利用光驱动的生物杂合系统实现CO_(2)转化生产化学品

太阳能作为清洁能源之一,为缓解化石燃料枯竭和温室气体排放等问题提供了一种高效、经济、可持续的解决方案.自然界中的植物和光合微生物通过自身的光合系统收集并转化太阳能,从而生产生物燃料和生物化学品.然而,由于自然光合系统存在光吸收范围相对较窄、光生电子在传输过程中易损耗等问题,限制了太阳能到化学品的转化效率.为了解决上述难题,科研人员模仿自然光合作用中的关键部分,探索构建人工光合系统,相关研究引起了广泛关注.本文通过将碲化镉量子点(CdTe QDs)与大肠杆菌(E.coli)相耦合,构建了一种光驱动无机-生物杂合系统(IBPHS),用于捕获太阳能并驱动CO_(2)转化合成高价值化学品.该系统主要由光催化模块和生物催化模块组成.在光催化模块中,通过生物合成CdTe QDs进行光能捕获,并将其转化为电子.通过敲除E.coli的Cd2+外排蛋白(ZNTA)编码基因,实现了E.coli胞内Cd2+过量积累.通过“时空耦合”方式,并借助共聚焦显微镜、高分辨率透射电镜和X射线能谱分析,确认了CdTe QDs在E.coli胞内的组装合成.利用紫外-可见分光光度计研究了光催化模块对光子的吸收能力.结果表明,光催化模块的吸收峰位于400-420 nm.利用瞬时光电流,评估了光催化模块的光生电子能力.实验发现,该模块可以产生0.07μA光电流,表明完成了光催化模块的构建.在生物催化模块中,将光催化模块产生的电子用于还原NAD+再生NADH.采用NADH生物传感器,分析了E.coli胞内NADH含量,结果表明,在蓝光照射下E.coli胞内NADH含量比黑暗条件下提高了5.1倍.在此基础上,通过表达NADH依赖型乳酸脱氢酶(LDH)将丙酮酸还原为乳酸,在蓝光光照下乳酸积累量达到了0.44 g/L,而黑暗条件下无乳酸积累,从而验证了生物催化模块的有效性.基于光催化模块和生物催化模块,进一步组装构建了IBPSH,用于驱动CO_(2)还原合成甲酸和丙酮酸.在蓝光照射下,IBPHS能够合成0.65 g/L甲酸和0.18 g/L丙酮酸,其CO_(2)利用速率分别达到51.98 mg/gDCW/h和21.92 mg/gDCW/h,超过了光合细菌.综上所述,本文利用光催化模块与生物催化模块相耦合的方式,组装构建了一种新型的人工光合系统,实现了光驱动CO_(2)还原合成高附加值化学品,为理性设计材料-生物杂合系统提供了借鉴,同时也为挖掘绿色生物制造潜力、开发太阳能化学制造平台提供参考.

Compliant Iontronic Triboelectric Gels with Phase-Locked Structure Enabled by Competitive Hydrogen Bonding

Rapid advancements in flexible electronics technology propel soft tactile sensing devices toward high-level biointegration,even attaining tactile perception capabilities surpassing human skin.However,the inherent mechanical mismatch resulting from deficient biomimetic mechanical properties of sensing materials poses a challenge to the application of wearable tactile sensing devices in human-machine interaction.Inspired by the innate biphasic structure of human subcutaneous tissue,this study discloses a skin-compliant wearable iontronic triboelectric gel via phase separation induced by competitive hydrogen bonding.Solvent-nonsolvent interactions are used to construct competitive hydrogen bonding systems to trigger phase separation,and the resulting soft-hard alternating phase-locked structure confers the iontronic triboelectric gel with Young’s modulus(6.8-281.9 kPa)and high tensile properties(880%)compatible with human skin.The abundance of reactive hydroxyl groups gives the gel excellent tribopositive and self-adhesive properties(peel strength>70 N m^(−1)).The self-powered tactile sensing skin based on this gel maintains favorable interface and mechanical stability with the working object,which greatly ensures the high fidelity and reliability of soft tactile sensing signals.This strategy,enabling skin-compliant design and broad dynamic tunability of the mechanical properties of sensing materials,presents a universal platform for broad applications from soft robots to wearable electronics.

