Considerable progress has been made in recent years to the development of sustainable polymers from bio-based feedstocks.In this study,100%bio-based nylons were prepared via an integrated chemical and biological proce...Considerable progress has been made in recent years to the development of sustainable polymers from bio-based feedstocks.In this study,100%bio-based nylons were prepared via an integrated chemical and biological process from lignocellulose.These novel nylons were obtained by the melt polymerization of 3-propyladipic acid derived from lignin and 1,5-pentenediamine/1,4-butanediamine derived from carbohydrate sugar.Central to the concept is a three-step noble metal free catalytic chemical funnelling sequence(Raney Ni mediated reductive catalytic fractionation-reductive funnelling-oxidative funnelling),which allowed for obtaining a single component 3-propyladipic acid from lignin with high efficiency.The structural and thermodynamic properties of the obtained nylons have been systematically investigated,and thus obtained transparent bio-based nylons exhibited higher Mw(>32,000)and excellent thermal stability(Td5%>265℃).Considering their moderate Tg and good melt strength,these transparent bio-based nylons could serve as promising functional additives or temperature-responsive materials.展开更多
本文探讨了微波加热在工业锡粉熔化中的应用。对离心雾化法制备的金属锡粉的形貌和粒径进行了表征。锡粉颗粒均匀且呈球形,90%的颗粒粒径为38～75μm。通过介电性能测试,研究了锡粉的微波吸收特性。微波的穿透作用对锡粉具有良好的整体...本文探讨了微波加热在工业锡粉熔化中的应用。对离心雾化法制备的金属锡粉的形貌和粒径进行了表征。锡粉颗粒均匀且呈球形,90%的颗粒粒径为38～75μm。通过介电性能测试,研究了锡粉的微波吸收特性。微波的穿透作用对锡粉具有良好的整体加热性能。温度高于150℃时,微波加热锡粉的主要机制是电导损耗。设计开发了20 k W微波熔炼锡合金装备,并将其应用于产业化。该装备的加热速率与常规方法相比能提高10倍以上,缩短了熔炼工艺。研究结果表明,微波加热加快了升温速率,缩短了熔炼时间,锡回收率为97.79%,渣量仅为1.65%,其他损失低于0.56%;单位能耗仅为0.17 k W·h·kg^(–1),远低于传统方法所需要的能量。因此微波冶炼提高了加热效率,降低了能耗。展开更多
Bio-based diamines are considered to be a promising alternative to traditional fossil-fuel-based diamines,the important platform chemical for the synthesis of polymer materials.In this review,the current status of the...Bio-based diamines are considered to be a promising alternative to traditional fossil-fuel-based diamines,the important platform chemical for the synthesis of polymer materials.In this review,the current status of the art of the synthesis of aliphatic and aromatic diamines from renewable biomass are considered.In the case of aliphatic diamines,we describe strategies for biologically producing diamines with different carbon numbers including 1,3-diaminopropane,1,4-butanediamine,1,5-pentanediamine,1,6-diaminohexane,1,8-diaminooctane,1,10-diaminodecane,and 1,12-diaminododecane.In addition,aromatic diamines produced from various kinds of renewable biomass,including lignin,cashew nut shell,and terpenoids,are reviewed here.Furthermore,the application of typical diamines in synthesis of polyurethane and polyamide are also reviewed.展开更多
Chemoenzymatic catalysis can give full play to the advantages of versatile reactivity of chemocatalysis and excellent chemo-,regio-,and stereoselectivities of biocatalysis.These chemoenzymatic methods can not only sav...Chemoenzymatic catalysis can give full play to the advantages of versatile reactivity of chemocatalysis and excellent chemo-,regio-,and stereoselectivities of biocatalysis.These chemoenzymatic methods can not only save resource,cost,and operating time but also reduce the number of reaction steps,and avoid separating unstable intermediates,leading to the generation of more products under greener circumstances and thereby playing an indispensable role in the fields of medicine,materials and fine chemicals.Although incompatible challenges between chemocatalyst and biocatalyst remain,strategies such as biphasic system,artificial metalloenzymes,immobilization or supramolecular host,and protein engineering have been designed to overcome these issues.In this review,chemoenzymatic catalysis according to different chemocatalysis types was classifiably described,and in particular,the classic dynamic kinetic resolutions(DKR)and cofactor regeneration were summarized.Finally,the bottlenecks and development of chemoenzymatic catalysis were summarized,and future development was prospected.展开更多
Compared with conventional cylinder airlift bioreactors(CCABs)that produce coarse bubbles,a novel rectangular dynamic membrane airlift bioreactor(RDMAB)developed in our lab produces fine bubbles to enhance the volumet...Compared with conventional cylinder airlift bioreactors(CCABs)that produce coarse bubbles,a novel rectangular dynamic membrane airlift bioreactor(RDMAB)developed in our lab produces fine bubbles to enhance the volumetric oxygen mass transfer coefficient(k_(L)a)and gas holdup,as well as improve the bioprocess in a bioreactor.In this study,we compared mass transfer,gas holdup,and batch and con-tinuous fermentation for RNA production in CCAB and RDMAB.In addition,unstructured kinetic models for microbial growth,substrate utilization,and RNA formation