLRP3) inflammasome pathway. MATERIALS AND METHODS: The Y maze, Morris water maze, and new objection recognition tests were applied to ascertain the spatial learning and memory capacities of amyloid precursor protein/presenilin 1 (APP/PS1) mice after KXS-treatment. Meanwhile, the biochemical indexes of the hippocampus were detected by reagent kits. The pathological alterations and mitochondrial autophagy in the mice' hippocampus were detected utilizing hematoxylin and eosin (H&E), immunohistochemistry, immunofluorescence staining, and transmission electron microscopy. Besides, the PTEN-induced putative kinase 1 (PINK1)/Parkin and NLRP3 inflammasome pathways protein expressions were determined employing the immunoblot analysis. RESULTS: The results of behavioral tests showed that KXS significantly enhanced the AD mice' spatial learning and memory capacities. Furthermore, KXS reversed the biochemical index levels and reduced amyloid-ß protein deposition in AD mice brains. Besides, H&E staining showed that KXS remarkably ameliorated the neuronal damage in AD mice. Concurrently, the results of transmission electron microscopy suggest that KXS ameliorated the mitochondrial damage in microglia and promoted mitochondrial autophagy. Moreover, the immunofluorescence outcomes exhibited that KXS promoted the expression of protein 1 light chain 3B (LC3B) associated with microtubule and the generation of autophagic flux. Notably, the immunofluorescence co-localization results confirmed the presence of mitochondrial autophagy in microglia. Finally, KXS promoted the protein expressions of the PINK1/Parkin pathway and reduced the activation of NLRP3 inflammasome. Most importantly, these beneficial effects of KXS were attenuated by the mitochondrial autophagy inhibitor chloroquine. CONCLUSION: KXS ameliorates AD-related neuropathology and cognitive impairment in APP/PS1 mice by enhancing the mitochondrial autophagy and suppressing the NLRP3 inflammasome pathway.

Identification and structural characterization of a novel chondroitin sulfate-specific carbohydrate-binding module: The first member of a new family, CBM100.

Chondroitin sulfate is a biologically and commercially important polysaccharide with a variety of applications. Carbohydrate-binding module (CBM) is an important class of carbohydrate-binding protein, which could be utilized as a promising tool for the applications of polysaccharides. In the present study, an unknown function domain was explored from a putative chondroitin sulfate lyase in PL29 family. Recombinant PhCBM100 demonstrated binding capacity to chondroitin sulfates with Ka values of 2.1 ± 0.2 × 106 M-1 and 6.0 ± 0.1 × 106 M-1 to chondroitin sulfate A and chondroitin sulfate C, respectively. The 1.55 Å resolution X-ray crystal structure of PhCBM100 exhibited a ß-sandwich fold formed by two antiparallel ß-sheets. A binding groove in PhCBM100 interacting with chondroitin sulfate was subsequently identified, and the potential of PhCBM100 for visualization of chondroitin sulfate was evaluated. PhCBM100 is the first characterized chondroitin sulfate-specific CBM. The novelty of PhCBM100 proposed a new CBM family of CBM100.

Amyloid-like aggregates of short self-assembly peptide selectively induce melanoma cell apoptosis.

With the rising global incidence of melanoma, new anti-melanoma drugs with low-inducing drug resistance and high selectivity are in urgent need. Inspired by the physiological events in which fibrillar aggregates formed by amyloid proteins are toxic to normal tissues, we here rationally design a tyrosinase responsive peptide, I4K2Y* (Ac-IIIIKKDopa-NH2). Such peptide self-assembled into long nanofibers outside the cells, while it was catalyzed into amyloid-like aggregates by tyrosinase which was rich in melanoma cells. The newly formed aggregates concentrated around the nucleus of melanoma cells, blocking the exchange of biomolecules between the nucleus and cytoplasm and finally leading to cell apoptosis via the S phase arrest in cell cycle distribution and dysfunction of mitochondria. Furthermore, I4K2Y* effectively inhibited B16 melanoma growth in a mouse model but with minimal side effects. We believe that the strategy of combining the usage of toxic amyloid-like aggregates and in-situ enzymatic reactions by specific enzymes in tumor cells will bring profound implications for designing new anti-tumor drugs with high selectivity.

