A series of polyhydroxyalkanoate(PHA)copolymers consisting of short-chain-length(SCL)and medium-chain-length(MCL)3-hydroxyalkanoate(3HA)monomers were synthesized in the recombinant Ralstonia eutropha PHB - 4 harboring...A series of polyhydroxyalkanoate(PHA)copolymers consisting of short-chain-length(SCL)and medium-chain-length(MCL)3-hydroxyalkanoate(3HA)monomers were synthesized in the recombinant Ralstonia eutropha PHB - 4 harboring a low-substrate-specificity PHA synthase PhaC2Ps from Pseudomonas stutzeri 1317. These polyesters,whose monomer compositions varied widely in chain length,were purified and characterized by acetone fractionation,nuclear magnetic resonance(NMR),gel-permeation chromatography(GPC),and differential scanning calorimetry(DSC).This was the first time that the physical properties of PHA copolymers polymerized by PhaC2Ps were characterized.The results indicated that the variation in MCL 3HA contents did not have an obvious influence on the molecular weights of these PHA copolymers but was effective in changing their physical properties. The variation in the thermal property of PHA copolymers with 3-hydroxyoctanoate(3HO)content was also inves- tigated in this study.展开更多
In this work, sucrose utilizing microbes from soil were screened to evaluate their ability for accumulation of biopolymer of polyhydroxyalkanoate （PHA）. Among 72 isolates were transferred to mineral salt medium （MS...In this work, sucrose utilizing microbes from soil were screened to evaluate their ability for accumulation of biopolymer of polyhydroxyalkanoate （PHA）. Among 72 isolates were transferred to mineral salt medium （MSM）, 33 strains can be grown on sucrose agar medium. However, only one strain showed a strong black color for Sudan Black and gave positive result for Nile blue A. Identification by 16S rDNA nucleotide sequence homology of the isolate showed very closely to Hydrogenophaga sp. （99% identify）. To consider PHA production, the isolate was grown in the medium containing sucrose as a sole carbon under controlled conditions of 35 ℃ and at pH 7. Maximum dry cell weight （DCW） and PHA production were obtained at 3.61 g/L and 2.41 g/L after 36 and 42 h batch fermentation. Sucrose uptake measured in term of total organic carbon （TOC） showed at 14.73 g within 48 h. The highest PHA was 68.15% （gPHA/gDCW） giving maximum PHA yield （YP/s） of 0.17 （gPHA/gs ） and a productivity of 0.057 gPHA/L.h. This highlights the potential of microbial resources in soil environment and may be an exploitable application for the industrial production of PHA.展开更多
A new technology was developed to couple the anaerobic digestion of food wastes with production of polyhydroxyalkanoates (PHAs). Acetic, propionic, butyric and lactic acids were produced during food wastes anaerobic d...A new technology was developed to couple the anaerobic digestion of food wastes with production of polyhydroxyalkanoates (PHAs). Acetic, propionic, butyric and lactic acids were produced during food wastes anaerobic digestion and their concentrations reached 5.5, 1.8, 27.4 and 32.7 g/L, respectively under appropriate digestion conditions. The fermentative acids were transferred through a dialysis membrane to an air-lift reactor for PHA synthesis by Ralstonia eutropha. Dry cell concentration and PHA content reached 22.7 g/L and 72.6%, respectively. The obtained PHA was a copolymer of b-hydroxybutyrate (HB) and b-hydroxyvalerate (HV) with 2.8% (mole ratio) of HV units in polymer.展开更多
In this work, sugar cane juice was fermented to produce polyhydroxyalkanoates （PHAs） by Alcaligenes latus TISTR 1403 and A. eutrophus TISTR 1095. The juice was characterized and composed of total sugars 105.5 g·...In this work, sugar cane juice was fermented to produce polyhydroxyalkanoates （PHAs） by Alcaligenes latus TISTR 1403 and A. eutrophus TISTR 1095. The juice was characterized and composed of total sugars 105.5 g·L^-1 （sucrose 36.6g·L^-1 , fructose 26.0g·L^-1 , glucose 21.8g·L^-1 and other sugars 21.1g·L^-1 ）. Each inoculums （ 10%, v/v） was separately cultivated in the medium containing 20g·L^-1 total sugars under condition （30℃, 200 rpm, pH 6.5-7）. It was found that the A. eutrophus can be grown better than the A. latus. Only the A. eutrophus was further cultured under different total sugar concentrations （20, 30, 40 and 50g·L^-1 ）. The optimal contents of total sugar, dry cell mass （DCM） and maximum PHAs were obtained at 50g·L^-1 , 6.013g·L^-1 and 1.84g·L^-1 , respectively after 60 h fermentation which were converted to biomass yield （Yx/s）, product yield （Yp/5）, specific product yield （Yp/x） and productivity of 0.163, 0.05, 0.306 and 0.031 g.Llhl. Large scale of PHAs production was conducted in 5 L fermentor using the optimal condition obtained under 30% dissolved oxygen. The DCM and the maximum PHAs were 5.881g·L^-1 and 1.281g·L^-1 which were calculated to values of Yx/s, Yp/s, Yp/x and productivity at 0.19, 0.04, 0.218 and 0.021g·L^-1 , respectively.展开更多