were established.In batch fermentation,biomass,RNA yield,and substrate utilization in the RDMAB were higher than those in the CCAB,which indicates that dynamic membrane aeration produced a high k_(L)a by fine bubbles;a higher k_(L)a is more bene-ficial to aerobic fermentation.The starting time of continuous fermentation in the RDMAB was 20 h ear-lier than that in the CCAB,which greatly improved the biological process.During continuous fermentation,maintaining the same dissolved oxygen level and a constant dilution rate,the biomass accumulation and RNA concentration in the RDMAB were 9.71% and 11.15% higher than those in the CCAB,respectively.Finally,the dilution rate of RDMAB was 16.7% higher than that of CCAB during con-tinuous fermentation while maintaining the same air aeration.In summary,RDMAB is more suitable for continuous fermentation processes.Developing new aeration and structural geometry in airlift bioreac-tors to enhance k_(L)a and gas holdup is becoming increasingly important to improve bioprocesses in a bioreactor.展开更多
In this study,we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate(c AMP)from adenosine triphosphate(ATP).First,adenylate cyclase from Escherichia coli MG1655(E...In this study,we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate(c AMP)from adenosine triphosphate(ATP).First,adenylate cyclase from Escherichia coli MG1655(EAC)and Bordetella Pertussis(BAC)were expressed in E.coli BL21(DE3)and comparatively analyzed for their activities.As a result,EAC from E.coli MG1655 exhibited a higher activity.However,amount of EAC were obtained in an insoluble form.Therefore,we expressed the first 446 amino acids of EAC(EAC446)to avoid the inclusion body.The effects of induction temperature,incubation time,and incubation p H were further evaluated to improve the expression of EAC446.Subsequently,the reaction process for the production of c AMP with ATP as a starting material was investigated.As none of c AMP was detected in the whole-cell based biocatalytic process,the reaction catalyzed by the crude enzyme was determined for c AMP production.What's more,the reaction temperature,reaction p H,metal ion additives and substrate concentration was optimized,and the maximum c AMP production of 18.45 g·L^-1was achieved with a yield of 95.4%after bioconversion of 6 h.展开更多
Here,a dopa decarboxylase(DDC)from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of dopamine.For the production of recombinant DDC,the cultivation conditions includ...Here,a dopa decarboxylase(DDC)from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of dopamine.For the production of recombinant DDC,the cultivation conditions including IPTG concentration,temperature and induction time were optimized and obtained an optimal specific enzyme activity of 51.72 U·mg^(-1) crude extracts.After the purification of DDC with a recovery yield of 68.79%,its activity was further characterized.The Vmax,Km,Kcat,and Kcat/Km of DDC for d ihyd roxy pheny la la nine(dopa)were 0.02 mmol·ml^(-1)·s^(-1),2.328 mmol·ml^(-1),10435.90 s^(-1) and4482.77 ml,mmol respectively.The highest DDC activity was observed at the condition of pH 7.5 and 45℃.With the purified DDC,the feasibility to produce dopamine from L-dopa was evaluated.The optimal yield was determined at the following bioconversion conditions:pH of 7,0,the reaction temperature of 40℃,0.4 mmol·L^(-1) of PLP and 4 g·L^(-1) of L-dopa,Subsequently,a fed-batch process for the production of dopamine was developed and the effect of oxygen was evaluated.The titer,yield and productivity of dopamine reached up to 21.99 g·L^(-1)80.88%and 14.66 g·L^(-1)·h^(-1) at 90 min under anaerobic condition.展开更多
The microbial production of D-lysine to replace chemical approach has gained great interest with the rising concerns over the environment.Here,we employed recombinant E.coli strain BL21-LYR with lysine racemase and st...The microbial production of D-lysine to replace chemical approach has gained great interest with the rising concerns over the environment.Here,we employed recombinant E.coli strain BL21-LYR with lysine racemase and strain BL-22A-RB-YB with L-lysine monooxygenase and 5-aminovaleramide amidohydrolase to establish a two-strain coupling whole-cell bioconversion system for D-lysine production from L-lysine.To improve the optical purity of D-lysine,the optimal reaction condition for resolution of DL-lysine after the racemization was investigated.The specificity of BL-22A-RB-YB for L^-lysine and the effects of reaction condition on bioconversion efficiency of whole-cell were accordingly determined.Under the optimal condition,a maximum 53.5 g·L^-1 D-lysine and 48.2 g·L^-15-AVA were obtained with yield of 47.4%and 42.3%,respectively,by the microbial racemization and asymmetric degradation process.The final D-lysine enantiomeric excess was over 99%.Meanwhile,a valuable compound 5-aminovaleric acid was synthesized with the production of D-lysine,indicating the economic feasibility of the two-strain coupling system.展开更多