Developing core competencies for clinical nurse educators: An e-Delphi-study.

BACKGROUND: Clinical nurse educator plays an indispensable role in promoting the development of nursing staff and nursing students in clinical settings. Too few core competencies for clinical nurse educators applicable to a given clinical setting are developed and validated by the research process. A better understanding of the core competencies for clinical nurse educators can inform the selection, training, and evaluation of clinical nurse educator. OBJECTIVE: To establish the core competencies for clinical nurse educators in China. DESIGN: Focus group interviews and the e-Delphi method were used. SETTINGS: This study was conducted in five teaching hospitals in China. PARTICIPANTS: Participants (n = 61), including nurse managers, clinical nurse educators, staff nurses, and nursing students were recruited for focus group interviews and 25 experts were selected for the e-Delphi study. METHODS: Based on a literature review and the focus group interviews, a preliminary set of clinical nurse educator's core competencies was formed. Subsequently, experts provided supportive and modification advice on core competencies in the two rounds e-Delphi study. The consensus percentage and the weight of each first-level, second-level index and its connotations were calculated. RESULTS: Two rounds of online Delphi expert consultation were completed by 25 experts, and the consensus was achieved on four first-level indices, 16 second-level specific competencies, and its 57 connotations. The first-level index included clinical teaching competency, clinical nursing skills, management and leadership competency, and innovation and research competency. Moreover, the consensus level of all indices was >75%, the coefficient of variation (CV) was less than 0.25 (p < 0.05) and the Kendall coefficient (W) was 0.169-0.503 (P < 0.01). CONCLUSIONS: The explicit statements of expected competencies for clinical nurse educators can be applied to diverse clinical scenarios and provide a reference for selection, training, and evaluation of the clinical nurse educators.

Mechanistic elucidation of the oral pungency of capsaicin-related dietary components: Spatial structural insights.

The mechanistic insights into the oral pungency of capsaicin-related dietary components have been elucidated from the spatial structural perspectives by establishing statistically significant and highly predictive three-dimensional quantitative structure-property relationship models. Our results visualized the possible favorable and unfavorable steric and electrostatic interactions with the pungent receptors with the assistance of pharmacophore models, and revealed the suitable electronegative/positive or bulky substitutions in the vanillyl group, amide moiety, linear alkyl chain and their adjacent structural area of capsaicin required for the desired pungency, which was not only complementary to the viewpoints proposed in our previous structure-pungency correlations, but also was applied to clearly clarify the pungent differences in compounds, and well predict the pungency of 21 capsaicin analogs though with ambiguous experimental data on pungency. Hopefully, this work would benefit the overall understanding of the pungent mechanism and facile discovery/design of analogs with desired pungency to expand their applications in foods.

Decision-making among the substitute decision makers in intensive care units: An investigation of decision control preferences and decisional conflicts.

AIMS: To explore decision control preferences and decisional conflicts and to analyse their association among the surrogate decision makers in the intensive care unit. DESIGN: The study carried out a cross-sectional survey among the surrogates. METHODS: The participants were 115 surrogate decision makers of critical patients, from August to September 2019. A Chi-squared test and logistic regression were used to assess decision control preferences and decisional conflicts, and Spearman's rank correlation coefficient was employed to examine their association. RESULTS: Of the 115 surrogate decision makers, 51.3% preferred a collaborative role, and 63.48% were somewhat unsure about making decisions. Logistic regression analysis identified decision control preferences was associated with surrogates' age, education level, and personality traits, while decisional conflicts was associated with surrogates' age, education level, character, medical expense burden, and Acute Physiology and Chronic Health Evaluation-II score. Cohen's kappa statistics showed a bad concordance of decision-making expectations and actuality, with kappa values of 0.158 (p < .05). Wherein surrogates who experienced discordance between their preferred and actual roles, have relatively higher decisional conflicts. CONCLUSION: This study identified individual differences of surrogate decision makers in decision control preferences and decisional conflicts. These results imply that incorporation of the individual decision preferences and communication styles into care plans is an important first step to develop high quality decision support. IMPACT: This research is a contribution to the limited study on decision control preferences and decisional conflicts among surrogate decision makers of critically ill patients. Moreover based on the investigation of understanding the status and related factors of decision preferences and decisional conflicts set the stage for developing effective decision support interventions.