Molecular cloning,characterization and promoter analysis of LbgCWIN1 and its expression profiles in response to exogenous sucrose during in vitro bulblet initiation in lily

Lily(Lilium spp.) is an important ornamental flower, which is mainly propagated by bulbs. Cell wall invertases(CWINs), which catalyze the irreversibly conversion of sucrose into glucose and fructose in the extracellular space, are key enzymes participating in sucrose allocation in higher plants. Previous studies have shown that CWINs play an essential role in bulblet initiation process in bulbous crops, but the underlying molecular mechanism remains unclear. Here, a CWIN gene of Lilium brownii var. giganteum(Lbg) was identified and amplified from genomic DNA. Quantitative RT-PCR assays revealed that the expression level of LbgCWIN1 was highly upregulated exactly when the endogenous starch degraded in non-sucrose medium during in vitro bulblet initiation in Lbg. Phylogenetic relationship, motif, and domain analysis of LbgCWIN1 protein and CWINs in other plant species showed that all sequences of these CWIN proteins were highly conserved. The promoter sequence of LbgCWIN1 possessed a number of alpha-amylase-, phytohormone-, light-and stress-responsive cis-elements. Meanwhile, β-glucuronidase(GUS) assay showed that the 459 bp upstream fragment from the translational start site displayed maximal promoter activity. These results revealed that LbgCWIN1 might function in the process of in vitro bulblet initiation and be in the response to degradation of endogenous starch.

Enhancing reversibility of LiNi_(0.5)Mn_(1.5)O_(4)by regulating surface oxygen deficiency

Oxygen deficiency has crucial effects on the crystal structure and electrochemical performance of spinel oxide lithium electrode materials such as LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode.In particular,the oxygen stoichiometry on the crystal surface differs from that on the crystal interior in LNMO.The detection of local oxygen loss in LNMO and its correlation with the crystal structure and the cycling stability of LNMO remain challenging.In this study,the effect of oxygen deficiency in LNMO controlled by sintering temperature on the surface crystal structure and electrochemical performance of LNMO is comprehensively investigated.The high concentration of oxygen vacancies segregates at the surface regions of LNMO forming a thin rock‐salt and/or deficient spinel surface layer.The atomic‐level surface structure reconstruction was demonstrated by annular dark‐field and annular brightfield techniques.For the synthesis of LNMO,the higher sintering temperature results in higher crystallinity but the higher oxygen deficiency in LNMO.The high crystallinity of LNMO would increase the thermal stability of LNMO cathodes while the high content of oxygen deficiency would decrease the surface structural stability of LNMO.Therefore,the LNMO sintered at a medium temperature of 850°C achieved the best capacity retention.The results suggest a competitive function mechanism between oxygen stoichiometry and the crystallinity of LNMO on the cycling performance of LNMO.

止血粉治疗急性上消化道出血的研究进展

急性上消化道出血是临床常见的急危重症之一.最常见的病因是消化性溃疡和食管胃底静脉曲张破裂出血.尽管内镜下止血技术不断改进,但仍有5%-15%的患者内镜下止血治疗失败.止血粉是内镜下止血的新兴药物,呈白色粉末状,在气泵的辅助下喷洒至出血部位,通过吸收水分以促进凝血物质的聚集和粘附在病变上方形成机械屏障等途径达到止血效果.该技术操作简单、无需精确定位并具有较高的即刻止血率,可作为常规止血无效的补救措施.然而,国内尚未推荐止血粉用于治疗急性消化道出血.本文旨在总结现有研究证据,阐述常见的五种止血粉的作用机制、临床应用及不良事件,以期加强内镜医生对止血粉的认识.

