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
The production of polyhydroxyalkanoates （PHAs） with a high fraction of 3-hydroxyvalerate （3HV） and 3-hydroxy-2-methylvalerate （3H2/MV） from mixed culture enriched by valerate-dominant hydrolysate was evaluated i...The production of polyhydroxyalkanoates （PHAs） with a high fraction of 3-hydroxyvalerate （3HV） and 3-hydroxy-2-methylvalerate （3H2/MV） from mixed culture enriched by valerate-dominant hydrolysate was evaluated in this study. After long-term enrichment, the culture showed strong ability to synthesize 3HV and 3H2MV, even with acetate-dominant substrate. The ultilization of single or mixed iso-/n-valerate by the enriched culture showed that the mixture of iso-valerate and n-valerate was more efficient substrate than any single in tenaas of balancing microbial growth and PHAs synthesis. Besides, through comparing the kinetics and stoichiometry of the tests supplying valerate and propionate, the enriched culture with equivalent valerate and propionate （1 ： 1 molar ratio） exhibited superior PHAs production performances to pure valerate or propionate, attaining more than 70 tool% of 3HVand 3H2MV. The above findings reveal that valerate-dominant hydrolysate is a kind of suitable substrate to enrich PHAs producing culture with great capability to synthesize 3HV and 3H2MV monomers, thus improving product properties than pure poly（3-hydroxybutyrate） （P3HB）; also 3HV and 3H2MV production behaviors can be regulated by the type of odd-carbon VFAs in the substrate.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
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
本文利用FTIR光谱法研究了常温下和升温、降温过程中PHB ,P(HO co HD)及不同组分的P(HB co HV)和P(HB co HH)共聚物的变化。结果表明 ,PHB、P(HB co HV)和P(HB co HH)在变温过程中红外光谱图发生了明显变化 ,此过程是物理变化 ,且过程...本文利用FTIR光谱法研究了常温下和升温、降温过程中PHB ,P(HO co HD)及不同组分的P(HB co HV)和P(HB co HH)共聚物的变化。结果表明 ,PHB、P(HB co HV)和P(HB co HH)在变温过程中红外光谱图发生了明显变化 ,此过程是物理变化 ,且过程可逆。展开更多
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The production of polyhydroxyalkanoates （PHAs） with a high fraction of 3-hydroxyvalerate （3HV） and 3-hydroxy-2-methylvalerate （3H2/MV） from mixed culture enriched by valerate-dominant hydrolysate was evaluated in this study. After long-term enrichment, the culture showed strong ability to synthesize 3HV and 3H2MV, even with acetate-dominant substrate. The ultilization of single or mixed iso-/n-valerate by the enriched culture showed that the mixture of iso-valerate and n-valerate was more efficient substrate than any single in tenaas of balancing microbial growth and PHAs synthesis. Besides, through comparing the kinetics and stoichiometry of the tests supplying valerate and propionate, the enriched culture with equivalent valerate and propionate （1 ： 1 molar ratio） exhibited superior PHAs production performances to pure valerate or propionate, attaining more than 70 tool% of 3HVand 3H2MV. The above findings reveal that valerate-dominant hydrolysate is a kind of suitable substrate to enrich PHAs producing culture with great capability to synthesize 3HV and 3H2MV monomers, thus improving product properties than pure poly（3-hydroxybutyrate） （P3HB）; also 3HV and 3H2MV production behaviors can be regulated by the type of odd-carbon VFAs in the substrate.
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。
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.