The Nanoassembly of an Intrinsically Cytotoxic Near-Infrared Dye for Multifunctionally Synergistic Theranostics.

The combination of diagnostic and therapeutic functions in a single theranostic nanoagent generally requires the integration of multi-ingredients. Herein, a cytotoxic near-infrared (NIR) dye (IR-797) and its nanoassembly are reported for multifunctional cancer theranostics. The hydrophobic IR-797 molecules are self-assembled into nanoparticles, which are further modified with an amphiphilic polymer (C18PMH-PEG5000) on the surface. The prepared PEG-IR-797 nanoparticles (PEG-IR-797 NPs) possess inherent cytotoxicity from the IR-797 dye and work as a chemotherapeutic drug which induces apoptosis of cancer cells. The IR-797 NPs are found to have an ultrahigh mass extinction coefficient (444.3 L g-1 cm-1 at 797 nm and 385.9 L g-1 cm-1 at 808 nm) beyond all reported organic nanomaterials (<40 L g-1 cm-1 ) for superior photothermal therapy (PTT). In addition, IR-797 shows some aggregation-induced-emission (AIE) properties. Combining the merits of good NIR absorption, high photothermal energy conversion efficiency, and AIE, makes the PEG-IR-797 NPs useful for multimodal NIR AIE fluorescence, photoacoustic, and thermal imaging-guided therapy. The research exhibits the possibility of using a single ingredient and entity to perform multimodal NIR fluorescence, photoacoustic, and thermal imaging-guided chemo-/photothermal combination therapy, which may trigger wide interest from the fields of nanomedicine and medicinal chemistry to explore multifunctional theranostic organic molecules.

Red/Near-Infrared Thermally Activated Delayed Fluorescence OLEDs with Near 100 % Internal Quantum Efficiency.

Developing red thermally activated delayed fluorescence (TADF) emitters, attainable for both high-efficient red organic light-emitting diodes (OLEDs) and non-doped deep red/near-infrared (NIR) OLEDs, is challenging. Now, two red emitters, BPPZ-PXZ and mDPBPZ-PXZ, with twisted donor-acceptor structures were designed and synthesized to study molecular design strategies of high-efficiency red TADF emitters. BPPZ-PXZ employs the strictest molecular restrictions to suppress energy loss and realizes red emission with a photoluminescence quantum yield (ΦPL ) of 100±0.8 % and external quantum efficiency (EQE) of 25.2 % in a doped OLED. Its non-doped OLED has an EQE of 2.5 % owing to unavoidable intermolecular π-π interactions. mDPBPZ-PXZ releases two pyridine substituents from its fused acceptor moiety. Although mDPBPZ-PXZ realizes a lower EQE of 21.7 % in the doped OLED, its non-doped device shows a superior EQE of 5.2 % with a deep red/NIR emission at peak of 680 nm.

Efficient Orange-Red Thermally Activated Delayed Fluorescence Emitters Feasible for Both Thermal Evaporation and Solution Process.

Development of red thermally activated delayed fluorescence (TADF) emitters has been lagging behind when compared with those of blue and green fluorophores, especially for solution-processable ones. In this work, two novel orange-red TADF emitters 3,6-di(10H-phenoxazin-10-yl)dibenzo[a,c]phenazine (DBPZ-DPXZ) and 10,10'-(11,12-bis(3,5-di-tert-butylphenyl)dibenzo[a,c]phenazine-3,6-diyl)bis(10H-phenoxazine) (tDBBPZ-DPXZ) are developed. A high-performance orange-red TADF emitter, DBPZ-DPXZ, is first prepared by connecting a rigid acceptor and two rigid donor segments. While this design strategy endows DBPZ-DPXZ with an excellent TADF performance leading to a vacuum-processed organic light-emitting diode (OLED) with a high external quantum efficiency (EQE) of 17.8%, the rigid segments limit its solubility and applications in solution-processed devices. Based on this prototype, tDBBPZ-DPXZ is designed with the addition of 3,5-di-tert-butylphenyl groups to boost its solubility with barely an influence on the photophysical properties. In particular, tDBBPZ-DPXZ maintains nearly an identical photoluminescence quantum yield of 83% and singlet-triplet energy splitting of 0.03 eV with EQE of 17.0% in a vacuum-processed orange-red OLED. Furthermore, it can be applied on the orange-red solution-processed OLED realizing an EQE as high as 10.1%, representing one of the state-of-the-art results of the reported orange-red solution-processed TADF-OLEDs. This work provides an effective strategy to address the conflicting requirements between high efficiency and good solubility and develop efficient soluble orange-red TADF emitters.