[Objective] This study aimed to develop a rapid propagation method in a novel temporary immersion bioreactor system(TIS) for herbal plantlets compared with solid culture method. [Method] Three herbal species,including...[Objective] This study aimed to develop a rapid propagation method in a novel temporary immersion bioreactor system(TIS) for herbal plantlets compared with solid culture method. [Method] Three herbal species,including Dendrobium candidum Wall. Ex Lindl(D. candidum),Anoectochilus roxburghii(Wall.) Lindl.(A. roxburghii) and Lilium davidii var. unicolor( L. davidii),were used and tested by TIS against solid culture method. [Result] When the two culture methods were compared,the multiplication rate of D. candidum in TIS was found to be 1∶24.71,which was 6.55 times to those of solid culture. The multiplication rate of A. roxburghii was higher than those of the solid culture,but the plantlets was poorer than those of solid culture at the last phase in bioreactor culture,under the culture condition tested. The multiplication rate in TIS of L. davidii was 1∶17.23 whilst the rate was only 1∶4.45 on solid culture,resulting larger bulbs than those in the solid culture. [Conclusion] The TIS designed in our study could provide a potential mean for industrial production of plantlets. However,the parameters vary greatly among different species,and it is to be optimized according to plant species.展开更多
Methanol is becoming an attractive fermentation feedstock for large-scale bioproduction of chemicals,due to its natural abundance and mature production technology.Native methylotrophs,which can utilize methanol as the...Methanol is becoming an attractive fermentation feedstock for large-scale bioproduction of chemicals,due to its natural abundance and mature production technology.Native methylotrophs,which can utilize methanol as the only source of carbon and energy,are ideal hosts for methanol bioconversion due to their high methanol utili-zation rate and have been extensively employed in the production of value-added chemicals from methanol.Here,we review the natural methanol utilization pathways in native methylotrophs,describing the available synthetic biology tools developed for engineering native methylotrophs,and discuss the strategies for improving their methanol utilization efficiency.Finally,the representative examples of engineering the native methylotrophs to produce value-added products from methanol are summarized.Furthermore,we also discuss the major challenges and possible solutions for the application of native methylotrophs in methanol-based biomanufacturing.展开更多
1,5-Pentamethylene diisocyanate, a novel aliphatic diisocyanate formed from bio-based 1,5-pentamethylenediamine, has been used as a hard segmented material to synthesize polyurethane. In this study, several waterborne...1,5-Pentamethylene diisocyanate, a novel aliphatic diisocyanate formed from bio-based 1,5-pentamethylenediamine, has been used as a hard segmented material to synthesize polyurethane. In this study, several waterborne polyurethane (WPU) dispersions have been successfully prepared by a prepolymer process from 1,5-pentamethylene diisocyanate poly(polyether) with different NCO/OH ratios and 1,6-hexanediol (HDO)/dimethylol propionic acid (DMPA) molar ratios. The Fourier transfonn infrared (FTIR) spectra, thermogravimetric analysis, differential scanning calorimetry, X-ray diffiraction, and a mechanical tensile test were used to investigate the structures, thermal stability, phase separation, crystallinity, mechanical properties, and adhesive performance of the WPU dispersions. The FTIR results indicate that the degree of hydrogen bonding and the numbers of urea groups increase as the NCO/OH ratio and HDO/DMPA molar ratio increase. Furthermore, the phase separation increases and the thermal stability decreases as the NCO/OH ratio increases or the HDO/DMPA molar ratio decreases. Finally, WPU3.0-2.4 (NCO/OH = 3, HDO/DMPA = 2.4) exhibits a maximum tensile strength and shear strength, pointing to its possible use as an adhesive. These results could provide a very valuable reference for industrial applications of WPU.展开更多
Strain QCG of the aerobic bacteria Bacillus cereus is capable of producing l-naphthol from naphtha-lene,this strain was first isolated and characterized in this study.Strain QCG was mutagenized to enhance l-naphthol p...Strain QCG of the aerobic bacteria Bacillus cereus is capable of producing l-naphthol from naphtha-lene,this strain was first isolated and characterized in this study.Strain QCG was mutagenized to enhance l-naphthol production,using atmospheric and room temperature plasma(ARTP)technology.Then,a microbial clone screening system was used to accelerate the operation.Meanwhile,a novel color-mediated high-throughput screening using 4-aminoantipyrine was performed to screen mutants.The optimal mutant strain QCG4 produced 19.58土0.34 mg·L-1-naphthol from naphthalene that was 47.32%higher than that of the original strain(13.29+0.28 mg·L-1).In addition,the optimal conditions for l-naphthol production via whole-cell catalysis of strain QCG4 were determined to be an OD600 of40,150 mg.L I naphthalene,and 7.5%dimethyl formamide as a co-solvent at pH 7.5 and 26℃ for 3 h,resulting in 41.18士0.12 mg·L-l-naphthol,i.e.,the mutant strain produces a 2.1-fold higher yield compared to the original strain.展开更多