长白山不同林型土壤有机碳特征

采用野外采样与室内分析相结合的方法,研究了长白山北坡6种不同林型(阔叶林、针叶林、云冷杉、岳桦林、岳桦-苔原、高山苔原)土壤有机碳及其组分的含量,分析了土壤有机碳分布与铁铝氧化物和黏粒矿物组成之间的关系。结果表明:不同林型之间,阔叶林土壤的有机碳、胡敏素碳、颗粒有机碳、2~0.25 mm大团聚体碳和0.25~0.053 mm微团聚体碳含量最高,云冷杉土壤的易氧化碳含量最高而水溶性有机碳、胡敏酸碳、富里酸碳和颗粒有机碳含量最低;此外,岳桦林土壤的胡敏酸碳和富里酸碳含量显著高于其他林型土壤,岳桦-苔原土壤的水溶性有机碳含量显著高于其他林型土壤,而高山苔原土壤的有机碳和易氧化碳含量显著低于其他林型土壤。相关性分析表明,土壤有机碳含量与非晶质氧化铝含量呈显著的正相关关系(P<0.05),富里酸碳含量与游离氧化铝含量呈显著的正相关关系(P<0.05),而0.25~0.053 mm微团聚体有机碳含量与2种形态氧化铝含量都呈显著的正相关关系(P<0.05)。上述结果指出,不同林型条件下各有机碳及其组分差异显著。

肿瘤微环境中脂肪细胞对肺腺癌A549细胞生物学行为影响的初步研究

背景与目的脂肪细胞在肿瘤微环境中可通过提供代谢燃料或信号传导媒介等方式以促进多种恶性肿瘤细胞的增殖与侵袭,但其在肺癌进展过程中的作用尚不清楚。本研究旨在探讨脂肪细胞对肺癌细胞生物学行为的影响。方法将3T3-L1前脂肪细胞诱导为成熟脂肪细胞;采用显微镜成像、油红O染色试验观察细胞形态;应用MTT、平板克隆形成实验、划痕实验以及Transwell检测肺癌细胞增殖、迁移及侵袭能力的变化;通过比色分析法测定细胞内甘油三酯的含量。结果与成熟脂肪细胞共培养后,肺腺癌A549细胞的形态变得更加纤长,增殖与克隆形成能力明显增强(P<0.05);此外,成熟脂肪细胞亦可促进A549细胞的迁移(P<0.05)、侵袭(P<0.01)以及胞内脂质的累积(P<0.05)。结论肿瘤微环境中的脂肪细胞可促进肺腺癌A549细胞的增殖、迁移与侵袭,且这一促进作用可能与脂质代谢相关。

Effects of Danqu Capsules on Arterial Blood Pressure,Heart Rate and Myocardial Tension Time Index in Rats

[Objectives] To explore the effects of Danqu capsules(the prescription of Lei Zhongyi, the master of traditional Chinese medicine for the syndrome of intermingling of phlegm and static blood of coronary heart disease) on arterial blood pressure, heart rate and myocardial tension time index in rats. [Methods] A total of 50 SD rats, weighing(300±20) g, were randomly and evenly divided into Danqu capsule observation groups(low, middle and high-dose groups) and control groups(saline group and captopril group). Under anesthesia, the rats in each group were administered with 0.6, 1.2 and 2.4 g/kg of Danqu capsule suspension, 1 mL/100 g of saline and 10 mg/kg of captopril, respectively through duodena, and their systolic blood pressure, diastolic blood pressure, mean arterial pressure, pulse pressure difference and heart rate were measured and recorded by RM6240 multi-channel physiological signal acquisition and processing system before administration, 10, 20, 30, 40, 50, 60, 90 and 120 min after the administration, respectively, and the myocardial tension time index was calculated. [Results] Compared with the saline group, the systolic, diastolic and mean pressure reduced 10, 20, 30, 40, 50, 60, 90 and 120 min after the administration, and the pulse pressure difference did not change significantly in the Danqu capsule groups(low, middle and high-dose groups), and the heart rate slowed down and the myocardial tension time index reduced in the high-dose Danqu capsule group. Compared with the captopril group, the Danqu capsule groups showed similar blood pressure-reducing effect. [Conclusions]Danqu capsules have obvious effect of lowering blood pressure and myocardial tension time index. High-dose Danqu capsules has the effect of slowing down the heart rate. The blood pressure-lowering effect of Danqu capsules shows a dose-dependent manner. Clinically, they can be used in patients with coronary heart diseases and hypertension, suggesting that they should be used with caution in patients with hypotension.