目的直观把握PHA相关领域的研究进展和热点,推动PHA领域的发展。方法以CNKI与Web of Science数据库中近10年的相关文献为对象,采用文献计量方法,使用CiteSpace软件绘制PHA研究知识图谱。结果相关文献的年度发文量不断上升,国内外学术界...目的直观把握PHA相关领域的研究进展和热点,推动PHA领域的发展。方法以CNKI与Web of Science数据库中近10年的相关文献为对象,采用文献计量方法,使用CiteSpace软件绘制PHA研究知识图谱。结果相关文献的年度发文量不断上升,国内外学术界对PHA领域的关注度越来越高,国际PHA领域的跨单位合作比国内更广泛。该领域的研究力量遍布全球,其中清华大学、葡萄牙里斯本新大学、马来西亚理科大学、昆士兰大学、布尔诺理工大学等机构的贡献突出、影响较大,陈国强是该领域发文量最多的学者。通过分析关键词可知,目前对PHA的关注重点主要集中在力学性能、生物降解、混合菌群、活性污泥、除磷脱氮等方面。结论在未来的PHA研究中,PHA的增强改性、在活性污泥中提取PHA及生物法合成PHA仍是研究热点。展开更多
Thick cathodes can overcome the low capacity issues,which mostly hamper the performance of the conventional active cathode materials,used in rechargeable Li batteries.However,the typical slurry-based method induces cr...Thick cathodes can overcome the low capacity issues,which mostly hamper the performance of the conventional active cathode materials,used in rechargeable Li batteries.However,the typical slurry-based method induces cracking and flaking during the fabrication of thick electrodes.In addition,a significant increase in the charge-transfer resistance and local cur-rent overload results in poor rate capabilities and cycling stabilities,thereby limiting electrode thickening.In this study,a synergistic dual-network combination strategy based on a conductive nanofibrillar network(CNN)and a nano-bridging amor-phous polyhydroxyalkanoate(aPHA)binder is used to demonstrate the feasibility of constructing a high-performance thick cathode.The CNN and aPHA dual network facilitates the fabrication of a thick cathode(≥250μm thickness and≥90 wt%active cathode material)by a mass-producible slurry method.The thick cathode exhibited a high rate capability and excel-lent cycling stability.In addition,the thick cathode and thin Li metal anode pair(Li//t-NCM)exhibited an optimal energy performance,affording high-performance Li metal batteries with a high areal energy of~25.3 mW h cm^(-2),a high volumetric power density of~1720 W L^(-1),and an outstanding specific energy of~470 W h kg^(-1)at only 6 mA h cm^(-2).展开更多
The environmental problems caused by plastics of fossil origin are well known. To reduce harmful impact on the environment, bacterial-based plastics, such as polyhydroxyalkanoates (PHAs), are a promising solution. Mic...The environmental problems caused by plastics of fossil origin are well known. To reduce harmful impact on the environment, bacterial-based plastics, such as polyhydroxyalkanoates (PHAs), are a promising solution. Microbial PHAs can be produced using abundant and inexpensive agricultural by-products as raw material. In this study, the potential use of Cupriavidus necator 11599 for the bioconversion of cassava starch into biodegradable PHAs was explored. Although Cupriavidus necator 11599 is a well-known PHA producer, it cannot grow directly on starch. Thus, acid hydrolysis was carried out on the starch extracted from cassava peels to obtain fermentable sugars. Optimal concentration of reducing sugars (RSs) was obtained by hydrolysis of cassava peel starch with sulfuric acid concentrations of 0.4 N and 0.6 N, at 95˚C and 4 h. The hydrolyzed starch was used for PHA production in Erlenmeyer flasks using reducing sugars (RSs) concentrations ranging from 10 g/L to 25 g/L. The best RS concentration 20 g/L and 25 g/L gave 85.13% ± 1.17% and 89.01% ± 2.49% of biomass PHA content and biomass concentrations of 8.18 g/L and 8.32 g/L, respectively in 48 hours. This research demonstrates that cassava peel starch as an inexpensive feedstock could be used for PHA production, paving the way for the use of other starchy materials to make bioplastics.展开更多
基金Supported by the National Natural Science Foundation of China （No.30225001, No.20334020）. The authors are very grateful to Prof. A. Steinbiichel of the University of Miinster in Germany for the generous donation of strain R. eutropha PHB 4.