Cadaverine is an important C5 platform chemical with a wide range of industrial applications.However,the cadaverine inhibition on the fermenting strain limited its industrial efficiency of the strain.In this study,we ...Cadaverine is an important C5 platform chemical with a wide range of industrial applications.However,the cadaverine inhibition on the fermenting strain limited its industrial efficiency of the strain.In this study,we report an engineered Escherichia coli strain with high cadaverine productivity that was generated by developing a robust host coupled with metabolic engineering to mitigate cadaverine inhibition.First,a lysine producing E.coli was treated with a combination of radiation(ultraviolet and visible spectrum)and ARTP(atmospheric and room temperature plasma)mutagenesis to obtain a robust host with high cadaverine tolerance.Three mutant targets including HokD,PhnI and PuuR are identified for improved cadaverine tolerance.Further transcriptome analysis suggested that cadaverine suppressed the synthesis of ATP and lysine precursor.Accordingly,the related genes involved in glycolysis and lysine precursor,as well as cadaverine exporter was engineered to release the cadaverine inhibition.The final engineered strain was fed-batch cultured and a titer of 58.7 g/L cadaverine was achieved with a yield of 0.396 g/g,both of which were the highest level reported to date in E.coli.The bio-based cadaverine was purified to>99.6%purity,and successfully used for the synthesis of polyurethane precursor 1,5-pentamethylene diisocyanate(PDI)through the approach of carbamate decomposition.展开更多
We have developed a whole-cell bioconversion system for the production ofD-1,2,4-butanetriol (BT)from renewable biomass.A plasmid pETduet-xylB-yjhG-T7- adhP-T7-mdlC was constructed and transformed to Escherichia coli ...We have developed a whole-cell bioconversion system for the production ofD-1,2,4-butanetriol (BT)from renewable biomass.A plasmid pETduet-xylB-yjhG-T7- adhP-T7-mdlC was constructed and transformed to Escherichia coli BL21(DE3)to obtain the whole cells of E.coli BL2I-XYMA capable of bioconversion D-xylose to BT.Then,the factors including carbon sources,nitrogen sources,metal ions,and culture conditions (pH,temperature,IPTG)were identified,and their effects on the wholecell activity for BT production were investigated.To obtain the highest whole-cell activity,the optimal cultivation parameters are:15g·L^-1 yeast extract,5g·L^-1 sucrose, 3g·L^-1 KH2PO4,5g·L^-1 NaCl,3g·L^-1 NH4Cl,0.25g·L^-1 MgSO4·7H2O and 1mL·L^-1 the mixture of trace elements.With the optimized whole cells of E.coli BL21-XYMA,60g·L^-1 of xylose was converted to 28g·L^-1 BT with a molar yield of 66%,which is higher than those reported in the biotechnological system.展开更多
Industrial microbes have become the core of biological manufacturing,which utilized as the cell factory for production of plenty of chemicals,fuels and medicine.However,the challenge that the extreme stress conditions...Industrial microbes have become the core of biological manufacturing,which utilized as the cell factory for production of plenty of chemicals,fuels and medicine.However,the challenge that the extreme stress conditions exist in production is unavoidable for cell factory.Consequently,to enhance robustness of the chassis cell lays the foundation for development of bio-manufacturing.Currently,the researches on cell tolerance covered various aspects,involving reshaping regulatory network,cell membrane modification and other stress response.In fact,the strategies employed to improve cell robustness could be summarized into two directions,irrational engineering and rational engineering.In this review,the metabolic engineering technologies on enhancement of microbe tolerance to industrial conditions are summarized.Meanwhile,the novel thoughts emerged with the development of biological instruments and synthetic biology are discussed.展开更多
基金support by National Key Research and Development Program of China(Grant No.:2023YFA0913604)Program of National Natural Science Foundation of China(Grant No.:22178170,22378195)+2 种基金Six talent peaks project in Jiangsu Province(SWYY-045)Program of National Natural Science Foundation of China(Grant No.22208155)Jiangsu Province Natural Science Foundation for Young Scholars(Grant No.BK20210552).