Quantitative structure-retention relationships of the chromatographic retentions of phthalic acid ester contaminants in foods.

The harmful health effects caused by phthalic acid esters have been supported from the increasing scientific evidence, developing the efficient methodologies to monitor the levels of phthalic acid esters in various foods become especially important from the aspects of human exposure assessment and their migration mechanistic understanding. In this study, quantitative structure-retention relationship studies on both the gas and liquid chromatographic retention times of 23 phthalic acid esters were performed by genetic function approximation, and the optimal quantitative structure-retention relationship models (r2  > 0.980, r2 CV  > 0.960, and r2 pred  > 0.865) passed the statistical tests of cross-validation, randomization, external prediction, Roy' rm 2 metrics, Golbraikh-Tropsha' criteria and applicability domain. The established predictive models elucidate the structural requirements for the retention of phthalic acid esters over different chromatographic columns, which were finally used to predict the retention times of 11 new phthalic acid esters. Hopefully, this work could provide useful guidelines for better understanding and accurate prediction of the retention behavior of undetermined phthalic acid esters when lacking standard samples or under poor experimental conditions, and make the simultaneous identification and quantification of numerous phthalic acid esters possible.

Norepinephrine-functionalised nanoflower-like organic silica as a new adsorbent for effective Pb(II) removal from aqueous solutions.

In order to remove Pb(II) ions efficiently from aqueous solutions, a new effective adsorbent of norepinephrine-functionalised nanoflower-like organic silica (NE-NFOS) was synthesised by a biomimetic method. Biomimetic functionalization with norepinephrine has the advantages of environment-friendly and easy operation. Characterization of the NE-NFOS using scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller method, and Fourier-transform infrared spectroscopy revealed that the NFOS was modified successfully by norepinephrine. Furthermore, the influences of different parameters including adsorption kinetics, solution pH, adsorption isotherms, concentrations of Na+, K+, Ca2+, and Mg2+, desorption and reusability were studied. The adsorption experiments showed that the capacity of NE-NFOS to adsorb Pb(II) ions improved greatly after functionalisation and adsorption equilibrium was attained within 90 min at a pH of 6.0. The Na+, K+, Ca2+, and Mg2+ concentrations had little influence on the adsorption, and after recycling for five times, the Pb(II) ion removal efficiency of the adsorbent was more than 79% of its initial value. Thus, it was demonstrated that the NE-NFOS with excellent adsorption performance could be a suitable adsorbent for Pb(II) ions removal in practical applications.

Manipulating exciton dynamics of thermally activated delayed fluorescence materials for tuning two-photon nanotheranostics.

Rational manipulation of energy utilization from excited-state radiation of theranostic agents with a donor-acceptor structure is relatively unexplored. Herein, we present an effective strategy to tune the exciton dynamics of radiative excited state decay for augmenting two-photon nanotheranostics. As a proof of concept, two thermally activated delayed fluorescence (TADF) molecules with different electron-donating segments are engineered, which possess donor-acceptor structures and strong emissions in the deep-red region with aggregation-induced emission characteristics. Molecular simulations demonstrate that change of the electron-donating sections could effectively regulate the singlet-triplet energy gap and oscillator strength, which promises efficient energy flow. A two-photon laser with great permeability is used to excite TADF NPs to perform as theranostic agents with singlet oxygen generation and fluorescence imaging. These unique performances enable the proposed TADF emitters to exhibit tailored balances between two-photon singlet oxygen generation and fluorescence emission. This result demonstrates that TADF emitters can be rationally designed as superior candidates for nanotheranostic agents by the custom controlling exciton dynamics.

Red Organic Light-Emitting Diode with External Quantum Efficiency beyond 20% Based on a Novel Thermally Activated Delayed Fluorescence Emitter.