Revealing the dominant factor of domain boundary resistance on bulk conductivity in lanthanum lithium titanates

Perovskite-type lithium lanthanum titanates(LLTO)display a high bulk ionic conductivity and are considered a promising electrolyte for building up to advanced solid-state Li-ion batteries.The LLTO crystals contain a high concentration of intrinsically formed 90ο-rotated domain boundaries(DBs)serving as barriers to bulk Li-ion conduction.However,the mechanism of how the DB concentration and DB resistance can compete with each other to determine the bulk conductivity of LLTO is still unknown.Here we report a comprehensive study of LLTO compounds,aimed to unravel the mechanism and hence explore new path(s)for further improving the conductivity of this material.Our results show that both the sintering temperature and chemical composition can affect significantly the domain structures in LLTO.It is found that a decrease in the DB concentration is always accompanied by increased DB resistance due to the increased lattice mismatch at DBs,and vice versa.By unifying the electrochemical impedance spectroscopy and transmission electron microscopy analysis,it is clearly shown that the high DB resistance,instead of DB concentration,acts as the dominant factor governing the bulk conductivity of LLTO.The results thus renew the conventional understanding of the bulk Li-ion conduction in LLTO and shed light on developing novel LLTO electrolyte materials with improved ionic conductivity.

Tropical cyclone genesis over the western North Pacific simulated by Coupled Model Intercomparison Project Phase 6 models

Threatening millions of people and causing billions of dollars in losses,tropical cyclones(TCs)are among the most severe natural hazards in the world,especially over the western North Pacific.However,the response of TCs to a warming or changing climate has been the subject of considerable research,often with conflicting results.In this study,the abilities of Coupled Model Intercomparison Project(CMIP)Phase 6(CMIP6)models to simulate TC genesis are assessed through historical simulations.The results indicate that a systematic humidity bias persists in most CMIP6 models from corresponding CMIP Phase 5 models,which leads to an overestimation of climatological TC genesis.However,the annual cycle of TC genesis is well captured by CMIP6 models.The abilities of 25 models to simulate the geographical patterns of TC genesis vary significantly.In addition,seven models are identified as well simulated models,but seven models are identified as poorly simulated ones.A comparison of the environmental variables for TC genesis in the well-simulated group and the poorly simulated group identifies moisture in the mid-troposphere as a key factor in the realistic simulation of El Niño-Southern Oscillation(ENSO)impacts on TC genesis.In contrast with the observations,the poorly simulated group does not reproduce the suppressing effect of negative moisture anomalies on TC genesis in the northwestern region(20°–30°N,120°–145°E)during El Niño years.Given the interaction between TC and ENSO,these results provide a guidance for future TC projections under climate change by CMIP6 models.