文摘Considerable progress has been made in recent years to the development of sustainable polymers from bio-based feedstocks.In this study,100%bio-based nylons were prepared via an integrated chemical and biological process from lignocellulose.These novel nylons were obtained by the melt polymerization of 3-propyladipic acid derived from lignin and 1,5-pentenediamine/1,4-butanediamine derived from carbohydrate sugar.Central to the concept is a three-step noble metal free catalytic chemical funnelling sequence(Raney Ni mediated reductive catalytic fractionation-reductive funnelling-oxidative funnelling),which allowed for obtaining a single component 3-propyladipic acid from lignin with high efficiency.The structural and thermodynamic properties of the obtained nylons have been systematically investigated,and thus obtained transparent bio-based nylons exhibited higher Mw(>32,000)and excellent thermal stability(Td5%>265℃).Considering their moderate Tg and good melt strength,these transparent bio-based nylons could serve as promising functional additives or temperature-responsive materials.
基金This work was supported by the National Key Research and Development Program （2016YFA0204300） the National Natural Science Foundation of China （21390200, 31440024） and the Tech- nology Support Program of Gansu Provincial S＆T Department, China （1304FKCE106）.
文摘本文探讨了微波加热在工业锡粉熔化中的应用。对离心雾化法制备的金属锡粉的形貌和粒径进行了表征。锡粉颗粒均匀且呈球形,90%的颗粒粒径为38～75μm。通过介电性能测试,研究了锡粉的微波吸收特性。微波的穿透作用对锡粉具有良好的整体加热性能。温度高于150℃时,微波加热锡粉的主要机制是电导损耗。设计开发了20 k W微波熔炼锡合金装备,并将其应用于产业化。该装备的加热速率与常规方法相比能提高10倍以上,缩短了熔炼工艺。研究结果表明,微波加热加快了升温速率,缩短了熔炼时间,锡回收率为97.79%,渣量仅为1.65%,其他损失低于0.56%;单位能耗仅为0.17 k W·h·kg^(–1),远低于传统方法所需要的能量。因此微波冶炼提高了加热效率,降低了能耗。
基金This work was supported by the National Key Research and Development Program of China(Grant No.2018YFA0901500)National Nature Science Foundation of China(Grant No.21606127,Grant No.21706126)Jiangsu synergetic innovation center for advanced bio-manufacture(Grant No.XTB1802,Grant No.XTE1844).
文摘Bio-based diamines are considered to be a promising alternative to traditional fossil-fuel-based diamines,the important platform chemical for the synthesis of polymer materials.In this review,the current status of the art of the synthesis of aliphatic and aromatic diamines from renewable biomass are considered.In the case of aliphatic diamines,we describe strategies for biologically producing diamines with different carbon numbers including 1,3-diaminopropane,1,4-butanediamine,1,5-pentanediamine,1,6-diaminohexane,1,8-diaminooctane,1,10-diaminodecane,and 1,12-diaminododecane.In addition,aromatic diamines produced from various kinds of renewable biomass,including lignin,cashew nut shell,and terpenoids,are reviewed here.Furthermore,the application of typical diamines in synthesis of polyurethane and polyamide are also reviewed.
基金The authors thank the financial support by National Natural Science Foundation of China(21776132,21878142)Jiangsu Province Natural Science Foundation for Distinguished Young Scholars(BK20190035)+2 种基金National Key Research and Development Program of China(2019YFD1101202)Jiangsu Province Natural Science Foundation for Youths(BK20200685)China Postdoctoral Science Foundation(2019M660113).
文摘Chemoenzymatic catalysis can give full play to the advantages of versatile reactivity of chemocatalysis and excellent chemo-,regio-,and stereoselectivities of biocatalysis.These chemoenzymatic methods can not only save resource,cost,and operating time but also reduce the number of reaction steps,and avoid separating unstable intermediates,leading to the generation of more products under greener circumstances and thereby playing an indispensable role in the fields of medicine,materials and fine chemicals.Although incompatible challenges between chemocatalyst and biocatalyst remain,strategies such as biphasic system,artificial metalloenzymes,immobilization or supramolecular host,and protein engineering have been designed to overcome these issues.In this review,chemoenzymatic catalysis according to different chemocatalysis types was classifiably described,and in particular,the classic dynamic kinetic resolutions(DKR)and cofactor regeneration were summarized.Finally,the bottlenecks and development of chemoenzymatic catalysis were summarized,and future development was prospected.