A novel thermally activated delayed fluorescence (TADF) emitter 12,15-di(10H-phenoxazin-10-yl)dibenzo[a,c]dipyrido[3,2-h:2',3'-j]phenazine (DPXZ-BPPZ) is developed for a highly efficient red organic light-emitting diode (OLED). With rigid and planar constituent groups and evident steric hindrance between electron-donor (D) and electron-acceptor (A) segments, DPXZ-BPPZ realizes extremely high rigidity to suppress the internal conversion process. Meanwhile, the highly twisted structure between D and A segments will also lead to an extremely small singlet-triplet energy split to DPXZ-BPPZ. Therefore, DPXZ-BPPZ successfully realizes an efficient fluorescent radiation transition and reverse intersystem crossing process, and possesses an extremely high photoluminescence quantum efficiency of 97.1 ± 1.1% under oxygen-free conditions. The OLED based on DPXZ-BPPZ shows red emission with a peak at 612 nm and a Commission Internationale de L'Eclairage (CIE) coordinate of (0.60, 0.40), and it achieves high maximum forward-viewing efficiencies of 20.1 ± 0.2% (external quantum efficiency), 30.2 ± 0.6 cd A-1 (current efficiency), and 30.9 ± 1.3 lm W-1 (power efficiency). The prepared OLED has the best performance among the reported red TADF OLEDs. These results prove that DPXZ-BPPZ is an ideal candidate for red TADF emitters, and the designing approach is valuable for highly efficient red TADF emitters.

High Performance Shape-Stabilized Phase Change Material with Nanoflower-Like Wrinkled Mesoporous Silica Encapsulating Polyethylene Glycol: Preparation and Thermal Properties.

Nanoflower-like wrinkled mesoporous silica (NFMS) was prepared for further application as the carrier of polyethylene glycol (PEG) to fabricate the new, shape-stabilized phase change composites (PEG/NFMS); NFMS could improve the loading content of PEG in the PEG/NFMS. To investigate the properties of PEG/NFMS, characterization approaches, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) analysis, and differential scanning calorimetry (DSC), were carried out. The characterization results illustrated that the PEG was completely adsorbed in the NFMS by physical adsorption, and the nanoflower-like wrinkled silica did not affect the crystal structure of PEG. As reported by the DSC test, although NFMS had a restriction influence on the activity of the PEG molecules, the melting and binding enthalpies of the PEG/NFMS could reach 136.6 J/g and 132.6 J/g, respectively. In addition, the TGA curves demonstrated that no evident weight loss was observed from 20 °C to 190 °C for the PEG/NFMS, and the results revealed that the PEG/NFMS had remarkable thermal stability. These results indicated that the NFMS is a potential carrier of organic phase change material for the preparation of shape-stabilized phase change composites.

Mesoporous silica nanoparticles with wrinkled structure as the matrix of myristic acid for the preparation of a promising new shape-stabilized phase change material via simple method.

Wrinkled mesoporous silica nanoparticle (WMSN), with a special and highly uniform morphology, large specific surface area and pore volume, high porosity and radial-like wrinkled channels, was successfully prepared by a simple and easy synthetic method. WMSN was used as the matrix of myristic acid (MA) to prepare a new attractive shape-stabilized PCM (MA/WMSN), and the wrinkled channels of WMSN are useful to prevent the leakage of PCM, and increase the thermal stability and phase change enthalpy of shape-stabilized PCM. Characterizations of MA/WMSN, such as structure, crystallization properties, chemical properties and thermal properties were studied, and the interaction mechanism between the WMSN and MA molecules was elucidated. TGA results suggested that MA/WMSN had excellent thermal stability. When the loading of MA in MA/WMSN was 65%, the melting and crystallizing enthalpies of MA/WSSN were 92.0 J g-1 and 86.0 J g-1, respectively. Additionally, the thermal conductivity of MA/WMSN was 0.37 W mK-1, which was about 1.37 times higher than that of the pure MA. All of the study results demonstrated that MA/WMSN possessed of favourable thermal conductivity, high latent heats and excellent thermal stability, and therefore it could be a suitable thermal energy storage material for practical applications.

A systematically chromosomally engineered Escherichia coli efficiently produces butanol.