代谢工程改造大肠杆菌生产戊二酸

戊二酸是一种重要的中间体,在化工、农业和医药等领域有着广泛的用途。目前,戊二酸的生物合成途径存在合成路径冗长、辅因子消耗多和产物得率低等问题。为开发高效的戊二酸合成方法,将酶工程与代谢工程相结合,构建了一条以葡萄糖为底物生产戊二酸的新途径。首先,通过数据库挖掘设计了一条由赖氨酸α氧化酶(LO)、单胺氧化酶(MAO)、α-酮酸脱羧酶(KDC)和醛脱氢酶(ALDH)组成的新型催化途径,引入赖氨酸生产菌株Escherichia coli(E.coli)CCTCC M2019435后实现了戊二酸的从头合成;为进一步提高该路径的合成效率,针对路径的限速酶Kp ALDH进行理性分析和蛋白质改造,使酶的酶活提高了61.0倍;在此基础上,通过代谢工程强化限速酶Kp ALDH的表达并阻断副产物乙酸代谢支路,使戊二酸得率提高了1.0倍;最后,优化戊二酸发酵条件,发酵结束时戊二酸产量提高到62.0 g/L,生产强度和得率分别达到1.7(g/L)/h和0.3 g/g葡萄糖。

Metabolic engineering strategies for microbial utilization of methanol

The increasing shortage of fossil resources and environmental pollution has renewed interest in the synthesis of value-added biochemicals from methanol.However,most of native or synthetic methylotrophs are unable to assimilate methanol at a sufficient rate to produce biochemicals.Thus,the performance of methylotrophs still needs to be optimized to meet the demands of industrial applications.In this review,we provide an in-depth discussion on the properties of natural and synthetic methylotrophs,and summarize the natural and synthetic methanol assimilation pathways.Further,we discuss metabolic engineering strategies for enabling microbial utilization of methanol for the bioproduction of value-added chemicals.Finally,we highlight the potential of microbial engineering for methanol assimilation and offer guidance for achieving a low-carbon footprint for the biosynthesis of chemicals.

Metabolic engineering strategies for microbial utilization of C1 feedstocks

The use of abundant and cheap one carbon(C1)feedstocks to produce value-added chemicals is an important approach for achieving carbon neutrality and tackling environmental problems.The conversion of C1 feedstocks to high-value chemicals is dependent on efficient C1 assimilation pathways and microbial chassis adapted for efficient incorporation.Here,we opted to summarize the natural and synthetic C1 assimilation pathways and their key factors for metabolizing C1 feedstock.Accordingly,we discussed the metabolic engineering strategies for enabling the microbial utilization of C1 feedstocks for the bioproduction of value-added chemicals.In addition,we highlighted future perspectives of C1-based biomanufacturing for achieving a low-carbon footprint for the biosynthesis of chemicals.

Advances in microbial engineering for the production of value‑added products in a biorefinery

Microbial biorefineries to produce chemicals from renewable feedstock provides attractive advantages,including mild reaction conditions and sustainable manufacturing.However,low-efficiency biorefineries always result in an uncompetitive biological process compared to the current petrochemical process.Thus,improving microbial capacity to maximize product yield,productivity,and titer has been recognized as a central goal for bioengineers and biochemists.The knowledge of cellular biochemistry has enabled the regulation of microbial physiology to couple with chemical production.The rapid development in metabolic engineering provides diverse strategies to enhance the efficiency of chemical biosynthesis pathways.New synthetic biology tools as well as novel regulatory targets also offer the opportunity to improve biorefinery environmental adaptivity.In this review,the recent advances in building efficient biorefineries were showcased.In addition,the challenges and future perspectives of microbial host engineering for increased microbial capacity of a biorefinery were discussed.

大肠杆菌FMME-N-26生产琥珀酸的发酵条件优化和放大

琥珀酸(Succinic acid)被认为是白色生物技术生产的最具潜力的大宗化学品之一,在工业上具有广泛的应用。微生物发酵生产琥珀酸具有环境友好和可持续发展等优点,展现出良好的发展前景,但是存在得率低、副产物积累、生产强度低等问题。为了实现琥珀酸的高效生产,在3.6 L发酵罐中对E. coli FMME-N-26生产琥珀酸发酵条件和补料策略进行了优化,建立了好氧-厌氧两阶段发酵工艺,最终确定发酵策略为:有氧发酵8 h后转为厌氧发酵,MgCO为pH中和剂,发酵72 h补加抗渗透压保护剂2 mmol/L甜菜碱,厌氧阶段控制葡萄糖浓度为1~5 g/L。优化后发酵72 h,琥珀酸的产量和厌氧阶段得率分别达到119.2 g/L和1.08 g/g葡萄糖(理论得率97%),分别比优化前提高了46.4%和4.8%,副产物乙酸和乳酸仅积累2.37和0.94 g/L,分别比优化前降低了37.1%和49.2%。在1000 L发酵罐中实现中试放大生产,E. coli FMME-N-26生产琥珀酸的产量、得率和生产强度在国内外属于领先水平,为琥珀酸工业化生产奠定了坚实的基础,同时也为其他高价值化学品的生产提供了借鉴。