基金supported by National Key Research and Development Program of China (2020YFE0100100, 2021YFC21041002018YFA0901500)+1 种基金Basic Science (Natural Science) Research Project of Jiangsu Province Colleges and Universities(21KJB530014)Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture
文摘Compared with conventional cylinder airlift bioreactors(CCABs)that produce coarse bubbles,a novel rectangular dynamic membrane airlift bioreactor(RDMAB)developed in our lab produces fine bubbles to enhance the volumetric oxygen mass transfer coefficient(k_(L)a)and gas holdup,as well as improve the bioprocess in a bioreactor.In this study,we compared mass transfer,gas holdup,and batch and con-tinuous fermentation for RNA production in CCAB and RDMAB.In addition,unstructured kinetic models for microbial growth,substrate utilization,and RNA formation were established.In batch fermentation,biomass,RNA yield,and substrate utilization in the RDMAB were higher than those in the CCAB,which indicates that dynamic membrane aeration produced a high k_(L)a by fine bubbles;a higher k_(L)a is more bene-ficial to aerobic fermentation.The starting time of continuous fermentation in the RDMAB was 20 h ear-lier than that in the CCAB,which greatly improved the biological process.During continuous fermentation,maintaining the same dissolved oxygen level and a constant dilution rate,the biomass accumulation and RNA concentration in the RDMAB were 9.71% and 11.15% higher than those in the CCAB,respectively.Finally,the dilution rate of RDMAB was 16.7% higher than that of CCAB during con-tinuous fermentation while maintaining the same air aeration.In summary,RDMAB is more suitable for continuous fermentation processes.Developing new aeration and structural geometry in airlift bioreac-tors to enhance k_(L)a and gas holdup is becoming increasingly important to improve bioprocesses in a bioreactor.
基金The National Natural Science Foundation of China(Grant No.21576134,Grant No.21606127,Grant No.21390200,Grant No.21706126)the National Key Research and Development Program of China(Grant No.2016YFA0204300)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions。
文摘In this study,we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate(c AMP)from adenosine triphosphate(ATP).First,adenylate cyclase from Escherichia coli MG1655(EAC)and Bordetella Pertussis(BAC)were expressed in E.coli BL21(DE3)and comparatively analyzed for their activities.As a result,EAC from E.coli MG1655 exhibited a higher activity.However,amount of EAC were obtained in an insoluble form.Therefore,we expressed the first 446 amino acids of EAC(EAC446)to avoid the inclusion body.The effects of induction temperature,incubation time,and incubation p H were further evaluated to improve the expression of EAC446.Subsequently,the reaction process for the production of c AMP with ATP as a starting material was investigated.As none of c AMP was detected in the whole-cell based biocatalytic process,the reaction catalyzed by the crude enzyme was determined for c AMP production.What's more,the reaction temperature,reaction p H,metal ion additives and substrate concentration was optimized,and the maximum c AMP production of 18.45 g·L^-1was achieved with a yield of 95.4%after bioconversion of 6 h.
基金funded by the National Natural Science Foundation of China(21576134 and 21706126)the National Key Research and Development Program(2016YFA0204300)。
文摘Here,a dopa decarboxylase(DDC)from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of dopamine.For the production of recombinant DDC,the cultivation conditions including IPTG concentration,temperature and induction time were optimized and obtained an optimal specific enzyme activity of 51.72 U·mg^(-1) crude extracts.After the purification of DDC with a recovery yield of 68.79%,its activity was further characterized.The Vmax,Km,Kcat,and Kcat/Km of DDC for d ihyd roxy pheny la la nine(dopa)were 0.02 mmol·ml^(-1)·s^(-1),2.328 mmol·ml^(-1),10435.90 s^(-1) and4482.77 ml,mmol respectively.The highest DDC activity was observed at the condition of pH 7.5 and 45℃.With the purified DDC,the feasibility to produce dopamine from L-dopa was evaluated.The optimal yield was determined at the following bioconversion conditions:pH of 7,0,the reaction temperature of 40℃,0.4 mmol·L^(-1) of PLP and 4 g·L^(-1) of L-dopa,Subsequently,a fed-batch process for the production of dopamine was developed and the effect of oxygen was evaluated.The titer,yield and productivity of dopamine reached up to 21.99 g·L^(-1)80.88%and 14.66 g·L^(-1)·h^(-1) at 90 min under anaerobic condition.