Biotechnological production of butanol in heterologous hosts has recently attracted many interests. Of the heterologous hosts investigated to date, engineered Escherichia coli has shown a superior butanol yield than the natural butanol-producing clostridial strains. However, all reported butanol-producing E. coli strains contain vectors and inducible promoters, which means antibiotics and inducers are required in the fermentation. The aim of this study was to develop a completely chromosomally engineered E. coli strain capable of producing butanol efficiently in the absence of vectors, antibiotics, and inducers. The challenges are the expression strength of chromosomally engineered genes under constitutive promoters is much weaker than the vector engineered genes under inducible promoters. To address these challenges, the butanol pathway was engineered into the chromosome in the first place, then the host and the butanol pathway was iteratively engineered through rational and non-rational strategies to develop an efficient butanol producer where the heterologous butanol pathway fits the host well. Finally, a systematically chromosomally engineered E. coli strain EB243, in which 33 native genes were deleted and 5 heterologous genes were introduced, was developed. Strain EB243 could produce 20g/L butanol with a yield of 34% (w/w, 83% of theoretical yield) in batch fermentation without any antibiotics and inducers, thus showed great potential for industrial application. This work also demonstrated a procedure on how to integrate the existing knowledge to engineer a strain with industrial application potential.

A functional recT gene for recombineering of Clostridium.

Recombineering is an efficient genetic manipulation method employing the mechanism of phagenic RecT-mediated homologous recombination. To develop a recombineering method for Clostridium, a putative recT gene (CPF0939) from Clostridium perfringens genome was functionally verified in a clostridial host Clostridium acetobutylicum. We show that a short synthetic oligonucleotide can be introduced into the target site for specific point mutation. This functional recT gene would therefore contribute to development of recombineering tools for Clostridium.

Biobutanol.

China initiated its acetone-butanol-ethanol (ABE) industry in the 1950s; it peaked in the 1980s, and ended at the end of the last century owing to the development of more competitive petrochemical pathways. However, driven by the high price of crude oil and environmental concerns raised by the over-consumption of petrochemical products, biofuels and bio-based chemicals including butanol have garnered global attention again. Currently, butanol produced from ABE fermentation is mainly used as an industrial solvent or a platform chemical for several bulk derivatives, and is also believed to be a potential biofuel. A number of plants have been built or rebuilt in recent years in China for butanol production with the ABE process. Chinese researchers also show great interest in the improvement of the production strains and corresponding processes. They have applied conventional mutagenesis methods to improve butanol-producing strains such as the Clostridium acetobutylicum mutant strains EA2018 (butanol ratio of 70%) and Rh8 (butanol tolerance of 19 g/L). The omics technologies, such as genome sequencing, proteomic and transcriptomic analysis, have been adapted to elucidate the characteristics of different butanol-producing bacteria. Based on the group II intron method, the genetic manipulation system of C. acetobutylicum was greatly improved, and some successful engineering strains were developed. In addition, research in China also covers the downstream processes. This article reviews up-to-date progress on biobutanol production in China.

Development of an anhydrotetracycline-inducible gene expression system for solvent-producing Clostridium acetobutylicum: A useful tool for strain engineering.

Clostridium acetobutylicum is an important solvent (acetone-butanol-ethanol) producing bacterium. However, a stringent, effective, and convenient-to-use inducible gene expression system that can be used for regulating the gene expression strength in C. acetobutylicum is currently not available. Here, we report an anhydrotetracycline-inducible gene expression system for solvent-producing bacterium C. acetobutylicum. This system consists of a functional chloramphenicol acetyltransferase gene promoter containing tet operators (tetO), Pthl promoter (thiolase gene promoter from C. acetobutylicum) controlling TetR repressor expression cassette, and the chemical inducer anhydrotetracycline (aTc). The optimized system, designated as pGusA2-2tetO1, allows gene regulation in an inducer aTc concentration-dependent way, with an inducibility of over two orders of magnitude. The stringency of TetR repression supports the introduction of the genes encoding counterselective marker into C. acetobutylicum, which can be used to increase the mutant screening efficiency. This aTc-inducible gene expression system will thus increase the genetic manipulation capability for engineering C. acetobutylicum.