细胞寿命在大肠杆菌细胞工厂构建中的应用

微生物细胞工厂以可再生资源为原料,为工业化学品的可持续生产提供了一种有前景的替代方案。然而,不适的外界环境显著影响了微生物细胞的存活率,降低了微生物细胞工厂的生产性能。通过延长微生物细胞的时序寿命,可以显著提升微生物细胞工厂的生产性能。首先,基于存活率的变化建立了细胞时序寿命和半时序寿命的评价体系;然后,发现半胱氨酸、肌肽、氨基胍和氨基葡萄糖抗衰老药物可以使大肠杆菌Escherichiacoli细胞的时序寿命分别延长80%、80%、50%和120%;最后,延长E.coli时序寿命可以显著改善E.coli细胞工厂的生产性能,可以用于改善具有本源代谢合成路径的E.coli细胞工厂的生产性能,使乳酸和丙酮酸的得率分别提升30.0%和25.0%,也可以用于改善具有异源代谢合成路径的E. coli细胞工厂的生产性能,使苹果酸的得率提升27.0%。这些研究结果表明延长E. coli细胞寿命提供了一种潜在的改善细胞工厂的生产性能的方法。

多酶组合催化制备L-高苯丙氨酸

【目的】L-高苯丙氨酸(L-HPA)是许多医药化学品的重要中间体,化学合成法生产L-HPA反应复杂、环境污染严重,本研究旨在开发高效环保的L-HPA酶法合成路线。【方法】采用模块化组装的方法,构建了一条以甘氨酸和苯乙醛为底物高产L-HPA的新途径。【结果】首先,根据文献挖掘设计了一条由苏氨酸醛缩酶(TA)、苏氨酸脱氨酶(TD)、苯丙氨酸脱氢酶(PheDH)和甲酸脱氢酶(FDH)组成的多酶组合催化途径,用于L-HPA的合成。其次,根据氨基基团的引入和重构,将L-HPA多酶组合催化途径分为基础单元和扩增单元,基础单元包括TA和TD,扩增单元包括PheDH和FDH。然后,利用不同表达水平的质粒,对基础单元和扩增单元进行蛋白表达的组合调节,获得最优工程菌BL21-C-M1-R-M2,使L-HPA产量达到208.6 mg/L。最后,我们对全细胞转化体系进行优化,使L-HPA产量进一步提高到1226.6 mg/L,苯乙醛摩尔转化率为34.2%。【结论】该工艺路线绿色高效,为未来大规模生产L-HPA奠定基础。

使用动态分子开关调控大肠杆菌生产莽草酸

莽草酸是大肠杆菌合成芳香族氨基酸的中间代谢物,也是抗流感药物"达菲"的重要合成前体。合成莽草酸需要截断莽草酸途径,导致芳香族氨基酸无法合成,因此面临细胞生长受到抑制的问题。使用动态调控策略通过将细胞生长和莽草酸的合成相互分离,可以提高菌株的生产性能。通过使用生长偶联型启动子和降解决定子(Degrons),组建动态分子开关。利用该动态分子开关实现细胞生长与莽草酸合成分离,在5L发酵罐中经过72h发酵得到了14.33g/L的莽草酸。结果表明,这种动态分子开关可以通过调控靶蛋白丰度来改变碳流量平衡,使菌株获得更优秀的生产性能。