基金financial supports from the National Natural Science Foundation of China(Grant No.21908099)the National Key Research and Development Program of China(Grant No.2016YFA0204300)+2 种基金Key Research and Development Program(Social Development)Project Jiangsu Province(Grant No.BE2018730)the Natural Science Research Projects of Colleges and Universities in Jiangsu Province(Grant No.18KJB530009)the Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture(Grant No.XTB1802,Grant No.XTE1846)。
文摘The microbial production of D-lysine to replace chemical approach has gained great interest with the rising concerns over the environment.Here,we employed recombinant E.coli strain BL21-LYR with lysine racemase and strain BL-22A-RB-YB with L-lysine monooxygenase and 5-aminovaleramide amidohydrolase to establish a two-strain coupling whole-cell bioconversion system for D-lysine production from L-lysine.To improve the optical purity of D-lysine,the optimal reaction condition for resolution of DL-lysine after the racemization was investigated.The specificity of BL-22A-RB-YB for L^-lysine and the effects of reaction condition on bioconversion efficiency of whole-cell were accordingly determined.Under the optimal condition,a maximum 53.5 g·L^-1 D-lysine and 48.2 g·L^-15-AVA were obtained with yield of 47.4%and 42.3%,respectively,by the microbial racemization and asymmetric degradation process.The final D-lysine enantiomeric excess was over 99%.Meanwhile,a valuable compound 5-aminovaleric acid was synthesized with the production of D-lysine,indicating the economic feasibility of the two-strain coupling system.
基金Supported by National Natural Science Foundation of China(30971898)
文摘[Objective] This study aimed to develop a rapid propagation method in a novel temporary immersion bioreactor system(TIS) for herbal plantlets compared with solid culture method. [Method] Three herbal species,including Dendrobium candidum Wall. Ex Lindl(D. candidum),Anoectochilus roxburghii(Wall.) Lindl.(A. roxburghii) and Lilium davidii var. unicolor( L. davidii),were used and tested by TIS against solid culture method. [Result] When the two culture methods were compared,the multiplication rate of D. candidum in TIS was found to be 1∶24.71,which was 6.55 times to those of solid culture. The multiplication rate of A. roxburghii was higher than those of the solid culture,but the plantlets was poorer than those of solid culture at the last phase in bioreactor culture,under the culture condition tested. The multiplication rate in TIS of L. davidii was 1∶17.23 whilst the rate was only 1∶4.45 on solid culture,resulting larger bulbs than those in the solid culture. [Conclusion] The TIS designed in our study could provide a potential mean for industrial production of plantlets. However,the parameters vary greatly among different species,and it is to be optimized according to plant species.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0901500)the Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture(XTD2218).
文摘Methanol is becoming an attractive fermentation feedstock for large-scale bioproduction of chemicals,due to its natural abundance and mature production technology.Native methylotrophs,which can utilize methanol as the only source of carbon and energy,are ideal hosts for methanol bioconversion due to their high methanol utili-zation rate and have been extensively employed in the production of value-added chemicals from methanol.Here,we review the natural methanol utilization pathways in native methylotrophs,describing the available synthetic biology tools developed for engineering native methylotrophs,and discuss the strategies for improving their methanol utilization efficiency.Finally,the representative examples of engineering the native methylotrophs to produce value-added products from methanol are summarized.Furthermore,we also discuss the major challenges and possible solutions for the application of native methylotrophs in methanol-based biomanufacturing.
基金the National Natural Science Foundation of China (Grant Nos. 21576134 and 51503097)the National Key Research and Development Program of China (Grant No. 2016YFA0204300)the Jiangsu Province Natural Science Foundation (No. BK20150244).
文摘1,5-Pentamethylene diisocyanate, a novel aliphatic diisocyanate formed from bio-based 1,5-pentamethylenediamine, has been used as a hard segmented material to synthesize polyurethane. In this study, several waterborne polyurethane (WPU) dispersions have been successfully prepared by a prepolymer process from 1,5-pentamethylene diisocyanate poly(polyether) with different NCO/OH ratios and 1,6-hexanediol (HDO)/dimethylol propionic acid (DMPA) molar ratios. The Fourier transfonn infrared (FTIR) spectra, thermogravimetric analysis, differential scanning calorimetry, X-ray diffiraction, and a mechanical tensile test were used to investigate the structures, thermal stability, phase separation, crystallinity, mechanical properties, and adhesive performance of the WPU dispersions. The FTIR results indicate that the degree of hydrogen bonding and the numbers of urea groups increase as the NCO/OH ratio and HDO/DMPA molar ratio increase. Furthermore, the phase separation increases and the thermal stability decreases as the NCO/OH ratio increases or the HDO/DMPA molar ratio decreases. Finally, WPU3.0-2.4 (NCO/OH = 3, HDO/DMPA = 2.4) exhibits a maximum tensile strength and shear strength, pointing to its possible use as an adhesive. These results could provide a very valuable reference for industrial applications of WPU.
基金This work was supported by COVESTRO,the National Key Research and Development Program(Grant No.2016YFA0204300)the Jiangsu Province Natural Science Foundation for Youths(No.BK20170997)China Postdoctoral Science Foundation(Nos.2018M642237 and 2017T100359).