文摘A series of polyhydroxyalkanoate(PHA)copolymers consisting of short-chain-length(SCL)and medium-chain-length(MCL)3-hydroxyalkanoate(3HA)monomers were synthesized in the recombinant Ralstonia eutropha PHB - 4 harboring a low-substrate-specificity PHA synthase PhaC2Ps from Pseudomonas stutzeri 1317. These polyesters,whose monomer compositions varied widely in chain length,were purified and characterized by acetone fractionation,nuclear magnetic resonance(NMR),gel-permeation chromatography(GPC),and differential scanning calorimetry(DSC).This was the first time that the physical properties of PHA copolymers polymerized by PhaC2Ps were characterized.The results indicated that the variation in MCL 3HA contents did not have an obvious influence on the molecular weights of these PHA copolymers but was effective in changing their physical properties. The variation in the thermal property of PHA copolymers with 3-hydroxyoctanoate(3HO)content was also inves- tigated in this study.
文摘In this work, sucrose utilizing microbes from soil were screened to evaluate their ability for accumulation of biopolymer of polyhydroxyalkanoate （PHA）. Among 72 isolates were transferred to mineral salt medium （MSM）, 33 strains can be grown on sucrose agar medium. However, only one strain showed a strong black color for Sudan Black and gave positive result for Nile blue A. Identification by 16S rDNA nucleotide sequence homology of the isolate showed very closely to Hydrogenophaga sp. （99% identify）. To consider PHA production, the isolate was grown in the medium containing sucrose as a sole carbon under controlled conditions of 35 ℃ and at pH 7. Maximum dry cell weight （DCW） and PHA production were obtained at 3.61 g/L and 2.41 g/L after 36 and 42 h batch fermentation. Sucrose uptake measured in term of total organic carbon （TOC） showed at 14.73 g within 48 h. The highest PHA was 68.15% （gPHA/gDCW） giving maximum PHA yield （YP/s） of 0.17 （gPHA/gs ） and a productivity of 0.057 gPHA/L.h. This highlights the potential of microbial resources in soil environment and may be an exploitable application for the industrial production of PHA.
文摘A new technology was developed to couple the anaerobic digestion of food wastes with production of polyhydroxyalkanoates (PHAs). Acetic, propionic, butyric and lactic acids were produced during food wastes anaerobic digestion and their concentrations reached 5.5, 1.8, 27.4 and 32.7 g/L, respectively under appropriate digestion conditions. The fermentative acids were transferred through a dialysis membrane to an air-lift reactor for PHA synthesis by Ralstonia eutropha. Dry cell concentration and PHA content reached 22.7 g/L and 72.6%, respectively. The obtained PHA was a copolymer of b-hydroxybutyrate (HB) and b-hydroxyvalerate (HV) with 2.8% (mole ratio) of HV units in polymer.
文摘In this work, sugar cane juice was fermented to produce polyhydroxyalkanoates （PHAs） by Alcaligenes latus TISTR 1403 and A. eutrophus TISTR 1095. The juice was characterized and composed of total sugars 105.5 g·L^-1 （sucrose 36.6g·L^-1 , fructose 26.0g·L^-1 , glucose 21.8g·L^-1 and other sugars 21.1g·L^-1 ）. Each inoculums （ 10%, v/v） was separately cultivated in the medium containing 20g·L^-1 total sugars under condition （30℃, 200 rpm, pH 6.5-7）. It was found that the A. eutrophus can be grown better than the A. latus. Only the A. eutrophus was further cultured under different total sugar concentrations （20, 30, 40 and 50g·L^-1 ）. The optimal contents of total sugar, dry cell mass （DCM） and maximum PHAs were obtained at 50g·L^-1 , 6.013g·L^-1 and 1.84g·L^-1 , respectively after 60 h fermentation which were converted to biomass yield （Yx/s）, product yield （Yp/5）, specific product yield （Yp/x） and productivity of 0.163, 0.05, 0.306 and 0.031 g.Llhl. Large scale of PHAs production was conducted in 5 L fermentor using the optimal condition obtained under 30% dissolved oxygen. The DCM and the maximum PHAs were 5.881g·L^-1 and 1.281g·L^-1 which were calculated to values of Yx/s, Yp/s, Yp/x and productivity at 0.19, 0.04, 0.218 and 0.021g·L^-1 , respectively.
