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
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
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
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.