文摘Strain QCG of the aerobic bacteria Bacillus cereus is capable of producing l-naphthol from naphtha-lene,this strain was first isolated and characterized in this study.Strain QCG was mutagenized to enhance l-naphthol production,using atmospheric and room temperature plasma(ARTP)technology.Then,a microbial clone screening system was used to accelerate the operation.Meanwhile,a novel color-mediated high-throughput screening using 4-aminoantipyrine was performed to screen mutants.The optimal mutant strain QCG4 produced 19.58土0.34 mg·L-1-naphthol from naphthalene that was 47.32%higher than that of the original strain(13.29+0.28 mg·L-1).In addition,the optimal conditions for l-naphthol production via whole-cell catalysis of strain QCG4 were determined to be an OD600 of40,150 mg.L I naphthalene,and 7.5%dimethyl formamide as a co-solvent at pH 7.5 and 26℃ for 3 h,resulting in 41.18士0.12 mg·L-l-naphthol,i.e.,the mutant strain produces a 2.1-fold higher yield compared to the original strain.
基金This work is supported by the National Key R&D Program of China(2021YFC2100800)Key Research and Development Program(Social Development)Project of Jiangsu Province(BE2018730)the Jiangsu Synergetic Innovation Center for Advanced Bio-Manufacture(XTE1844 and XTB1806).
文摘Cadaverine is an important C5 platform chemical with a wide range of industrial applications.However,the cadaverine inhibition on the fermenting strain limited its industrial efficiency of the strain.In this study,we report an engineered Escherichia coli strain with high cadaverine productivity that was generated by developing a robust host coupled with metabolic engineering to mitigate cadaverine inhibition.First,a lysine producing E.coli was treated with a combination of radiation(ultraviolet and visible spectrum)and ARTP(atmospheric and room temperature plasma)mutagenesis to obtain a robust host with high cadaverine tolerance.Three mutant targets including HokD,PhnI and PuuR are identified for improved cadaverine tolerance.Further transcriptome analysis suggested that cadaverine suppressed the synthesis of ATP and lysine precursor.Accordingly,the related genes involved in glycolysis and lysine precursor,as well as cadaverine exporter was engineered to release the cadaverine inhibition.The final engineered strain was fed-batch cultured and a titer of 58.7 g/L cadaverine was achieved with a yield of 0.396 g/g,both of which were the highest level reported to date in E.coli.The bio-based cadaverine was purified to>99.6%purity,and successfully used for the synthesis of polyurethane precursor 1,5-pentamethylene diisocyanate(PDI)through the approach of carbamate decomposition.
基金the Open Funding Project of the State Key Laboratory of Bioreactor Engineering,the National Natural Science Foundation of China (Grant Nos.21576134, 21606127,21390200)the National Key Research and Development Program of China (Grant No.2016YFA0204300).
文摘We have developed a whole-cell bioconversion system for the production ofD-1,2,4-butanetriol (BT)from renewable biomass.A plasmid pETduet-xylB-yjhG-T7- adhP-T7-mdlC was constructed and transformed to Escherichia coli BL21(DE3)to obtain the whole cells of E.coli BL2I-XYMA capable of bioconversion D-xylose to BT.Then,the factors including carbon sources,nitrogen sources,metal ions,and culture conditions (pH,temperature,IPTG)were identified,and their effects on the wholecell activity for BT production were investigated.To obtain the highest whole-cell activity,the optimal cultivation parameters are:15g·L^-1 yeast extract,5g·L^-1 sucrose, 3g·L^-1 KH2PO4,5g·L^-1 NaCl,3g·L^-1 NH4Cl,0.25g·L^-1 MgSO4·7H2O and 1mL·L^-1 the mixture of trace elements.With the optimized whole cells of E.coli BL21-XYMA,60g·L^-1 of xylose was converted to 28g·L^-1 BT with a molar yield of 66%,which is higher than those reported in the biotechnological system.
基金supported by the National Key R&D Program of China(2021YFC2100800)Research and Development Program of PetroChina(21-LH-38-05).
文摘Industrial microbes have become the core of biological manufacturing,which utilized as the cell factory for production of plenty of chemicals,fuels and medicine.However,the challenge that the extreme stress conditions exist in production is unavoidable for cell factory.Consequently,to enhance robustness of the chassis cell lays the foundation for development of bio-manufacturing.Currently,the researches on cell tolerance covered various aspects,involving reshaping regulatory network,cell membrane modification and other stress response.In fact,the strategies employed to improve cell robustness could be summarized into two directions,irrational engineering and rational engineering.In this review,the metabolic engineering technologies on enhancement of microbe tolerance to industrial conditions are summarized.Meanwhile,the novel thoughts emerged with the development of biological instruments and synthetic biology are discussed.