文摘目的直观把握PHA相关领域的研究进展和热点,推动PHA领域的发展。方法以CNKI与Web of Science数据库中近10年的相关文献为对象,采用文献计量方法,使用CiteSpace软件绘制PHA研究知识图谱。结果相关文献的年度发文量不断上升,国内外学术界对PHA领域的关注度越来越高,国际PHA领域的跨单位合作比国内更广泛。该领域的研究力量遍布全球,其中清华大学、葡萄牙里斯本新大学、马来西亚理科大学、昆士兰大学、布尔诺理工大学等机构的贡献突出、影响较大,陈国强是该领域发文量最多的学者。通过分析关键词可知,目前对PHA的关注重点主要集中在力学性能、生物降解、混合菌群、活性污泥、除磷脱氮等方面。结论在未来的PHA研究中,PHA的增强改性、在活性污泥中提取PHA及生物法合成PHA仍是研究热点。
基金supported by the Basic Science Research Program of the National Research Foundation of Korea(NRF)funded by the Ministry of Education(RS-2023-00302689 and NRF-2021R1A4A2001403)funded by the Korea Institute of Science and Technology(KIST)Institutional Program(2V09840).
文摘Thick cathodes can overcome the low capacity issues,which mostly hamper the performance of the conventional active cathode materials,used in rechargeable Li batteries.However,the typical slurry-based method induces cracking and flaking during the fabrication of thick electrodes.In addition,a significant increase in the charge-transfer resistance and local cur-rent overload results in poor rate capabilities and cycling stabilities,thereby limiting electrode thickening.In this study,a synergistic dual-network combination strategy based on a conductive nanofibrillar network(CNN)and a nano-bridging amor-phous polyhydroxyalkanoate(aPHA)binder is used to demonstrate the feasibility of constructing a high-performance thick cathode.The CNN and aPHA dual network facilitates the fabrication of a thick cathode(≥250μm thickness and≥90 wt%active cathode material)by a mass-producible slurry method.The thick cathode exhibited a high rate capability and excel-lent cycling stability.In addition,the thick cathode and thin Li metal anode pair(Li//t-NCM)exhibited an optimal energy performance,affording high-performance Li metal batteries with a high areal energy of~25.3 mW h cm^(-2),a high volumetric power density of~1720 W L^(-1),and an outstanding specific energy of~470 W h kg^(-1)at only 6 mA h cm^(-2).
文摘The environmental problems caused by plastics of fossil origin are well known. To reduce harmful impact on the environment, bacterial-based plastics, such as polyhydroxyalkanoates (PHAs), are a promising solution. Microbial PHAs can be produced using abundant and inexpensive agricultural by-products as raw material. In this study, the potential use of Cupriavidus necator 11599 for the bioconversion of cassava starch into biodegradable PHAs was explored. Although Cupriavidus necator 11599 is a well-known PHA producer, it cannot grow directly on starch. Thus, acid hydrolysis was carried out on the starch extracted from cassava peels to obtain fermentable sugars. Optimal concentration of reducing sugars (RSs) was obtained by hydrolysis of cassava peel starch with sulfuric acid concentrations of 0.4 N and 0.6 N, at 95˚C and 4 h. The hydrolyzed starch was used for PHA production in Erlenmeyer flasks using reducing sugars (RSs) concentrations ranging from 10 g/L to 25 g/L. The best RS concentration 20 g/L and 25 g/L gave 85.13% ± 1.17% and 89.01% ± 2.49% of biomass PHA content and biomass concentrations of 8.18 g/L and 8.32 g/L, respectively in 48 hours. This research demonstrates that cassava peel starch as an inexpensive feedstock could be used for PHA production, paving the way for the use of other starchy materials to make bioplastics.
